Slowing Age-Related Macular Degeneration with Vitamins
Seeing Spots: The Story of Floaters
Blindsided by Night Blindness
Performance-Enhancing Contact Lenses?
Eyeing up Safety in Contact Lenses By Daniel Halperin
Lose Your Reading Glasses, Permanently
Eye for an Eye: How to Counteract Cataracts
Save Your Sight: Preventing Vision Loss from Diabetes
Dry Eye for the Regular Guy
Glaucoma: An Overview
Laser Surgery for Glaucoma
Strabismus, or Lazy Eye
Natural Vision Correction
Surgical Vision Correction (Refractive Surgery with the Excimer Laser)
Vision Correction: Are LASIK and PRK Your Only Options?
Slowing Age-Related Macular Degeneration with Vitamins By: Christine Haran
One of the scary things about age-related macular degeneration—the leading cause of vision loss in older people—is that there is often little that can be done to slow down the disease.
But a combination of dietary supplements, which includes high levels of antioxidants and zinc, may help preserve the sight of people with age-related macular degeneration (AMD). And while studies have not yet proven that this supplement combination prevents AMD, some ophthalmologists recommend it to people who are at risk for this eye condition, such as those with a parent or sibling and those with fair skin and blue eyes.
AMD is a disorder of the macular, the central part of the retina, that makes vision less sharp and affects the ability to see straight ahead. There are two forms of the disease, dry and wet. The dry form is more common than the wet form and involves a more gradual loss of vision. In the early stage of the dry form of disease, someone will have several yellow deposits, called "drusen," on the macula. Intermediate AMD is marked by medium-sized drusen or one or more large drusen. And advanced AMD involves the breakdown of cells and tissue in the central retina. The "wet" form of AMD occurs when new blood vessels form behind the retina and start to grow toward the macula and leak or bleed into the eye.
Below, Lylas Mogk, MD, an ophthalmologist at the Visual Rehabilitation and Research Center in the Henry Ford Health System in Detroit and a spokesperson for the American Academy of Ophthalmology, discusses how dietary supplements may help improve eye health.
Do dietary supplements slow the progression of AMD?
We know from a very good National Eye Institute (NEI)-sponsored study, called the Age-Related Eye Disease Study (AREDS), that a certain combination of nutritional supplements retards the progress of macular degeneration. In the 10-year study, the supplements slowed the progress of the disease by about 25 percent in people with intermediate AMD or AMD in one eye but not the other eye. The study did not show whether or not the supplements made a difference to people who don't have macular degeneration or who have early AMD. So you can't say, "You should definitely take these if you are at risk for macular degeneration." However, in my judgment, it only makes sense that antioxidant supplements, in moderate amounts, are likely to make a difference in terms of prevention. But I always explain to people that that is not proven, so that's their choice.
What supplements are recommended?
The recommended dietary supplement contains five ingredients. Four of them are functional and one of them is there as an add-on. The four are vitamin C, 500 mg; vitamin E, 400 mg; beta-carotene, 25,000 international units; and zinc, 80 mg. Two milligrams of copper is also in there, because zinc can cause a copper deficiency. For those who do not have AMD but are at risk, I would recommend only half of that amount of zine, and for those who are smokers, less or no beta-carotene.
How does this combination of dietary supplements keep the eye healthy?
The leading theory about macular degeneration is that free radicals are damaging the macula, which is the central part of the retina. Free radicals are little molecules that we produce normally just by breathing oxygen. We think of them as electrically charged, and they have to have a partner right away to be neutralized. The way they get neutralized is by antioxidants, and the vitamins serve as antioxidants.
With macular degeneration, either we have too many free radicals or we don't have enough antioxidants. Beyond the amount that we produce just by breathing oxygen, free radicals are produced by air pollution, herbicides, pesticides, smoke and sunlight. In the last 50 years, we have been pumping many of those things into our air, water, soil and food, and the ozone layer is thinner, so we're all getting hit with more sunlight. So we have a bigger load of free radicals.
On the antioxidant side, we have to get antioxidants from food. We don't make our own. But over the same 50 years, we've changed how we grow food. We grow food in big industrial farms in demineralized soil, we don't rotate crops, and we spray them with herbicides and pesticides. So the thought is that there is less actual antioxidant power in the food, so we need supplements to counteract the extra load of free radicals.
Are these doses of antioxidants unsafe for some people?
The only safety consideration has been beta-carotene in smokers because it increases lung cancer risk. Of course, not smoking is a cardinal rule of macular degeneration because it increases risk. So if you have macular degeneration, or are at high risk for it, and you're smoking, you're really inviting it.
Do you recommend a particular dietary formulation to people?
I tell them that any combination of those supplements works. People can buy each supplement individually, or they can buy them in a prepared formulation, or they can take them as a part of a general multiple vitamin. Ocuvite PreserVision is the formulation made by Bausch & Lomb, the company that collaborated in the AREDS study.
Can lutein reduce risk of AMD?
I often suggest that people add the carotenoid lutein and the antioxidant selenium, though there is no proof that they decrease risk. There was a good study out of Harvard in 1994 indicating that people who ate five servings or more of green, leafy vegetables that were rich in carotenoids had 42 percent less macular degeneration. So there is reason to believe that lutein might be a good contributor to this antioxidant formula. The amount of lutein recommended runs from 6 mg to 20 mg. Six milligrams is the amount that would be in, for instance, a serving of dark green, leafy vegetables.
[The NEI is currently studying lutein and zeaxanthin, and a randomized, controlled study published in April 2004 in Optometry showed that lutein alone, or in combination with other antioxidants, improved visual function in people with AMD.]
What other dietary components can reduce risk?
The other thing I recommend is eating extra omega-3 fatty acids, or taking omega-3 supplements. The richest source of omega-3 fatty acids is flaxseed oil. It's also in fish oil, so, if people prefer, they can take cod liver oil. This recommendation is based on another Harvard study that showed that people who consumed more omega-3 fatty acids had less macular degeneration. People who consumed a lot of omega-6 fatty acids, however, regardless of how much omega-3 they ingested, still had a lot of macular degeneration. The reason is that in our bodies, omega-6s compete with omega-3s for the same receptors. Omega-6s are in vegetable oils that are used in all processed and packaged foods. So I tell people to take extra omega-3 fatty acids and to eat as few packaged and processed foods as they can.
Why are dietary supplements a good option for people with AMD?
There has been very little that has really been proven to make a difference with AMD, but dietary supplements are in that group that does make a difference. In the face of a condition that is stealing your central vision, those are pretty awesome stakes. So it makes sense to do it.
It also is psychologically beneficial to do something about AMD. If you're told, "Well, sorry, we don't exactly know what causes this condition and we can't really stop it from progressing," that's a pretty big weight to carry. If you can say, "There are some things you can do that may reduce your risk and here they are," at least you can be a little bit proactive about it.
Seeing Spots: The Story of Floaters By: Karen Barrow
Did you ever look up at the sky and see grayish specks floating in front of your eyes? These "floaters" are a common and normal occurrence, generally not a cause for worry. Most of the time you will simply look past them as they come and go.
But occasionally floaters, especially those associated with a flash of light or a loss of peripheral vision, may indicate a more serious problem. Donald Schwartz, MD, associate clinical professor of ophthalmology at the University of California, Irvine and the University of Southern California's Doheny Eye Institute, explains when you need to worry about floaters.
What are floaters?
Floaters are spots or wispy objects that people see in front of their eye, typically when they're looking at a background that doesn't provide much contrast, like a blue sky or a blank wall. People are able to see particles of different sizes or shapes, wispy lines or little dots. When people move their eyes in one direction, they will see these "floaters" move in different directions and then settle down.
Almost everybody at one point in their life will see floaters. Floaters were documented thousands of years ago by the Latins as muscae volitantes, or flying gnats, so it is not a new phenomenon.
What causes floaters?
The front part of the eye is comprised of the cornea, which refracts the light coming into the eye. The lens focuses an image on the retina, which is like camera film in the back of the eye. The large space between the lens and the retina is filled with a gel known as the vitreous humor. It's a gel of the same consistency of the white of a raw egg. That gel has debris left over from the formation of the eye. So, if some debris in the vitreous humor floats between the front part of the eye and the retina, it casts a shadow on the retina, and we see this as floaters. At different times the debris moves more in line with a patient's line of sight, which is why floaters come and go.
Do floaters ever go away?
While they don't leave the eye, most patients eventually stop noticing floaters. The floaters are simply no longer apparent within the visual axis of the eye, the line of sight. Over time, gravity causes the floaters to sink down below the line of sight as the gel in the eye becomes more liquefied. Most floaters do tend to diminish with time.
Are floaters ever serious?
When people look at a blue sky or white clouds, they're apt to see floaters more often. But, if the number of floaters increases dramatically, or they change in nature from being wispy floaters to a multitude of tiny, little dot-like floaters, or they're associated with a flashing light or flashes of light, it may indicate a change from the normal floaters that almost all see to something more significant.
These symptoms might indicate a change in the vitreous humor, the gel of the eye, which is also a normal aging phenomenon. As the vitreous gel changes with age, there is more movement of the particulate matter and debris and, because of that, we see the floaters more frequently.
Along those lines, a flashing light that's associated with an increase in floaters, especially if it's a quick flashing light, usually indicates that the gel is pulling on the retina as it is separating from it. Again, this is normal, called a vitreous separation. As the gel becomes more liquified and pulls away from the retina, we'll see a sort of lightning flash off to the side. This, again, is a normal type of aging change, which usually occurs in patients in their 50s and 60s.
