Comparison of microkeratome assisted sub-Bowman keratomileusis with photorefractive keratectomy

To compare the outcomes of photorefractive keratectomy (PRK) and thin-flap Laser-Assisted in Situ Keratomileusis/sub-Bowman keratomileusis (SBK) with intended flap thicknesses of 100μm using the One Use-Plus SBK microkeratome. Ninety-eight eyes of 52 subjects with myopic manifest refraction spherical equivalent (MRSE) of up to −5 diopters (D), a stable refraction for 1year and a corrected distance visual acuity (CDVA) of at least 20/20 in each eye which had undergone SBK or PRK were reviewed retrospectively. Primary outcome measures were MRSE, uncorrected distance visual acuity (UDVA), CDVA, pachymetry and higher order aberrations (HOA). All patients were seen at 1 and 3days, 1week, and 1, 3, and 6months after surgery. Both MRSE and UDVA showed a statistically significant improvement at postoperative 1, 3 and 6months from baseline in both SBK and PRK groups. At postoperative 6months, 100% of eyes were within ±0.50 D of attempted correction in both groups. However, SBK group demonstrated better outcomes with 81% of eyes within ±0.13 D, compared to 70% eyes in the PRK group. Both SBK and PRK group demonstrated similar refractive astigmatism accuracy at postoperative 6months, with 88% of eyes having cylindrical error ⩽0.25 D. None of eyes lost any lines of CDVA in the PRK, and 2% eyes lost one line of CDVA in SBK group at postoperative 6months. The visual and refractive outcomes after both PRK and microkeratome assisted SBK are comparable, albeit with a higher complication rate in the SBK group.