Impact of self-contact lens fitting with uncorrected refractive error on visual acuity and lens movement in contact lens wearers

Abstract

Background: Contact lenses are increasingly popular for refractive error correction. An eye examination and
contact lens fitting for individual wearers are very important for best visual acuity and fitting accomplishment.
Most Thai contact lens users buy their lenses from local shops and fitted the lens themselves without
professional eye care services. This article reports on the impact of self-contact lens fitting on visual acuity and
lens movement to establishes the requirement of contact lens access control.

Objectives: To investigate the impact of self-contact lens fitting focusing on the uncorrected refractive error via visual acuity measurement and to determine the effect of lens base curve on lens movement in contact lens wearers.

Methods: A total of sixty eyes of 30 contact lens wearers were recruited. The contact lens parameters were taken from the lenses’ package. Corneal curvature was determined using corneal topography. A best-corrected visual acuity and over-refraction were assessed by placing contact lens of the subjects with or without prescription using a phoropter and a distance chart for Early Treatment Diabetic Retinopathy Study (ETDRS). Lens movement was determined for a proper fitting via ocular micro-bioscope.

Results: All subjects used contact lenses with 8.6 mm base curve and 14.2 mm diameter. All of them bought their lenses without a prescription. There was a significant difference between corrected spherical equivalent refraction and subject’s contact lens power ( < 0.001). The poor visual acuity with the subject’s lenses was significantly improved upon over-refraction ( < 0.001). Only half of eligible eyes qualified for an optimal lens movement with their recent contact lens.

Conclusion: The self-contact lens fitting without eye examination might induce lens complications. There
is a high prevalence of contact lens wearers who fitted their lenses depending on their own decision without an eye examination. There is 91.7% of subjects who required an over-refraction to achieve the best visual acuity. Only half of eligible eyes showed appropriate lens movement with the contact lens used. A regular contact lens assessment by eye practitioners should be done prior to and during using contact lens for improvement of best vision.