However, if the light changes from a quick flash of light to a persistent light, if there is a significant increase in the number of floaters or if there's missing side vision, like a curtain coming across the vision, it can indicate that the normal process of the vitreous change has possibly caused damage to the retina. This can be a significant finding. It could be a retinal tear. As the gel peels away and tugs on the retina, there is the potential to tear a small hole in the retina. Worst case, the fluid goes through that hole and behind the retina and peels the retina off, then we have a retinal detachment. So, as the process of a vitreous separation is occurring, there is the potential—and the numbers are quite small—of a retinal tear and then a retinal detachment.
Can a retinal tear or detachment be fixed?
If the retina is damaged with a tear, there are a number of different techniques that can be used to seal the tear and repair the retina. A retinal tear is a very urgent situation to protect the remaining vision. If the peripheral retina has a small hole or tear, it may be sealed off with a laser, a cryogenic probe, which is a freezing cold probe, or even with an air bubble. These are techniques to close the small hole before it becomes a retinal detachment.
If a detachment has occurred, then surgery needs to be performed to replace the retina to its normal location. That is a more significant surgery.
When should someone see a doctor about floaters?
If floaters become worse, they need to be evaluated to make sure the floaters do not indicate the possibility of retinal damage. If a patient sees a sudden change in the nature of their floaters, and particularly if they notice flashing lights or missing vision in their peripheral vision, they should see a doctor.
Blindsided by Night Blindness By: Karen Barrow
Walking into a dark movie theater, it may take a little while for your eyes to adjust to the dim lighting before finding your seat. But for someone who has night blindness, this process can take much longer. Night blindness causes problems seeing in any dark or dim lighting. These symptoms can lead to problems getting around at night-or even a fear of the dark.
Night blindness can be caused by a variety of problems, and some are easily treated. Donald Schwartz, MD, associate clinical professor of ophthalmology at the University of California, Irvine and the University of Southern California's Doheny Eye Institute explains what a doctor can do to help restore your night sight.
What is night blindness?
Night blindness can be a number of things. One of the things that is called night blindness is a decreased ability to see at night. Some people become more nearsighted at night as the pupil dilates in dark conditions, a condition called spherical aberration. People with this condition become more nearsighted in the dark. In this case, signs off in the distance, such as freeway signs, may not be as clear at night.
Another situation is where people have problems adapting to light changes. For example, when they go to the movies, they find that it takes a very long time for their vision to come back in the dark room. This may simply be caused by a deficiency in vitamin A, or it can reflect an underlying medical condition.
Lastly, there is a completely different kind of night blindness, which is quite significant, involving the loss of receptors. These cells in the back of the eye and the retina, called the rods, allow peripheral vision and vision in dim light. The loss of these rods can indicate a problem such as retinitis pigmentosa, which leads to progressive vision loss.
How does a doctor determine the cause of night blindness?
When a patient says that he or she is night-blind, it is important to find out specifically the conditions they're addressing: if a distant object is blurrier at night, if they are unable to be mobile at night or in dark conditions or if they're unable to see off to the side and their peripheral vision is compromised. Those types of things need to be determined to get proper treatment.
How is night blindness treated?
If a doctor thinks that night blindness might be caused by simply being more nearsighted at night, the first thing they will do is check visual acuity to see what the vision is in the normal office setting. Then they should check refractive error, to see how far out of focus the patient's eye might be. If the night blindness is found to be caused by nearsightedness, the patient may need to wear glasses at night, and this sometimes means that a different type of lens is needed at night as opposed to during the day.
If nearsightedness is determined not to be the cause, and there is concern about the possibility of night blindness caused by a loss of some of the function of the rods, then a visual field examination is performed. This examination determines the extent of the person's peripheral, or side, vision, which is the vision that uses low-level light. Tests would need to be done to determine whether the receptor cells in the retina are not functioning well or if the problem is in the ganglion cells, other important cells needed for vision. These can be evaluated, but many times there's nothing that can be done if those cells are damaged.
If a doctor determines that there is simply a need for vitamin A to help the night blindness, then that would be recommended. For those patients who have retinitis pigmentosa, vitamin A is being used to help, but there's no cure at this time.
When should someone with night blindness see a doctor?
Someone doesn't need to see a doctor in the space of days if he is having trouble seeing at night, but certainly he should speak to a doctor within a couple of weeks or a month, after determining how different circumstances impact vision. It is helpful to be able to tell the evaluating doctor what the problem is like: if it's looking at signs, if it's difficulty when the lights are very dim or off in the house at night, if it's going from the bed to the bathroom or walking down the hall. Those kinds of difficult situations would be very helpful to the physician to determine what the problem might be. Additionally, retinitis pigmentosa is usually inherited, so people that have relatives with this disease should be sure to tell their doctor, as their chances of getting the disease are particularly high.
Performance-Enhancing Contact Lenses? By: Karen Barrow
With the controversy over performance-enhancing drugs quieted for now, a new performance-enhancing substance is hitting the baseball field—contact lenses. And with both kids and adults seeking an athletic edge, the question is: will these new lenses be the safe and legal advantage they are looking for?
Developed by Nike, the new high-tech contact lenses are designed to give both amateur and professional athletes an enhanced view of their playing field. The tinted, soft contacts, called MaxSight, filter out 95 percent of UV light, and highlight the objects an athlete most needs to see.
Older color contacts merely change the color of the eye, but MaxSight is among the first contacts to have a UV-protective tint covering its entire surface, shielding the entire pupil and iris from sun damage. While contacts do leave the white of the eye exposed, a region less prone to damage, sunglasses can’t even claim to protect your entire eye, as light can enter through the top and sides of glasses.
The amber lens used for fast-moving sports blocks out the “visual noise” surrounding a ball, highlighting the red seams of a baseball and giving hitters and fielders a better view of their target. If a slower-moving game like golf is more your speed, the gray-green lenses help to highlight the various shades of green in a course and eliminate glare.
For those who don’t like to wear sunglasses, MaxSight’s tint should help prevent squinting and eye strain, allowing one to relax more easily on the field or golf course. And since they act like sunglasses, the contacts will help to prevent macular degeneration and cataracts, which are caused by UV damage. Additionally, contacts naturally prevent the sweating and fogging that sunglasses can cause, not to mention preventing the visual distortion created by a plastic or glass lens.
“These lenses are OK for participation in activities where sunglasses are cumbersome,” said Dr. Cykert. “But if you live where there is constant sunlight, sunglasses will better protect your eye.”
The tinted lenses will cost about the same as a pair of normal contact lenses and need to be replaced about once a month. They are available with or without vision correction, so a current contact-lens wearer may have little to lose by trying them out. Younger users will, no doubt, be turned on simply by the raging-bull-like red tint they give to the eye.
“It makes the eye look distinct,” says Alan Reichow, an eye doctor and Nike Vision Consultant, “It looks competitive.”
Eyeing up Safety in Contact Lenses By Daniel Halperin
More than 30 million Americans comfortably wear contact lenses, carefully fitted and prescribed by an eyecare professional. But the increased nonprescription use of cosmetic lenses, from tinted colors to striking designs, is causing some concern among healthcare professionals. Cosmetic contact lenses are of particular interest to teens and adults, especially at Halloween time. Reports are surfacing that nonprescription lenses are causing all sorts of eye problems that include corneal damage, scarring, infection, vision loss and, in some rare cases, permanent blindness.
Any contact lens, prescription or nonprescription, has the potential to cause allergic reactions, bacterial infections, corneal abrasions and corneal ulcers, particularly when they are improperly fitted and cared for. But the problem is worsened when people purchase these products without the guidance of an eye specialist.
An optometrist or ophthalmologist takes preventative measures to avoid the complications that contacts may cause, by evaluating your eye to be sure that lenses are not aggravating existing problems. They fit lenses specific to your eye, and instruct you in proper handling and sterilization. Doctors also continue to monitor patients on a regular basis to prevent future problems.
Cosmetic contact lenses are highly available to the general public; one can find unregulated lenses readily available in locations like novelty stores, websites, and beauty salons. These unregulated lenses, however, mean that users probably do not even know the manufacturer of lenses. Furthermore, there are no assurances that these products are being manufactured using safe, approved materials under sanitary conditions.
Dr. H. Dwight Cavanagh, vice chairman of ophthalmology at the University of Texas Southwestern Medical Center at Dallas cautions that "By purchasing contact lenses over-the-counter, you would abrogate every single safety guarantee in place." He added that tinted lenses are available in professional offices, even in non-vision-correcting lenses.
Dr. Cavanagh advises, "Letting an underage member of the family use these lenses without supervision is like giving them the car keys without a license and without an adult in the front seat."
Lose Your Reading Glasses, Permanently By: Christine Haran
Many men and women resist buying their first pair of reading glasses. To them, reading glasses—no matter how stylish—are irrefutable proof that the aging process is marching on. Fortunately, new alternatives are available to those who don't like the thought of fishing glasses out of their bag or their pocket each time they need to read a menu.
Below, Penny A. Asbell, MD, a professor of ophthalmology at Mount Sinai School of Medicine in New York, discusses why people lose their ability to read close-up—a condition called presbyopia—and reviews their vision options.
Why does our vision change as we age?
Inside the eye is a lens, and that lens actually changes shape. When we are young and we're looking into the distance and then close-up, the lens changes shape so that we can focus and continue to have good vision. What happens as we age is that lens gets a little stiffer, and it doesn't change shape as easily. That is when you start reaching for reading glasses, because you need the extra power that your own lens can't provide anymore. We call that presbyopia, when you can no longer see close-up.
