5-year follow-up of combined non-topography guided photorefractive keratectomy and corneal collagen cross linking for keratoconus.

Aim: To evaluate the visual outcomes of simultaneous non-topography guided photorefractive keratectomy (PRK) and corneal collagen cross-linking (CXL) in eyes with keratoconus 5y after the procedure.

Methods: Prospective, interventional, non-randomized, and non-controlled case series design was used. Sixty eyes of 30 patients (16 males and 14 females; age: 21-41y) with mild, non-progressive (stages 1-2) keratoconus were enrolled. Refraction, uncorrected distance visual acuity (UDVA) and corrected distance visual acuity (CDVA), flat and steep keratometry readings, and adverse events were evaluated preoperatively and postoperatively. Data were collected preoperatively and postoperatively at 3mo, 1, 2, 3, 4, and 5y follow-up visits after combined non-topography-guided PRK with CXL was performed. All patients had at least 5y of follow-up.

Results: All study parameters showed a statistically significant improvement at 5y over baseline values. The mean follow-up time was 68.20±4.71mo (range: 60-106mo). Patients showed a significant improvement in UDVA from 1.24±0.79 logMAR prior to combined non-TG-PRK+CXL to 0.06±0.15 logMAR postoperatively at the time of their last follow-up visit. CDVA significantly increased from 0.06±0.19 logMAR preoperatively to 0.03±0.12 logMAR postoperatively. A significant decrease in the mean spherical equivalent (SE) refraction was observed from -2.28±1.8 to -0.79±0.93 diopters (D) (<0.05), and the manifest sphere decreased from -1.62±1.23 to -0.27±0.21 D (=0.001). The manifest cylinder significantly decreased from -1.73±0.86 to -0.29±0.34 D postoperatively (=0.001). The mean steep keratometry was 45.13±1.32 47.28±2.12 D preoperatively (<0.05), and the preoperative mean steepest keratometry (Kmax) 48.6±3.1 was reduced significantly to 46.8±2.9 postoperatively (<0.05).

Conclusion: Combined non-TG-PRK with 15min CXL is an effective and safe option for correcting mild refractive error and improving visual acuity in patients with mild stable keratoconus.