Comparative analysis of safety and efficacy of photorefractive keratectomy versus photorefractive keratectomy combined with crosslinking

Purpose: To assess the safety, efficacy, and refractive predictability of half-fluence accelerated corneal collagen crosslinking (CXL) applied concurrently with photorefractive keratectomy (PRK), and compare the results to standard PRK. Setting: Refractive Services, The Eye Foundation, Coimbatore, India. Design: Interventional comparative case series. Methods: Patients seeking refractive correction for myopia or myopic astigmatism were included in the study. Photorefractive keratectomy with concurrent half-fluence crosslinking (PRK Xtra) was performed in eyes with borderline suspicious tomography (not amounting to forme fruste keratoconus) or low pachymetry between 450 and 474 mu m with an otherwise unremarkable corneal tomography. Eyes with normal corneal tomography and thickness between 475 and 500 mu m underwent standard PRK. The minimum follow-up period was 1 year. Results: In total, 109 eyes underwent PRK Xtra (Group A) and 118 eyes underwent PRK alone (Group B). The preoperative MRSE was -3.64 D and -3.38 D in Groups A and B, respectively (P=0.28). Group A had a significantly higher number of eyes with thinner corneas (P<0.01) and corneal tomographic abnormalities (P=0.02). At 1 year follow-up, 96.3% of eyes in group A as against 99.1% of eyes in group B achieved a best corrected distance visual acuity (CDVA) of 20/20 or better. No iatrogenic ectasia or hyperopic shift secondary to progressive flattening was noted in the PRK Xtra group. No significant difference in incidence of haze was noted. Conclusion: PRK Xtra showed comparable safety, efficacy, and stability to PRK in eyes with thinner pachymetry and tomographic abnormalities. Combining crosslinking with PRK in suspicious tomographies augurs for safe and predictable outcomes.