DO THINNER RIGID GAS-PERMEABLE CONTACT-LENSES PROVIDE SUPERIOR INITIAL COMFORT

To test the hypothesis that thinner rigid gas permeable (RGP) contact lenses provide superior initial comfort, RGP lenses of 3 center thickn esses, 0.08, 0.12, and 0.16 mm, in otherwise matched parameters, were worn for 30 min by 17 unadapted subjects in a controlled, double maske d, randomized study. Comfort ratings (0 to 100) after 30 min of wear w ere 42 +/- 30, 55 +/- 27, and 57 +/- 28 for the 0.08-, 0.12-, and 0.16 -mm thick lenses, respectively (p = 0.04, multiple analysis of varianc e (MANOVA)), and 93 +/- 13 for the hydrogel control lens. The thinnest RGP lens was significantly less comfortable than its thicker counterp arts (p = 0.03, Univariate F-test). There were no differences among th e test lenses in edge shape, front surface wettability, or static lens fittings, and small differences in movement, vertical decentration, a nd front surface geometry were not significantly related to comfort. W e hypothesize that the greater flexibility of the thinnest lens result ed in greater deformation of the lens during a blink cycle, causing tr ansient peripheral lens lifting and interaction with the upper eyelid, thereby reducing comfort. In conclusion we found that thinner RGP len ses do not provide an initial comfort advantage and that very thin and , as a corollary, very flexible, RGP lenses can actually be less comfo rtable initially than stiffer, but otherwise matched, designs.