Glaucopsia: an occupational ophthalmic hazard.

Glaucopsia is a transient disturbance of vision that results from the development of corneal epithelial oedema and associated microcysts produced by exposure to the vapour of certain industrial chemicals, notably aliphatic, alicyclic and heterocyclic amines. After a latent period of a few hours of exposure, there is typically a blurring of vision, objects take on a blue-grey appearance and halos develop around bright objects. Corneal changes can be seen on biomicroscopy and corneal thickness increase is measurable by pachymetry. At concentrations higher than threshold values, visual acuity may be decreased, but contrast sensitivity is a better measure of visual effects. On vacating the causative vapour, vision returns to normal in a few hours without leaving permanent ocular sequelae. Vapour concentration of the causative amine is a major factor in the development of glaucopsia, and a concentration-effect relationship is usually evident. A correlation exists between the vapour concentration, degree of corneal oedema, corneal thickness and subjective symptoms, which permits no-effect and threshold-effect concentrations to be determined. The disturbance of vision is a nuisance factor and this may impair work efficiency, predispose to physical accidents and hinder the performance of coordinated tasks (e.g. driving). As a consequence, development of glaucopsia is considered a hazard and is thus an important consideration in assessing workplace safety. From a knowledge of threshold and no-effect concentrations, a workplace permissible vapour exposure concentration can be developed along with industrial hygiene precautionary measures.