Who ends up needing reading glasses?
Everybody ends up needing reading glasses. This is universal. There are people who had great vision their whole life. They said, "I'm eagle eyes. I can see everything far away." Now they're in their 40s, and they're having trouble reading, and it's really disturbing to them.
When does presbyopia begin?
Typically, you first become symptomatic in your 40s, requiring a low-plus lens, usually a +1. And then it moves up to about a +3. So as we age we end up needing a little bit more over time.
What kind of glasses are available?
They now sell reading glasses in the drugstore. Those work fine for many people. And for people who already need corrective lens for distance, there are glasses called progressives that have a different power on the top for distance, and the bottom power has reading power. They look like normal glasses, but they actually give you good distance vision and good reading vision. Bifocals are the glasses where you actually can see the line in the glass. Those work terrifically but in our youth-oriented culture, people don't like to wear glasses that make them look old, so to speak.
And now there are contact lenses that act like bifocals that give you distance and near vision, and some patients do very well with those.
What is monovision?
Monovision is where you correct one eye for distance and the other eye for reading. Sometimes they call it blended vision because you actually continue to use both eyes together. It is just that one eye is doing more of the distance vision, the other one is doing more of the reading vision.
This is something we have done for many years with contact lenses. You cannot do it with glasses. It's just creates an unbalanced feeling if you have one glass that is good for distance and one good for reading. But we can also create monovision with surgical procedures, such as conductive keratoplasty (CK) and laser surgery.
Does monovision work for everyone?
Monovision works very well for many people. However, in some people, they may feel a little unbalanced or even have a change in their depth perception. So if somebody is thinking of monovision, whether it's with contact lenses or refractive surgery, the best way to decide whether it is for you is to try it with contact lenses first.
What does the laser surgery involve?
Laser surgery, such as LASIK, has now been around for more than 10 years. When we use a laser, we change the shape small part of the cornea. If we change the shape of the cornea, we can change the vision. The laser is used to cut and remove tissue, so there is a permanent change to the eye.
What is conductive keratoplasty (CK)?
In CK, we use a tiny probe that delivers radiofrequency energy to the part of the cornea called the stroma, and it shrinks that tissue, kind of like cinching a belt, to tighten the cornea and make the central part steeper. CK has become an exciting alternative for people who are presbyopic. It is minimally invasive. There is no laser. There's no cutting. There's no tissue removed. And the chances are you'll have excellent vision.
Are there people who are not good candidates for these surgeries?
If you come into laser surgery with significant dry eyes, they may get worse after the laser procedure. Sometimes patients may experience a glare or halo after the procedure, especially when driving a car.
When assessing people for either surgery, one of the things I like to find out from patients is what kind of work they do. If it's somebody who's cutting diamonds, these surgeries may not be for them. On the other hand, somebody who does interviewing—half the day they're talking to people, writing notes about the interview—they may be a perfect candidate for monovision with CK or LASIK. So it's very important for me to understand how they're using their eyes and what it is they want to be able to do to find out what's going to be good for them.
How long does it take to recuperate from these surgeries?
There is some variability in how someone is going to respond, how they're going to heal and the final result that they're going to have. For CK, there is some discomfort for at least one or two days afterwards. Pain and discomfort varies, so it is often hard to predict, but most patients are back to their normal function within the following week. Recovery from laser surgery is similar. There is a little less discomfort, but complete visual recovery takes a little while.
Why do some patients still need glasses after surgery?
One of the things you are going to discuss with your surgeon is what are the chances that you will need glasses for some activities. There are some patients who do not get full correction, so they may still need reading glasses for intensive activities. So they may have good everyday vision for driving a car around town, reading a menu. But they may want to have reading glasses for their very best vision for reading. So if they going to read War and Peace, 1,000-page book, they may want glasses to give them the best vision for both eyes.
Do people ever have to repeat the surgeries?
In general, the results are quite stable, particularly if you are just correcting moderate reading vision. With age, you may need to increase the amount of power you need. So if you correct someone for reading vision, and they're 45, they're going to need more power when they're 55, because aging continues to change your vision. So people need to realize that they may need to come back and do a little bit more because their eyes have aged.
Eye for an Eye: How to Counteract Cataracts
As people age, there are certain medical issues that they can practically bank on, and one of them is cataracts, or a clouding of the lens of the eye. If you're middle-aged and you're finding it difficult to take afternoon walks on sunny days because of the glare, or if the TV screen has started blurring even when you're wearing glasses, you may have cataracts.
According to the National Eye Institute, almost 20.5 million Americans aged 40 and over have cataracts, and more than half of Americans have cataracts by the time they are 80. As a result, more than 1.4 million cataract surgeries, in which the cloudy lens is replaced with an implant, are performed in the United States each year. Below, Penny A. Asbell, MD, a professor of ophthalmology at Mount Sinai School of Medicine in New York City, talks about the timing of cataract surgeries and improvements that have helped make this surgery so successful.
What are cataracts?
Inside the eye is a lens like a lens in glasses. If that lens gets cloudy, we change its name from lens to cataract. So a cataract is a cloudy lens inside the eye.
What causes cataracts?
We know that some diseases are associated with cataracts, such as diabetes, and that some drugs can cause cataracts, such as steroids or prednisone. Exposure to ultraviolet light causes a kind of cataract. But in general, we see an increased incidence of cataracts as we age. So it's one of those things that happens to almost everybody if they live long enough.
Can cataracts eventually cause blindness?
Cataracts gradually cause a loss of vision. If cataracts are not treated, vision can get so poor that you become legally blind, meaning you see light, but no images, no detail. Fortunately, in the United States, most people seek care before they get that bad.
How do you know that you have a cataract?
The symptoms of cataracts are typically a change in vision. Maybe you can't read anymore. Maybe you're having trouble driving. Another symptom can be glare, particularly when driving at night with headlights coming toward you, so you may feel you're not seeing as well as you used to when you drove at night. Some people also complain that colors don't seem as rich as they used to be. This change of vision isn't improved with glasses. So if you change your glasses and you still can't see well, the most common cause is cataracts.
How quickly does vision loss progress?
Cataracts typically progress slowly. At first you may not have any problem, and even if the doctor notices the cataract, your vision may still be very good and very functional. In most patients, it may be 10, 20 years before it's actually significant.
There is a certain kind of subgroup of cataracts that progress more quickly, and those patients usually are the ones who experience lots of glare, so sunlight really bothers them. Their cataracts often change over a period of months.
How are cataracts diagnosed?
In order to diagnose cataracts, we check to see if someone's glasses need to be corrected, and then we use a slit lamp, which is a machine to look at the eye and the lens with magnification. One of the reasons to have an eye exam is not just to diagnose cataracts, but to make sure there isn't any other problem that's causing loss of vision, such as glaucoma.
When is it time to think about having surgery to have the cataract removed?
The timing for cataract surgery almost always depends on the patient. When does your vision become a problem? When can you no longer drive, no longer do the activities you like to do, see TV, read, do your crossword puzzle? When you can't get by, that's the time to do cataract surgery.
Who is a good candidate for surgery?
Cataract surgery is one of the most successful surgeries that are done today. The patient comes in and goes home the same day, and the surgery only lasts about an hour or even less. Given all of that, it can be done in almost any patient at any age when it's appropriate for vision needs.
What happens during surgery?
The eye doctor will put drops in the eyes to numb up the surface of the eye. Sometimes we give an injection near the eye to numb the eye. If that's done, typically you work with an anesthesiologist who will sedate you so the injection doesn't bother you.
The eye doctor may ask you to look at a light to keep your eye from moving around too much during the surgery, and we make a tiny incision in the eye and then start removing the cataract. Typically what we do is take out the lens but leave a capsule behind to enclose the lens that we will be replacing it with. The replacement is an intraocular lens, or IOL. It's made out of plastic. It's measured to give the right power, and it's put back in after you take the cataract out.
Are there surgery complications?
There is some risk with every surgery, including cataract surgery. Some of the complications that can occur can be minor, but others can be more serious, such as bleeding, infection, damage to the inside of the eye, the retina, all of which can cause loss of vision. So that's why we don't just do the surgery on everybody who walks in. They have to have a visual complaint in order to consider taking on the risk, albeit a small risk.
Sometimes the envelope or capsule around the cataract that's left behind gets cloudy over time, and that is called an aftercataract. The good news is a laser administered in the office can make a little hole in that leftover envelope or capsule, and then your vision comes back again. So it's not back to the operating room.
Can you describe the recovery from surgery?
Typically, cataract surgery is done as an outpatient in an ambulatory surgery center. So you come in the morning, have the surgery and go home the same day. The next day, you're going to see your eye doctor to make sure it's beginning to heal. You'll typically see the doctor again about a week later, and then maybe about a month or so later after that.
During that time you're going to be using eye drops, maybe for a week to a month. After about a month, you'll find out if you need a change in your glasses. Or if you're lucky, maybe you won't use glasses at all.
The key thing after surgery is avoid getting hit in the eye. So some patients wear a plastic glasses or sunglasses to protect their eye. And for the first couple of weeks, you want to be careful with swimming, because that water probably isn't clean or sterile.
Should you have both eyes done if you have cataracts?
Cataracts usually develop in both eyes, though a slightly different rate. In most cases in the United States we do one eye and make sure it's healed and wait about a month before we proceed with the other eye. In some patients, the other eye still has good vision, so don't have to do anything about it. But if you do have loss of vision, the studies suggest if you do both eyes you improve your visual function. There are a few centers that are doing both eyes on the same day.
