CAUSES OF BLINDNESS 155 TABLE 5-8. PREVALENCE AND ESTIMATED NUMBER OF CASES OF PRIMARY OCULAR DISORDER (COD-S) BY NUMBER OF EYES AFFECTED (NBS 1981) Bilateral Unilateral Combined Estimated Number of Cases Estimated Number of Cases Estimated Number of Cases Disorder % % % No disorder Cataract Trachoma Trauma Infection Nutritional Refractive error Glaucoma Aphakia Smallpox Retinal disease Amblyopia 11.834,361 195,452 831,348 5,493 93,857 67,711 85,782 4,260 7,722 3,416 4,984 4,271 83.5% 1.4 5.9 0.0 0.7 0.5 448,824 117,269 17,411 103,359 60,823 21,575 94,566 8,044 26,271 14,935 15,594 20,215 3.2% 0.8 0.1 0.7 0.4 0.2 0.7 0.1 0.2 0.1 0.1 0.1 12,283,138 312,720 848,759 109,852 154,680 89,286 181,348 12,303 33,992 18,350 20,578 24,487 86.7% 2.2 6.0 0.8 1.1 0.6 1.3 0.1 0.2 0.1 0.1 0.2 0.6 o.o 0.1 0.0 0.0 0.0 Source: JLCALCRUN 5.4 Causes of Blindness 5.4.1 Causes of Unilateral Blindness Unilateral blindness is so common in Nepal that there is a well- known Nepali word ("kano") for one-eyed persons. Table 5-9 shows the distribution of unilaterally blind right eyes by cause, Table 5-10 shows unilaterally blind left eyes. Table 5-11 shows the distribution of all unilateral blindness (right or left eye) by causes. Of the estimated 233,612 Nepalese who are blind in one eye, cataract ranks as the leading cause, accounting for 79,886 cases (34.2%), followed by trauma with 31,870 cases (13.6%). A series of infections, surgical failures, corneal scars, and phthisis of undetermined origin follows. The nature, presentation, and history of many of these unilateral cases of visual loss suggests that many were caused by infection following mild eye injuries that were perhaps unperceived at the time or are now unremembered (see Chapter 9). Iatrogenic sequelae of cataract blindness accounts for an additional 15,098 cases, 6.6 percent of the total unilateral blindness. Smallpox has left as much residual unilateral blindness as trachoma, each with 9,000-10,000 cases and about 4 percent of unilateral blindness. The number of eyes blinded by nutritional dis-
