Ординатура / Офтальмология / Английские материалы / The Eye Care Sourcebook_Lavine_2001

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and is also sent for culture, we can determine which bacterium is causing the infection. That may help guide our choice of antibiotic. Many ophthalmologists do not routinely perform such a culture before beginning treatment, but I think it is a good idea, at least in those cases in which there is a great deal of discharge. Performing a culture later on, after antibiotic treatment has been begun, is less likely to allow identification of the infecting bacterium.

Getting Eyedrops into a Child’s Eyes

For many children, it may not be difficult. Calm reassurance may be all that is necessary. I usually explain that we’re going to put a little, cold drop of water in the eye. Drops do feel a little cold, and cold has a numbing connotation. When you are expecting a cool or cold sensation, you anticipate it and are less likely to mind any stinging that may accompany it.

But if you can’t gently pry the child’s eyelids open, it’s best to avoid a fight, which will only make it worse the next time around. Instead, try the following technique. Have the child lie down on his or her back and with eyes closed. Place two or three eyedrops in the little well between the inner corner of the eyelids and the bridge of the nose. Sooner or later, the child’s eye will have to open. When that happens, at least some of the drops will go in the eye! You may lose a little of the medication, but better than not getting it in at all.

Allergies and the Eye

The hallmark of eye allergy is itching. Itching may be one of the symptoms of other problems, such as blepharitis and dry eye syndrome, but with allergies it is by far the most prominent. Allergies occur in response to antigens—substances that cause the immune system to react. The cells of the immune system release substances that cause itching, dilation of blood vessels, swelling, hives, and other effects, such as wheezing. The antigens may come from the air or be introduced into the eye by the fingers or instillation of eye medications.

Hay Fever

Hay fever is one of the most common eye allergies. It is seasonal, occurring only when pollen or other offending substances, such as molds, are present in the air. Dust, animal dander, and chemicals may also be problematic. Itching

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and scanty mucous discharge are common. The conjunctiva may swell, as may the eyelids. The eye may or may not become red. Sneezing and itching of the throat are often present as well.

Treatment is aimed at reducing or preventing the symptoms in the safest way. Obviously, avoidance of the source of allergy, if possible, is the ideal approach. Air filters and avoidance of cigarette smoke can also be helpful. Rubbing the eyes should be avoided, as this can increase the itching, swelling, and redness. Simply splashing a little cool water in the eye from time to time washes out some of the antigen adhering to the tissues of the eye and soothes the eye as well.

Artificial tear drops, preferably preservative free, sold over the counter as a lubricant for the eye, can accomplish the same thing. As the next step, over-the-counter drops contain-

ing both an antihistamine (pheniramine or antazoline) and a decongestant drug can be used. The antihistamine counters the effects of histamine, one of the chemicals released from the cells. The decongestant constricts the blood vessels in the eye, which can also help control symptoms. Decongestant-containing eyedrops should not be used on a long-term basis, however. The eyes become “hooked” on them, and rebound redness occurs when their blood vessel– constricting effects begin to wear off.

Various prescription remedies are also available. Levocarbastine (Livostin) and emedastine (Emadine) are antihistamines that are used alone without a decongestant. Some drugs of the nonsteroidal anti-inflammatory class,such as ketorolac (Acular), are available as eyedrops and can effectively combat the symptoms as well. This class of drug was originally used for the treatment of arthritis.

The antihistamine drugs mentioned before work by blocking the action of histamine after it has already been released by the cells. Other drugs work by preventing the release of histamine and other substances from the cells involved in allergic reactions. These preventive drugs include cromolyn sodium (Opticrom and Crolom), lodoxamide (Alomide), nedocromil (Alocril), and permirolast (Alamast). For optimal effectiveness, they are generally used continuously during the allergy season, as they do not affect the symptoms caused by histamine once the histamine has been released. A recent study showed that lodoxamide was superior to cromolyn sodium in the treatment of vernal conjunctivitis (described on page 101). Olopatadine (Patanol)

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and ketotifen (Zaditor) have a dual effect: They not only prevent the release of histamine; they also block its action.

