Long-Term Stability of Minimally Invasive Radial Keratotomy for Mild to Moderate Keratoconus

This study aimed to evaluate the long-term stability of minimally invasive radial keratotomy (mini-RK) for eyes with mild to moderate keratoconus.

Retrospective observational case series.

Eleven eyes from 6 patients with hard contact lens (HCL)-intolerant keratoconus underwent mini-RK and were followed up for more than 5 years. The mini-RK consisted of 8 radial incisions with depths of 90% of the thinnest corneal thickness, based on the Lindstrom nomogram. Best-corrected visual acuity (BCVA), keratometry, and corneal endothelial cell density (ECD) were examined preoperatively and for 5 to 10 years postoperatively. Changes in keratometric astigmatism were evaluated using power vector analysis. Severities of keratoconus preoperatively and 1 year postoperatively were graded using the Amsler-Krumeich classification.

The postoperative observation periods were from 6 to 10 years (mean, 7.9 years). There were no changes in the BCVA, ECD, and keratometric astigmatism. The mean keratometric refraction significantly decreased from 47.5 diopters (D) preoperatively to 44.0 D at 1 month after mini-RK (P = 0.037) and was stable over 5 years, whereas keratometric astigmatism did not change from preoperatively through the postoperative period (P > 0.59). Keratoconus of grade 2 or higher improved to lower grades.

The mini-RK treatment was safe and effective for HCL-intolerant eyes with mild to moderate keratoconus.