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Diabetic Retinopathy

Diabetes has reached epidemic proportions worldwide. As one of the major complications of diabetes, diabetic retinopathy is a leading cause of blindness that is typically associated with diabetic macular edema. This is caused by the blood vessels of the retina becoming abnormal, causing decreased vision. Normally, blood vessels in the retina do not leak and provide nourishment to the retina and its neural fibers. In diabetic retinopathy, however, the blood vessels leak and cause fluid and blood to enter the retina, particularly the macula. When this becomes swollen and thickened, the macula (center of vision) cannot properly function. This is called macular edema, which causes the central vision to become blurred. This type of leakage in the blood vessels of the retina is called nonproliferative diabetic retinopathy (NPDR) or background diabetic retinopathy (BDR).

Sometimes the blood vessels in diabetes become obstructed, and the part of the retina that depends on those vessels for nutrition is no longer able to function. New blood vessels will then become present to try to provide nourishment to the areas that are no longer able to get the proper nourishment from the blocked vessels. This develops neovascularization, which can cause bleeding and scarring that often leads to severe vision loss and sometimes total blindness. This form of diabetic retinopathy is called proliferative diabetic retinopathy (PDR). Both of these can occur together in the same eye.

Nonproliferative Diabetic Retinopathy (NPDR) and Macular Edema

Normal retinal blood vessels are watertight and do not leak. In diabetes, the retinal blood vessels can become damaged and develop tiny leaks. This is called nonproliferative diabetic retinopathy (NPDR). Blood and fluid seep from the leaks in the damaged retinal blood vessels, and fatty material (called exudate) can deposit in the retina. This causes swelling of the retina. When leakage occurs and causes swelling in the central part of the retina (the macula), it is called macular edema, and vision will be reduced or blurred. Leakage elsewhere in the retina will usually have no effect on vision.

A patient with macular edema, or with exudate in the macula, will usually experience some loss of vision, including blurring, distortion, and darkening. If one eye is affected, the other eye is frequently affected also, though the problem may not be equally severe in both eyes. If the diabetic retinopathy has affected each macula severely, central vision may be lost from each eye. But even if the ability to see detail has been lost from both eyes, the person with severe NPDR will usually be able to get along fairly well by learning to use the areas just outside of the macula to see more detail. This ability to look slightly off center usually improves with time, though the eyesight will never be as good as it was before the macula was damaged by the leakage of blood vessels. So patient who have severe NDPR will usually be able to see well enough to take care of themselves and continue those activities that do not require detail vision.

Proliferative Diabetic Retinopathy

In PDR, large areas of the retinal blood vessels become obstructed causing the retina to lose its source of nutrition and oxygen. When this happens, peripheral, or side vision, is usually reduced, and the patient's ability to see at night and to adjust from light to dark is often diminished.

As a result of this loss of nourishing blood flow, the retina responds by developing new blood vessels that are abnormal and are called neovascularization. The development of neovascularization is the retina's attempt to compensate for the obstruction of its own blood vessels and the loss of nourishment. Many people with diabetes have some obstruction of the retinal blood vessels without ever developing neovascularization; but when neovascularization develops, it is dangerous to the eye. Neovascularization does not nourish the retina properly and may cause other problems. One problem is bleeding into the vitreous cavity called vitreous hemorrhage. A second problem is the growth of scar tissue on the retina. The scar tissue can pull the retina off the back wall of the eye. When this occurs, it is referred to as a traction retinal detachment. Either of these serious problems, vitreous hemorrhage or traction retinal detachment, can lead to severe loss of vision or even total blindness.

Preventing Diabetic Retinopathy

In diabetes, there is too much sugar in the blood. When the blood sugar is constantly or frequently high, many complications occur: eyesight can suffer, heart attacks, stroke, and other blood vessel problems can occur, and one's life span can be shortened. When the blood sugar is maintained at a normal level, between 80 and 120 mg/dl, the complications of diabetes can be reduced, including serious diabetic retinopathy. Controlling blood sugar is the single most important thing a person with diabetes can do to prevent or reduce the complications of diabetes and diabetic retinopathy.

