The effect of under and over refractive correction on visual performance and spectacle lens acceptance

As a follow-on from a previous study by Miller, Kris and Griffiths (1997, O ptom. Vis. Sci. 84, 521-526), we investigated the effect of small prescript ion errors on spatial visual performance and spectacle lens acceptability. We included both negative and positive errors and binocular and monocular e rrors. Data were collected on 15 young adult subjects. Clinical measures we re taken of pupil size, ocular dominance, binocular visual acuity, negative and positive relative accommodation, distance and near heterophorias, and stereopsis. Visual performance was measured with the best correction and fo r +/-0.50 D spherical binocular and monocular errors. Subjects wore spectac les, each containing a different error in turn, for 2 days and compared the m with a reference pair. Following the wearing period subjects assessed the performance of the spectacles by completing a short questionnaire. The onl y ocular tests for which these small prescription errors had significant ef fects were binocular visual acuity and negative relative accommodation. No significant relationship was observed between any of the clinical test resu lts and overall lens acceptance. Despite this, the reference pair was gener ally perceived as better than the test pairs containing errors, and a consi derable proportion of subjects reported pairs with errors as being unaccept able. In conclusion, the questionnaire findings support the need for both a ccurate monocular and binocular refractions. Subjects differed in their cri teria for judging lens acceptability. (C) 2001 The College of Optometrists. Published by Elsevier Science Ltd. All rights reserved.