Achromatopsia

The Island of the Colorblind and Cycad Island.

By Oliver Sacks.

Knopf. 298 pages. $24. The title of Oliver Sacks' latest book may lead us to suppose that we are in for a selection of tales as fantastic as "The Man Who Mistook His Wife for a Hat," an earlier book by Sacks. But we are in for a surprise. "The Island of the Colorblind" is part South Seas travelogue, part natural history writing, and part exploration of neurological illness. As Sacks writes in his preface, "I went to Micronesia as a neurologist, or neuroanthropologist, intent on seeing how individuals and communities responded to unusual endemic conditions a hereditary total colorblindness on Pingelap and Pohnpei; a progressive, fatal neurodegenerative disorder on Guam and Rota. But I also found myself riveted by the cultural life and history of these islands, their unique flora and fauna, their singular geologic origins." Most color blindness is only partial and fairly common. But the loss of ability to see any color achromatopsia is rare. Sacks induces us to wonder what that world is like: "Would they, perhaps, lacking any sense of something missing, have a world no less dense and vibrant than our own? Might they even have developed heightened perceptions of visual tone and texture and movement and depth, and live in a world in some ways more intense than our own, a world of heightened reality one that we can only glimpse echoes of in the work of the great black-and-white photographers?" When Sacks hears of an island called Pingelap where, because of inbreeding, 10% of the population has total color blindness, he decides to travel there. One of his traveling companions is Knut Nordby, a physiologist at the University of Oslo, who happens to be an achromatope. Nordby, like all achromatopes, is exquisitely sensitive to bright light. They land in Pingelap, and Nordby immediately spots his fellow achromatopes in the crowd that comes to meet the plane: " `Beautiful!' whispered Knut, enraptured, by my side, and then, `Look at that child and that one, and that . . . ' I followed his glance, and now suddenly saw what I had first missed: here and there, among the rest, clusters of children who squinted, screwed up their eyes against the bright sun, and one, an older boy with a black cloth over his head." As they spend their time on Pingelap and Pohnpei, examining patients and distributing dark glasses, it is Nordby and his poignant tale that fascinates us: this white man wearing dark glasses and carrying magnifying glasses and a telescope who has found a community of other citizens of a black-and-white world in Micronesia. The second part of the book deals with Sacks' visit to Guam, where neurologist John Steele has been studying something called lytico-bodig disease, a condition that resembles Lou Gehrig's disease. Sacks visits patients, expounds on the history of this disease and points out its similarities to encephalitis lethargica, the condition he described in "Awakenings." There are tantalizing clues, many theories, but ultimately no explanation. There is the possibility that the consumption of fadang food prepared from cycads, a variety of palm, which are known to be toxic unless prepared correctly has in some way triggered this illness. Many different cultures around the world, however, have learned to detoxify and eat these ancient plants without adverse effects. Perhaps the explanation if one is ever found will be a complex interaction of genetic, environmental and infectious factors. At times, the different threads in this narrative botany, travel, natural history, illness strain in different directions. And whereas descriptions of human illness are inherently interesting, it is difficult for most readers to get as worked up about cycads and ferns as Sacks seems to be. Nevertheless, "The Island of the Colorblind" is a delightful inner and outer journey, destined to surprise and please the devoted Sacks reader. ------------ Abraham Verghese is professor of medicine at Texas Tech University and the author of "My Own Country: A Doctor's Story."

Copyright 1997
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