Type 1 diabetes usually begins at a young age. People with Type 1 diabetes must take insulin to survive and to control blood sugar. Most people with Type 1 diabetes take an intermediate-acting type of insulin, such as human NPH or Lente, or a long-acting type of insulin, such as human Ultralente, to provide a small, constant level of insulin throughout the day. In addition, they often take quick-acting regular human insulin before meals to control the rise in blood sugar that occurs with meals. Some people with diabetes wear insulin pumps. People with Type 1 diabetes should test their own blood sugar with a blood sugar-monitoring device or meter several times daily so they can adjust their diet, exercise, and insulin doses to keep the blood sugar level between 80 and 120 mg/dl most of the time. They should follow a controlled diet of carbohydrates and foods that are low in fat and cholesterol. Regular exercise is also very important as it helps reduce blood sugar.

Type 2 diabetes usually starts in adult life and is often not dependent on insulin for control of blood sugar. Maintaining normal weight and a diet low in calories, fat, and cholesterol is very important. Blood sugar can be controlled either with diet alone or in combination with pills to lower blood sugar. In some cases, insulin treatment is also necessary.

All people with diabetes should remain under the care of a general physician, internist, or endocrinologist who has knowledge of the important ways to help people with diabetes carefully control their blood sugar. The doctor will probably measure the patient's hemoglobin A1c, which reflects the average blood sugar level for the past three months, several times yearly, review control of blood sugar, and look for other complications of diabetes.

In addition to the importance of diet and exercise, there are other factors that can affect diabetes. High blood pressure is very bad for people with diabetes because it increases the likelihood of complications, including loss of vision. Blood pressure should be strictly controlled and kept normal if at all possible. Smoking is known to be particularly bad for people with diabetes because it promotes the obstruction of blood vessels.

Finally, the severity of diabetic retinopathy is often related to the length of time the person has had diabetes. It is unusual for someone with Type 1 diabetes to have significant diabetic retinopathy during the first 10 years of the disease. After 10 years, and especially after 20 years, most people with Type 1 diabetes have some retinopathy, although it may not be severe, especially if the blood sugar level has been well-controlled. In people with Type 2 diabetes, the diabetic retinopathy may be discovered shortly after, or sometimes even before, the diabetes has been diagnosed.

All people with diabetes should have regular eye examinations, particularly examinations of the retina through a dilated pupil. This is especially important to those who have had diabetes a long time. This will insure that diabetic retinopathy is not developing or progressing to a level at which laser surgery is required.

New Treatments for Diabetic Retinopathy

Many scientific studies to find new treatments for diabetic retinopathy are currently being conducted. New treatments, which may be helpful for severe macular edema, are the injection of steroid medication into the vitreous cavity, vitrectomy, or both. New drugs to prevent blood vessel leakage or closure, or new blood vessel growth (neovascularization), are also being used; new ones are also being investigated. We will be able to discuss these with you.

Questions and Answers About Laser Surgery

1. What is the purpose of laser surgery?

In nonproliferative diabetic retinopathy (NPDR), leaking blood vessels can cause the retina to become wet and swollen, resulting in macular edema and loss of vision. The goal of laser surgery in NPDR is to stop the leaking from these vessels and to prevent further visual loss.

In proliferative diabetic retinopathy (PDR), neovascularization can cause severe visual loss by bleeding into the eye called vitreous hemorrhage and by developing scar tissue that can pull on the retina and cause traction retinal detachment. The goal of laser surgery in PDRs is to stop the growth of these vessels and to prevent vitreous hemorrhage, traction retinal detachment, and severe visual loss.

2. Will I have to go to the hospital?

Laser surgery is usually done in the doctor's office or in the hospital as an outpatient surgery. You may eat before the laser surgery. After the surgery, you will be able to go home and resume your normal activities without special restrictions.

3. Is the laser surgery safe?

In most cases, no complications occur, but as with all surgery, there are some risks. There is a remote chance that the laser beam might not be aimed properly and the healthy retina might be destroyed and vision lost. Laser may also cause bleeding, new blood vessel growth under the retina, or an unusually large scar. Fortunately, these complications are rare.