How has cataract surgery changed?
Cataracts surgery has undergone a tremendous improvement over the last quarter century. We do smaller and smaller incisions, and we have quicker and easier methods to take out the cataracts. We have implants now that can block UV light and correct astigmatism. And just recently an implant was approved that can correct for distance and reading vision. So it's a little bit like you are young again: you can see well at a distance and near.
Save Your Sight: Preventing Vision Loss from Diabetes By Christine Haran
While senior citizens can expect some decline in their sight, vision loss is rarely a problem for younger people. But now that people are being diagnosed with diabetes at younger ages, diabetes-related vision loss is also occurring in middle-aged people. Sometimes vision problems are even the first sign of the disease.
A study published in the April issue of the Archives of Ophthalmology found that more than 4 million US adults aged 40 or older have diabetic retinopathy, a leading cause of blindness. Retinopathy occurs when high blood sugar levels damage blood vessels in the retina, which is the tissue at the back of the eye.
"The results of our study are important for public policy because they demonstrate that there's a large need for management and detection of eye disease in people with diabetes," says John H. Kempen, MD, PhD, an assistant professor of ophthalmology and epidemiology at the Johns Hopkins University and coordinator of study, which was authored by the Eye Diseases Prevalence Research Group.
Below, Dr. Kempen discusses the effectiveness of laser treatments and the importance of regular eye exams and consist control of blood sugar levels.
What kinds of vision problems do people with diabetes experience?
People with diabetes can develop a progressive condition called diabetic retinopathy, and it can cause either moderate or severe vision loss. Diabetic retinopathy is caused by high blood sugar levels. These high levels of sugar lead to a lack of blood supply to parts of the retina and also to leakage of fluid through the blood vessels in the retina. The leakage of fluid can cause swelling in the retina called macular edema that can lead to mild to moderate vision loss.
In the advanced stage of retinopathy known as proliferative retinopathy, the lack of blood supply can cause new, abnormal blood vessels to grow. It can also cause secondary damage such as retinal detachment or bleeding into the eye, leading to severe vision loss.
What are the risk factors for diabetic retinopathy?
High blood sugar is perhaps the most important factor, but high blood pressure and high lipid levels such as cholesterol also substantially increase the risk of getting diabetic retinopathy. So all three need to be controlled.
Because the prevalence of diabetes increases with age, diabetic retinopathy is more common in older people. But the other diseases we studied that are typically diseases of elderly people (cataracts, glaucoma and age-related macular degeneration) are strongly related to increased age, whereas diabetic retinopathy is more related to time with diabetes. So often people are diagnosed with diabetes at a young age, and therefore we see diabetic retinopathy in people aged 40 and older.
Are there early warning signs of diabetic retinopathy?
There can be, but the big problem with the disease is that it's often silent until suddenly major vision loss occurs. People might notice that their vision's getting blurry or a sudden onset of floating spots in their vision. These signs may indicate substantially advanced retinopathy.
Is retinopathy ever a first sign of diabetes?
Yes, in the population-based studies that have been done, a number of people who had diabetic retinopathy had not realized they had diabetes.
How often should people be screened for retinopathy?
Some studies have found that only 41 percent of people with diabetes are getting annual eye exams. It's recommended that everybody with type 2 diabetes, or the adult-onset type of diabetes, be screened annually for diabetic retinopathy and persons with type 1 diabetes should be screened annually, beginning five years after they were diagnosed with diabetes.
What does that eye exam involve?
Generally, a complete eye exam is done, but the key part of the exam is to examine the retina while the pupil is dilated. This involves what is called indirect ophthalmoscopy, which allows me to look through a lens at the retina, so I get a panoramic view of all the different parts of the retina.
It's best to be screened on a regular basis. Clinical experience suggests that there are a number of people who come in too late, or at a point where we're sort of picking up pieces rather than preventing things from going wrong.
How is diabetic retinopathy treated?
Laser treatment for diabetic retinopathy has been the subject of some of the most successful clinical trials ever done in the field of ophthalmology because the risk of progressing to severe vision loss from diabetic retinopathy can be reduced by as much as 90 percent.
There are also a number of promising pharmacologic treatments for diabetic retinopathy in development, although none of them have been approved by the Food and Drug Administration as of yet.
Who is eligible for laser treatment and what does it involve?
Laser treatment is available to people with certain kinds of diabetic retinopathy. If someone develops clinically significant macular edema, or swelling of the retina, they are treated with what's called focal laser treatment or grid laser treatment. This involves making small little burns in the retina that are aimed at leaky blood vessels to prevent them from leaking. If a person develops increased leaking over time or new areas of leakage, there might be a need for subsequent laser treatments.
The advanced stage of retinopathy, or proliferative retinopathy, is treated with another kind of laser, so the demand for blood supply is reduced and the drive to develop the new blood vessels is removed. This usually leads to regression of the disease and often it's not necessary to give further treatments.
Are there side effects of laser treatment?
Laser treatment for people with proliferative disease can cause people to have slightly reduced subjective color vision, maybe more difficulty seeing at night and maybe a loss of about one line on the vision chart. That's compared to 50 percent of people developing visual acuity of 20/800 or worse within a few years if they don't get the treatment. So there's a tremendous tradeoff there.
The laser treatment for clinically significant macular edema has fewer side effects, although people will often describe that there are little spots that are missing or reduced in their vision in one eye or the other.
What is your overall advice to people with diabetes with regard to their eye health?
There are two things they can do to reduce the risk of blindness. The most important thing is to try to prevent diabetic retinopathy from occurring by controlling their blood sugar, controlling hypertension, if it exists, and controlling their blood lipids, such as cholesterol, if they're abnormal. The other thing is to come for the eye exams, which enables the ophthalmologist to provide treatment to prevent severe vision loss.
So both primary prevention and secondary prevention are strongly recommended. The primary prevention can also prevent the numerous other complications of diabetes that can occur, too, such as kidney disease, nerve disease and higher risk of heart problems.
Dry Eye for the Regular Guy By Christine Haran
As the warm humid air of summer lifts and the heat begins to creak on in homes and offices, some people will find that their eyes feel like a sheet of sandpaper. Dry eye syndrome, which can cause dryness, irritation and a gritty sensation, can be exacerbated by dry indoor heating. But there are other tear-stealers, such as wind and soft contact lenses.
This common but frequently undiagnosed syndrome occurs when not enough tears are being produced or when tears are evaporating too quickly. While dry eye can affect anyone, a recent study published in the American Journal of Ophthalmology found that nearly 3.2 million American women over the age of 50 suffer from dry eye syndrome, leading some experts to think it may also be related to hormones. When untreated, dry eye can interfere with daily activities such as driving and reading, and can sometimes impair vision.
Below, Dr. Reza Dana, an associate professor at Harvard Medical School and a researcher at the Schepens Eye Research Institute and Cornea Service at the Massachusetts Eye & Ear Infirmary, discusses how to ease the symptoms of dry eye syndrome.
What is dry eye syndrome?
"Dry eye syndrome" is a name that encapsulates a number of different conditions, all of which share eye dryness. It's like "headache"; there are many different types of headaches and causes of a headache, but they all share the same general symptoms of pain in and around the head region. The different types of dry eye are classified into dryness that has to do with inadequate production of tears, what we call tear-deficient dry eye, and dry eye syndrome that is due to enhanced loss (or evaporation) of the tears. We don't know exactly what percentage of people with dry eye syndrome have each type, and this issue is complicated by the fact that many people have both types of dryness at the same time.
The one thing that all of these patients have in common is a sensation of burning and dryness on their eye, which can be quite debilitating in moderate to severe dry eye.
How common is dry eye syndrome?
It affects far more women as compared to men in all age groups. There are many theories regarding that. But, the overarching hypothesis is that the differences are due to sex hormones.
Male sex hormones, like androgens or testosterone, tend to inhibit many, but not all, forms of immune and inflammatory responses. [Inflammation contributes to dry eye.] And consequently, because women have a much lower amount of circulating testosterone as compared to men, that might be an important factor in predisposing women to dryness. It's theorized that dry eye is more common in women after menopause because there is a decrease in androgens as well as estrogen.
There are now clinical trials ongoing where testosterone drops are actually being given to patients with certain forms of dry eye to see if they respond.
What are the symptoms?
Dryness of the eye can be present without signs or symptoms. But there are several dozen symptoms that can occur, including grittiness, foreign body sensation, irritation, pain, change in vision and redness. These symptoms might be helpful in diagnosis, but on the other hand, they're really not that helpful because there are many other conditions such as allergy, to name one, that can lead to many of the same symptoms. It has taken decades for people to realize that dryness is one of the most reliable symptoms used in the diagnosis of dry eye syndrome.
Are there risk factors for dry eye syndrome?
There are many factors that can either cause or exacerbate dry eye syndrome. A very common cause of dryness in the eye is soft contact lenses. Because soft contacts have a very high water content, they act like a sponge and suck up the moisture on the eye surface.
Another cause of dryness, which we keep seeing more and more of, is LASIK refractive surgery. All the reasons for it are not quite understood. But in essence, the cutting into the cornea leads to a cutting of the nerves whose functioning is important in the physiology of the cornea. And that leads to dryness.
Exposure to dry air, in particular, dry heat, which occurs in people's homes during the winter, or even exposure to air conditioning, which is dry air in the summertime, can also cause dryness. Another factor is exposure to wind.
