Computer Vision Care
Today, more than ever, people of all ages are spending time in front of computer screens. Its no surprise that more computer time results in increased eye strain.
The image produced by your computer is made up of “pixels” (little dots of light that constantly renew themselves) forming a moving, blurry image. The screen seems stable and clear to us, but to our brain the image is very difficult to focus accurately on.
As seen in the image above, "print" image reflects a square-wave of light to the eyes and is relatively easy to focus on. The computer monitor’s image of pixels is rounded and harder to focus on.
This moving, blurry image causes the focusing (ciliary body) muscles to try over and over again to focus. Additionally, your focus drifts to the RPA and then back to the screen. This effort to focus and refocus causes muscle fatigue and other symptoms of Computer Vision Syndrome (CVS).
Drs. Stokol uses the PRIO instrument to determine the best prescription for working at the computer. The glasses put your eyes at rest at the computer screen and your focusing muscles relax.
Wearing the glasses whenever you work on the computer produces comfort over time. These glasses are not intended for other use such as driving.
What are cataracts?
A cataract is a clouding of the eye's internal lens that causes loss of vision.
The lens lies behind the iris and the pupil (see diagram). The lens in the human eye works much like a camera lens in that it focuses light onto the retina at the back of the eye, where an image is transmitted to the brain. The lens also adjusts the eye's focus, letting us see things clearly both up close and far away.
The lens consists mostly of water and protein, and a fine balance of these two elements must exist in order to maintain clear vision. But as we age, some of the protein may clump together and start to cloud a small area of the lens. This is a cataract. Over time, the cataract may worsen and cloud more of the lens, making clear vision difficult.
What causes cataracts?
In most cases, the protein in the lens just changes from the wear and tear it takes over the years. This type of age related cataract will affect just about all of us if we live long enough. Other contributing factors such as diabetes and lifestyle behaviors such as smoking can affect the development of cataracts. Severe trauma to the eye and excessive exposure to UV light can also result in cataract formation.
When is one most likely to have a cataract?
The term "age-related" is a little misleading. One doesn't have to be a senior citizen to get this type of cataract. In fact, people can have age-related cataracts in their 40s and 50s, but during middle age, most cataracts are not visually significant. By the age of 70, most people begin to notice reduced vision due to cataracts.
What are cataract symptoms?
Cataracts start out insignificantly, having little effect on vision. As a cataract becomes more dense, patients frequently describe their vision as blurry or hazy at all distances. Many experience bright and bothersome glare from the sun, headlights, or lamps, and some describe colors as appearing less bright and vivid. Eventually, reading and other normal tasks become challenging.
How is a cataract detected?
Although one might think he or she has a cataract, the only way to know for sure is by having an eye examination. Should Dr. Stokol determine the presence of a cataract, they can monitor the progression of the cataract, and advise when surgery is indicated.
How can cataracts be treated?
A surgeon removes the clouded lens from the eye, and an artificial lens, or IOL, is then inserted behind the iris in place of the original lens. Although any surgery can potentially have complications, cataract surgery is very successful in the hands of a skilled surgeon. In fact, the procedure is one of the most common surgeries performed in the United States, with over 1.5 million cataract surgeries done each year. The surgery is done on an outpatient basis, and recovery takes anywhere from a week to a few months.
When should cataracts be treated?
If Dr. Stokol determines the presence of a cataract, surgery may not be necessary for several years, if at all. The doctors will measure vision in all cataract patients, but ultimately, surgery is indicated when the patient's lifestyle becomes affected due to reduced vision.
For Information on these and other diseases of the eyes, visit http://www.nei.nih.gov/pubpat.htm
Diabetic Retinopathy
What is diabetic eye disease?
Diabetic eye disease refers to a group of eye problems occurring as a complication of the systemic disease Diabetes Mellitus. All can cause severe vision loss or even blindness. Risk of complications from diabetes increases the longer one has the disease and with poorly controlled sugar levels. Anyone with diabetes is at risk for diabetic eye disease and should have a complete eye exam with dilation every year. Diabetic eye disease may include diabetic retinopathy and glaucoma. Cataracts and glaucoma also affect many people who don't have diabetes.