For PDR, most patients who receive panretinal laser photocoagulation have already lost some night vision. Panretinal laser photocoagulation may cause more loss of night vision. It is common for the patient with PDR who has had panretinal laser photocoagulation in each eye to have difficulty with night driving. This is not always the case, but it is frequent. Also after panretinal laser photocoagulation, the peripheral, or side vision, is often not as good as before surgery. In a few patients, the pupil remains dilated for many months, and in some very rare cases, the pupil could remain dilated forever. Most patients have some degree of blurring of central vision immediately following panretinal laser photocoagulation. In a few patients, this blurring may be permanent. Usually, this blurring is not great, but on rare occasions it is. Rarely, there is so much swelling inside the eye after laser surgery that the pressure within the eye can become dangerously high. If the pressure becomes very high, the patient will experience a great deal of pain and should promptly call the treating doctor.

4. In NPDR, will the leaking blood vessels be permanently closed by laser, and in PDR, will the abnormal new retinal blood vessels be permanently destroyed by panretinal laser photocoagulation?

In most cases of NPDR that have been treated with laser, the leaking blood vessels remain closed. But because the diabetes continues, it is common for the leakage to begin in new areas. If laser surgery is indicated, however, the chances of controlling blood vessel leakage are much better with laser treatment than without.

In most cases of PDR, the growth of neovascularization is stopped permanently after laser surgery, and most of the neovascularization that was present becomes inactive or disappears. Nevertheless, it is quite possible that the neovascularization will not disappear totally. When only a small amount of neovascularization remains after panretinal laser photocoagulation, it is generally not a problem, and further laser is frequently not necessary. If the amount of neovascularization remaining is great enough, or if it continues to grow after laser surgery, more laser may be necessary. In some patients who have had panretinal laser photocoagulation, small vitreous hemorrhages will occur from time to time. Generally, these are quite mild. If a patient sits up during the day and keeps the head somewhat elevated during sleep, the blood in the eye will settle, and the vision returns to normal within a day or two. Such hemorrhages are called "nuisance" or "tolerable" hemorrhages, and further laser surgery is not usually necessary.

5. Does the laser surgery cause any pain?

For NPDR, laser surgery is almost always painless, though a few patients do experience some discomfort. In rare instances, the eye must be anesthetized to keep it steady for the laser surgery. An anesthetic is injected through the lower eyelid and behind the eye so that it cannot move and will not feel anything. After the laser surgery, the eye is patched for the rest of the day.

In PDR, many patients who receive panretinal laser photocoagulation experience some discomfort or pain. In those patients where the pain is great, is it best to anesthetize the eye. The anesthetic is injected behind the eye. After laser surgery, the eye is patched for the rest of the day. After the anesthetic wears off, the patient may experience discomfort or pain. We can advise you as to the need for pain medication. If the pain is severe, call your doctor promptly as there could be a serious problem.

6. How long does laser surgery take?

Depending on the extent of the problem, laser surgery for NPDR may take anywhere from a few minutes to one-half hour; for PDR, it may take anywhere from fifteen minutes to one hour or more.

7. Are all forms of laser the same?

The various types of laser differ according to their wavelength (or color). The lasers used in treating diabetic retinopathy are argon green, krypton red, tunable dye, and diode infrared. Each wavelength or color is absorbed differently by the tissues of the eye. We will decide which laser is best for your particular situation.

8. Are there any after effects?

Because of the intense brightness of the laser beam, there is a light-dazzle or "flashbulb" effect immediately afterwards, and vision may be very dark or have a purplish hue for 10 or 15 minutes. This is not harmful to the eye. The eye takes a few hours to recover from this glare.

9. What will my vision be like immediately after laser?

Following laser surgery for NPDR, vision is often blurred, but it usually improves within a month. There may be small black areas or blind spots where the laser spots were placed, usually just to the side of the central vision. These blind spots, if present, will be permanent but will become less noticeable as time passes. When grid laser is done, patients may notice a great many spots in all directions from center.

Following panretinal laser photocoagulation for PDR, vision is often blurred, but it usually improves within a month or two. Side, or peripheral vision, and night vision are likely to be reduced permanently. In a few patients, central vision is blurred permanently. Generally, this blurriness is not great.

10. Do I need to avoid any activities after surgery?

After both NPDR and PDR treatments, you may resume normal activities and use of the eyes the same day as laser surgery.

