Refractive Outcomes of Topography-Guided Photorefractive Keratectomy With Simultaneous CXL for Keratoconus

Tuesday, April 21, 2015: 8:31 AM
Room 1B (San Diego Convention Center)
Simon P. Holland, MB, FRCSC
David T.C. Lin, MD, FRCSC
Johnson Tan, MBBS, FRCSEd (Ophth)
Gregory Moloney, MBBS, FRANZCO

Evaluate refractive outcomes, efficacy and safety of simultaneous topography-guided photorefractive keratectomy (TG-PRK) with collagen cross-linking (CXL) for keratoconus (KC) using a neutralization technique and determine degree of hyperopic effect of CXL induced keratometric flattening after first year.

Epithelial removal by trans-epithelial laser, riboflavin 0.1% until aqueous staining, UV irradiation 370nm 8-15 minutes, 3mW/cm2 - 5.4 J/m2 , hypotonic  riboflavin if less than 400um, bandage contact lens, standard post PRK management Degree of refractive correction based on residual stromal depth of 300 microns with target correction of -1.25 diopters (D). Symptom score (10 point) , uncorrected visual acuity (UCVA), best spectacle corrected visual acuity (BSCVA), keratometry(K), efficacy, and safety were  at 12 months.

At 1 year result, 288 out of 464 eyes met all inclusion criteria. 144(50%) had UCVA of 20/40 or better. 49(17%) had UCVA of 20/25 or better. 147(51%) had BSCVA improved, 69(24%) gained 2 lines or more, 17(6%) lost 2 lines or more. Average symptom score improved from 6.7 to 4.2. Mean reduction of astigmatism was 1.69±1.78 diopters (D). Mean spherical equivalent reduced from -2.74±2.81D to -1.24±2.18D. Complications included 7 with delay in epithelial healing, 4 with subsequent haze, 4 sufficient to reduce BCVA more than 2 lines, with one undergoing keratoplasty. One developed herpetic keratitis recovering pre-operative BCVA after PTK.

Early satisfactory refractive outcomes were obtained with simultaneous topographically-guided PRK with CXL for keratoconus.  Progressive hyperopia probably related to cross linking, sufficient to be visually significant, occurred in 4 eyes. At one year follow-up, half of the eyes achieved UCVA of 20/40 or better and more than half improved BSCVA.