Comparison of penetrating keratoplasty outcomes with or without microwave thermokeratoplasty

Microwave thermokeratoplasty (MTK) is a surgical procedure for the correction of pathologic corneal steepening. The purpose of this study was to examine the postoperative outcomes of eyes with advanced keratoconus that underwent femtosecond-laser zig-zag penetrating keratoplasty (z-PK) following MTK for reshaping of the central cornea. This study involved 32 eyes of 32 consecutive advanced keratoconus patients; i.e., 25 eyes of 25 patients who underwent MTK prior to z-PK (MTK + z-PK group), and 7 eyes of 7 patients who underwent z-PK alone (z-PK group). In all treated eyes, visual acuity (VA) and corneal topography were measured before surgery and at 6-months postoperative. At 6-months postoperative, the mean uncorrected distance VA (logarithm of the minimum angle of resolution) and surface regularity index (SRI) of the MTK + z-PK group was 0.62 ± 0.39 (mean ± standard deviation) and 1.26 ± 0.45, respectively, while that in the z-PK group was 1.02 ± 0.18 and 7.64 ± 3.22, respectively. Both variables were significantly better in the MTK + z-PK group than in the z-PK group (P < 0.05). The findings in this study reveal that MTK prior to z-PKP is effective for improving UDVA and reducing the irregularity of corneal topography in patients with advanced keratoconus.