Use of angle kappa in myopic photorefractive keratectomy

Abstract

Hamid Khakshoor,1 Michael V McCaughey,2 Amir Hossein Vejdani,1 Ramin Daneshvar,1 Majid Moshirfar3 1Department of Ophthalmology, The University of Mashhad, Mashhad, Iran; 2Department of Ophthalmology, The University of New Mexico, School of Medicine, Albuquerque, NM, USA; 3Department of Ophthalmology, Francis I Proctor Foundation, University of California San Francisco, CA, USA Purpose: To explore utilization of the coaxially sighted corneal light reflex (CSCLR) for centration during myopic photorefractive keratectomy (PRK) for patients with relatively high angle kappa (κ) values.Methods: Patients were stratified into two groups preoperatively, on the basis of angle κ values. Group A was composed of 166 eyes with an angle κ value <5°. Group B consisted of 182 eyes with an angle κ value >5°. Intraoperative centering of ablation was performed within group A by utilizing the pupillary center, and within group B by using the CSCLR. Visual acuities were evaluated and compared at 6 months and 12 months postoperatively between groups.Results: Mean uncorrected visual acuities (UCVA) for all patients at 6 months and 12 months were -0.073 logMAR and -0.080 logMAR, respectively. A total of 98.9% of patients had a UCVA of 0.00 logMAR (≈20/20 Snellen) 12 months postoperatively. There was not a significant between-group difference in regard to residual refractive error at 6 months or 12 months (P=0.53 and P=0.97), or in UCVA at 6 months and 12 months (P=0.76 and P=0.17). There were no subjective complaints of monocular diplopia, glare, or haloes within either group at any time during follow-up.Conclusion: Availing use of the CSCLR for centration of ablation within myopic patients with high angle κ values may aid in providing better refractive outcomes after performance of PRK. Keywords: angle kappa, photorefractive keratectomy, PRK, CSCLR, myopia, Purkinje reflex