Unilateral photorefractive keratectomy for myopic anisometropia improves contrast sensitivity☆
Received 26 November 2002; accepted 15 September 2003.
Abstract
Objective
To evaluate visual performance after unilateral photorefractive keratectomy (PRK) performed for ≥2.75-diopter (D) myopic anisometropia.
Design
Prospective observational case series.
Participants
Eleven patients exhibiting ≥2.75-D myopic anisometropia appropriate for PRK.
Methods
Photorefractive keratectomy was performed on 11 eyes of 11 patients for myopic anisometropia ranging from –2.75 to –9.00 D. Best spectacle-corrected visual acuity (VA), contrast sensitivity (CS), and pattern visual evoked potentials (pVEPs) were measured preoperatively and at 3 and 6 months.
Main outcome measures
Best spectacle-corrected VA; pVEPs; and CS, measured as the area under the CS curve.
Results
Best spectacle-corrected VA increased nonsignificantly 6 months after PRK. A tendency towards decreased latency time of pVEPs for both eyes was observed after PRK. A significant increase in CS occurred after PRK in the operated eye at 6 months, but a tendency toward decreased CS appeared in the unoperated eye at 3 months. Preoperative CS levels, however, were reached at 6 months.
Conclusions
The adult central visual system is sensitive to visual deprivation caused by anisometropia. Imbalance between eyes may improve visual performance in the more emmetropic eye. Anisometropia appears to reduce visual performance in the more myopic eye, but this can probably be reversed by refractive correction.
1Department of Ophthalmology, University of Helsinki, Helsinki, Finland
Correspondence to Juha Holopainen, MD, PhD, Department of Ophthalmology, University of Helsinki, P.O. Box 220, 00029 HUS, Finland.
Financial support: Helsinki University Central Hospital, Finnish Eye Foundation, Instrumentarium Science Foundation, Mary and Georg C. Ehrnrooth Foundation, Ella and Georg Ehrnrooth Foundation, and University of Helsinki.
ABSTRACT