154 CHAPTER FIVE TABLE 5-7. PREVALENCE AND ESTIMATED NUMBER OF CASES OF PRIMARY OCULAR DISORDER (COD-S) FOR ALL EXAMINED PERSONS (NBS 1981) Estimated Number of Cases COD-S Right Eye COD-S Left Eye Sample N Rank Percentage 1 2 3 4 6 6 7 No disorder Trachoma Other cause Cataract Infection Refractive error Nutritional etiology Undetermined No disorder No disorder Other cause Trauma No disorder No disorder Infection Refractive error No disorder Cataract Cataract Other cause All others No disorder Trachoma Other cause Cataract Infection Refractive error Nutritional etiology Undetermined Trauma Other cause No disorder No disorder Refractive error Infection No disorder No disorder Cataract No disorder Other cause Cataract 33,052 2,531 1,023 662 270 243 192 206 133 132 131 130 83 80 71 67 56 52 43 40 790 11,834,361 831,348 362,893 195,462 93,867 86.782 67,711 66,896 47,752 47,461 47,032 46,741 29,932 27,915 25,183 24,768 19,986 18,219 15,493 14,180 279,147 83.5% 6.9 2.6 1.4 0.7 0.6 0.5 0.6 0.3 0.3 0.3 0.3 0.2 0.2 0.2 0.2 0.1 0.1 0.1 0.1 2.0 100.0 8 9 10 11 12 13 14 15 16 17 18 19 20 Total 39,887 14,173,103 Source: JLCALCRUN 312,720 primary disorders, was also diagnosed as a secondary dis- order in an additional 61,544 cases. Thus, excluding aphakics, couched, after-cataracts, and other iatrogenic sequelae of cataract surgery, the total number of cataract cases is 374,264. (See Chap- ter 6 for a full discussion on cataract prevalence). Likewise, for trachoma, the ophthalmologist determined that trachoma was the major ocular disorder in 848,759 cases and a less important disorder in an additional 61,075 cases for a total national prevalence of 909,834 cases (see Chapter 7). These examples show the difficulties in interpreting the preva- lence estimates for single disorders in a community in which there are often multiple coexisting ocular disorders. Each of these dis- eases has special diagnostic criteria as discussed in Chapters 6-9.
