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

410 / OTHER THINGS YOU NEED TO KNOW

further irrigation, debridement—removal of foreign particles or injured tissue—medication, or an eye patch.)

“Black Eye” and Other Trauma

No matter how you got it—by falling, being punched, or getting elbowed while shooting hoops—the same injury that causes the classic “shiner” can cause severe internal eye damage, which may include bleeding within the eye, iritis (arthritis-like inflammation in the eye), glaucoma, double vision (due to difficulty moving the eye), a detached retina, and even temporary or permanent loss of vision. If the floor of the orbit is fractured, this could cause muscle damage, which may limit eye movement and create the appearance of a sunken eye- ball—either of which may require surgery. So don’t be your own expert and simply apply the beefsteak. First, let your eye doctor or local emergency room physicians check it out.

Corneal Abrasions and Foreign Bodies

Even though these can be some of the most uncomfortable eye problems, they’re also among the most easily treated.

Why does it hurt so much? It’s because a host of sensory nerves make their home in the cornea and conjunctiva. Their job is to sound the alarm, alerting the eye’s defense mechanisms to dryness, foreign bodies, in-

EYE TRAUMA AND EMERGENCIES / 411

jury, even temperature change. The eye then responds— by blinking or producing tears, for example.

When a foreign body, such as a tiny fleck of metal or rock, invades the cornea and becomes embedded in it, these same sensory nerves can make a splinter feel like a log. Note: They can also cause misleading sensations, making you think that something actually lodged in the center of the cornea is under the upper eyelid, when in fact it’s the movement of the eyelid over the foreign object in the cornea that’s so painful.

Treatment: Most foreign bodies stay on the surface of the cornea. They’re fairly easily removed, under high magnification at the slit lamp, using a cotton-tipped applicator, needle, or other instrument. Your eye doctor will want to make sure that the foreign body is a lone invader (or, if it’s not, to remove any other specks or splinters), that it hasn’t perforated the eyeball, and that there’s no associated infection, trauma, or injury. (This may require a dilated eye examination.)

To prevent the risk of infection after the fact, your doctor may also give you an antibiotic eye ointment under a pressure patch worn for twelve to twenty-four hours. Fortunately, because the corneal epithelium grows so fast, the cornea usually repairs itself, quickly covering any dents or scratches left when a foreign body is removed. Usually the cornea heals in twenty-four hours, with no permanent visual defect. (If, however, the foreign body manages to penetrate the center of the cornea, it may cause a corneal scar, and this may affect vision permanently.)

412 / OTHER THINGS YOU NEED TO KNOW

Preventing Eye Injuries: Caution and

Common Sense

There are some easy, commonsense steps you can take to prevent one of the most common causes of eye problems in this country: eye injuries, which result from an unbelievable variety of activities. Obviously, it’s not possible to prevent a car crash or freak accident. But it doesn’t take long, when you take care of patients in a busy hospital emergency department, to grasp a few lucid points. One of them is that using a grinding wheel or chain saw without goggles can and does result in eye injuries. Letting your kids run around holding scissors with the points exposed is not a good idea. Nor is putting in contact lenses at a bathroom counter cluttered with household chemicals. Being a little neurotic about protecting your eyes from injury just makes good sense.

Recurrent corneal erosion (see chapter 11): Materials with rough surfaces—paper, wood, even fingernails— can cause a corneal abrasion. Either by becoming lodged within the eye or simply by rubbing or poking the cornea, they can significantly alter the corneal epithelium’s basement membrane. Picture a slab of cement, with a single layer of epithelial cells as bricks upon it: damage to this cement affects the way these cells stick to the basement membrane and eye. They may become

414 / OTHER THINGS YOU NEED TO KNOW

much more serious than this. Note: By “loss of vision” we mean here partial or total loss of sight in one or both eyes—not just something funny going on with your vision, such as floaters, migraine patterns, second images of cataracts, or blurry vision caused by dry eyes or infection (although these too are important and also require medical attention).

One Eye, or Both?

If you are suffering vision loss, your eye doctor’s first step will be to figure out what’s causing the problem. In addition to receiving a thorough eye exam, you’ll be asked a lot of detailed questions. The first will probably be, Is this happening in one or both eyes?

This is terribly important, because if you’re having simultaneous loss of vision in both eyes, chances are that the trouble isn’t originating in your eyes. One cause of a sudden vision loss in both eyes (called a bilateral loss) is a breakdown in the pathways that connect the eyes to the brain. The occipital lobe is the brain’s vision center; a stroke or infarct (caused by a blocked blood vessel) here can cause a sudden, and often permanent, bilateral loss of vision. Migraines too can cause temporary bilateral visual loss (see chapter 18).

