The short-term effects of PMMA and RGP contact lens wear on keratometric behaviour: a pilot study

This article represents the preliminary findings of a larger study that included 24 subjects that were equally divided into three groups, namely, the PMMA (polymethyl methacrylate) group, the RGP (rigid gas permeable) group and the control group. The aim of this study was to establish the short-term effects (if any) of PMMA and RGP contact lens wear on keratometric behaviour. A control subject was also included in the study to establish a reference for normal diurnal changes in keratometric behaviour. Fifty successive auto-keratometric measurements were taken before and immediately after three hours of rigid contact lens wear for the first subject in the PMMA group and the first subject in the RGP group (experimental samples). Fifty successive auto-keratometric measurements were also taken on the first subject of the control group before and immediately after three hours of no lens wear (control sample). Data collected were analysed using multivariate statistical methods that in the past have been used infrequently in this area of study. This investigation revealed that, at least in these two randomly selected subjects, rigid contact lens wear appears to influence keratometric behaviour (PMMA contact lenses more so than RGP contact lenses).