Dr. John Gamel 2012-12-11 00:06:41
Lions know all about ways to save vision: screenings, eyeglass recycling and surgeries. But here is an eye-opening primer on the focus of our efforts–the wondrously complex, frighteningly fragile human eye. They aren’t what most people think they are. Human eyes, touted as ethereal objects by poets and novelists throughout history, are nothing more than white spheres, somewhat larger than your average marble, covered by a leather-like tissue known as sclera and filled with nature’s facsimile of Jell-O. Your beloved’s eyes may pierce your heart, but in all likelihood they closely resemble the eyes of every other person on the planet. At least I hope they do, for otherwise he or she suffers from severe myopia (nearsightedness), hyperopia (far-sightedness) or worse. Such uniformity is essential: for an eye to focus properly, its length and optical system must match to within a fraction of a millimeter. When a man and woman toss their genes together to make a baby, nature sets the focal point (determined by the optical power of the cornea and crystalline lens) at a standard distance, then adjusts the length of the eyeball to that same distance: twenty-four millimeters, or about one inch. Thus unlike livers and kidneys and hearts and brains—those ordinary, non-spherical organs— eyes tend to an impressive sameness all over the world. My spleen may be half again bigger than yours, our intestines can vary by five feet in length, but, with rare and often disastrous exceptions, eyes resemble so many peas in a pod. Trust me. I’ve handled hundreds of eyeballs, removed from their owners for a variety of unpleasant reasons. One of my jobs—that of the ophthalmic pathologist—is to slice these globes into wafer-thin strips, stain the strips with vivid colors, then examine the results under a microscope. Given these credentials, I can assure you that your lover’s eyes differ from those of your most despised enemy in only the most superficial ways—in the color and texture of the iris and in the size of its pupil. When we wax eloquent about “beautiful eyes,” we are usually moved more by the trimmings— the lids, the lashes, the brows, the prominence of the globe in its orbit—than by anything contained within the eye itself. The Japanese sometimes refer to westerners as “big eyes,” an illusion caused by the lid position and orbital structure of Occidentals, while in truth Asians exhibit a collective tendency toward myopia that gives them, on average, larger eyeballs. A crisis came upon me during my fourth year of medical school. This was the crucial moment, the ultimate decision: to what specialty would I devote my life? Should I tend to phlegmy children who wriggle and scream and scratch my face when I thrust an otoscope into their ear? Should I slice open bellies, wander among livers and spleens and gallbladders, grope my way through greasy omental fat pads to explore coil after coil of diseased intestines? Or should I tend to the human heart, throbbing in its nest between the foamy pink lungs? I flirted with cardiology, then settled on neurology. Nothing rivals the complexity of the human brain, I reasoned, and no goal is more noble than curing its various ailments. The ultimate dialectic: using the skilled synapses of my own brain, I would diagnose and cure the diseased brains of others. Fortunately, before it was too late, a sixweek elective in neurology revealed the terrible truth: almost every patient on the ward suffered from a stroke, a seizure, or an incurable brain tumor, and they almost never—NEVER—got better. Worse yet, the rare patient with a curable lesion was snatched up by the neurosurgeons, the most arrogant species on earth. By the end of the elective I felt like a zombie myself. How about ophthalmology? Clean, precise, offering its own dialectic: with my intact eye I would diagnose and cure the diseased eyes of others. It didn’t take long, only one good look into the ocular depths through a dilated pupil, and my quest was finished. There before me lay a stunning panorama—a delicate lacework of arteries and veins spread on a burnt umber palate swirled and streaked with shades of ocher. Most spectacular of all was the retina, a transparent wafer that gleamed like polished glass under the light of my ophthalmoscope. In the center the optic nerve shone like a risen sun. I was in love. In 1977, at the age of 33, I got my first real job. It had been a long slog: 13 years through high school (I flunked the first grade), four years of college, five years of medical school, one year of internship, three years of residency and two years of fellowship. At last, briefcase in hand, I entered my new home: the Kentucky Lions Eye Research Institute fondly referred to as “KLERI,” or “The ‘Tute,” which had been built in 1968. This well-designed building houses the University of Louisville’s Department of Ophthalmology, the Kentucky Lions Eye Bank and numerous research laboratories. In the Eye Clinic, the faculty care for patients referred from private ophthalmologists