Characteristics and localization of cortical cataracts at an early stage: subjects from the Reykjavik Eye Study in Iceland

Background: The frequency and characteristics of cortical cataract localiza tion within a dilated pupillary area were investigated in a population-base d cataract epidemiological survey performed in the city of Reykjavik in Ice land. Materials and Methods: Among 1045 randomly selected individuals, the right eyes of 277 persons with mild cortical lens opacification (Grade I) were se lected for our study. The localization of cortical cataracts was examined u sing retroillumination images, which were divided into 56 circular and radi al sections, and calculations were made of the percentages for each opacifi ed area. A questionnaire was used to record the number of hours spent outdo ors during week days, the time of the day and whether the subjects wore spe ctacles, sunglasses or hats when outside. Results: The percentage of cortical opacification was significantly higher in the lower nasal quadrant than in all other quadrants (p<0.05). Furthermo re, the percentage of opacification localized in the lower nasal quadrant w as higher in individuals with a longer history of outdoor activity than tho se without (p<0.05). The percentage of opacification in individuals, who ha ve had the habit of wearing sunglasses for outdoor activities lasting longe r than half an hour during weekdays in their 20's and 30's was lower in all quadrants and statistically significantly lower in the upper temporal quad rant (p<0.05) compared to those not wearing sunglasses. Conclusion: This suggests that wearing sunglasses is effective in preventin g the development and/or progression of cortical cataracts.