VISUAL IMPAIRMENT AND BLINDNESS 133 TABLE 4-22. DISTRIBUTION, ESTIMATED NUMBER OF CASES, AND PREV- ALENCE OF BILATERAL BLINDNESS BY SAMPLING STRATA (NBS 1981) Estimated Number of Cases Percentage of Nepal's Total Sampling Strata Sample N Prevalence (per 100)a Eastern Terai Far East Hills Eastern Hills Central Terai Kathmandu Valley Central Hills Western Terai Western Hills Western Mountains Far West Terai Far West Hills Far West Mountains Urban Sites Subtotal Missing Total 5,427 2,070 1,824 6,036 2,774 2,756 2,216 3,812 1,448 3,326 4,885 979 1,990 39,543 344 39,837 lR,526 3,760 4,642 22,495 8,304 3,858 7,582 5,897 4,181 6,687 17,343 4,559 9,789 117,623 NA 117,623 0.99 (1.13) 0.52 (0.44) 0.77 (0.67) 1.02 (1.00) 0.80 (0.76) 0.40 (0.36) 0.94 (0.79) 0.46 (0.43) 0.85 (0.65) 0.71 (0.97) 0.97 (1.06) 1.24 (1.01) 0.99 (1.01) 0.84 NA 0.84 15.8% 3.2 3.9 19.1 7.1 3.3 6.4 5.0 3.6 5.7 14.7 3.9 8.3 100.0 NA 100.0 Source: FR4.003 AN.5 aFigures in parentheses are age-sex-standardized blindness preva- lence rates. which a high proportion of the cataract blind reside. In addition, there is a high prevalence of blindness throughout the Far West of Nepal, although since the population in this area is less dense, there are not as many blind people. 4.4 Discussion 4.4.1 Size of the Problem The current WHO criterion for the Prevention of Blindness Programme suggests that the overall target of the programme is to reduce the prevalence of blindness to less than 0.5 percent in com- munities where it is over 1 percent. This quantitative identification of problem communities (i.e., those with more than 1 percent preva- lence of blindness) is helpful; however, the use of crude blindness prevalence rates may not place the size of the problem of blindness in Nepal into an understandable perspective. The major determinant of blindness is age. Communities that have a higher percentage of people over the age of 60 are likely to