What is the most common diabetic eye disease?
Diabetic Retinopathy. This disease is a leading cause of blindness in American adults. Due to increased sugar in the circulation, the blood vessels of the retina swell and leak fluid as seen in the picture on the right. This leads to a swelling of the macular area (the part of the retina that provides sharp, central vision) which leads to vision loss.
Another, more serious complication is neovascularization. The blood vessels in the retina become faulty as a result of the diabetes and do not provide adequate oxygen and nutrients to the surrounding tissues. As a result, new blood vessels begin to grow on the retina. This sounds like an OK adaptation, but these new vessels are not like normal blood vessels. They leak fluid, blood, and lipids, which can greatly disrupt retinal function. This can lead to retinal detachments, more macula edema, and even new blood vessel growth in and around the iris. These complications can lead to severe vision loss and glaucoma.
Who is most likely to get diabetic retinopathy?
Anyone with diabetes is likely to get diabetic retinopathy. The longer one has diabetes, the more likely he or she will get diabetic retinopathy. Nearly half of all people with diabetes will develop some degree of diabetic retinopathy during their lifetime. Hence, the importance of a yearly eye exam with Dr. Stokol.
What are the symptoms of diabetic retinopathy?
Similar to glaucoma, diabetic retinopathy has no symptoms in the early stages. Many people do not bother with eye exams because they feel their vision is fine. This is a big mistake as preventative care is critical, especially in patients who have diabetes, as sight may not change until the disease becomes severe. Once symptoms develop due to swelling in the macula, blurred vision becomes the major complaint. Vision can fluctuate significantly. Symptoms vary greatly, and even in advanced cases of diabetic eye disease, some patients have minimal complaints. However, this does not mean that the disease will not affect sight. Eventually, if uncontrolled, progressive diabetic eye disease will cause severe vision loss. Once again, yearly monitoring and early intervention by Dr. Stokol is the key.
How is diabetic retinopathy detected?
During an eye exam, our assistants will administer drops that dilate the pupils. This allows Dr. Stokol a more extensive view of the inside of the eyes, most specifically the retina, to check for signs of diabetic retinopathy. Without dilation, Dr. Stokol can not completely assess the retina.
Can diabetic retinopathy be treated?
Yes. Dr. Stokol may suggest laser surgery by a retina specialist in which a strong light beam is aimed onto the retina to shrink and/or seal the abnormal, leaking vessels. This stops the swelling and can control macula edema. Laser surgery reduces the risk of severe vision loss from this type of diabetic retinopathy by 60 percent. However, if vision loss has already become significant, treatment usually only prevents further vision loss and does not restore vision to previous levels. Once again, finding diabetic retinopathy early is the best way to prevent vision loss.
Can diabetic retinopathy be prevented?
Everyone with diabetes will have some degree of diabetic retinopathy, but one's risk can be greatly reduced by controlling blood sugar levels. Adequate control of glucose slows the onset and progression of retinopathy and lessens the need for laser surgery. Studies show that people who keep their blood sugar levels as close to normal as possible have much less eye, kidney, and nerve disease. See your internist regularly to determine the right sugar level for you based on your age and lifestyle. Once determined, follow your doctor's recommendations closely to keep blood sugar levels under control.
How common are the other diabetic eye diseases?
Cataract- Studies show that diabetes patients are twice as likely to get a cataract as a person who does not have the disease. Also, cataracts develop at an earlier age in people with diabetes. Cataracts can usually be treated by surgery.
Glaucoma- this may also become a problem. A person with diabetes is nearly twice as likely to get glaucoma as other adults, and as with diabetic retinopathy, the longer one has diabetes, the greater one's risk of developing glaucoma. Glaucoma may be treated with medication or laser. Please refer to our glaucoma section for more information.
What can one do to protect one's vision?
Finding and treating diabetic retinopathy early, before it causes vision loss or blindness, is the best way to control diabetic eye disease. So, if you have diabetes, make sure you get a dilated eye examination at least once a year, and also stay in close contact with your physician.
