The development of corneal astigmatism in contact lens wearers

In this study of 131 eyes, a comparison of the corneal astigmatism present before wearing hard contact lenses was made with that found after several years of wear (mean length of time: 4.4 years). The eyes were divided into 3 groups according to their ocular rigidity measurements. Statistical analysis of these groups showed that eyes with low ocular rigidity developed a high incidence of with-the-rule astigmatism change and that, furthermore, this change was of significant amount (twice that developed by eyes in the other groups). It was notable that all of the eyes that developed more than 1 1/2 diopters of astigmatism had low ocular rigidity.