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

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in your corneal endothelium. As soon as these changes progress and cause your cornea to swell and retain fluid, you can begin helping your eye’s “pumps” by using hypertonic saline drops and ointments to draw out excess water.

Unfortunately, for many people dystrophy ultimately progresses to the point where ointments no longer work and vision is impaired. The next step, then, is a corneal transplant. Like a replacement window for your home, this is a fresh start, and it can improve your vision dramatically. (The transplant tissue, or “graft,” comes from an organ donor, after death.) Corneal grafting was the first widely successful human transplant operation. The key to its success—particularly when compared with other tissue transplant operations—is the fact that corneas have very few blood vessels; thus, because there’s little interaction with the rest of the body, the graft is less likely to be rejected as “foreign.” Today the odds of success have been boosted even higher by improved tissuematching techniques and the wider network of eye banks (foundations devoted to matching donor eye tissue with that of recipients in need).

Corneal Ultraviolet Light Burns

Your eye can get sunburned, too. And like sunburn on the skin, injury to the cornea from ultraviolet light is acutely uncomfortable—but mercifully short-lived.

As their name suggests, these injuries to the cornea are caused by overexposure to ultraviolet light—from a sun

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lamp, from sunlight reflected off snow or water, or even from brief exposure to the intense flash of electric arc welding. (Note: Sunglasses are adequate protection against an ultraviolet corneal burn from snow or water, but not from strong sunlamps or “welder’s flashes.” A safe encounter with one of these powerful sources of ultraviolet light means wearing extremely dense, ultravi- olet-blocking lenses.)

As with sunburn, it takes a while for the rays of ultraviolet light to start hurting your eye—usually about six to twelve hours—so you might wake up in the middle of the night with your eyes feeling like they’re on fire and watering like crazy. The good news, again, is that—al- though intensely painful—most ultraviolet light burns of the cornea heal quickly. Immobilizing the eyelid with a patch (described above, under “Corneal Abrasion”) helps the eye heal quickly.

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often sweeping through a school several times, for instance, before finally moving on to torment some other group of people.

Unpleasant as it is, however, you might say that pink eye has received a “bad rap.” Not that pink eye isn’t awful, but it’s not the cause of every single case of eyes with inflamed, red, or pink conjunctiva. Actually, pink eye itself is a very specific problem, a viral conjunctivitis. (In fact, many people who believe they’ve endured pink eye probably had something else—symptoms caused by bacteria or by an allergic or chemical reaction.)

Pink eye, in the true ophthalmic sense, is caused by an adenovirus, one of the viruses responsible for the common cold. As noted above, it’s extremely contagious, with a leisurely incubation period: symptoms usually manifest themselves seven to ten days after you come in contact with someone who’s infected with it. It’s a miserable condition. Besides being predominantly pink—as opposed to the bright red, mucus-oozing eye seen in bacterial conjunctivitis, for instance—the affected eye is also itchy and watery. These symptoms may spread to the other eye within a day or two; sufferers may also experience swollen lymph nodes in front of the ear or below the rim of the jaw.

Treatment: Like the common cold, pink eye usually has a long course: it can last weeks. Blurred vision, sensitivity to light, and watery, runny, itchy, swollen eyes are very common with pink eye. Antibiotics aren’t much help, just as they’re often ineffective at speeding recovery from a sore throat, runny nose, and other symptoms of

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the common cold. Thus, the treatment for pink eye conjunctivitis sounds a lot like that recommended for the common cold: lots of rest, plenty of fluids, aspirin or Tylenol for the discomfort, and antihistamines. Eye doctors often prescribe antihistamine eye drops and recommend cold compresses to ease eye puffiness and swelling. (Some doctors also prescribe steroid eye drops, but there’s some question as to when this is appropriate.) Because true pink eye is so very contagious, you also need to take extra precautions in preventing its spread: don’t share face towels, pillowcases, or washcloths, and don’t leave tissues or other potentially infected items in places where they’re likely to be touched by others.

Bacterial Conjunctivitis

If viral conjunctivitis is “pink eye,” bacterial conjunctivitis might be considered “technicolor eye”—markedly inflamed, bright red eyes with a thick yellow mucous discharge. Its onset is quicker—within days of coming in contact with someone who has it—than that of pink eye. (Another difference is that swollen lymph nodes are rare with this form of conjunctivitis.)

How’d you get this? The possibilities are limitless. It is ridiculously easy to introduce infectious bacteria into your eye, because they’re everywhere. Rub your eye after coming into contact with one of these organisms, and boom! Whatever you just touched may have been transferred right into your conjunctiva: potentially infectious bacteria from, perhaps, your mouth, nose, or scalp, from your grandchild’s sticky fingers, from the stranger’s hand

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you just shook, or even from the dog’s head you just scratched. Note: The conjunctiva of the eye, like the mouth, normally contains bacteria. The bacteria that cause bacterial conjunctivitis are not the bacteria that are usually present in the eye, however; they are introduced from somewhere else.

Now, the eye has some pretty good defenses—namely, its protective eyelids, plus bacteria-fighting ingredients in tears and epithelial cells—that help keep normal bacterial flora in check. (Otherwise, conjunctivitis would be the norm, not the exception.) Trouble happens when the eye somehow becomes compromised: if the eyelids don’t close the way they should, for instance, or if you have dry eyes, or a scratch, or chemical exposure, or some other injury—all of these things (and even viral conjunctivitis) can weaken the eye’s resistance to infection.