If the vision loss is in one eye (called unilateral loss), the important question is, Is the problem temporary? The most common cause of transient unilateral loss of vision is “fleeting blindness,” or amaurosis fugax. In this case, the loss often progresses from the edge to the center of vision, like a dark curtain closing. Then, seconds

EYE TRAUMA AND EMERGENCIES / 415

to minutes later, the curtain opens again, with vision returning gradually but completely within about twenty minutes. This odd and often frightening problem is believed to be caused by platelets or other tiny impediments that briefly interrupt blood flow in the retina. Many people who suffer from fleeting blindness have carotid artery disease—atherosclerosis in the carotid artery, another problem not to be taken lightly. They should undergo a careful physical examination; if significant blockage or buildup is discovered, these patients may need a surgical procedure called an endarterectomy, the surgical cleaning out of cholesterol plaque from the carotid artery. Other causes of transient unilateral vision loss include atypical migraines, hypotension, anemia, arteritis (see below), and elevated intracranial pressure from a variety of causes, including tumors and bleeding in the brain.

If the vision loss in one eye is permanent, the next big question is, Where’s the loss—in your central or your peripheral vision? Because the optic nerve or retina can be involved in both cases, a thorough eye examination, including a dilated optic nerve and retinal evaluation, is crucial for pinpointing the problem.

Several things can cause sudden loss of central vision in one eye, including inflammation of the optic nerve, blockage of a main or branch retinal artery (see chapter 15), blockage or inflammation of other nerves in the eye, a detached retina, or a subretinal neovascular membrane (see chapter 9)—a problem often associated with macular degeneration. Note: It is rarely caused by cataracts,

416 / OTHER THINGS YOU NEED TO KNOW

glaucoma, or diabetic retinopathy, and it’s never caused by inadequate eyeglasses.

Giant Cell Arteritis

Giant cell arteritis, also called temporal arteritis, is a fairly common condition in people over age sixty-five that can lead to sudden permanent vision loss in one or both eyes. A disorder of the body’s autoimmune system, giant cell arteritis is an inflammation that affects blood vessels—particularly those near the eye. Symptoms of giant cell arteritis, or inflammation of the blood vessels supplying the optic nerve, may begin with transient visual disturbances—brief episodes of losing central or peripheral vision, like temporary blackouts in an overheated city. Eventually these blackouts may become permanent, resulting in the total loss of central vision, or loss of the top or bottom half of the visual field.

What’s happening here? The inflammation shuts off blood flow to the nerve, a condition called ischemic optic neuropathy (see chapter 16). Although there’s no blood clot involved, the nerve damage is like that brought on by a stroke or heart attack: without oxygen, the optic nerve quickly begins to deteriorate, causing permanent dam- age—and, perhaps, irreversible loss of vision. Giant cell arteritis often causes other problems, including headaches, tenderness in the temples or scalp, trouble hearing, jaw pain, and trouble chewing. Clearly, if you’re having any of these symptoms—particularly the vision disturbances described above—call your doctor immediately. Another worry is that giant cell arteritis often af-

EYE TRAUMA AND EMERGENCIES / 417

fects both eyes; therefore, early diagnosis and treatment are crucial.

Diagnosis and treatment: Your eye doctor will begin with a careful medical history. If giant cell arteritis is indeed suspected, you’ll need a blood test called a sedimentation rate (also known as a “sed” rate). This test isn’t definitive, but it can show whether the body’s immune system is working overtime, as it does in arteritis. However, a similar immune response happens in other diseases, including arthritis and cancer; therefore, if the sedimentation rate confirms that giant cell arteritis is a possibility, your doctor will perform another, more specific test: a temporal artery biopsy. There are two temporal arteries, one located near each temple; the biopsy —which causes no lasting effects, poses minimal risks, and is performed under local anesthesia—will probably be done on both sides.

The treatment in giant cell arteritis, to protect the other eye from ischemic optic neuropathy, or to preserve vision in the first one, is high-dose steroids; your doctor may even prescribe them before performing the biopsy. Because steroids can cause many problems of their own (see chapter 20 and Appendix), they’re never prescribed lightly; because treatment for this disorder is often longterm, lasting months or even years, your eye doctor or internist will want to monitor you carefully for any sign of side effects.

418 / OTHER THINGS YOU NEED TO KNOW

Nonarteritic Ischemic Optic Neuropathy

There is another form of ischemic optic neuropathy that also affects people in their fifties and sixties; because it is not related to arteritis, its name, by default, is nonarteritic ischemic optic neuropathy (see chapter 16). It differs from the arteritic form in that it often affects only one eye, it’s associated with only mildly elevated sedimentation rates, steroid therapy doesn’t help, and—per- haps most important—vision loss is usually not as severe or as permanent. Its cause is not known, though it seems to be found more often in people with hypertension. Unfortunately, there is no widely accepted treatment for this condition.

18

General Health Problems

That Can Affect the Eyes

Sometimes the problem doesn’t begin in the eye at all. The disease is systemic—that is, it affects the whole body. But as far as the eye is concerned, the consequences of some of these general health problems are as serious as any specific eye disease could ever be. Some of these disorders are discussed in this chapter, beginning with the big threat to eyesight posed by diabetes.

Diabetes

Diabetes cuts a wide, devastating swath through the body. No cell or organ, it seems, is immune to its ravages, and the eyes seem particularly vulnerable. In fact, among Americans of working age, diabetes is the leading cause of new cases of blindness.

Diabetes can cause trouble in the lens, eye muscles, iris, and other eye structures. People with diabetes are more