158 CHAPTER FIVE TABLE 5-11. CAUSES OF UNILATERAL BLINDNESS IN EITHER LEFT OR RIGHT EYE (NBS 1981) Estimated Number of Cases Cause of Blindness Sample N Rank Percentage 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 Cataract Trauma Infection Iatrogenic sequelae of cataract Corneal scars (undetermined etiology) Phthisis (undetermined etiology) Smallpox Trachoma Retinal disease Amblyopia Glaucoma Measles Refractive error Nutritional etiology Vitreous opacity Other optic atrophy Multiple causes Miscellaneous Undetermined cause 228 88 66 43 38 33 26 26 25 20 15 9 8 6 4 2 1 14 10 79,886 31,870 22,920 15,098 13,039 11,731 10,089 9,066 8,953 7,036 5,206 3,079 2,890 2,124 1,439 670 363 4,816 3,339 34.2% 13.6 9.8 6.5 5.6 5.0 4.3 3.9 3.8 3.0 2.2 1.3 1.2 0.9 0.6 0.3 0.2 2.1 1.4 100.0 Total 662 233,612 Source: JLCALCRUN the top ten causes of blindness, there is little practical or significant difference between the rankings of blindness caused by retinal dis- ease, glaucoma, infections, trachoma, trauma, and smallpox. Each of these diseases claims 2 or 3 percent of the nation's total blind- ness, and each accounts for between 2,500 and 4,000 cases of blind- ness in Nepal. These six blinding diseases are remarkably close to each other in terms of the share of blindness attributable to each. Nutritional disease accounts for an estimated 1,095 cases of blind- ness in Nepal, a small fraction (0.9%) of the nation's total. However, it should be remembered that keratomalacia serious enough to cause blindness and is very often fatal.17 As will be dis- cussed subsequently, the Nepal Blindness Programme was designed to reduce the prevalence of avoidable blindness. When looked at in the context of preventable or curable blindness only (Section 5.5), cataract accounts for more than four-fifths of avoidable blindness. Cataract accounts for over 60 percent of blindness in every geographic, demographic and community group in Nepal. It is the cause of 80 percent of the blindness in the terai, 82 percent in the