Corticosteroid (cortisone) medication is well known for its anti-inflammatory and antiallergic properties. It is also well known for its many side effects. Corticosteroid eyedrops are very effective at relieving allergic symptoms, but with long-term use they can cause cataracts of the posterior subcapsular type, and they can raise the pressure in the eye, causing a transient secondary glaucoma. They can also reduce the resistance of the eye to infection and can allow the growth of bacteria and fungi that are dangerous to the eye. Thus, these drops are used only when necessary and then only on a short-term basis.

When allergy or any other source of irritation affects the eyes, congestion and overactivity of the tiny oil glands in the eyelids may occur. This produces an inflammation of these oil glands. Some people are predisposed to this type of problem because of the way their oil

glands operate. This oil gland inflammation, or blepharitis, can produce symptoms of its own, exacerbating the allergic problem. These symptoms include burning, feeling of some-

thing in the eye, tearing, crusting on the eyelid margins, and eyelashes stuck shut on awakening in the morning. Even worse, the blepharitis may become self-perpetuating and persist even after the allergy has resolved. Treatment of blepharitis entails carefully cleaning the eyelashes and margins of the eyelids with water and diluted baby shampoo anywhere from one to four times a day. (See “Blepharitis,” page 59, in chapter 6.)

Acute Allergic Reactions

Whereas hay fever normally begins almost imperceptibly, we occasionally see someone who suddenly develops extreme itching and swelling in one eye. The swelling may be so severe that the conjunctiva balloon outward and almost hang over the edge of the lid. This kind of reaction may occur after you touch a plant or blossom and then later rub your eye. The appearance of the eye when this happens can be frightening. If this happens to you, try to rinse the eye out with cool water right away. If you have any antihistamine pills for allergy or antihistamine/decongestant eyedrops, use them. Hold a cool, moist washcloth over the closed eye. In some cases, we may instill a corticosteroid

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drop as well. The good news is that this condition resolves very quickly because the foreign substance (antigen) that got in the eye gets washed out and there is no continuing exposure to the antigen. Generally, the eye looks much better in twenty-four hours and is almost back to normal in forty-eight hours.

A different kind of reaction can sometimes occur when people are outside, perhaps in their yard, and a tiny bit of organic matter, dirt or plant, gets in an eye. Rather than itching or swelling, one sector of the white of the eye becomes red, and there may or may not be any other symptoms. This redness may persist for days or weeks but usually goes away on its own. (See “Episcleritis,” below.)

Vernal

Vernal keratoconjunctivitis, as it’s officially known, is a type of allergic problem that occurs in children, especially boys, and may persist into adulthood but often improves with time. It produces a great deal of itching, mucous discharge, and tearing, and it is most prevalent

when the temperatures are warm. It may affect the inside lining of the eyelids or the conjunctiva right at the edge of the cornea. The disease causes the formation of small,

blood vessel–containing bumps in these areas that can easily be seen on examination. A form of scarring may occur on the upper part of the cornea, and, in the most severe cases, an ulcer may even form in this area.

Treatment of vernal is similar to hay fever treatment. Avoiding exposure to the pollen or dust by filtering the air or moving away from a hot, dry climate can help. Preventing the release of histamine is the goal of medical treatment, and this involves the continuing use of drops like cromolyn sodium and lodoxamide, as described earlier. As a last resort, corticosteroid drops can be used on a short-term basis to get the disease back under control.

Episcleritis

Episcleritis is an inflammation on the surface of the eye that, like conjunctivitis, causes the blood vessels to be dilated, thereby giving the appearance of redness. But the appearance differs from conjunctivitis in two important ways.

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First, usually only one portion of the eye is involved, for example, the side toward the nose or the side toward the temple, whereas in conjunctivitis, the white of the eye becomes red all over. Second, episcleritis involves primarily the deeper blood vessels, those next to the sclera, the white coat of the eye. Conjunctivitis, in contrast, involves mainly the more superficial vessels. Episcleritis may cause discomfort or a feeling of irritation, or there may be no symptoms at all. It generally occurs in young adults, and either one or both eyes may be involved.

Two types of episcleritis exist: simple and nodular. Simple episcleritis, the more common form, presents pretty much as just described. Nodular episcleritis looks similar, but on close inspection, one can see one or more small bumps (nodules) that have formed in the conjunctiva in the area of redness.

