Long-Term Comparison of Simultaneous Topography-Guided Photorefractive Keratectomy Followed by Corneal Cross-linking versus Corneal Cross-linking Alone

To report the refractive, topographic, and clinical outcomes 3 years after corneal collagen cross-linking (CXL) in eyes with progressive keratoconus. Prospective, randomized controlled trial. One hundred eyes with progressive keratoconus were randomized into the CXL treatment or control groups. Cross-linking was performed by instilling riboflavin 0.1% solution containing 20% dextran for 15 minutes before and during the 30 minutes of ultraviolet A irradiation (3 mW/cm(2)). Follow-up examinations were arranged at 3, 6, 12, 24, and 36 months. The primary outcome measure was the maximum simulated keratometry value (Kmax). Other outcome measures were uncorrected visual acuity (UCVA; measured in logarithm of the minimum angle of resolution [logMAR] units), best spectacle-corrected visual acuity (BSCVA; measured in logMAR units), sphere and cylinder on subjective refraction, spherical equivalent, minimum simulated keratometry value, corneal thickness at the thinnest point, endothelial cell density, and intraocular pressure. The results from 48 control and 46 treated eyes are reported. In control eyes, Kmax increased by a mean of 1.20±0.28 diopters (D), 1.70±0.36 D, and 1.75±0.38 D at 12, 24, and 36 months, respectively (all P <0.001). In treated eyes, Kmax flattened by -0.72±0.15 D, -0.96±0.16 D, and -1.03±0.19 D at 12, 24, and 36 months, respectively (all P <0.001). The mean change in UCVA in the control group was +0.10±0.04 logMAR (P = 0.034) at 36 months. In the treatment group, both UCVA (-0.15±0.06 logMAR; P = 0.009) and BSCVA (-0.09±0.03 logMAR; P = 0.006) improved at 36 months. There was a significant reduction in corneal thickness measured using computerized videokeratography in both groups at 36 months (control group: -17.01±3.63 μm, P <0.001; treatment group: -19.52±5.06 μm, P <0.001) that was not observed in the treatment group using the manual pachymeter (treatment group: +5.86±4.30 μm, P = 0.181). The manifest cylinder increased by 1.17±0.49 D (P = 0.020) in the control group at 36 months. There were 2 eyes with minor complications that did not affect the final visual acuity. At 36 months, there was a sustained improvement in Kmax, UCVA, and BSCVA after CXL, whereas eyes in the control group demonstrated further progression. Copyright © 2014 American Academy of Ophthalmology. Published by Elsevier Inc. All rights reserved.

To assess the effectiveness of ultraviolet A (UVA) irradiation-induced collagen cross-linking (CCL) on keratoconus (KC) progression. A patient with bilateral, progressive KC underwent UVA irradiation (3 mW/cm for 30 minutes) after topical 0.1% riboflavin drops over a deepithelialized cornea. Twelve months later, a topography-guided penetrating keratoplasty (PRK; wavelight 400 Hz Eye-Q excimer) was performed in 1 eye for a refractive error of -3.50 -4.00 x 155 by using an attempted treatment of -2.50 -3.00 x 155. At all postoperative follow-up visits to 18 months, uncorrected visual acuity (UCVA), best spectacle-corrected visual acuity (BSCVA), pachymetry, and topography were performed. In the treated left eye, the UCVA after the UVA CCL improved from 20/100 to 20/80, and the BSCVA improved from 20/50 to 20/40. Eighteen months after the topography-guided PRK, the UCVA was 20/20, and the BSCVA was 20/15, with a refractive error of Plano -0.50 x 150. The cornea was clear, and the endothelial cell count remained unchanged. The untreated right mate eye continued to progress during the same period. The significant clinical improvement and the apparent stability of more than a year after UVA CCL, and subsequent PRK compared with the untreated mate eye, seems to validate this treatment approach for KC. An adjusted nomogram may be considered in the ablation of cross-linked cornea tissue to avoid overcorrections.