Floaters
Many patients experience floaters, which appear as tiny dots, strands, or even strands attached to dots that seem to move or float across the field of vision. Some patients describe floaters as shadows or crawling bugs. While floaters may look strange, they are a natural product of the anatomy of the eye. Behind the internal lens, the eye is filled with a gel called the vitreous. This gel contains mostly water and strands of protein. When a patient notices a floater, he or she is actually visualizing these strands of protein floating around in the fluid matrix of the vitreous. A patient sees a floater due to the fact that the floater casts a shadow on the retina, resulting in the perception of a floating object. Some patients find floaters very annoying, but no treatment is indicated or exists. Eventually, most people learn to tune out floaters and cease to be bothered by their appearance.
While the vast majority of floaters are benign, floaters can be a sign of a retina tear. In this case, floaters do not appear as one or a few isolated objects drifting across the field of view, but rather as a shower of spots. If you experience floaters such as these, call Dr. Stokol's office immediately.
Flashes
Flashes appear as sudden lightning streaks or camera flash bulbs exploding in one's vision. They can occur randomly and without any specific preceding activity. This can indicate a retinal tear or detachment and Dr. Stokol recommends an examination immediately or referral to a retina specialist if one experiences such an event. Flashes can be harmless, arising from a natural tugging on the retina from the vitreous gel, but Dr. Stokol advocates a thorough retina examination to rule out a retinal tear.
Glaucoma
Advanced defects are evident in this picture of primary open angle glaucoma.
What is glaucoma?
Glaucoma is a group of eye diseases in which the fibers of the optic nerve degenerate usually due to an increase in the intraocular pressure. Glaucoma consists of two main subgroups:
Primary Open Angle Glaucoma:
In this condition, the intraocular pressure rises for unknown reasons. This constitutes the vast majority of glaucoma cases and will be discussed in more depth below.
Closed Angle Glaucoma:
In this type of glaucoma, the patient has an anatomical defect in which the drainage angle in the eye is too narrow. This causes fluid to build up in the anterior chamber resulting in greatly elevated intraocular pressure. This rise in pressure damages the optic nerve at the back of the eye and can be extremely painful.
Glaucoma can cause blindness, so close monitoring of the condition is paramount.
What causes glaucoma?
Traditionally, scientists believe that increased pressure inside the eye causes glaucoma. The mechanism is as follows:
At the front of the eye lies a small space called the anterior chamber. The eye constantly produces clear fluid inside this chamber in order to bathe and nourish nearby tissues. This fluid drains out of this chamber through a special outflow system called the trabecular meshwork. The fluid is constantly produced and drained so that the pressure never rises too high. In glaucoma, either the drainage system is faulty or the eye produces too much fluid, resulting in increased liquid in the anterior chamber. This excess fluid eventually compresses the optic nerve and damages its blood supply. If left untreated, sight loss ensues.
New research indicates that a second mechanism may be at work in glaucoma. Increasing evidence suggests that a loss of blood flow to the optic nerve causes the cell death. A loss of blood flow deprives the tissues of necessary oxygen and nutrients. Scientists have yet to pinpoint the exact cause or nature of this lack of perfusion to the optic nerve, but much research now focuses on this potential cause of glaucoma.
Once damage occurs to these nerve cells, restoration of vision is minimal. Needless to say, control of the disease is extremely important.
How can glaucoma be treated?
Although open-angle glaucoma cannot be cured, it can usually be controlled. The most common treatments are:
Eye Drops:
The patient administers medicated eye drops every day. The four most common drops are Beta-blockers, Prostaglandin Analogs, Beta-blocker/Prostaglandin Analog combinations, Carbonic Anhydrase Inhibitors, and Alpha-agonists. Each medication has its own dosing and possible side effects, so the patient must adhere closely to doctor recommendations. For most people with glaucoma, regular use of medications will control the intraocular pressure, but patients can develop resistance to these drugs. Dr. Stokol may select other drugs, change the dosage, or suggest other ways to deal with the problem.