11. How many treatments will I need?

For NPDR, although we are always hopeful that only one laser surgery will be necessary, the blood vessels may become leaky again or new leaks may develop, and for many patients, additional laser surgery is necessary. The need for more than one laser surgery for NPDR is common.

For PDR, one to three laser surgery sessions are all that are usually needed initially. But, if the neovascularization does not go away, or if more develops, additional laser surgery may be required.

12. How does one know if the laser surgery has helped?

Several weeks or months after laser surgery, you will return for a follow-up examination and possibly a fluorescein angiogram. If you had NPDR, the leakage should have stopped by this time. If you had PDR, the neovascularization should have shrunk. If this is the case, the laser surgery will be considered to have been temporarily successful. We will advise you when to return for a follow-up examination.

13. What if the laser surgery did not work?

In NPDR, if there is still a significant leakage and persistent macular edema, additional laser surgery or grid laser may be helpful. In fact, more than one treatment is usually necessary for NPDR. For some cases, further laser surgery may not be helpful. New experimental treatments to control severe macular edema may be helpful in certain cases. These include the injection of a medication into the vitreous cavity, vitrectomy, or both. We will be able to discuss these with you.

In PDR, if there is more growth of neovascularization, or it the neovascularization has not gone away adequately, additional laser surgery may be necessary. If, despite adequate laser surgery, a vitreous hemorrhage develops and does not clear, or if scar tissue forms and wrinkles or detaches the retina, vitrectomy can be performed.

14. Can anything help if central vision is lost in each eye?

Those patients who have lost central or detailed vision in both eyes will be referred to a low vision specialist who helps patients learn to use the remaining vision to its fullest capacity. Low vision specialists can fit magnifying lenses to assist close-up vision and telescopic lenses for seeing at a distance. There are other visual and mechanical devices, including special filters, increased lighting, and special tools for reading that can help patients function better. Patients will learn about books on tape, radio programs that read the news, and support groups to help patients cope with the problems of central vision loss so as to live their lives to the fullest, even with reduced vision.

15. Will using my eyes hurt them?

It is important to know that you cannot hurt your eyes by using them. There is no way in which using your eyes can do your eyes any harm, whether by reading, watching television, or driving for long periods of time.

16. Do I need to wear sunglasses?

There has been some research suggesting that increased exposure to sunlight may be associated with some eye problems. While the connection between exposure to sunlight and damage to the eye has not been proven, it is probably a good idea to use dark sunglasses in bright sunlight, preferably sunglasses designed to filter out blue and ultraviolet light.

17. Is it normal to have trouble adjusting quickly between bright sunlight and dim light?

Many patients who have diabetic retinopathy have difficulty adjusting quickly between bright light and dim light. It may be difficult to adjust when driving from bright sunlight into a dark tunnel or reading a menu in a dark restaurant when one has just come in from bright sunlight. This difficulty can be overcome somewhat by using clip-on sunglasses over regular glasses. These clip-on sunglasses can be slipped off easily when going from light to dark and can then be slipped back on again when going from dark to light.

Questions and Answers About Vitrectomy Surgery For Proliferative Diabetic Retinopathy (PDR)

1. How long will I be in the hospital for my vitrectomy surgery?

You will be admitted to the hospital or ambulatory surgery center the day before or the morning of surgery. Most patients are able to leave the hospital the same day or one day after surgery.

2. How is the surgery performed?

The surgery is performed under general or local anesthesia. Small openings are made in the white part of the eye called the sclera. Small, thin instruments are placed into the eye through these openings. These vitrectomy instruments include a fiber optic light used to light the inside of the eye and a variety of cutters, scissors, and forceps. The surgery is done using a microscope that focuses through the pupil.

3. What are the possible complications of vitrectomy surgery?

There are risks and complications that can occur with any surgery. The risk sand complications that can occur with vitrectomy include: infection, retinal detachment, retinal tear, cataract formation, glaucoma, more vitreous hemorrhage after surgery, and the development of scar tissue. Although these complications can often be managed by further treatment, any one of them may cause the vision to get worse or cause a total loss of vision and perhaps eventual loss of the eye.