Medications such as anti-hypertensive medications, diuretics, cardiovascular medications and psychotropic medications, including antidepressants, can lead to significant dryness. Antihistamines used in allergy treatments can also lead to dryness. Also, medications used by older men to control what is called BPH, or benign prostatic hypertrophy, likewise can cause dryness. There are many causes of dryness that can be explained, but there are plenty of people who have dry eye without any identifiable issue.
How does dry eye affect vision?
Two-thirds of refraction, or the bending of light, occurs at the interface between the air and the tear film of the eye. Without this bending, light could not get to the retina (the film in the back of the eye), which is required for vision. When the eye is dry, the tear film on the surface of the eye is not uniformly smooth, so the light does not always get bent in the proper way, and visual distortion occurs. One way of determining if someone has visual distortion from dryness is to have them blink a couple of times. If the distortion goes away, this is a pretty reliable indicator that at least part of their problem is due to dryness.
What does diagnostic evaluation involve?
In general, we assess the patient's symptoms. We do a history evaluation to try to identify contributing factors such as contact lens wear, environmental conditions and medications. Then we evaluate the eye. We use specific dyes called vital dyes, which are put on the eye surface to look at the so-called staining of the eye surface to assess the degree of ocular surface damage, which can be brought on by dryness. The tears carry many growth factors for the eye surface cells so in addition to dryness, lack of tears almost "chokes" many of these cells. We also do a measurement of tear secretion called the Schirmer test.
How is dry eye treated?
The common denominator of dryness is an unstable or inadequate tear film. That can be caused by either deficient tear secretion and/or enhanced evaporation. But in either case, artificial tears can theoretically help.
In general, we recommend using artificial tears without preservatives, as preservatives can irritate the eye. It may be better to buy single-vial doses with a twist-off cap. For people who need the occasional application of artificial tears, the ones in bottles are fine.
Another treatment is the use of punctal plugs. They are commonly used to suppress the drainage of tears by blocking off the outflow drainage system of the eye so that tears stay in the eye longer. There are also anti-inflammatory drops, which work particularly well in the tear-deficient form of dry eye syndrome. There are also many new technologies in the pipeline of biotechnology and pharmaceutical firms designed to address the various facets of dry eye syndrome.
Some people with severe tear-deficient dry eye may have the autoimmune disease called Sjögren's syndrome. These patients have severe dry eye as well as severe dry mouth and are treated with medications that are used to promote the secretion of salivary glands in the mouth, as well as the glands that secrete tears. Some of those medications are being looked into for people with dry eye syndrome.
How do you treat people whose tears evaporate too quickly?
People with evaporative dry eye have a problem with the oil-secreting glands of their eye. The tear film itself is comprised of multiple layers. The most superficial layer, the one that is in contact with the air, is the oil layer. Just like oil layers over vinegar or water, oil also layers over the water layer in the tear film. If you don't have oil covering the water, the water will evaporate much more quickly.
There are a number of treatments that we use to make the openings of these oil-secreting glands function better. These include antibiotics and anti-inflammatory drops.
What advice do you have for people hoping to minimize the effects of dry eye syndrome?
People can minimize exposure to adverse environmental conditions such as wind and dry air, and they can promote a more humid environment by using a humidifier indoors. They can also pay attention to medications that dry the eyes. That doesn't mean that one stops their antidepressant or antihistamine, but someone could potentially use a different type of medication or moderate its use. Other than that, we really don't know how to prevent dry eye syndrome.
Glaucoma: An Overview By: Bruce Cameron, MD
Who is at Risk?
What is Glaucoma?
Causes of Glaucoma
Different Types of Glaucoma
Open-Angle Glaucoma Treatment
Narrow-Angle Glaucoma Treatment
How Can I be Sure Glaucoma Does not Affect My Vision?
Glaucoma is one of the leading causes of permanent blindness in the world. It affects more than two million Americans, and more than one hundred million people worldwide. Glaucoma takes away a victim’s sight slowly, but relentlessly, and in most cases, without any warning. Visual damage from glaucoma is irreversible and permanent. Blindness from glaucoma, however, can be prevented with proper preventive eye care.
Who is at Risk?
Glaucoma can strike people of any age, sex, and race. Certain individuals, however, are at increased risk. Those at increased risk include persons of African descent, those with a family history of glaucoma, and possibly those with nearsightedness or high blood pressure. The risk of glaucoma also increases as one gets older. The risk of glaucoma increases markedly in people of African descent over the age of 35 years, and in people of Caucasian descent over the age of 50 years. Other risk factors for glaucoma include diabetes and a history of trauma to the eye.
What is Glaucoma?
Glaucoma is a disease of the optic nerve, which is the nerve that connects your eye to your brain. This nerve transmits visual information from the eye to the brain, thereby allowing you to see. In most cases, glaucoma damage progresses very slowly, over a period of several years. However, sometimes this damage can progress more rapidly. As the damage to the nerve progresses, a person begins to lose vision. This loss of vision begins with the side, or peripheral, vision. This is vision that you may not be aware of, but is very important in everyday activities such as walking and driving. The loss of this peripheral vision progresses as long as the disease is not treated. If treatment is not given, then the visual loss can progress until it begins to involve the central, or reading, vision. It is at this point that a victim of glaucoma may begin to notice trouble with vision. If treatment is still not given, then all vision in the eye can be lost. Visual loss from glaucoma is irreversible. Because vision lost from glaucoma can never be restored, it is critical to detect glaucoma before significant damage has occurred to the nerve. Proper treatment for glaucoma can be given to prevent further loss of vision.
Causes of Glaucoma
High pressure inside the eye is known to cause glaucoma. The normal eye continuously produces and drains fluid internally in order to maintain the normal shape and pressure of the eye. This normal shape and pressure is necessary for you to see properly. In glaucoma, there may be a blockage of fluid drainage or an excess of fluid production, which leads to high pressure inside the eye. If you have high eye pressure, the increased pressure may damage your optic nerve. Some people, however, are able to tolerate high eye pressure without developing glaucoma damage to the optic nerve. The reason for this is unknown. The Ocular Hypertension Treatment Study is currently underway to investigate whether all people with increased eye pressure need treatment to prevent glaucoma.
Some people develop glaucoma even without evidence of increased pressure inside the eye. In fact, recent studies show that up to 50 percent of people with glaucoma may not have high eye pressure measurements. For example, persons of Japanese descent are more prone to have glaucoma without elevate d eye pressure, and normal-pressure glaucoma is more common in Japan than high-pressure glaucoma.
Many studies are in progress to discover the reason for glaucoma damage in people who do not have increased eye pressure. The two leading theories are that damage to the nerve is caused by poor circulation to the nerve, or that abnormally high concentrations of naturally occurring chemicals or hormones cause the damage.
Scientists who believe that poor circulation causes glaucoma have used special ultrasound testing to show decreased blood flow to the eyes of some people with glaucoma. Many of these people with normal-pressure glaucoma also have other problems with their circulation, such as heart disease, poor circulation to their legs and feet, or hardening of the arteries.
Other scientists have shown increased concentrations of glutamate and other chemicals in the eyes of people with glaucoma. These chemicals are naturally produced by the body, and in normal amounts, help with normal eye functions. In abnormally high concentration, however, these naturally occurring chemicals can actually harm the very nerve tissues from which they are produced. The scientists still have not discovered why the body produces abnormally high amounts of these chemicals in eyes with glaucoma.
Doctors and scientists are working to discover treatments for poor circulation to the optic nerve and treatments to decrease the concentration of these harmful hormones in the eye. Studies are under way to determine if improving circulation or decreasing the hormone concentration will help stop damage from glaucoma.
When the ophthalmologist (eye MD) examines your eye, he or she can detect glaucoma damage by the appearance of your optic nerve. A normal healthy nerve has a small cup-shaped hole in the center. As damage from glaucoma progresses, this hole in the center of the nerve enlarges, and replaces the healthy tissue of the nerve. Your eye doctor can detect progression of the disease by periodically examining the appearance of the nerve.
Your doctor may also take photographs of the nerve in order to document the appearance at a specific point in time. Doing so allows better comparison in the future to be certain that the disease has been stabilized. These photographs, called disc photos, are particularly helpful if your doctor has decided that you are a glaucoma suspect. A glaucoma suspect is a person whose optic nerve appearance is suspicious for glaucoma, but does not demonstrate definite glaucoma damage. If you are a glaucoma suspect, your doctor will want to examine your optic nerve two or three times a year, and compare it to the baseline disc photos to detect definite glaucoma damage as soon as it occurs. This will allow your doctor to begin treatment before the glaucoma has a significant effect on your vision.
Another way to measure the amount of damage to the nerve is to measure the amount of peripheral or side vision that has been lost. Glaucoma does not affect your central reading vision until the late stages of the disease. At this late stage, a glaucoma victim may already be partially blind. Therefore, it is important to measure the peripheral vision in the early stages of the disease so that proper treatment can be given to prevent blindness. This is accomplished with visual field testing, which is an examination that measures the amount of vision lost.
To test the visual field, your doctor uses an instrument that flashes lights of various intensities. You place your head against a headrest and stare at a target light that is placed directly in front of the eye being tested. The machine then flashes lights in your peripheral vision. Some of these lights are bright and easy to see. Others are so dim that they are impossible to see even if you have no visual damage. Most lights are somewhere in between. When you see the light, you press a button and the machine registers your response. The machine then prints out a map showing any areas where you cannot see properly. Your eye doctor can repeat this measurement periodically to determine if the glaucoma treatment has been effective in stabilizing the damage.