Pills:
Oral medications to control eye pressure may be prescribed in conjunction with topical drops.
Laser surgery:
If topical drops do not adequately control the intraocular pressure, laser surgery may be recommend. In this procedure, the surgeon focuses a strong beam of light on the part of the anterior chamber where the fluid leaves the eye. This results in the creation of a series of small channels, which makes it easier for fluid to exit the eye. Over time, the effect of laser surgery may wear off, and the patient may need additional laser treatments. Patients who have this form of surgery may need to keep taking glaucoma drugs.
Surgery:
If all else fails, a surgeon can operate to open the drainage angle. This procedure called trabeculectomy is usually reserved for patients whose pressure cannot be controlled with eye drops, pills, or laser surgery.
Also, filtration surgery can be performed to drain fluid from the eye.
Who is most likely to get glaucoma?
Nearly five million people have glaucoma, a leading cause of blindness in the United States. Although anyone can get glaucoma, some people are at higher risk. They include:
- Anyone over age 60
- African Americans over age 40
- Those with a family history of glaucoma.
- Five times more likely to occur in African Americans than in Caucasians.
- About four times more likely to cause blindness in African Americans than in Caucasians.
- Fifteen times more likely to cause blindness in African Americans between the ages of 45-64 than in Caucasians of the same age group.
What are the symptoms of glaucoma?
Glaucoma has no symptoms until major damage has occurred to the optic nerve. Vision remains normal with no pain until eventually, a person with glaucoma may notice his or her side vision gradually failing. For example, objects in front may still be seen clearly, but the person may not notice objects to the side. As the disease worsens, the field of vision narrows and blindness can result.
Hence, early detection remains the best method of spotting the onset of the disease.
How is glaucoma detected?
There are various instruments that are used to measure eye pressure in an eye examination, but pressure tests alone cannot detect glaucoma, as this is only one factor used in diagnosing glaucoma. By carefully studying the optic nerve directly via an examination through dilated pupils, Dr. Stokol can detect early glaucoma. Many patients wonder why dilation is necessary every year. This is just one of many good reasons. By checking the appearance of the optic nerve, Dr. Stokol can assess the health of the tissue and inform patients of any early glaucomatous changes.
If Dr. Stokol has any suspicion of glaucoma, they will recommend a visual field evaluation. Designed to detect any early changes in peripheral vision, this highly sensitive procedure is one of the most important factors in making a glaucoma diagnosis. Obtaining a visual field evaluation not only illustrates current defects in vision, but also serves as a reference point for comparison of future visual field results.
In summary, follow Dr. Stokol's recall schedule for an eye exam to screen for glaucoma. Remember, simply checking the pressure in the eye does not rule out glaucoma!
For Information on these and other diseases of the eyes, visit http://www.nei.nih.gov/pubpat.htm
Age-Related Macular Degeneration (AMD)
What is the Macula?
The macula lies at the center of the sensory retina. The retina lines the back surface of the eyeball much the same way that wallpaper adheres to a wall. This tissue contains rods and cones, the cells that transduce light into neural signals that eventually travel to the brain. Once in the brain, these signals are assembled into images that humans perceive as sight. The macula contains the highest concentration of cones, which function to provide color and detailed, central vision. People use central vision to perform tasks such as reading, driving, and anything else that requires sharp, straight-ahead vision.
What is age-related macular degeneration (AMD)?
AMD is a common eye disease that gradually destroys the macula leading to a degradation of sharp, central vision. In some patients, age-related macular degeneration advances so slowly that it will have little effect on their vision in the early stages. But in others, the disease progresses faster.
How does AMD damage vision?
By causing a breakdown of the macula, age-related macular degeneration destroys the clear, straight ahead central vision necessary for reading, driving, identifying faces, watching television, doing fine detailed work, safely navigating stairs and performing other daily tasks. Although it rarely causes total blindness, age-related macular degeneration can dim contrast sensitivity and color perception. Peripheral vision may not be affected, and it is possible to see using the remaining intact retina. AMD occurs in two main forms: wet and dry.
