Mechanism Of Toric Hydrogel Lens Fit.

Toric hydrogel contact lenses present a multiplicity of challenges in the fitting process. Factors such as lens thickness, lens adherance, lens hydration, lid shape & movement, and center of gravity affect the lens fit. In spite of these variables, this study proposed that the mechanism by which toric hydrogel contact lenses correct corneal astigmatism involves sphericalization of the eye-lens system. The Eyesys Corneal Analysis System was utilized to establish the cylinder power and axis as well as for calculation of keratometric data. The study found that both an established toric hydrogel lens wearer and an emmetropic patient with a nearly spherical cornea who had a toric lens placed on the eye supported the concept of sphericalization. Non-established toric hydrogel lens wearers did not support the hypothesis. The potential impact of a possible tear lens effect and a potential adaptation period was addressed.