Evaluating The Outcomes Of Topoguided Prk Combined With Crosslinking (Cxl) And Establishing Management Thresholds For Treating Keratoconus.

To describe the 3-month postoperative outcomes following topoguided PRK combined with crosslinking (CXL) in keratoconic eyes, and to identify the preoperative Kmax measurement that may help predict favorable postoperative results.

Cathedral Eye Clinic, Belfast, Northern Ireland, UK.

This retrospective chart review included 45 eyes who received topoguided PRK and CXL for keratoconus. The 3-month corrected distance visual acuity (CDVA), KMax and thinnest central corneal thickness (CCT) at 3 months were assessed. Initially, patients were categorised based upon postoperative CDVA, and KMax and CCt were compared. Secondly, patients were categorised based upon preoperative Kmax to determine the level which produces a postoperative CDVA of 0.1logMAR or better. 

The preoperative CDVA was 0.23 ± 0.21 (range, -0.12 to 0.74) which improved to 0.13 ± 0.16 logMAR (range, -0.2 to 0.54). The preoperative Kmax and thinnest CCT were 56.07 ± 5.18D and 467.47 ± 35.57um respectively, with 51.82 ± 6.52D and 422.67 ± 41.06um found postoperatively. Patients with CDVA of 0.1 logMAR or better had a significantly lower KMax (P=0.02) than patients with a CDVA of 0.2 or worse. A cutoff of preoperative Kmax 55D appears to be appropriate, with 76.2% of eyes achieving 0.1 logMAR or better postoperatively. Patients with preoperative Kmax <55D displayed a statistically significant improvement in CDVA.

A preoperative cutoff <55D appears to result in satisfactory postoperative CDVA (0.1 logMAR) and leads to a significant improvement in CDVA. A preoperative Kmax greater than this may warrant treatment via an alternative methodology, such as CAIRS.

Greater numbers will be reported at the conference.