Purpose
To examine the predictability of flap thickness using a mechanical microkeratome (One Use-Plus) and identify factors related to variations in flap thickness in sub-Bowman keratomileusis (SBK).
Setting
Tadawi Surgical Center, Taif, Saudi Arabia.
Design
Retrospective case series.
Methods
Patients with a stable refraction for 1 year, corrected distance visual acuity (CDVA) of at least 20/20 in each eye, and minimum central corneal thickness of 480 μm in each eye had microkeratome-assisted SBK. Parameters included manifest refraction, uncorrected distance visual acuity (UDVA), CDVA, pachymetry, and higher-order aberrations (HOAs).
Results
Seventy eyes (36 patients) were enrolled. The mean flap thickness was 88.74 μm ± 15.40 (SD) and the mean change in HOAs, 0.11 ± 0.30 μm2. There was no correlation between flap thickness and age (r = −0.10), preoperative manifest refraction spherical equivalent (MRSE) (r = −0.08), preoperative cylinder (r = 0.13), postoperative CDVA (r = −0.17), or postoperative change in HOAs (r = −0.07). A strong positive correlation with preoperative pachymetry (r = 0.41) and a weak negative correlation with preoperative sphere (r = −0.21) were observed. There was no or a moderate negative correlation of pachymetry with age (r = −0.14), preoperative sphere (r = −0.36), cylinder (r = −0.04), or MRSE (r = −0.36).
Conclusions
The microkeratome was reliable with reasonable predictability for SBK flap creation. Extra caution in handling the flaps to avoid flap striae or tears is advised. Flap thickness correlated positively with preoperative pachymetry; however, the variation in flap thickness did not affect visual outcomes.
Financial Disclosure
The author has no financial or proprietary interest in any material or method mentioned.