There are other types of specialized testing that have recently become available, such as measurement of the thickness of the nerve with a technique called scanning laser polarimetry (GDx Nerve Fiber Analyzer), and short wavelength perimetry, which uses colored lights to test the visual field (peripheral vision). Both of these technologies are particularly helpful if a person is suspected of having glaucoma, but there is no definite visible damage (glaucoma suspect).
Different Types of Glaucoma
The most common type of glaucoma is open-angle glaucoma. Open-angle glaucoma means that there is no visible obstruction to the drainage area inside the eye. It is thought that there may be an invisible obstruction to fluid drainage in the trabecular meshwork, which is the structure in the eye that drains the fluid. This type of glaucoma typically causes no symptoms until the damage and visual loss is very advanced.
Another type of glaucoma is narrow-angle glaucoma. This type of glaucoma is most common in persons of Chinese and Vietnamese descent, and less common in persons of African and Caucasian descent. However, it can affect a person of any race. This type of glaucoma may cause symptoms of sudden pain, redness, blurred vision, and colored haloes around lights. This condition is called acute narrow-angle glaucoma, and must be treated immediately. Failure to treat this condition immediately can cause permanent loss of vision. Sometimes narrow-angle glaucoma is a chronic condition that does not cause any symptoms, like open-angle glaucoma.
Open-Angle Glaucoma Treatment
There are several ways to treat this problem. Most commonly, treatment begins with eye drops that are designed to lower the pressure in the eye. These drops are used from once to four times daily, depending on the medication. They are designed to decrease the amount of fluid produced in the eye, or to increase the amount of fluid drained from the eye. Like all medications, these eye drops can have side effects. There are also oral medications that are available to lower the eye pressure. When you begin eye-drop treatment, you should discuss with your doctor the potential side effects and interactions with other medications that you may be taking.
Another way of treating glaucoma is with a laser. This laser is designed to increase the amount of fluid drained from the eye, thereby lowering the pressure in the eye. The laser treatment is usually performed in the office, takes only a few minutes, and is normally painless.
The third way to treat glaucoma is with microsurgery in the eye operating room. In this procedure, a small drainage hole is created in the eye, usually under the upper eyelid. This allows fluid to drain out of the eye and into the circulation behind the eye in the eye socket. This drainage allows the eye pressure to be lowered, thereby preventing further damage from glaucoma.
Open-angle glaucoma is generally a disease that stays with an affected person for life. Whether the treatment has been with medications, laser, or microsurgery, the victim of glaucoma must continue to be monitored by the ophthalmologist several times a year. Your doctor will monitor the eye pressure, the appearance of your optic nerve, and will periodically test your peripheral vision to be certain that the disease has been stabilized, and that further loss of vision will not occur.
Narrow-Angle Glaucoma Treatment
Your ophthalmologist will check to see if you have a narrow drainage area in your eye in order to know if you are at risk of developing narrow angle glaucoma. Your doctor will perform an examination known as gonioscopy to evaluate your risk. Gonioscopy is performed with a special contact lens that the doctor places on your eye. This lens contains mirrors that allow your doctor to see the part of the eye that contains the drainage area. If you are at risk for narrow angle glaucoma, your ophthalmologist will recommend a preventive laser treatment. If you already have narrow angle glaucoma, this can sometimes be cured with the laser treatment. Sometimes narrow angle glaucoma is a chronic condition that is treated with the same medicines or microsurgery described above for open angle glaucoma.
How Can I be Sure Glaucoma Does not Affect My Vision?
The best way to prevent visual loss from glaucoma is through regular eye examinations by an ophthalmologist. Eye examinations are recommended for adults as follows:
once between the ages of 19 and 35, three times between the ages of 35 and 50
every two years between the ages of 50 and 65
yearly after age 65
More frequent examinations are recommended if you have any problems with your vision or have a family history of glaucoma (every one to two years). More frequent examinations are also recommended if you have certain medical conditions, such as diabetes or high blood pressure. For children, routine yearly screening examinations by the pediatrician are usually sufficient, unless an eye appears abnormal, or if the child has trouble seeing.
Laser Surgery for Glaucoma By: Bruce Cameron, MD
Different Types of Glaucoma
Laser Treatment for Open-Angle Glaucoma
Laser Treatment for Narrow-Angle Glaucoma
Laser Treatment for Open-Angle Glaucoma
Open-angle glaucoma may be treated with a laser in an attempt to lower the pressure inside the eye. This treatment usually involves minimal discomfort, and is completed in fewer than 30 minutes. This laser is generally effective in about 80 percent of patients who undergo the procedure. Sometimes the beneficial effect of the laser is not permanent. In approximately 50 percent of patients, the laser helps to lower pressure for as long as ten years.
It is usually performed in the office with topical anesthetic drops. The laser is attached to a machine that is similar to the one that your ophthalmologist (eye doctor) uses to examine your eyes. During the laser procedure, the patient sees multiple bright flashes of light, and may occasionally feel a mild stinging sensation in the eye. Usually, however, the patient doesn’t experience pain. In laser treatment for open-angle glaucoma, the laser beam is directed toward the drainage area of the eye (trabecular meshwork) between the cornea and the iris. In some types of glaucoma, there is an invisible blockage in the trabecular meshwork that blocks the outflow of fluid, thereby increasing the pressure inside the eye. It has been discovered that treating the trabecular meshwork with a laser can lower the pressure inside the eye. It is thought that the laser increases the flow of fluid through this drain.
Many times, your ophthalmologist will treat only one half of the drainage area with the laser treatment. One reason for this is to decrease the risk of possible complications from the laser. Possible complications include an actual increase in the eye pressure, or inflammation inside the eye. These two complications are normally treated with eye drops. If treatment of one half of the drainage area works to lower the pressure, then treatment to the other half of the drainage area can be performed at a later date if the eye pressure rises.
After laser treatment for open-angle glaucoma, the complete effect may not be noticed until about six weeks after the procedure. Glaucoma medications should be continued following laser treatment unless your ophthalmologist instructs you otherwise.
Laser Treatment for Narrow-Angle Glaucoma
Laser treatment for narrow-angle glaucoma can be used to prevent an attack of narrow-angle glaucoma, and it can also be used during an attack, in order to lower the eye pressure. The laser is used to create a tiny microscopic hole in the iris of the eye, so that fluid may pass through this hole. This allows the iris to fall back away from the drainage area. This usually prevents or cures narrow-angle glaucoma.
The treatment is usually performed in the office with topical anesthetic drops. It can usually becompleted in fewer than thirty minutes and involves minimal discomfort for the patient. The laser is attached to a machine that is similar to the one your ophthalmologist uses to examine your eyes. During the procedure, the patient will notice multiple bright flashing lights, and may experience occasional stinging in the eye—much like laser surgery for open-angle glaucoma. Normally, the patient does not experience any discomfort.
After the laser treatment, your ophthalmologist will ask you to stay in the office for approximately one hour so that the eye pressure can be checked. Sometimes, you may be asked to return in 24 hours for a repeat pressure check. Usually, you will also be asked to return in one week for another pressure check and assessment of the treatment.
This treatment is approximately 98% effective in preventing narrow-angle glaucoma. The treatment used during an attack of narrow-angle glaucoma is about 85% effective in stopping the attack. In cases where the laser does not work, treatment with medicines or microsurgery will be necessary.
Another type of laser treatment for both open-angle and narrow-angle glaucoma is called cyclophotoablation. This procedure directs the laser to the ciliary body of the eye, which is the part of the eye that produces fluid. The ciliary body is located behind the iris. The laser destroys part of the ciliary body so that less fluid is produced inside the eye, thereby lowering eye pressure.
Since the ciliary body is located behind the iris of your eye, it is not readily visible and accessible for laser treatment. For this reason, the laser cyclophotoablation procedure must be performed using either an endoscope or a special probe that focuses the laser energy through the sclera, which is the white shell of the eye. The endoscope is a tiny, one millimeter flexible telescope which is inserted through a small incision in the eye, and which allows the surgeon to see and precisely direct the laser treatment to the appropriate area. The other probe is designed to focus the laser treatment on the appropriate area, but the surgeon cannot actually see the treatment as it takes place.
Because cyclophotoablation destroys part of the eye in order to decrease eye pressure, many surgeons consider it a destructive procedure, and only recommend this treatment as a last resort for treatment of advanced glaucoma. The endoscopic laser treatment may be less destructive to the eye since the surgeon controls it more precisely. Some surgeons use this endoscopic laser treatment at the time of cataract surgery if the patient has glaucoma, even if the glaucoma is not advanced.
This treatment is effective in lowering the eye pressure about 90% of the time, though oftentimes, multiple treatments are necessary.
Laser surgery can be very effective treatment for glaucoma. It is usually a quick and relatively painless procedure and frequently is performed right in the office. It is also covered by most types of medical insurance.
Strabismus, or Lazy Eye By: Gary D. Markowitz, MD
Strabismus is a condition in which the eyes are misaligned or are not looking at the same target at the same time. The word "strabismus" is derived from the Greek word "strabismos", which means, "to squint". Many patients with strabismus will squint on occasion, especially in bright light outdoors. It is sometimes referred to as "lazy eye" because the wandering eye appears to be lazy. Many people think that strabismus is the result of an eye muscle problem but this is usually not the case. In most instances, the eye muscles are quite healthy. The problem lies in the part of the brain that controls fusion, or keeping both eyes simultaneously directed toward the object of interest.
