High gas permeability contact lens effects on the cornea: A comparative study

The aim of this paper is to compare the physiological responses, degree of comfort, vision quality, and acceptance of two types of high gas permeable contact lenses over a period of 3 months usage. Both contact lens materials were initially unknown to the authors; once the study was concluded, the manufacturing laboratories were consulted to determine the chemical composition of both materials. The lens types were fluoropolymer (Equalens) (lens A) and siloxane acrylate (lens B). Ocular responses of 30 patients to these lenses were studied. Fifteen of these patients were veteran contact lens wearers; the rest of the patients were new contact lens wearers. Each patient was fitted with lens A on one eye, and lens B, on the other eye. The degree of comfort experienced with both lens types as well as any changes in the corneal thickness, anterior corneal curvature, ocular refraction, and ocular physiology were noted. Lens A produced more discomfort than did lens B, due possibly to its wetting angle and edge design. No significant change in corneal curvature was found for either type of lens. Although lens B produced a greater increase in corneal thickness than did lens A, it is important to point out that, from the first week of contact lens usage through the 3 months of usage, corneal edema caused by both lenses was within the physiological limits of adaptation.