Stability of hydrated curvature of Quantum II lenses

Abstract

Twenty-five Quantum II rigid gas permeable corneal lenses, in a range of five negative back vertex powers but otherwise of identical nominal specification, were immersed in distilled water for up to 6 weeks and the back optic zone radius of each lens was measured periodically to determine the magnitude and time course of curvature changes during hydration. Changes in back optic zone radius were of small magnitude and were less than the tolerance limits of ±0.05mm listed in British Standard BS7208: Part 1: 1992 (‘Specification for Rigid Corneal and Scleral Contact Lenses’) for rigid gas-permeable corneal lenses.