4. Are there risks to anesthesia?

General anesthesia always carries a degree of risk. Minor risks include postoperative nausea, vomiting, and hiccupping. Some patients experience an upset stomach following surgery. If nausea does develop, it can be controlled with medication. Occasionally, patients will experience some confusion and prolonged sleepiness. Older men may have trouble urinating. Very rarely, serious reactions occur that may result in liver failure, cardiac arrest, and even death. Local anesthesia involves placement of a needle through the lower eyelid, beneath the eye. There is the rare possibility that the needle could penetrate the eye or cause damage to the optic nerve.

5. Will my eye hurt after surgery?

Most patients will note some discomfort around the eye that can be relieved with medication if necessary. Severe pain is very unusual. The eye will remain swollen, red, and somewhat tender and uncomfortable for several weeks. Itchiness or a scratchy, foreign-body sensation when opening or closing the eyes is common. This is cause by small stitches. These stitches will gradually become soft and fall out or be absorbed.

6. What is I do experience a great deal of pain?

If you experience a great deal of pain, please let your surgeon know promptly. Pain can be an important symptom indicating infection, excessive pressure in the eye, or injury to the front surface of the cornea. You should notify your surgeon promptly if you are experiencing more that mild pain.

7. What instructions must I follow when I go home after surgery?

We ask that patients not engage in strenuous activity or exercise for about a week after surgery. They may return to work or to driving when they feel able to do so; this is usually within a week or two. They are encouraged to take walks and engage in normal activity as soon as possible.

If a patient has had the front surface of the cornea removed during surgery, a snug "pressure" patch or a bandage contact lens may be applied to the eye until the front surface heals. It is alright to remove the patch temporarily when eye medications are given.

If a gas bubble has been placed in the eye to hold the retina in position, the patient may be asked to lie face down or on one side. Usually, the patient is required to remain in this position most of the time for several days. This positioning will place the gas bubble in the correct position within the eye so that the retina stays in place. If a gas bubble is in your eye, you should not sleep on your back. Otherwise, the gas bubble rises and rests again the lens of your eye and may cause a cataract. Also, the gas bubble may rise and close off the normal flow of fluid out of the eye, which will increase the pressure in the eye. If a gas bubble has been used as part of your surgery, you may not travel by airplane until the gas bubble has absorbed, and travel to high altitudes should be done in a gradual fashion. It usually takes several weeks for the gas bubble to disappear. We will advise you as to when you may lie flat on your back and when you may travel by air.

8. What medicines do I use after surgery?

Most surgeons will use a type of dilating drop that eases the discomfort of the inflamed eye. An antibiotic drop may be used to help prevent infection. A steroid drop is often used to reduce inflammation and make the eye more comfortable.

If your surgeon is concerned about increased pressure in the eye, pressure-lowering eye drops or oral medications may be prescribed. Your surgeon will decide when to stop these medications, but most drops are used for a few weeks. If you run out of medications, call your physician and ask if more are required.

9. How long will I need to wear a patch or metal shield?

The patch may be worn for up to one week for the patient's comfort. In most instances, it plays no role in the healing of the eye.

The use of a metal shield may be encouraged for protection. If a patient normally wears glasses, they may be work over the patch during the day and the metal shield worn at nighttime. We will advise you whether a patch or shield is necessary.

10. Will I see better right after surgery?

The eye and the retina may take several weeks to fully heal. When vitrectomy is done for a vitreous hemorrhage, there will always be some blood left. This causes some cloudiness of vision that may take several weeks to clear.

There may be oozing of blood from the retina after surgery, which may result in even more vitreous hemorrhage. This hemorrhage usually clears after several days to weeks. If it does not clear, it can sometimes be removed on an outpatient basis by removing the fluid in the eye and replacing it with a gas bubble. The gas bubble will slowly disappear over several weeks and be replaced by clear fluid made by the eye. Infrequently, it may be necessary to reoperate in order to remove this repeat hemorrhage.

If surgery has been performed for a retinal detachment, it will take time for the retina to resume its normal position again the back wall of the eye.

When retinal tears are present, gas may be used to fill the eye at the end of surgery. The gas is used to press the retina flat again the back wall of the eye. The vision will be very poor until the gas bubble disappears.

Often the retina is treated with laser during the surgery. This is done to keep it attached, to seal retinal tears, and to prevent the growth of neovascularization. A special laser instrument is placed inside the vitreous cavity of the eye to do this. This laser surgery can result in inflammation and cloudiness that may take a few weeks to clear.

