Correlation between ocular sun exposure and pterygium: A hospital-based study

Abstract

Background: The term “pterygium” comes from the Greek word “Pterygos,” which means “wing.” The major predisposing factors are the hot and dry climate and long periods of ultraviolet light exposure. Epidemiological studies have revealed that the prevalence of pterygium is inversely related to latitude, and that it is greater among outdoor workers than indoor workers. Although sun exposure has been accepted as a risk factor for pterygium, there is no objective diagnostic tool to measure the total amount of sun exposure of an individual. Materials and Methods: This is a prospective study carried out for a period of 1 year on 100 eyes with pterygium. Demographic variables including age, sex, residence, education, income, smoking, alcohol drinking, exercise, and especially sun exposure were collected from interviewing the patients as per the pro forma. Their occupation was categorized according to the fields of profession. A detailed eye examination which included slit-lamp examination, visual acuity, refractive status, and size of the pterygium was recorded. The size of the pterygium was measured in millimeters from its apex to the limbus using the slit-lamp beam. Pterygium was graded, depending on the extent of the corneal involvement, and all the patients were divided into five grades (Grades I to V). Results: Out of 100 pterygia, 89' were located nasally, whereas only 11' were temporal. Nearly 84' of the total pterygia were found in unilateral eyes, whereas only 16' were seen in bilateral eyes. The male-to-female ratio was 1.8' (65 males: 35 females). Nearly 35' of the pterygia were seen in middle-aged males (41–60 years), followed by 20' in 21–40 years' age group. Grade III pterygium was seen in 15' of male patients in 41–60 years' age group, whereas only 8' were seen in the same age group in females. Maximum number of patients having pterygium 10' (Group B) and 15' (Group C) showed a maximum duration of daylight exposure of 8 and 10 h, respectively. Conclusion: This study shows that outdoor work and sunlight exposure are positively associated with the development of pterygium. Besides sun exposure, other factors which favor pterygium formation such as dusty environment, smoking, and genetics should also be taken into consideration, and further research should be done to ascertain their role in pterygium formation. Public education should focus on encouraging people to take appropriate protective measures, such as wearing sunglasses and brimmed hats when outdoors, and to avoid unnecessary sunlight exposure.