What Is Dry AMD?
A retina affected by Dry Age-Related Macular Degeneration
This is the most common type of AMD affecting 90% of the people who have the condition. In the dry form, the underlying cells that provide support and nutrition to the macula begin to break down. This disrupts normal macular function and leads to the characteristic reduction of central vision and color perception. Generally, the damage caused by the "dry" form is not as severe as that of the "wet" form; however, patients with dry AMD can eventually develop wet AMD.
What Is Wet AMD?
A retina affected by Wet Age-Related Macular Degeneration
This is the more severe type of age-related macular degeneration. Although it afflicts only 10 percent of those who have the condition, 90 percent of blindness resulting from macular degeneration comes from this form of the disease. In this type of AMD, the membrane underlying the retina thickens, and then breaks. This disrupts the oxygen supply to the macula leading to a hypoxic state. The body responds to this lack of oxygen by growing new blood vessels in an attempt to restore adequate flow. These new, fragile blood vessels do not function well and leak blood, fluid, and fats. They grow through the breaks in the membrane behind the retina and can raise and detach the macula.
To visualize this process, imagine the roots of a tree (the new blood vessels) growing and spreading until they actually uproot a sidewalk (the retina and macula). Then imagine rainwater (the leaking fluid and blood) seeping up throughout the cracks. This process damages the macula and causes scarring, hence resulting in rapid central vision loss.
Who is most likely to get AMD?
The greatest risk factor is age. Although AMD may occur during middle age, studies show that people over age 60 are clearly at greater risk than other age groups. For instance, a large study found that people in middle-age have about a 2 percent risk of getting macular degeneration, but this risk increased to nearly 30 percent in those over age 75.
Other Age-Related Macular Degeneration risk factors include:
- Gender--Women tend to be at greater risk for AMD than men.
- Race--White Caucasian are much more likely to lose vision from AMD than African Americans.
- Smoking--Smoking increases the risk of AMD.
- Family History--Those with immediate family members who have AMD are at a higher risk of developing the disease.
What are the symptoms of AMD?
Both dry and wet age-related macular degeneration cause no pain. The most common early sign of AMD is blurred or distorted vision. As fewer cells in the macula are able to function, patients with AMD will see details less clearly, such as faces or individual words in a book. For example, when looking at a person, his or her face may appear blurry while the rest of the person is in focus.
Another classic early symptom of both wet and dry AMD is that straight lines appear crooked. For example, a doorway or telephone wires may look wavy or disconnected. As AMD progresses, patients notice an enlarging blind spot in the middle of their field of vision.
If sudden, central vision loss occurs, this can be a sign of wet AMD. With any symptoms of sudden vision loss, contact Dr. Stokol immediately.
Here are some examples of what a patient with macular degeneration might see. Figure 1 shows the typical wavy lines at the center of vision. Figure 2 shows the missing image that is characteristic either of wet macular degeneration or of the later stages of dry macular degeneration.
How is AMD detected?
Dr. Stokol may suspect age-related macular degeneration if a patient is over age 60 and has had recent changes in his or her central vision. To look for signs of the disease, the doctors use high magnification lenses to study the macula after the pupils have been dilated. Viewing an Amsler grid, a pattern that looks like a checkerboard, also provides important diagnostic data. Early changes in central vision will cause the grid to appear distorted, a sign of AMD. Below is an example of an Amsler grid. Hold the grid at 33 cm while covering one eye and look at the dot in the center of the grid. Keep staring at the center dot, and if while doing this, the lines around the dot appear wavy or distorted, schedule an appointment to see Dr. Stokol. DO NOT rely on this grid alone for any diagnoses. The only way to determine the presence or absence of age-related macular degeneration is to have a thorough examination by Dr. Stokol.
The following graph depicts the appearance of an Amsler grid to a patient who has Age-Related Macular Degeneration.
How Can AMD Be Treated?
No treatment now exists for dry age-related macular degeneration, although use of antioxidant vitamins may slow the progress of dry AMD. Please see our Vitamins and Your Vision section for an in depth discussion on the role of vitamins and nutrition in eye care.
