Ординатура / Офтальмология / Английские материалы / The Eye Book A Complete Guide to Eye Disorders and Health_Cassel, Billig, Randall_2001

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think might be caused by a blood clot, call your doctor immediately. Prompt treatment may save your vision— as well as your life!

Finally, in rare instances hormone supplements can cause other side effects, including double vision (caused by loss of function of the extraocular muscles, the muscles that move our eyes); optic neuritis (inflammation of the optic nerve); increases in myopia (nearsightedness); and damage to the macula (the part of the retina that provides central vision) secondary to fluid swelling. Except when there has been retinal photoreceptor damage, these side effects are reversible when the medications are discontinued. Women taking hormonal supplements should see their eye doctor routinely.

Steroids

Steroids, such as prednisone, mimic the action of the body’s own hormones (particularly those produced by the adrenal glands to control inflammatory reactions in the body). They’re most often prescribed for diseases in which there’s major inflammation in multiple areas of the body—including rheumatoid arthritis, giant cell arteritis, Crohn’s disease, sarcoidosis, and systemic lupus erythematosus. Long-term steroid use can cause many other problems, including posterior subcapsular cataracts and changes in intraocular pressure.

Posterior subcapsular cataracts occur in 30 to 49 percent of the people taking 10 to 15 milligrams of prednisone daily for one to two years. These cataracts can be

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very dense and cause a rapid loss in vision. Even worse, they don’t go away if you stop taking the medication, and they are only treatable by surgical removal (see chapter 7).

Changes in intraocular pressure, although not as common as cataracts, are still a serious problem. Steroids— whether taken orally or topically, or injected around the eye—can lead to glaucoma by causing an elevation in eye pressure, usually after prolonged use. When the eye’s fluid pressure builds beyond the normal range, this can cause significant damage to the nerves in the retina that process visual images and can lead to glaucoma (see chapter 8). The good news is that this intraocular pressure usually returns to normal if the steroid is discontinued. The bad news is that any damage caused by the increased intraocular pressure remains.

Steroids can also damage the eyes indirectly. For example, prolonged steroid use can raise someone’s blood sugar, causing diabetes. Skyrocketing levels of sugar in the blood can produce a shift in the focusing power of the eye’s crystalline lens, making nearsightedness worse (or actually causing farsightedness to improve); it may also cause vision to fluctuate. Other ocular changes from diabetes can result as well. (For more on the ocular effects of diabetes, see chapter 18.)

Steroid use can raise someone’s blood pressure, and as we discussed in chapter 18, this can damage blood vessels within the retina, causing hemorrhaging and damaging nearby nerve tissue. People on high doses of steroids should see their eye doctor every three to six months.

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Other Medications That Can Cause Problems

in the Eye

Chloroquine and Plaquenil

As far as the eye goes, chloroquine and hydroxychloroquine (Plaquenil) are serious, potentially toxic drugs (although Plaquenil seems to cause considerably fewer eye problems than chloroquine), and if you’re taking one of these medications, such as chloroquine for malaria or Plaquenil for arthritic problems, we recommend that you be checked thoroughly for any signs of side effects at least every six months.

The big worry here is retinal toxicity (drug-caused damage to the retina). Fortunately, regular eye exams can detect changes in the retina (mainly in the pigmentation) very early; and these changes can diminish or go away altogether after you stop taking the drugs.

Regular eye exams are so important because in their earliest stages these retinal changes cause no symptoms. (Rarely, the visual field can be damaged even if there aren’t any obvious retinal changes.) The most common vision problems attributed to the retinopathy, or retinal changes, include difficulties with reading and seeing (such that words, letters, or parts of objects appear to be missing), blurred distance vision, missing or blacked-out areas in the central or peripheral vision, light flashes, and streaks. Difficulty seeing red targets (sometimes called premaculopathy) may also be an early warning sign; this usually goes away when therapy is stopped. In fact, most

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of these side effects seem to be reversible. (However, for some people they actually continue to progress, and unfortunately, there’s nothing that can be done.)

Another unfortunate twist is that in a few people taking chloroquine, retinal damage has shown up several years after the antimalarial drug therapy was stopped— another reason why regular eye exams are so important, whether you’re having symptoms of any trouble or not!