Types of Strabismus
Congenital strabismus is present at birth or develops within the first six months of life. If strabismus develops after six months of life, it is considered to be acquired strabismus. Some forms of strabismus are the result of abnormally functioning eye muscles, or nerves that stimulate an eye muscle; this is known as paralytic strabismus because a muscle is believed to be paralyzed. There are also medical conditions that can cause an eye muscle to be too tight or restricted, causing restrictive strabismus. Some people are born with a special form of strabismus that results from unique eye muscle, or eye muscle nerve abnormalities. If an eye is crossed inward toward the nose, esotropia exists. If an eye is turned away from the nose (toward the ear), exotropia exists. If an eye is turned upward or downward, a hypertropia or hypotropia, respectively, exists.
Who Gets Strabismus?
In the preschool age group, three to five percent of children have some form of strabismus. The genetics or inheritance pattern of strabismus is very complex and in most instances, it is not completely understood. I usually tell my patients that overall, about 30 percent of patients with strabismus will have a first-degree relative who has some form of strabismus, too. It may be a sibling, parent, or a child. In most cases, however, there is no known relative with strabismus. There are certain groups of patients who have a higher incidence of strabismus. These include those children born prematurely, children who had retinopathy of prematurity (a potentially blinding condition of premature infants that affects the retina in the back of the eyes), children who are developmentally delayed, children with a family history of strabismus, and children with craniofacial (skull shape) abnormalities, just to name a few. Adults can develop strabismus, also. It may be the result of a medical or neurological problem that has developed in adulthood or it can be a recurrence of childhood strabismus. Strabismus can also develop following certain forms of head trauma in both children and adults.
Why is Treatment Necessary?
There are several reasons why strabismus needs to be treated. For one, it does not improve by itself. It is a myth that children usually outgrow strabismus. Second, young children with strabismus have a significant chance of permanently losing vision in one eye-a vision loss that is not recoverable with eyeglasses. If a child does not develop the ability to use both eyes together as a young child, this ability will not develop later in life. For children whose vision develops in only one eye, as older children and later as adults, they may also experience limitations or restrictions in both their vocations and avocations. Some people whose eyes are visibly misaligned have difficulty communicating with others, and some may have difficulty with self-esteem. Finally, and certainly not least important, strabismus can be an early sign of a serious, ocular or neurologic problem.
In children, strabismus may be detected by the child's primary care practitioner during routine exams. Sometimes it is first noticed by family members, childcare providers, or friends. Older patients may notice it themselves or may develop double vision.
An adult who suspects he or she may have strabismus should get a referral to an eye doctor who is experienced in treating this condition. A complete examination should then be performed. The exam includes taking a thorough history and reviewing the patient's medical history, measuring the patient's vision, examining the health of the eyes, measuring the eye alignment with the patient looking in different directions, measuring how well the eyes move in various directions, and measuring the patient's refractive error, i.e., whether the patient is nearsighted, farsighted, has an astigmatism, or some combination of these. Sometimes additional testing may be necessary.
Medical or Nonsurgical Treatment
There are many different ways to treat strabismus, depending on the clinical situation and the patient's age. Some patients with strabismus will be treated with eyeglasses if it is thought that eyeglasses will improve the sight in one or both of the eyes. Sometimes, by improving the clarity of the vision, the strabismus disappears. If one eye does not see as well as the other, and the patient is a child, the doctor may decide to patch the eye that is functioning better to help recover vision in the poorer seeing eye. This is known as amblyopia therapy.
Esotropia, or crossing of the eyes, is sometimes caused by excess farsightedness in a child. This type of strabismus may be treated with eyeglasses to help the child focus and to eliminate the inward crossing of the eyes. Some of these children may even be given bifocal eyeglasses to give extra help with focusing on near objects if it is felt that the near focusing is contributing to the strabismus.
Prescription eyedrops are sometimes used in one or both eyes for weeks or months at a time. There are also some forms of strabismus that may be treated with eye exercises.
Eye muscle surgery is sometimes necessary for patients with strabismus. Eye muscle surgery is almost always performed on an outpatient basis, which means that the patient does not stay overnight at the hospital. For children and some adults, general anesthesia is used and the patient is "asleep" during the entire operation. Sometimes local anesthesia is used and the patient is awake during the operation, although they may be sleepy from systemic or intravenous medications that are also used.
In most operations, one or more of the eye muscles are repositioned. In some cases, a muscle may be weakened, or recessed, by separating it from the eye and reattaching it in a slightly weaker position. Alternatively, a muscle may be strengthened, or resected, by splicing out a small piece of the muscle and then reattaching the muscle so it has a stronger effect on the eye's position.
For some cases of strabismus, the doctor will inject a powerful paralyzing agent, botulinum toxin, into the muscle to weaken the muscle's action. Some surgeons will use adjustable sutures for older children and adults, especially if the patient has had eye muscle surgery previously. An adjustable suture is a stitch that is used during surgery that can be manipulated within 24 hours after the surgery when the patient is no longer under anesthesia in order to increase the success of the surgery. This procedure is performed on the patient after anesthetic eyedrops are instilled. Using special instruments, one or more eye muscles can be repositioned and then secured. This "fine tuning" may increase the success of the surgery.
There are many different kinds of strabismus that can affect both children and adults. It is important that patients with strabismus be evaluated, as early diagnosis and treatment result in the best outcome. In most instances, strabismus can be treated effectively, and the patient can enjoy many years of good vision as well as a more normal ocular appearance.
Natural Vision Correction
Ayurveda: According to Ayurvedic theory, most vision problems are due to digestive disorders. Emphasis is given to regular eye exercises, as well as the use of the herbs amla, licorice, and triphala, and a diet rich in organic, whole food with abundant quantities of antioxidant rich vegetables such as carrots and spinach.
The Bates Method: The Bates Method was developed at the beginning of the 20th century by Dr. W. H. Bates, M.D. (1865-1931), a prominent American ophthalmologist, to improve sight and restore natural habits of seeing, which Dr. Bates believed became impaired through strain, tension and the resulting misuse of the eyes. The aim of the Bates Method is to teach people with vision problems such as astigmatism, farsightedness, and nearsightedness how to get the eyes and mind working together harmoniously to significantly improve eyesight.
The Bates Method is not a medical treatment, but a method of re-education that involves both active learning and the receptive awareness of how to appreciate what we see, such as the appreciation of a detailed painting, a beautiful garden, or a classic cathedral. Dr. Bates believed that healthy eyesight is the result of a relaxed state of mind and body in which the individual feels a direct contact with the surrounding world through his or her five senses. Poor eyesight, he believed, is the result of tension, feeling isolated from the outside world and locked into a pattern of psycho-physical tensions, such as worry, anxiety, rigidity, day-dreaming, boredom, confusion, impatience, and so on.
The Bates Method is taught via a student-teacher relationship in which the student is shown how to relax the eyes, then the body, and then the body and eyes together. As the relaxation progresses, the mind, eyes, and body begin to focus together more harmoniously, allowing eyesight to improve naturally by itself, along with the overall health of the eyes.
Biofeedback Training: Biofeedback training has been shown to be helpful for improving a variety of vision disorders, including astigmatism, near- and farsightedness, and night blindness. Traditional biofeedback training helps patients become better able to relax the muscles of their forehead, thus reducing pressure of the eyeball and overall eyestrain.
A specific biofeedback instrument for improving poor eyesight is the Accommotrac Vision Trainer®, developed by optometric physician Joseph, Trachtman, O.D., Ph.D., of New York City. This device works by measuring how clearly and effectively the retina perceives images. As patients change their focus, the Accommotrac transforms the visual images they are viewing into sound. This enables them to become better able to detect and control their changes in focus, thus also improving their control over the eye muscles themselves. Treatment sessions are typically scheduled once a week for an hour each time. The Accommotrac has been shown to provide significant improvements in refractory vision problems, including astigmatism, near- and farsightedness, and night blindness.
Diet: Emphasize a diet of organic, whole foods, with a daily abundance of fresh fruits and vegetables. Choose from a wide variety, focusing on those foods rich in antioxidants. These include red, orange and purple bell peppers, carrots, celery, dark-green leafy vegetables such as chard, kale, collard, spinach and richer colored green leaf lettuces, parsley, tomatoes and yellow squash. Fruits high in anti-oxidants include berries, especially raw or juiced Acai berries, Goji berries and dark colored berries, purple and red grapes, plums, cherries, mangos, melons and citrus fruits. For a sweet treat or to help curb chocolate cravings, enjoy the anti-oxidant rich unsweetened cacoa. Mixed with natural sweeteners such as raw honey or agave syrup, cacoa is a scrumptious alternative to the typical refined sugar in conventional chocolate products.
Organic egg yolks are also recommended because they are rich in carotenoids, an important class of antioxidants. It is best to eat soft, rather than hard cooked egg yolks to preserve the heat sensitive valuable carotenoids. Soft boiled, poached, sunny side up, or raw eggs are best. Raw eggs may be eaten if they come from a reliable organic source and are washed prior to cracking. Samonella travels on the shell of the egg and enters the egg from the outside, so washing eggs with hot sudsy water minimizes exposure.
Avoid all processed and fried foods, sugar and sugar products, refined, simple carbohydrates, alcohol, and unhealthy hydrogenated and partially hydrogenated oils. Milk and dairy products should be consumed sparingly, and preferably raw and organic. Avoid conventional flesh foods and overcooked/grilled meats. In addition, test for food allergies and sensitivities and eliminate those foods that test positive.
Also be sure to drink plenty of pure, filtered water throughout the day, at least half your body weight in ounces, to help flush out accumulated debris in the eye drainage channels. Proper hydration is also essential for maintaining the suppleness of the eyes' lenses. Fresh raw green juices are also an important addition to one's daily food plan. See the recipe section for green juice suggestions.
