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Vitamin a and Dark Adaptation
705
BOOK NOTICES
VITAMIN A AND DARK ADAPTATION Almost one hundred years ago, cases of softening of the cornea, occurring in infants and young children, began to be reported; and the names keratomalacia and xerophthalmia came into use. Colonel Wright has said that at Madras, India, there have been more cases of blindness from this disease than from ophthalmia neonatorum. In 1866 Lobo reported cases, occurring in Brazil, associated with bad nutrition in Negro children. The same year Blessig reported it in Saint Peters burg, as being caused by prolonged fasting in Lent. In 1883 Weeks, of New York, re ported a case due to bad nutrition. In 1915 it began to be understood, from ani mal experiments, that the disease was due to dietary deficiency of fat-soluble vita min A. In 1924 Blegvad published in a monograph and in the American Journal of Ophthalmology accounts of the cases occurring in Denmark from 1909 to 1920, a total of 434 cases. The bulk of these cases occurred during the World War, reaching their maximum in the early months of 1916 and 1917, at the time when cow's milk and milk foods were being sent into Germany. When normal milk and milk foods became available, the number of cases decreased immediately. Blessig connected xerophthalmia with hemeralopia; and in 1907 Schiele noticed it occurred in nurslings whose mothers suffered from hemeralopia. It is now proposed by Harris and Abrasy (Lancet, December 23 and 30, 1939) that dark adaptation shall be used as a test for vitamin-A deficiency. From experiments begun in 1937, which demonstrated that poor dark adaptation is a reliable test of the presence, and somewhat of the extent, of vitamin de ficiency, they found that of 100 poor-class children attending elementary schools, 57 were below standard for dark adaptation but rose to normal when treated with
large amounts of vitamin A. Among 30 well-fed children, 28 had good dark adaptation. The test chiefly relied on was that of the Birch-Hirschfeld photometer. This was a black disc with five openings, giving different degrees of illumination. When all these were recognized the adap tation was normal. When one, two, or three of them were not seen, different de grees of poor adaptation were indicated. The test was applied repeatedly in each case, the eyes being prepared by ten minutes in complete darkness. They con clude that the theoretical basis for the test is reliable; and that it is capable of detecting deficiency, although not of assessing the different degrees of defect. They found vitamin-A deficiency less common among adults than in children. In using dark adaptation to test for vitamin-A deficiency, we must remember that the adaptation is rapid at first, Adler indicates, for a half-hour; but it goes on for hours before it is complete. Instead of the ten-minutes darkness, used by the experimenters in securing their statistics, it would be better to have the eye in dark ness for a half-hour, or even longer. For the individual case we can not depend on the averages that may be reached in an extended original investigation. We should use longer periods of darkness and always repeat the test. EDWARD JACKSON.
BOOK NOTICES TRANSACTIONS O F T H E AMERI CAN OPHTHALMOLOGICAL SO CIETY, Volume 37, 1939. Clothbound. 467 pages. Philadelphia, Wm. Fell Co., 1940. The transactions of the seventy-fifth meeting of the society are given. Twentyeight papers presented by the members of the society are reported. Dr. Harry Friedenwald's address "The
BOOK NOTICES
VITAMIN A AND DARK ADAPTATION Almost one hundred years ago, cases of softening of the cornea, occurring in infants and young children, began to be reported; and the names keratomalacia and xerophthalmia came into use. Colonel Wright has said that at Madras, India, there have been more cases of blindness from this disease than from ophthalmia neonatorum. In 1866 Lobo reported cases, occurring in Brazil, associated with bad nutrition in Negro children. The same year Blessig reported it in Saint Peters burg, as being caused by prolonged fasting in Lent. In 1883 Weeks, of New York, re ported a case due to bad nutrition. In 1915 it began to be understood, from ani mal experiments, that the disease was due to dietary deficiency of fat-soluble vita min A. In 1924 Blegvad published in a monograph and in the American Journal of Ophthalmology accounts of the cases occurring in Denmark from 1909 to 1920, a total of 434 cases. The bulk of these cases occurred during the World War, reaching their maximum in the early months of 1916 and 1917, at the time when cow's milk and milk foods were being sent into Germany. When normal milk and milk foods became available, the number of cases decreased immediately. Blessig connected xerophthalmia with hemeralopia; and in 1907 Schiele noticed it occurred in nurslings whose mothers suffered from hemeralopia. It is now proposed by Harris and Abrasy (Lancet, December 23 and 30, 1939) that dark adaptation shall be used as a test for vitamin-A deficiency. From experiments begun in 1937, which demonstrated that poor dark adaptation is a reliable test of the presence, and somewhat of the extent, of vitamin de ficiency, they found that of 100 poor-class children attending elementary schools, 57 were below standard for dark adaptation but rose to normal when treated with
large amounts of vitamin A. Among 30 well-fed children, 28 had good dark adaptation. The test chiefly relied on was that of the Birch-Hirschfeld photometer. This was a black disc with five openings, giving different degrees of illumination. When all these were recognized the adap tation was normal. When one, two, or three of them were not seen, different de grees of poor adaptation were indicated. The test was applied repeatedly in each case, the eyes being prepared by ten minutes in complete darkness. They con clude that the theoretical basis for the test is reliable; and that it is capable of detecting deficiency, although not of assessing the different degrees of defect. They found vitamin-A deficiency less common among adults than in children. In using dark adaptation to test for vitamin-A deficiency, we must remember that the adaptation is rapid at first, Adler indicates, for a half-hour; but it goes on for hours before it is complete. Instead of the ten-minutes darkness, used by the experimenters in securing their statistics, it would be better to have the eye in dark ness for a half-hour, or even longer. For the individual case we can not depend on the averages that may be reached in an extended original investigation. We should use longer periods of darkness and always repeat the test. EDWARD JACKSON.
BOOK NOTICES TRANSACTIONS O F T H E AMERI CAN OPHTHALMOLOGICAL SO CIETY, Volume 37, 1939. Clothbound. 467 pages. Philadelphia, Wm. Fell Co., 1940. The transactions of the seventy-fifth meeting of the society are given. Twentyeight papers presented by the members of the society are reported. Dr. Harry Friedenwald's address "The