Lovastatin (MEVACOR, MSD)

Lovastatin works by specifically inhibiting an enzyme in the liver needed to synthesize cholesterol, and its goal is to lower someone’s risk of having a heart attack or stroke by reducing levels of “bad” cholesterol in the blood. But many patients have recently begun to worry that taking these drugs might cause other problems— namely, the development of cataracts.

The good news is that they probably don’t. So why all the fuss? It seems to have started when lovastatin was in the “clinical evaluation” stage of testing, being put through its paces in humans after laboratory and animal tests, to make absolutely certain that the drug was safe. Part of the battery of tests included checking the eyes. Early studies on lovastatin seemed to suggest an association between its use and the development of cataracts; however, because the tests were highly subjective, this link remained unclear. Later, after a three-year doubleblind controlled trial, investigators were not able to show any clear tie between the drug and the development or progression of cataracts.

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Tamoxifen (NOLVADEX, Zeneca)

As part of their treatment for breast cancer, some people take the chemotherapy drug tamoxifen. In a very small segment (less than 1 percent) of them, tamoxifen produces certain side effects in the eyes.

The most common eye problem tamoxifen may cause is a retinopathy, characterized by small deposits— thought to be by-products of retinal nerve tissue dys- function—found in the retina’s inner layers. Although not particularly troublesome by themselves, these deposits often serve as signposts of more significant trouble, because they are sometimes linked with macular edema and retinal hemorrhages that may compromise vision. These retinal lesions usually go away once a person stops taking the drug.

Other side effects can include corneal and lens changes. In the cornea, tamoxifen deposits can build up, leaving superficial erosions and opacities; these usually regress when tamoxifen is stopped. In the lens—again, very rarely—these tiny deposits may cause irreversible cataracts, which may require surgery.

All of these side effects seem to be dose-dependent: people who take conventional doses of tamoxifen have much fewer, and much more minor, drug-related eye problems than those taking higher doses.

A P P E N D I X

A Guide to Eye Medications and Their Side Effects

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This table provides an overview of the more common medications used to treat eye conditions. It will help put in perspective some of the drops, ointments, and pills you may use or hear about. Using this table, you will be able to identify these medications by category (such as antibiotics or glaucoma medications) and by their generic names as well as their aliases, or “brand names.” You will also have a pretty good idea of the potential side effects of these medications.

Our side-effect list might appear formidable at first glance. In fact, after looking over this list of potential side effects, you may even ask why anyone would want to take any of these medications at all! And we have not even listed every side effect that has been attributed to each medication—only those we believe are the most important. The reality, however, is that most of these side effects are not common; they occur infrequently. Moreover, your doctor would not prescribe a medication for you unless she or he felt that the benefit of the treatment far outweighed the risk of developing a reaction. Of course, if you are allergic to sulfa or have a history of reactions to any of these drugs, you should discuss this with your doctor. Package inserts and information provided at the time of drug dispensing are also very important, and you should read such information carefully to check the safety of the medication for you. After all, the best person to watch out for you is you. Don’t be afraid to ask questions if something does not sound right or if something concerns you.

There are basically two types of reactions to medications: allergic and toxic. In allergic reactions the eye recognizes the medication as foreign and attacks it. These reactions are generally mild, causing symptoms of eye irritation and itching that are often accompanied by conjunctival redness and swelling. Once the medication wears off or is washed out, the eye feels a lot better. Toxic reactions, on the other hand, are usually more severe and may damage or inhibit function of the eye or other organs. Many toxic reactions are reversible once there is no longer any contact between the tis-

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sue and the medication, but recovery from a toxic reaction—such as a reaction that causes damage to corneal epithelial cells or retinal pigment epithelium, for example—can take days or months. Fortunately most ocular side effects from a medication, whether allergic or toxic, usually go away without doing permanent damage to a person’s sight.

When taking any medications, it is essential that you discuss any unusual signs or symptoms with your prescribing doctor as soon as you notice them.

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Anesthetics

Bupivacaine

Lidocaine

Proparacaine

Tetracaine

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Ocular: Allergic reactions causing redness and itching.

Chloromycetin Ocular: Allergic reactions causing burning or stinging.