Improved vision after retinal surgery is not immediate. It may take several months before the vision improves to its best possible level. In most cases, when the diabetes has caused such damage to the retina that vitreous or retinal surgery is necessary, the eye will never again see normally. Sometimes, small amount of visual impairment occur, and occasionally, a great deal of improvement occurs. Each eye is different. Before your surgery, we will discuss with your chances for better eyesight.

11. Is it possible that I might not see after surgery?

Despite our increasing knowledge of diabetic retinopathy, and despite the sophisticated surgical equipment and techniques that we bring into the operating room, we may find ourselves unable to improve a patient's vision. The chance for blindness in PDR is very real. When considering surgery, the patient and the doctor together must weigh the risks, including the possibility of total blindness, against the possible benefits of either stabilizing or improving vision. It is important for the patient to know that surgery may fail because of complications or simply due to the progressive nature of diabetes.

Malignant Melanoma of the Eye

A melanoma is a malignant tumor that most often arises in the skin. Less commonly, it is found in the eye and other sites of the body. In the eye, melanoma arises from the pigmented cells (melanocytes) of the uvea (iris, ciliary body, or choroid). Melanoma carries the potential to spread from the eye to other parts of the body. Larger melanomas carry greater potential to spread than smaller tumors.

Melanoma affects approximately 2,000 to 2,500 people in the United States each year. It affects about six people per million population per year. Importantly, melanoma of the eye typically occurs in fair-skinned, blue or green-eyed men or women. Rarely is this tumor found in dark-skinned individuals. Hence, it is relatively rare in Asia and Africa.

The cause of melanoma is unknown. It has not been related to nutrition, smoking, drinking, or any environmental cause. Chronic sun exposure may play a role, but this is debatable. Melanoma almost always affects only one eye, and it is not hereditary. Therefore, family members are not at increased risk for this cancer. It can develop in an otherwise healthy patient.

The uveal melanoma is rarely diagnosed in children. In most situations, the median age at diagnosis is about 55 years. The rates of melanomas drop in both sexes after age 70 years. This is contrast of the majority of adult cancers in which the incident increases exponentially with age. In addition, uveal melanomas tend to be diagnosed nearly a decade earlier than most adult cancers.

Over the last several decades, a variety of alternative therapies to enucleation have been introduced for the treatment of intraocular melanomas in an effort to preserve the eye and whatever possible useful vision. The most commonly used methods today include radiation using charged particles (proton and helium ions), radioactive plaques such as Cobalt (Cobalt 60), iodine (iodine-125), and ruthenium (ruthenium-106), and local resection. Newer approaches include transpupillary thermal therapy in conjunction with or without simultaneous plaque radiotherapy, episcleral iridium water therapy, ultrasonically-induced hyperthermia as an adjunct to plaque therapy, palladium (palladium-103), Gamma-knife radiosurgery, and microwave thermotherapy combined with plaque. The vast majority of patients treated with plaque therapy retain full functioning in vision-related activities, particularly if the melanoma is outside the area centralis.

Benign-Appearing Choroidal Nevus

Like a raised freckle on the skin, nevi can also occur inside your eye. The most common choroidal nevus are unusual and can only be seen by a dilated eye examination. Like a nevus on the skin, a choroidal nevus can grow into a malignant melanoma. This is why it is important to be followed on an annual basis as these can lay dormant for 10 years and suddenly develop into a malignant melanoma.

A choroidal nevus rarely requires treatment. Photography is typically used to document the size of a choroidal nevus. If the nevus has an orange pigmentation, is leaking fluid, or is 2 mm or greater in size, it may become a malignant choroidal melanoma.

Depending upon its appearance, patients with a choroidal nevus should have their eyes examined at least every year. Currently, photography and fluorescein angiogram are valuable tools with examination to assess whether or not the nevus has changed over time or whether it is developing vascularity, which may be leaking. If the choroidal nevus has orange pigment or has thickened, it should be checked more often. If a choroidal nevus is leaking subretinal fluid, this is a particularly ominous sign. Such tumors should be followed more closely for evidence of growth or malignant transformation into a choroidal melanoma.

