Long-term Outcomes of Photorefractive Keratectomy for Anisometropic Amblyopia in Children Evelyn A. Paysse, MD, David K. Coats, MD, Mohamed A. W. Hussein, MD, M. Bowes Hamill, MD, Douglas D. Koch, MD

Purpose: To evaluate the long-term visual acuity (VA) and refractive error responses to excimer laserphotorefractive keratectomy (PRK) for treatment of anisometropic amblyopia in children. Design: Prospective interventional case– control study.

Participants: Eleven children, 2 to 11 years old, with anisometropic amblyopia who were noncompliant withconventional therapy with glasses or contact lenses and occlusion therapy were treated with PRK. A cohort derived retrospectively of 13 compliant and 10 noncompliant children with refractive errors similar to those of the PRK group who were treated with traditional anisometropic amblyopia therapy served as control groups.

Main Outcome Measures: (1) Refractive error reduction and stability in the treated eye, (2) cycloplegic refraction, (3) VA, (4) stereoacuity, and (5) corneal haze up to 3 years after PRK. Compliant and noncompliant children with anisometropia amblyopia were analyzed as controls for refractive error and VA.

Patient Demographics and Refractive Results of the Children Who Underwent Photorefractive Keratectomy for Anisometropia Myopia Hyperopia No. of patients 8 3 Mean age (yrs) (range) 4 (2–8) 9 (8–11) Mean preoperative keratometry readings SD (D) Mean preoperative corneal thickness SD (m) Mean preoperative SE RE SD (D) Mean interocular SE RE difference SD (D) Maximum refractive SE RE dose (D) Mean target SE RE SD (D) Plano Mean target SE RE reduction SD (D) Mean 12-mo SE RE reduction SD (D) Mean 36-mo SE RE reduction SD (D) Mean 12-mo postoperative SE RE SD (D) Mean 36-mo postoperative SE RE SD (D) Mean SE RE 12-mo regression SD (D) * Mean SE RE 12- to 36-mo regression SD (D) No. of patients within 1 D of target at last follow-up 2/8 1/2 No. of patients within 2 D of target at last follow-up 5/8 2/3 % reduction in RE at last follow-up 74% 70% D diopters; RE refractive error; SD standard deviation; SE spherical equivalent.

Methods Criteria for selection UCVA, BSCVA,Stereoacuity, Motility, Corneal haze, Cyclo refraction, Fundoscopy, IOP. PRK under GA with Iris plane observation Control group Reval at 12, 24 and 36 month

Results In the Myopia group, the RE was within 3D of fellow eye in 4/8 and 5/8 were within 2D of target. No overcorrection in Hyperopia group Mod regression 2.5D in Myopia group and mild 1.5 in Hyperopia group Corneal haze was minimal UCVA improved by >2 Snellen lines in 7/9 BSCVA improved by >2 Logmar lines in 3/9 SE RE was significantly better in the both groups versus control BSCVA of compliant control group (20/40) was sig better than non- compliant group (20/270) Stereoacuity improved in 5/9 No change in ocular alignment

Author Discussion Most children treated with PRK showed mild to mod improvement in UCVA and BSCVA esp compared to non compliant control group. Improved stereoacuity in 5/9 Safety and efficacy of PRK over 36 month reasonably established Better results may be obtained if PRK done at an earlier age.

Limitations Small sample size Bias towards myopia Hyperopia group already had BSCVA of 20/50 Analysis should be made of Myopia and Hyperopia separately Minification effect of minus numbers Strabismus is a confounding factor in control Long term corneal stability