CHARACTERIZATION OF THE VISUAL PERFORMANCE WITH SOFT DAILY WEAR DISPOSABLE CONTACT-LENSES

We investigate the Visual performance associated with adaptation to a daily wear soft contact lens on the human eye. For this purpose, we us ed four parameters, one of which was an objective parameter, while the rest were subjective parameters, The objective parameter was a single quality parameter, a Merit function (Mf) derived from the modulation transfer function (MTF) of the overall [eye + contact lens] system The subjective parameters were the visual acuity (VA), the contrast sensi tivity function (CSF) and the standard adaptation criterion of Terry e t al. (1993), The normality criterion for the MTF was determined by ev aluating the fluctuations of the Mt over a day in five emmetropic obse rvers, Fluctuations with no statistically significant differences in t he merit function (p>0.05) and their standard deviation (8%) defined o ur standard criterion, The CSF and the VA were similarly measured (for emmetropic observers), The results obtained with emmetropic observers allowed us to establish a standard criterion for the evaluation param eters we propose, When this criterion is applied to daily soft wear di sposable contact lenses, their performance proves to be good, since bo th the objective (MTF) and the subjective parameters (CSF, Va, adaptat ion criterion) always lie within the range defined by our criterion. ( C) 1998 The College of Optometrists. Published by Elsevier Science Ltd .