Phototherapeutic keratectomy versus mechanical epithelial removal followed by corneal collagen crosslinking for keratoconus

Objective: To compare the visual outcomes of patients with keratoconus treated with either phototherapeutic keratectomy (PTK) or mechanical epithelial removal prior to corneal collagen crosslinking (CXL). Design: Comparative study. Participants: The records of 34 patients (34 eyes) who had PTK (17 eyes) or mechanical (17 eyes) epithelial removal prior to CXL for keratoconus were reviewed retrospectively. Methods: CXL was performed by 1 of 3 surgeons (G.M., W.B.J., or K.B.). Of the eyes, 17 had undergone mechanical epithelial removal prior to CXL and were consecutively selected, after matching with the 17 eyes in the PTK group, for the variables of procedure date, average keratometry, and pachymetry. All eyes had central cones. Manifest refraction spherical equivalent, sphere, cylinder, best-corrected distance visual acuity, and pachymetry were measured and compared preoperatively and in follow-up. Results: The mean change between the pre- and postoperative manifest refraction spherical equivalent for the PTK and mechanical groups was 1.68 +/- 0.80 and 0.26 +/- 0.90, respectively (p < 0.05). The mean change between pre- and postoperative cylinder for the PTK and mechanical groups was 0.53 +/- 0.28 and 0 +/- 0.18, respectively (p < 0.05). The mean number of lines of improvement in the PTK and mechanical groups were 0.33 +/- 0.82 and -0.58 +/- 0.45 lines, respectively (p > 0.05). Conclusions: Early results suggest that CXL with laser epithelial removal is superior to CXL with mechanical epithelial removal because it reduces refractive error in qualified patients. Although not statistically significant, there was also a trend for PTK CXL patients to have better visual outcomes.