In some cases, it may not be obvious on first examination whether one is dealing with episcleritis or conjunctivitis. Two techniques can help differentiate between the two. First, the doctor can numb the eye with an anesthetic eyedrop and then lightly manipulate the conjunctiva with a cotton-tipped applicator. In episcleritis, the dilated blood vessels, which are deep down and attached to the sclera, do not move as the conjunctiva moves over them. In conjunctivitis, the blood vessels move. A second technique is to instill a vasoconstrictor (decongestant) eyedrop in the eye. These are the familiar over-the- counter eyedrops for “getting the redness out.” Some of the redness may go away with conjunctivitis, but there will be no change with episcleritis.

Causes of Episcleritis

The cause of episcleritis is often obscure, but it represents a derangement of the immune system. You might think of it as a strange kind of allergic reaction. Some people with episcleritis have an underlying medical problem, such as rheumatoid arthritis or lupus. But most people with episcleritis have no such problems. Occasionally, a small piece of dirt or decaying material from the backyard may get in someone’s eye and trigger the reaction. Other people may have an underlying chronic blepharitis. (See “Blepharitis,” page 59, in chapter 6.) Substances produced by the bacteria that become overgrown in this condition can cause a number of allergic types of reaction in the eye, one of which is episcleritis. Wearing contact lenses seems to increase the risk of episcleritis as well.

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Treating Episcleritis

Treatment depends on the form of episcleritis and whether symptoms are present. Simple episcleritis often goes away on its own after a few weeks. Therefore, if there are no symptoms, no treatment is needed. Episcleritis rarely causes any damage of a permanent nature to the eye, so

such a “hands off” approach is often best. However, if it fails to improve on its own or if significant symptoms are present, then treat-

ment with mild anti-inflammatory drops such as prednisolone (a cortisone medication) usually does the trick. The drops must be tapered gradually; stopping them suddenly may cause a rebound in the inflammation. Nodular episcleritis responds to this treatment as well. Unfortunately, episcleritis has a tendency to recur, especially if an underlying eye or general medical problem is present.

Pterygium

A pterygium is similar in appearance to a pinguecula (see “Pinguecula,” page 105), but instead of remaining in the conjunctiva, it begins to grow over the cornea. As with pingueculae, they are generally seen on the side toward the nose. The most aggressive, rapidly growing ones contain many blood vessels. Older, more slowly growing pterygia may be lacking in blood vessels and often reach a point where they are no longer growing. Extensive exposure to the ultraviolet radiation from the sun as well as the irritative and drying effects of wind and dust are probably the causes. Pterygia are much more common in sunny and tropical areas than they are in places where the sun exposure is less.

Ophthalmologists who practice in the midwestern and northeastern portions of the United States generally regard pterygia as harmless growths that rarely require surgical removal. People in the Sun Belt areas, in contrast, sometimes see aggressively growing pterygia that may distort the curvature of the cornea or even grow over the pupil of the eye, obstructing vision. Clearly, active pterygia such as these should be removed.

When to Remove Pterygia

In general, if a pterygium is not growing rapidly or causing any problems, it is best to leave it alone. Up to 40 percent of pterygia grow back after being

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removed, and these recurrent pterygia sometimes grow more rapidly than they did before removal.

Newer surgical techniques are improving the results and lowering the recurrence rate, but a conservative philosophy about removing these growths is best. In general, a pterygium that has grown

a distance of less than 1 millimeter onto the surface of the cornea should simply be observed. If it is 1 millimeter or more onto the cornea and is showing signs of active

growth, with a “juicy,” blood vessel–rich appearance, it should be removed. Waiting longer only results in a still more aggressive pterygium that is all the more likely to grow back.

Removing Pterygia

A pterygium can be surgically removed in a variety of ways. One of the more promising approaches involves transplanting a piece of conjunctiva into the area where the pterygium is removed. This piece of conjunctiva comes from elsewhere on the eye where it is not needed. In addition to surgery, other treatments are sometimes performed to reduce the chance of a recurrence. For example, chemicals like thiotepa or mitomycin C, which interfere with rapidly growing cells, can be applied to the eye. Alternatively, a type of radiation called beta radiation can be applied to the eye immediately after the surgery. The problem is that all of these approaches can have side effects. For example, severe thinning of the sclera, the white coat of the eye, may occur many years after beta radiation, at least according to some studies.

