Light scattering from the human cornea.

A clinical method of measuring angular scatter from the human cornea is described. The method entails the use of a slit-lamp photometer with a pin-light attachment to control the angle of measurement. Corneal scatter and corneal thickness were measured in 93 normal subjects and 56 patients recently operated on for cataract. In the latter group, the surgically induced increase in corneal thickness was found to increase corneal scatter markedly, demonstrating the well-known dependence of scatter on corneal hydration. For the normal cornea, thickness and scatter were only insignificantly correlated. This finding was interpreted as evidence that the normal variation in corneal thickness is caused by a variation in mass content rather than in water content of the cornea. An increase in corneal scatter with age was demonstrated. Because this was seen at a constant corneal thickness, the mechanism was presumably that of age-related alterations in the latticelike organization of the collagen fibrils. These results suggest that clinical measurements of scatter may be used as a means to study hydration and ultrastructural characteristics of the human cornea in vivo.