!"( CHAPTER FOUR TABLE 4-16. DISTRIBUTION, ESTIMATED NUMBER OF CASES, AND PREV- ALENCE OF BLINDNESS BY TERRAIN (NBS 1981) Estimated Number of Cases Percentage of Nepal's Total Sample N Prevalence (per 100)8 Terrain Terai (plains) Hills Mountains Valley Subtotal Missing 17,135 18,885 1,562 1,961 39,543 344 61,379 47,619 3,778 4,846 117,623 0 1.01 (1.06) 0.71 (0.66) 0.67 (0.59) 0.63 (0.67) 0.84 NA 52.2% 40.5 3.2 4.1 100.0 NA Total 39,887 117,623 0.84 100.0 Source: FR4.003 AN.8 8Figures in parentheses are rates. age-sex-standardized blindness prevalence TABLE 4-17. DISTRIBUTION, ESTIMATED NUMBER OF CASES, AND PREV. ALENCE OF UNILATERAL BLINDNESS BY TERRAIN (NBS 1981) Estimated Number of Cases Percentage of Nepal's Total Sample N Prevalence (per 100) Terrain Terai (plains) Hills Mountains Valley Subtotal Missing Total 17,135 18,885 1,562 1,961 39,543 344 39,887 104,709 105,599 12,304 11,000 233,612 NA 233,612 1.73 1.58 2.18 1.43 1.66 NA 1.66 44.8% 45.2 5.3 4.7 100.0 NA 100.0 Source: FR4.003 AN.8 19) is similar. The preponderance of the blindness region is due both to the high density of population in the Central and to a high prevalence of cataract blindness (see Chapter 6). Zones: The distribution and estimated number of blind by zone is shown in Table 4-20. The zones with the highest prevalence of blindness are Seti (1.24%), Karnali (1.13%), and Narayani (1.0%). When age- and sex-standardized blindness prevalence rates are used, Bheri and Koshi zones also exceed or approach the WHO criterion of 1 percent. Karnali zone has the highest age-sex-
