Increase of Myopia—Possible Interaction of Environmental Chemicals

Abstract

An increase of myopia especially in Oriental countries is a serious problem. In order to find out the functional differences of a given myopia, we have classified myopes to the following three groups matching approximately their ages: (1) Emmetrope (38/56 eyes examined); (2) Early onset myopes (37/54); and (3) Late onset myopes (31/46).Their tonic accommodation (aftereffect) followed by 2 minutes viwing of a 4 Diopters (D) near task was measured using an infrared electric optometer. An empty field was used to measure accommodative aftereffect. An obvious increase of aftereffect was seen in the group 3, which can be determined from the slope of tonic accommodation after the stimulus. There was a correlation between the slope and erythrocutes cholinesterase activity in group 3. No correlation existed in the other groups, A possibility of neuro-muscular potentiation caused by environmental exposure to organophosphorus pesticides at the ciliary muscle was considered.