Surgeons treat some cases of wet age-related macular degeneration with thermal laser procedures. In this treatment, the surgeon aims a high energy laser beam on the fragile, abnormal vessels in the retina to seal them shut and stop their growth. This treatment accomplishes this task well, but the heat generated by the laser can damage nearby healthy tissue. For this reason, surgeons are reluctant to use thermal laser directly on the macula for fear of causing more damage than already exists.
A new treatment called Photodynamic Therapy (PDT) or Visudyne® reduces this problem. In this procedure, the surgeon injects a drug into the arm where it travels to the abnormal, leaking vessels in the retina. Then, a "cool" beam of laser light is directed into the eye causing excitement of the Visudyne chemicals, which in turn, seal the abnormal blood vessels. Since the laser used in this treatment generates no heat, and the Visudyne chemical allows for specific treatment of the pathological vessels, no normal tissue or blood vessels suffer from extraneous burns. Surgeons can aim the beam directly at the macula and destroy and/or seal only the leaking vessels, sparing healthy macular tissue. This treatment is still new and in experimental stages, but the outlook for therapeutic management of wet age-related macular degeneration looks very promising. Unfortunately, PDT has no beneficial effects on dry age-related macular degeneration. The treatments are expensive and must be repeated every three months to be effective.
What Can I Do To Protect My Vision?
Dr. Stokol supports the notion that AMD is a vascular (blood flow) condition. In order to maximize efficient blood flow in your system, follow these steps. Remember, you have control over some of the known risk factors for macular degeneration, and healthy habits, started young, will provide the most benefits. We recommend the following steps:
If you are a smoker, STOP SMOKING IMMEDIATELY! Tobacco appears to interfere with the absorption of lutein, an important antioxidant that protects the retina from damaging ultraviolet light. Smokers are likely to have low levels of lutein, putting them at greater risk of developing macular degeneration than nonsmokers. Here's a great reason to quit smoking.
Control high blood pressure. The eye is a highly vascular organ, having a rich supply of blood vessels. In fact, the rate of blood exchange in the eye is the highest of any organ in the body. The link between high blood pressure and AMD is well established. If you have high blood pressure, keep it under control by following your internist's advice.
Protect your eyes from exposure to harmful sunlight. Ultraviolet light and blue light can damage your retina and may increase your chances of developing macular degeneration and/or speed up its development. Therefore, it is extremely important to protect your eyes when you are outdoors. Wear a hat or visor whenever you are outside, even on overcast days. Ultraviolet light passes through cloud cover and is just as dangerous as direct sunlight. Look for sunglasses that screen 99-100% of ultraviolet A and B rays. Recent research points to blue light (the short wavelengths of the light spectrum) as an even more damaging factor. A certain percentage of sunglasses are mislabeled, therefore at our optical, we take great care to carry only high quality sunglasses that provide maximum sun protection.
Click here for additional information on how to protect your eyes.
The most helpful colors for blocking out blue light are red, orange, yellow and amber. Because glare is often a problem for people with AMD, choose this protection carefully. You can also have your regular glasses treated with ultraviolet protection - a clear coating that will not interfere with your sight. We would be happy to discuss sunglass options for you. Just stop in and ask to speak with one of our opticians.
Eat a healthy diet and engage in regular cardiovascular exercise. The diet widely recommended as beneficial for cardiovascular good health (low in saturated fats, high in fruits and vegetables) also seems to help people suffering from AMD. A healthy lifestyle that includes regular cardiovascular exercise also contributes to both cardiac and eye health. One explanation: A healthy heart increases the blood flow to the capillaries in peripheral tissues, thus speeding the delivery of essential nutrients to the eyes that nourish the macula.
Limit alcohol consumption. Reduce your alcohol intake to just a few drinks a week. Limiting alcohol improves circulation, vascular health, and liver health. With a healthy liver, the body can produce essential nutrients and metabolize toxic wastes.
For additional related information, please see: www.amd.org and www.nei.nih.gov
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