in the greater Louisville area and adjoining counties. Lions clubs across Kentucky also refer indigent patients here for treatment at no cost. One of my most satisfying roles was staffing the Lions’ laser clinic. Here I soon met a man who had been referred by his local club because he couldn’t afford treatment for the diabetic retinopathy that would soon have blinded him without proper intervention. This charming man apologized again and again for not having insurance, though I reassured him our clinic was established for just such a purpose. Ten years later, when he brought his diabetic son for treatment of his retinopathy, he proudly announced, “Now I can pay you back. He has the best health insurance money can buy.” During my time at KLERI, the success of our department continued to grow with every passing year. In 1985 the Lions raised a million-dollar trust fund, and with this they established a research professorship. Chris Paterson, our first director of research, hired several new scientists who brought with them their grants from the National Eye Institute. As a result, we became one of the most heavily funded research departments at the Medical School. In 1997, because of an ever-growing need for more space, especially laboratories, the Lions funded a new addition to the original building. This almost doubled the available footage for research, administration and patient care. When I finally retired as a professor emeritus in 2001, I felt my career could not have been spent in a better place! Since every normal eye displays a clear cornea and a white scleral coat, any notion of special beauty attributed to the globe itself must derive from the iris, the dynamic membrane that contains the pupil and rests in front of the crystalline lens. The iris comes in many colors, but if one trusts the obsession of poets and novelists, the most beautiful ones are always blue: light-blue, velvety-blue, sloeeyed, peacock, midnight, cobalt, ice-blue. In overblown love stories, green gets an occasional nod—“she had jewelbright emerald eyes, so lustrous and fetching they pierced my heart”—but most of the time blue runs the show. The rankest discrimination and a bit ironic, since blue irises contain no intrinsic pigment, showing only the raw color of the tissue itself. In Caucasians, the iris often plays a trick by suppressing its pigment during gestation. This breaks the heart of many a parent when the gorgeous blue eyes of their newborn turn muddy-brown as the months go by. The texture of the iris is all but invisible to the unaided eye, but the ophthalmologist’s slit-lamp microscope discloses a panorama of crypts and valleys, diaphanous spokes, flecks and spots and strands that dance about with each twitch of the pupil. Dark irises tend toward a tight weave, while light irises fluff up like a shag rug. And there’s the all-important pupil: squeezed into a dot by morphine and bright light, enlarged by fear, darkness, sexual arousal, and death. Yes, the coroner’s final measure, the mark of a departed soul—enormous black pupils that give nary a twitch to even the brightest light. Despite this morbid sign, many cultures regard large pupils a sign of beauty. “Belladonna,” Spanish for “beautiful lady,” is also the name of a pupil-dilating poison extracted from the plant Atropa belladonna, more commonly known as deadly nightshade. A note on cosmetics: under the ophthalmologist’s microscope, false lashes look like mutilated telephone poles, while mascara shows up as greasy black lumps that squiggle across the corneal tear film with every blink. For the efficiency- minded woman there is permanent eyeliner, a dark line tattooed along the lid margin. It works beautifully, provided styles don’t change, and provided the tattooist, working millimeters from the cornea, doesn’t inject ink into the eyeball. About myopia—if you have it, be happy. Numerous studies have shown that near-sighted men and women boast a higher average intelligence than their non-myopic cohorts. The precise cause of this association remains unknown, but there are two popular theories: nature and nurture. Those who support nature argue that during embryologic development, the eyes develop from the same neural tube as the brain itself. Since large eyes tend to be myopic, big eyes and big brains might go together in much the same fashion as long arms and long legs. Those who favor nurture insist that myopia leads to high intelligence because of its effect on childhood development. Most near-sighted kids wander around undiagnosed for several years, and during this formative period— unable to see the baseballs, Frisbees, and rocks thrown at them by their playmates—they spend a lot of time indoors. Those who take up reading get high scores on their SATs, while those who take up eating give us claustrophobia by overflowing the adjacent seats on airplanes. Nearsightedness also exerts a powerful influence on career choice: it affects 85 percent of my fellow ophthalmologists, an incidence far greater than that of the normal population. Pathology