320 CHAPTER EIGHT TABLE 8-2. PREVALENCE, ESTIMATED NUMBER OF CASES, AND DISTRIBUTION BY MONTH OF EXAMINATION, BITOT'S SPOTS (XlB), CHILDREN UNDER AGE 6, DECEMBER-APRIL (NBS 1981) Percentage of Nepal's • Total Sample N Estimated Cases Prevalence per 100 Month December January February March April Subtotal Missing data 1,948 1,437 814 818 2,518 7,535 45 8,027 4,080 756 1,018 1,653 15,534 0 1.2 0.8 0.3 0.4 0.2 0.6 NA 51.7% 26.3 4.9 6.5 10.6 100.0 NA 100.0 Total 7,580 15,534 0.6 Source: FR8.002 AN.97 or phthisis in 41 (12%) cases. Of these 41 cases, 9 were due to trachoma, 8 were linked to a history of traumatic eye injury, 9 were due to other unknown causes, and in 3 cases a history compatible with keratomalacia was elicited in the interview. These 3 cases represent a population estimate of 1,095 persons blind from keratomalacia, less than 1 percent of the total blind population of Nepal. Two of these three cases of nutritional blindness were under 15 years old, and of these, one was under 10 years old. Twelve cases of bilateral corneal scars of phthisis remain for which no diagnosis could be made. In some of these cases the patient could not communicate a history of the loss of vision, in some cases the history did not match a well-known syndrome, or there was no history of trauma, malnutrition, eye infection or other precipitant. The decision was made to label these cases either "cause unknown" or "miscellaneous combinations," depending on whether both eyes appeared to have been blinded by the same cause or not. In half of the cases, information gathered in the interview suggested that both eyes became blind simultaneously. These six individuals have been labeled "cause of blindness undetermined." ln the other six cases, the history suggested that although the cause of blindness was not clear, it appeared that each eye was blinded by a different event, in time if not in etiology. These six persons were grouped into the "miscellaneous combination" category. One of the most important factors in making a diagnosis of keratomalacia is age of onset of the disease. In any case in which the onset of bilateral corneal scars or bilateral phthisis of unknown