It is reasonable to have a retinal specialist or ophthalmologist check your choroidal nevus to see if it looks suspicious. This examination may include the use of ultrasonography, specialized photography, such as fluorescein angiogram, and optical coherence tomography (OCT) testing. It is a good idea to keep a picture of your choroidal nevus so that, if you were to transfer ophthalmologists or retinal specialists from one are of the country to another, you have a baseline by which a new examination can be compared. This picture can therefore be compared to future examinations to help determine if the nevus has changed or stayed the same.

Rarely a choroidal nevus can leak or be associated with the growth of abnormal blood vessels. These changes can cause a localized retinal detachment/degeneration, flashing lights, and loss of vision. A typical choroidal nevus is asymptomatic, causing no symptoms, and is usually found on a routine dilated examination with ophthalmoscopy.

A choroidal nevus is usually a pigmented tumor of the blood vessel layer called the choroid, which is beneath the retina. A choroidal nevus is typically grey but can be brown, yellow, or variably pigmented. Examination will reveal whether or not the choroidal nevus is raised, meaning it has thickness, or whether there is orange pigment called lipofuscin, or is leaking fluid, which is called subretinal fluid. If the choroidal nevus has one or more of these findings, it is labeled as a suspicious choroidal nevus that might manifest into a small choroidal melanoma.

A choroidal nevus can also have yellow-white dots on the surface called drusen. This is a sign that the choroidal nevus is preventing the eye from removing retinal waste products. It is also a sign that the choroidal nevus has been present for a long enough time for those waste products to accumulate. There are no studies to show how long it takes for drusen to form on a choroidal nevus.

Treatments for a benign choroidal nevus are not required. There is no way to safely remove them. Since the choroidal nevus can turn into a choroidal melanoma, it is recommended to have it periodically checked by a retinal specialist.

The differential diagnosis of choroidal nevi can be congenital hypertrophy of the retina pigment epithelium combined, hamartomas of the retina pigment epithelium, choroidal metastases, or choroidal hemangiomas. The differentiation of this is usually done by a retinal specialist. Followup is advised even though calculations of Ganley and Constock in the American Journal of Ophthalmology, 1973, showed that only 1 of 500 patients with choroidal nevi will develop a malignant change in a 10-year period.

A suspicious nevi usually has the presence of two of the following features:

1. Largest diameter is between 2 and 5 disc diameters.
2. Thickness is from 1-2 mm.
3. There is a significant effect on the overlying structures with most important being the presence of orange pigment on the tumor surface.

The presence of subretinal fluid and visual field defects is of little significance.

High-Intensity Distracting Lights of Emergency Vehicles at Accident Scenes

When truck drivers approach accident scenes with multiple vehicles, including police, fire trucks, and EMS, with their new, high-intensity lights, this can be blinding and a danger to the truckers. The two questions to address are:

1. Is this damaging to my eyes?
2. How can I deal with this situation?

In addressing the first question, "Is this damaging to my eyes," there is no direct damage to the eye that is permanent. What occurs is that the rods and cones of the retina are affected by the overstimulation of the high-intensity light. Therefore, there is a normal period of time with which the eye has to recover. The typical amount of time for recovery is approximately 12 minutes. This can occur when you are sitting in a doctor's office and he shines lights into your eyes to see the back of your eye or when being blasted by high-intensity lights from emergency vehicles. This approximate 12-minute period is required whether you are at the scene of an accident with high-intensity lights or in a doctor's office who is examining your eyes with bright lights. There is no damage to the eye.

In addressing the second question, "How can I deal with this situation," the first issue is you must be aware this will not be permanently damaging to your retina or cause blindness to the eye. The best practice to prevent this would be avoiding the lights by turning your head or wearing dark sunglasses to minimize the effect of the high-intensity lights. The best solution is to anticipate that it will take 12 minutes to recover from this. It would be advantageous to drive slowly, avoid the direct visualization of the light by looking at the edge of the road or center line to maintain your safety but avoid the direct confrontation of these high-intensity lights.

Again, the effect is not a permanent one, and there is no permanent damage done to the retina of the eye. Avoiding it by looking elsewhere or wearing dark sunglasses are the best techniques to minimize the discomfort while passing the motor vehicle accident or other emergencies you may encounter while on the road.