Abstract
Purpose :
Topography-Guided photorefractive keratectomy (TG-PRK) is an effective treatment to improve vision, refraction, and corneal contour in patients with keratoconus. Generally, there is a myopic shift after treatment with TG-PRK which may increase manifest refractive spherical equivalent (MRSE) and anisometropia post-operatively. This study aims to evaluate a novel technique, utilizing a superior mask to cover the peripheral ablation profile to reduce a postoperative myopic shift.
Methods :
13 eyes of 13 patients underwent TG-PRK with superior-masking technique. A LASIK eye drain (Wilson Oph Corp, USA) was cut to mask the superior portion of the topography-guided ablation. Topography measurements were obtained on the Pentacam (Oculus, Germany). Preoperative and 12-month post-operative MRSE, uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), maximum keratometry (Kmax), thinnest pachymetry (Pthin), and average anterior and posterior radii of curvature (ARC and PRC) were recorded and analyzed.
Results :
Compared to baseline vision, the mean UDVA improved from 1.00 ± 0.35 (SD) to 0.45 ± 0.14 logMar lines (LL) (P=0.004) and the mean CDVA improved from 0.48 ± 0.31 LL to 0.19 ± 0.08 LL (P=0.04) at the 12 month visit. MRSE improved from baseline of -5.85 ± 3.66D to -1.82 ± 3.75D at the 12 month visit (p=0.02). Kmax decreased from 60.78 ± 8.87D pre-operatively to 51.77 ± 4.62D at the 12 month visit (P=0.04). Finally, Pthin decreased from 429.08 ± 46.07µm at baseline to 408 ± 73.72µm at the 12 month visit (P=0.33); however these values were not statistically significant.
Conclusions :
TG-PRK with a superior mask is a novel technique to minimize the post-operative myopic shift in treated patients with keratoconus. In addition, this technique appears to improve UDVA, CDVA, and cornea curvature after treatment. Additional data will be presented at ARVO 2021.
This is a 2021 ARVO Annual Meeting abstract.