Pterygium in Ceylon.

The geographical situation of Ceylon led Cameron (I965) to suggest that the pterygium rate there would range from 5-5 to over io per cent., but the actual incidence appears to be much less for reasons which are discussed below. The incidence of pterygium has not been closely studied, first perhaps because it rarely causes blindness, secondly because the world's earliest eye hospitals were situated in temperate climates where the condition is rare, and thirdly because it has not attracted the interest of ophthalmic surgeons in the same way as cataract, retinal detachment, strabismus, and corneal grafting. The surgery ofpterygium tends to be labelled 'minor' and to be relegated to assistants. The chief method of assessment has been the compilation of statistics based on hospital and private practice; it is difficult to obtain figures for a whole population except in small and accessible groups. Cameron (I965) found an incidence of 12.3, i0 o9, and I4o0 per cent. in three ophthalmic practices in and around Brisbane. Alvaro found a rate of 4.9 per cent. in a hospital practice in Rio de Janeiro (Anderson, I 954). Dimitry (I 937) estimated the rate in the United States of America by studying the percentage of pterygium operations. States lying close to the equator showed an average of 7 per cent., while those lying further north showed an average of 2 5 per cent. and those beyond Lat. 400 North an average of 2 per cent. Similarly, in the Princess Alexandra Hospital in Brisbane, the rate for July to December, I 96 I, was I 5 -9 per cent. (Cameron, I 965), and Law (I 959) found that in Brisbane there was a percentage of 40X5 pterygium operations in a total of 700, whereas there was not one among 36,ooo patients attending the Westminster Hospital, London. Saif, El Gammal, Barrada, and Mahfouz (I967) reported 54,187 pterygium operations out of 577,428 eye operations for the years 1953-56, i96i, and I964 in Egypt, which gives an incidence of 9.3 per cent. Corboy (I94I) found an incidence of 17 per cent. in a population of 503 plantation workers and Crawford (i944) estimated an overall incidence of 14 per cent. in Hawaii. Mann (i 96I) found 6 75 per cent. among 402 persons forming the entire population of Cocos, and 2.7 per cent. among 650 persons in the Marshall Islands.