breeds preoccupation. However beautiful the human eye, it serves a more important purpose than romantic allure. Forty percent of the brain is devoted to vision, which provides us with more information than our other four senses combined. The optic nerve transmits millions of impulses to the brain every second, impulses that specify the location, color, and intensity of light for all the points in our visual space. More remarkable yet, our visual cortex fuses the slightly disparate images from each eye to give us the three-dimensional miracle known as depth perception. A stunning feat, given that video cameras, arguably the benchmark of modern technology, can muster only two dimensions. Certain ocular tissues stand on the pinnacle of evolution. How does nature, so crude in claw and fang, create a surface that brings light to a pin-point focus? This surface must be perfectly curved, perfectly transparent, perfectly smooth. It must be—water! Which is to say, the cornea owes its optical precision to a tear film whose dissolved salts, lipids and proteins allow it to maintain a flawless wetted surface. A man who has no tears stands on the threshold of blindness. That man will also writhe in agony: a bone-dry cornea responds to each blink with a tormenting jolt, a jolt so painful it has been compared to rubbing shards of glass on the eye. Another evolutionary triumph: for light to reach the retina unimpeded, the cornea and lens must remain transparent, and yet, like all living tissues, they must be nourished by oxygen. More than 99.9 percent of all human cells obtain their oxygen from capillary blood flow, but capillaries lacing through the cornea and lens would veil our vision with an opaque net. To remain crystal clear, the outer portion of the cornea must survive on oxygen absorbed from the surrounding air, while the lens and the inner cornea depend on aqueous, a colorless fluid that flows through the chambers of the eye. Since normal aqueous contains neither hemoglobin nor cells of any sort, it carries only a tiny fraction of the oxygen contained in blood. And the rate of aqueous flow must be precisely controlled: a deficiency shrivels the eye into a useless spitball, while glaucoma, caused by a blockage of the trabecular drainage channels near the base of the iris, leads to throbbing pain and blindness. Thus painfree vision, the presumed birthright of every newborn, demands an arrangement as delicate and wondrous as that achieved by any space-age gadget. Of all the ugly things in this world, I would argue that diseases top the list: cancer, syphilis, leprosy, gangrene, fungating ulcers. Even the pictures lying flat and odorless on the pages of a textbook bring a surge of nausea. And let us not forget elephantiasis, an infestation by filarial worms that wriggle through the lymphatic system, causing such severe edema the legs often swell to the size of tree trunks. But surely the eye, the most delicate of organs, is afflicted by only the subtlest diseases. Or so one might think. I soon discovered the fallacy of this logic. Indeed, some of the most grotesque diseases known to medicine are those that disfigure the eye. Ophthalmology did not prove the sanitary refuge I had hoped for. On the second day of my student elective in the Stanford Eye Clinic, I examined Justine Jewell, a tall, slender diabetic in her late teens. She was accompanied by a tall mother who carried twice her daughter’s bulk. Justine complained, “My eyes are full of floaters.” Good, I thought. Floaters. No problem. Everything looked fine from the outside—white sclera, clear corneas, pale blue irises. Then I shined my ophthalmoscope through her dilated pupils. “Excuse me,” I said, and stepped out of the room. By that time in my career, I had seen the interior of a few dozen eyes, each a breath-taking panorama of amber and brown, yellow and pink, shading through a delicate lacework of arteries and veins. But Justine’s eyes were filled with tangles of angry red spiders. Dark clots rose into the vitreous gel, trailing streamers of blood in all directions. I rushed into the hall to grab Doug Jacobson, the retinal specialist in clinic that morning. It took only an instant. He focused the beam of his ophthalmoscope on the patient’s right eye, then her left, removed the ophthalmoscope from his head and hung it on the wall. “You have diabetic retinopathy,” he said. “And I’m sorry to say it’s very severe.” The mother burst into tears. “Oh, doctor,” she sobbed, “my grandmother, my cousin Ernest, this woman across the street—so many people I know went blind from diabetes! Can’t you do something?” Justine said nothing. Her eyes were dry, wide open, the irises stretched into pale blue rims around the blackness of her dilated pupils. Later, in private, Jacobson gave me her diagnosis in the vernacular—jungle-osis. Jungle-osis meant dense black clots, arching streamers of blood, a traction retinal detachment bound with scars so dense they defy the reparative efforts of the most skillful surgeons. It meant blindness, both eyes, and