Abstract Body:

Purpose: To compare result of 2 groups of keratoconus (KC) eyes undergoing combined topographic guided photorefractive keratectomy (TG-PRK) and phototherapeutic keratectomy (PTK) both in combination with corneal collagen cross-linking (CXL).

Study Design: Retrospective series

Methods: Schwind Amaris 1050 used with simultaneous CXL, UV-X 9 mW/cm2 x 10 min. for both groups. TG-PRK with CXL, n = 305 eyes and 31 treated with trans-epithelial PTK evaluated at 6 months. Data analyzed: manifest refraction, spherical equivalent (SE), uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), average K, and central corneal thickness. Safety and efficacy evaluated.

Results: Astigmatism reduction was greater in the TG-PRK group 1.56D compared to PTK group 1.16D (P=0.1). TG-PRK group had better UDVA, 61% achieved 20/40 vs 40% in PTK group. 78% of the TG-PRK maintained or had improvement in CDVA versus 58% of PTK group. The Spherical equivalent for TG-PRK group dropped from -2.79+/-3.33D to -0.62+/-2.29D while it is -2.19+/-2.83D to -1.72+/-3.16D for the PTK group. PTK group shows slight corneal flattened, with pre-operatively 48.76+/-4.45D to post-operatively 46.32+/-3.91D.

Conclusions: TG-PRK CXL for keratoconus is superior to PTK CXL in refractive outcomes, including reduction in both spherical equivalent and astigmatism, UDVA and CDVA. While TE-PTK may be less likely to cause progression, this advantage is offset by no useful improvement in astigmatism or vision compared to significant gain in TG-PRK with CXL.