Contralateral eye comparison of the efficacy and safety of two artificial tear formulations for corneal subbasal nerve fiber regeneration after photorefractive keratectomy

Abstract

Background: Currently, artificial tears (ATs) are the first-line agents for managing dry eye disease (DED). This study compared the efficacy and safety of two different AT formulations, Systane® Hydration (SH) and Systane® Ultra (SU), on symptoms of DED and regeneration of the subbasal corneal nerve fiber length (CNFL) in photorefractive keratectomy (PRK)-treated eyes.
 Methods: This prospective contralateral comparative study recruited myopic eyes scheduled for PRK, and either SH or SU were administered for up to 3 months postoperatively. All participants underwent a standard comprehensive preoperative ophthalmological examination, in vivo confocal microscopy to evaluate the subbasal CNFL, and completed Ocular Surface Disease Index (OSDI) questionnaire for assessing dry eye symptoms. Image analysis software was used to calculate the subbasal CNFL (micrometer/mm2). Assessments were repeated at the 1- and 3-month follow-up visits. Pre- and postoperative subbasal CNFL and OSDI scores were compared to determine inter- and intra-group differences.
 Results: Fifty eyes of 25 participants were included in this study. The mean (standard deviation) age of the participants was 22.7 (3.8) years. The OSDI scores for both groups increased significantly at 1 month (both P<0.05), followed by a decrease at 3 months to values comparable to the preoperative scores (both P>0.05). Although OSDI scores were comparable at baseline and at the 1-month postoperative visit (both P>0.05), the SU-treated eyes had a significantly better OSDI score at the 3-month visit (P<0.05), despite being clinically insignificant. Preoperative subbasal CNFL differed significantly between the groups (P=0.001), yet the mean values at both postoperative visits were comparable (both P>0.05). In both groups, subbasal CNFL was significantly reduced at 1 month, followed by a significant increase at the 3-month postoperative visit compared to baseline (all P<0.05). No treatment-related complications were observed at the end of the study period.
 Conclusions: No significant difference was found between the preoperative and 3-month postoperative OSDI scores in the SH- or SU-treated eyes. Subbasal CNFL regeneration indicated a positive effect of both ATs, with a longer mean CNFL noted in the SH-treated eyes at the final visit. This suggests that SH may be a better option for improving corneal reinnervation after PRK. These observations must be verified in further trials with longer follow-up periods and larger sample sizes.