Eye Exercises: Useful for preventing and reversing most types of vision problems.
Juice Therapy: Drink 16 ounces of carrot juice and/or carrot juice combined with freshly juiced celery, cucumber, parsley, and spinach in two divided doses (eight ounces per serving) each day.
Lifestyle: Make it a point to sit up straight in a relaxed manner, and to avoid unnecessarily tilting your head for extended periods of time. In addition, avoid eyestrain by refraining from working at a computer terminal or reading for long periods of time, especially in bed. Also refrain from watching television or movies in the dark, as well as spending prolonged periods in darkness.
Nutritional Supplementation: Useful nutrients include vitamin A, vitamin B complex, vitamin C, vitamin E, beta-carotene, flavonoids, lutein, N-acetyl-cysteine (NAC), riboflavin, selenium, taurine, zeaxthanin, and zinc.
Traditional Chinese Medicine (TCM): According to TCM theory, most vision problems are due to diminished liver function. To restore healthy liver function, TCM practitioners combine acupuncture with dietary changes and traditional Chinese herbs, such as ginkgo biloba and ginseng.
Surgical Vision Correction (Refractive Surgery with the Excimer Laser) By: Peter S. Hersh, MD
How Does the Laser Work?
How the Excimer Laser Corrects Vision
Laser In Situ Keratomileusis (LASIK)
Photorefractive Keratectomy (PRK)
Correction of Nearsightedness, Farsightedness, and Astigmatism
How Much Tissue Should be Removed?
Differences Between LASIK and PRK
Laser vision correction (LASIK and PRK) is a relatively new procedure used to reduce or eliminate a person's dependence on glasses and contact lenses. The procedure is performed on an outpatient basis and is effective for treating nearsightedness, farsightedness, and astigmatism. To date, over two million procedures have been performed worldwide.
How Does the Laser Work?
The goal of excimer laser LASIK and PRK is to reshape the cornea so that the rays of light that enter the eye are focused clearly onto the retina. The laser produces an ultraviolet beam of light that meticulously removes tissue. Tissue is removed in a precise fashion on a microscopic level, without harming or heating adjacent corneal tissue. This process of tissue removal is called photoablation.
The excimer laser is unique amongst the many types of lasers used in eye surgery. There are three basic categories of medical lasers—thermal (heats tissue), mechanical (cuts tissue), and photochemical (interacts directly with molecules). For example, argon lasers heat tissue and have been used for years to treat disorders such as glaucoma and diabetic eye disease. YAG lasers break tissue bonds by creating a shock wave and are generally used following cataract surgery and to treat certain types of glaucoma. The excimer laser is the only laser properly suited to the task of refractive corneal surgery since it does not heat or mechanically damage tissue. Rather, it directly interacts with chemical bonds, neither heating nor disrupting the tissue, thus minimizing possible scarring.
In addition, the precision of the excimer laser makes it uniquely suited to the task of refractive corneal surgery. Each pulse of the laser removes only 0.25 microns of tissue (1/28 of a red blood cell) in four-billionths of a second. This allows the surgeon to safely sculpt the cornea into a more optically desirable shape, ultimately allowing the rays of light to focus properly on the retina.
How the Excimer Laser Corrects Vision
To correct nearsightedness, the excimer laser removes a small amount of tissue from the center of the cornea to flatten the curvature of the cornea. In the case of farsightedness, tissue is removed from the periphery of the cornea to steepen its curvature. In the case of astigmatism, an elliptical, or football-shaped corneal surface shape, is made more spherical. In all cases, the laser reshapes the cornea’s front surface to change its optical characteristics to focus light better.
In actually applying the laser to the eye, the corneal stroma (the tissue beneath the corneal epithelium) must be exposed. This can be accomplished by directly removing the surface corneal epithelial cells (photorefractive keratectomy or PRK) or by creating a corneal flap with a microkeratome (laser in situ keratomileusis or LASIK).
Laser In Situ Keratomileusis (LASIK)
The LASIK procedure also uses the excimer laser to reshape the cornea, but this is done under a thin corneal flap, which preservers the surface epithelial cells. Rather than scraping away the epithelial cells to expose the corneal stroma as in PRK, a specialized surgical instrument known as a microkeratome (which works somewhat like a carpenter’s plane) creates a flap of corneal tissue that is attached by a hinge. This flap is gently pulled back like a clear, hinged pancake and the corneal stroma is exposed. The laser part of the LASIK procedure takes place in the exposed corneal bed (corneal stroma). The laser application itself lasts about 30 to 90 seconds.
After the exposed corneal bed is treated by the laser and minute amounts of cells are vaporized, the flap is replaced in its original position. The flap is held in position by the eye’s natural suction facility and natural sticky sugars, and provides increased comfort and decreased recovery time for the patient.
Photorefractive Keratectomy (PRK)
This is a procedure in which the front surface of the cornea is directly sculpted by the excimer laser. The surgeon prepares the eye by gently removing the surface layer known as the corneal epithelium. This layer regenerates itself within a few days. As in the LASIK procedure, computer-controlled pulses are directed at the exposed surface (the corneal stroma) to reshape the cornea. Less than ten percent of the cornea is affected, with the deeper layers remaining untouched.
Correction of Nearsightedness, Farsightedness, and Astigmatism
Patients with nearsightedness have corneas that are too steep for the length of their eye. The excimer laser is used to flatten the cornea so that the light rays that pass through it come to a point of focus on the retina, rather than in front of it.
Patients with farsightedness have corneas that are too flat for the length of their eye. The excimer laser is used to steepen the cornea so that the light rays are focused on the retina, rather than behind it.
In astigmatism, the cornea is elliptical (or football shaped) rather than being round. In this case, the laser reshapes the front surface of the cornea into a rounder shape, again improving the eye's focus.
How Much Tissue Should be Removed?
The amount of tissue removed in each of these procedures is determined by the patient’s degree of refractive error. Before the laser is used, the degree of refractive error is translated into numbers that are entered into the laser’s computer. The quantity and pattern of tissue removal unique to each patient are then calculated. Both PRK and LASIK are refractive procedures that utilize the precision of the excimer laser to reshape the optical surface of the eye.
Differences Between LASIK and PRK
Refractive vision correction performed under a flap (LASIK) offers numerous advantages over refractive vision correction performed on the cornea’s surface (PRK). Notably, there is a more rapid improvement in vision and decreased discomfort with LASIK since the surface epithelial cells have been preserved and do not need to regrow. This is undoubtedly the reason that LASIK has become the corrective surgery of choice for both doctors and patients. However, in some patients, PRK is a safer alternative that may promise better outcomes. Patients who might benefit from PRK include those in whom the cornea might too thin for LASIK, or in some patients with corneal irregularities or scars.
Which procedure you should have is best determined by consulting with your surgeon. Although the surgeon cannot promise 20/20 vision without correction, approximately 95 percent of typical myopic patients achieve vision within two or three lines of 20/20 without correction. In fact, the many patients can drive without glasses the day after their LASIK surgery. Future articles will deal with some of the complications and side effects, which are possible with these procedures.
Vision Correction: Are LASIK and PRK Your Only Options? By: Julius Shulman, MD
If you've heard about vision correction, you've probably heard about the two most common options: LASIK (laser in situ keratomileusis) and PRK (photorefractive keratectomy). These procedures have become increasingly popular in recent years - last year, an estimated 1.5 million surgeries were performed in the United States alone. Though they are quick, safe, and effective in most cases, LASIK and PRK are not the only vision correction procedures, and some patients may want to consider other options. We talked to Julius Shulman,MD an opthalmologist in New York and the author of No More Glasses (Simon and Schuster, 1984, revised St. Martin's Press, 1993) about the current alternatives.
How common are the alternatives to LASIK or PRK?
Most people who have a corrective procedure have LASIK or PRK. Other options fill about 5 to 10% of procedures done to correct vision.
What are some of these other options?
Intacs are one option. Intacs are appropriate for people who have low degrees of myopia, or nearsightedness. They're tiny little plastic pieces that are inserted into the cornea to reshape it. The surgery takes about 15 minutes and it is as effective in most cases as LASIK or PRK but it's only for low degrees of myopia.
Another option that's fairly new is LTK (as opposed to PRK). LTK is laser thermal keratoplasty. That is only for low degrees of farsightedness or hyperopia. Without touching the eye, the laser reshapes the cornea by placing 16 tiny spots on the outside of the cornea. The whole procedure takes three seconds, and a minute or two after this procedure the farsightedness is gone and people can read without glasses. It's not for everyone. No procedure is for everyone, but it is very effective.
How does a person know if they should have one procedure over another?
It comes down to talking to your doctor, trusting your doctor, and letting him guide you through this array of procedures to correct your vision. You can also get educated yourself by reading material, searching the Internet, and talking to other people, including your family doctor. But it really comes down to trusting your ophthalmologist.
There are certain people who are not necessarily candidates for LASIK or PRK. Would they still be candidates for, let's say, Intacs?
Yes. In certain cases, someone who is not a good candidate for PRK or LASIK can have Intacs or LTK.
What is "wavefront" technology?
Wavefront technology is being done in Europe, and it involves taking a light and shining it into the patient's eye. The light then comes out in a certain pattern which reflects any aberrations or abnormalities, and that pattern is programmed into the laser which is used for vision correction. This differs from regular laser correction in which it's your eyeglass prescription that is programmed into the laser. So theoretically this has the potential for making a perfect eye and giving you vision way beyond 20/20. It's still in its infancy but it's projected that vision of not only 20/20 but 20/10, 20/8, or 20/5 might be possible.