soon—weeks, perhaps a month or two. The victim, not yet twenty years of age, was doomed to stumble through the remaining decades of her life with a white cane or a guide dog. Worse yet, she might develop absolute glaucoma, a devastating rise in pressure that causes so much pain and nausea that the victims often beg to have their eyes removed. But—perhaps not. Her only hope was a treatment so recently developed we had no proof that it worked, a treatment whose promise was based on the crudest evidence. For decades ophthalmologists had noted a strange phenomenon: when one eye of a diabetic showed widespread retinal scars from an old injury or infection, that eye often retained vision long after diabetic hemorrhages had blinded the unscarred eye. Apparently, by a mechanism no one understood, these scars protected the surviving portions of the retina from the ravages of diabetes. And so, by a logic that might impress a blacksmith or a witchdoctor, the new treatment called for obliterating much of the nonessential peripheral retina in an effort to save the central portion that gives us our sharpest vision. Since there was no other option, we advised Justine—a young girl speechless with fear, poised on the brink of blindness—to let us experiment on her. Just months before her arrival, our clinic had acquired the Coherent Radiation Model 800, one of the first lasers used to treat the human eye. Its console, six feet long and three feet high, looked like a coffin on legs. When activated by a foot switch, a glass tube buried deep within its circuitry gave off a high-pitched whine and emitted an eerie, bluishgreen beam of light. Shown against a wall, the beam formed a circle of shimmering motes that scurried about like atoms in a nuclear furnace. A fabulous instrument, more precise than any razor, but now its tightly focused beam would serve a crude purpose— destroying retinal tissue. By the hundreds, by the thousands, the laser emitted tiny flashes that lasted onetenth of a second, each flash the space-age equivalent of a magnifying lens burning a hole in a leaf. When the treatment was complete, lifeless white scars obliterated more than half of the patient’s peripheral retina. Care was taken to avoid the vital central portion, assuring that, if the treatment worked, the patient would maintain the acute vision needed to read and drive a car. Justine suffered. To dull the pain from those hundreds of burns, we injected Xylocaine deep behind her eyes. The contact lens used to deliver the laser beam sometimes caused a painful corneal abrasion. For several days after every treatment, fluid leaking from the burns seeped into the central retina, blurring and distorting her vision. Her mother was always there, wringing her hands and squeezing her eyes shut when her daughter moaned under our long needle. But after six treatments the vitreous hemorrhages began to clear. The tangle of spiders melted away. Nine months after her first visit, Jacobson announced, “That’s it. All the hemorrhages are gone.” The mother burst into tears, dropped her purse on the floor, and threw her arms around him. His face blushed fiery red as he struggled against her grip, muttering, “No, no, it’s too soon to tell for sure,” but he was a small man, a few inches shorter and many pounds lighter than the joyful mother. Four years later, during the last months of my residency, Justine’s vision was still 20/20 in both eyes. There was no trace of the hemorrhage or spidery vessels that would signal a recurrence of her disease. Over the next three decades, recoveries like this would number in the hundreds of thousands as laser surgery became the gold standard for treating diabetic retinopathy. A study published in 1976 showed a fourfold reduction in visual loss among treated patients, but modifications to the original method have reduced total blindness among diabetics to a tiny fraction of the original incidence. By the turn of this century, the Lions, together with other agencies, had sent improved versions of the Coherent Model 800 to developing nations across the globe, allowing hundreds of thousands of patients to enjoy its benefits. Unfortunately, there remains a dark side to this story: many diabetics slip through the system, seeking care only after rampant hemorrhages have obliterated all hope of treatment. In addition, a few patients suffer an attack of retinopathy so fulminant and destructive, even the most timely therapy cannot sustain good vision. Despite these limitations, laser surgery has proved a medical triumph of the first order. Here is something crude in principle, simple to perform and easily learned, but it works! In the miracle that defeated jungle-osis, my role— treating thousands of patients, plus teaching the procedure to almost a hundred residents—has been the greatest privilege of my career. Adapted from an essay that originally appeared in the Alaska Quarterly Review and also in “The Man Who Lived in an Eggcup: A Memoir of Triumph and Self-Destruction.”
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