Preventing Pterygia

As with everything in medicine, the best approach to pterygia is prevention. People who spend a great deal of time in the sun should wear glasses that absorb the ultraviolet rays of sunlight. Many of the better sunglasses have this type of protection, and regular prescription glasses can be made to block out the ultraviolet as well. Glasses or goggles to protect the eyes from the drying effect of wind and the irritating effect of dust can also be helpful to people who work or play in windy environments.

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Pinguecula

A pinguecula is a white or yellowish irregular bump that appears over the white of the eye on either side of the cornea, although most commonly on the side toward the nose. It actually forms in the conjunctiva. The conjunctiva in these areas undergoes a kind of degeneration after years of exposure to sunlight and to wind. Thus, pingueculae frequently occur in people who work outdoors, especially in hot, sunny climates. As opposed to a pterygium (see “Pterygium,” page 103), a pinguecula does not grow onto the surface of the cornea.

A pinguecula may go unnoticed for a very long time. Sometimes people with a slightly reddened, irritated eye notice a whitish bump, which prompts them to see their doctor right away. They complain that a growth has suddenly appeared on their eye. Of course, the pinguecula didn’t suddenly appear. It was there all along but couldn’t be seen because its color was similar to the color of the white of the eye. When the eye became reddened, however, the pinguecula stood right out because the thickened, opaque tissue did not become red as the rest of the eye did! A little reassurance is all that is needed in this situation.

Pingueculae may grow very slowly over the years. They occasionally become irritated, and over-the-counter artificial tear drops or decongestant drops can be used, although sometimes a very weak steroid (cortisonelike) eyedrop is prescribed. Surgical removal is rarely needed, but if they become so large that they interfere with contact lens wear or if their cosmetic appearance becomes unacceptable, they can be easily removed as an office procedure.

Subconjunctival Hemorrhage

A subconjunctival hemorrhage is simply a small spot of blood that collects between the conjunctiva and the sclera. It may cover only a small area or the entire white of the eye. Typically, people don’t even know it’s there until they look in the mirror and get the shock of their lives! These hemorrhages don’t cause pain, but sometimes people begin to imagine a pain or ache after seeing what the eye looks like. The only real feeling that may be present is an occasional feeling of something in the eye.

Most of the time there is no obvious cause for a subconjunctival hemorrhage. Sometimes a hard sneeze or a bout of coughing causes a tiny blood vessel to

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break. Any trauma to the eye, including small foreign bodies, can cause the bleeding. Less commonly, an underlying eye problem is present. Some severe forms of viral conjunctivitis (viral infection of the eye) can cause hemorrhages. In this situation, the ophthalmologist can see dilated blood vessels on the eye, as in any case of conjunctivitis. However, conjunctivitis generally causes pain, watering, and occasional light sensitivity, so it is usually obvious that an infection is present. Sometimes we can see dilated, deep blood vessels in only one segment of the eye. This is called episcleritis (see “Episcleritis,” page 101), a kind of allergic reaction on the eye. Episcleritis may cause no symptoms at all, but usually a person with the condition sees the localized dilated blood vessels on the eye before the hemorrhage occurs.

A subconjunctival hemorrhage is one of those things that look much worse than they are. No harm comes to the eye from it. The treatment is simple reassurance. It takes up to three weeks for the red spot to go away. Some people make up a good story about someone hitting them in the eye. But if it becomes too much of a “conversation piece,” you may require sunglasses to get you through the three weeks!

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Eye Muscles

THE ADVANTAGE OF HAVING TWO EYES THAT WORK TOGETHER is something that most of us don’t normally think about— until one eye is patched shut after an injury. Have you ever tried to drive a car

with just one eye open? It’s not easy, unless you’re used to it. Having two eyes that work together allows a kind of depth perception that most of us have learned to rely on. Without it, we have great difficulty judging distances. Even if our eyes do work together most of the time, we may experience headache and other symptoms if we have weak eye muscles that become strained as we try to keep our eyes straight and aligned with each other. If, as adults, one of our eyes suddenly turns in or out, we have double vision, which makes it impossible to function until one of the eyes is covered. Since eye straightness problems are more common in children than adults, we will begin by focusing on the common pediatric eye muscle problems. In most cases, these are problems that are recognized right after birth or in early childhood. It should be emphasized that in any person, child or adult, in whom an eye suddenly deviates and stays that way, immediate medical attention is imperative. The problem could be the result of a nerve palsy and reflect a serious problem in or around the brain.

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