Contrast (modulation) sensitivity functions measured in patients with high refractive error with emphasis on aphakia: II. Determinations of patients.

Measurements of Constrast Sensitivity Functions (CSF) were made on normal observers made artificially highly ametropic with spectacle lenses (with high back vertex) distance in order to determine the effect of retinal image size alterations upon CSF measures. While not an exact model for high ametropia per se, this experiment served to familiarize the experimenters with problems associated with the task. Image size alterations occur normally in aphakic patients and highly myopic patients. As a clinical trial, a series of aphakic observers were tested using an interferometric acuity device. CSF measures were made with the patient's spectacle corrections in place and again with correcting contact lenses substituted. The contact lenses reduce induced image size alterations in these cases. The use of contact lenses in such measures allows differentiation between artifactual low frequency fall off in aphakia due to lens effects and possible low frequency fall-off due to other causes.