Treatment: Antibiotics do a great job of treating bacterial conjunctivitis; the trick is figuring out which antibiotic you need. (It’s not uncommon for an eye doctor to start a patient on one form of antibiotic eye drops and then change medications midstream if the infection doesn’t respond within a few days.) Sometimes the eye doctor will take a culture of a severe or persistent infection, to identify the bacterium and determine its sensitivity to various antibiotics. (In rare cases, patients need to take antibiotics orally or even by intravenous injection.)

Note: As with any form of infection, good hygiene is crucial here. This means you’ll need to scrub away any accumulated crust and debris along the eyelids and apply warm compresses regularly (see chapter 10).

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Allergic Conjunctivitis

Your body’s being invaded. At least it thinks it is, and it’s reacting to the enemy—cat hair, pollen, mold, dust, even food—by making antibodies, sending specialist “warrior” cells into battle. Soon the skirmish gets ugly. Chemical weapons released by these warrior cells are called into play, causing the battleground—in this case, your eyes—to become even more inflamed. This inflammation, your basic allergic reaction, can range from mild to severe.

In the eye, allergic reactions are usually characterized by mild redness, itchiness, and swelling of the conjunctiva, and excess tearing. (This often happens in both eyes at once.) Most people who get this form of conjunctivitis are no strangers to allergies; they’ve probably had some allergy-related conditions—asthma, hay fever, or hives—all their lives.

For some people, allergic conjunctivitis is a predictable, seasonal event, rearing its ugly head without fail whenever the air is rich in oak pollen, for example. Other people never figure out what’s driving their eyes crazy. And for some people, allergic conjunctivitis hits with the subtlety of a freight train, producing dramatic, instantaneous swelling of the conjunctiva that makes the eye seem to bulge from its socket. (This effect, called chemosis, is the eye’s version of a sudden hive on the skin; with treatment it tends to go away as quickly as it came.)

Some eye care products can also cause allergic conjunctivitis. Eyeglass-cleaning soaps or detergents, for ex-

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ample, can irritate the eye if you don’t rinse away every last trace of residue. Preservatives in eye drops—drops for treating dry eyes or glaucoma, for example—produce allergic reactions in many people. Also, some contact lens wearers develop a form of allergic conjunctivitis called giant papillary conjunctivitis (see chapter 5).

Treatment: Treatment is just what you might expect for an allergic reaction: antihistamines, decongestants, cold compresses, and occasionally such medications as aspirin, Tylenol, and Advil for discomfort. Note: Steroid eye drops should be used with caution! Regular, prolonged use of these drops can cause glaucoma. Also, take care not to overuse Visine or similar over-the-counter drops that “get the red out.” Although these medications alleviate redness and itching at first, if used too frequently (four times a day for three or four days, for instance) they can produce “rebound redness” (similar to the rebound effect caused by overuse of nasal decongestants) when they wear off. This leads to more red in the eye instead of less.

Recently, several new kinds of eye drops have become available for treating allergic conjunctivitis (see Appendix); you might want to ask your eye doctor whether one of these is right for you. Some of these new drops can even be used prophylactically, as preventive measures for allergy sufferers during hay fever season and other highrisk times.

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Conjunctivitis Caused by Chemicals and Irritants

Really, very few things in this world were meant to be placed in or near the eye. Thus, any exposure to chemicals or irritants—either directly spilled into the eye or carried in by smoke, fumes, or dust—can cause conjunctivitis. Reaction may be severe (such as that caused by exposure to strong household cleaners; see chapter 17), or it may be fairly mild (getting suntan lotion in your eye stings, for instance, but the discomfort usually doesn’t last long).

Treatment: Even if you don’t know what got into your eye, wash it out! It’s best to use a chemically balanced irrigating solution if you have one on hand—drug stores sell several different brands, and you may want to buy one for emergencies—but the old standby, tap water, is also fine. If you can, remove any solid material from the eye by gently dabbing it with a cotton-tipped applicator. There’s no such thing as using too much water. Irrigation should be copious, and if your injury was caused by an acid or alkali, such as lye and certain cleaning ingredients, you should bathe your eye continuously for half an hour to an hour. (For more on eye injuries, see chapter 17.) Afterward, try holding a cold cloth or ice bag to your eye for the pain; aspirin, Tylenol, Advil, or similar medications may also ease the discomfort. Then, call your eye doctor—especially if the pain and irritation persist. You may need additional treatment, including prescription eye drops (which help relieve pain but can also prevent

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Image not available.

Fig. 12.1. Pinguecula

a secondary bacterial infection; see “Bacterial Conjunctivitis,” above).

Lumps and Bumps of the Conjunctiva:

Pingueculae and Pterygia

What the heck is this? Thousands of people visit their eye doctor each year because they’ve spotted something that wasn’t there before: a raised cream-colored, white, or chalky growth on their conjunctiva. These tissue growths commonly appear on the surface of the conjunctiva nearest the nose (this is called the nasal, or medial, side), but they can also occur on the opposite side (called the temporal, or lateral, side) of the eye. They’re particularly noticeable when the eye becomes inflamed (such as in bacterial or allergic conjunctivitis, described above). These areas are called pingueculae (pronounced

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ping- -u-lee). When their growth extends onto the

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cornea, we call them pterygia (te- -e-a).