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Purpose: To investigate the in vivo, corneal, biomechanical changes after corneal collagen cross-linking (CXL) using the Ocular Response Analyzer (ORA) in patients with keratoconus and post-laser in situ keratomileusis (LASIK) ectasia., Methods: Single-center, prospective, randomized, controlled, clinical trial. After CXL (69 eyes, 46 keratoconus and 23 post-LASIK), corneal hysteresis (CH) and corneal resistance factor (CRF) were measured using the ORA and analyzed in a treatment, sham control, and fellow eye control group at baseline and 1, 3, 6, and 12 months., Results: There were no significant changes in CH (change = 0.05 ± 1.5; P = 0.78) or CRF (change = 0.29 ± 1.4; P = 0.1) at 1 year compared with preoperative values. Changes in CH and CRF were not correlated with changes in clinical outcomes of uncorrected visual acuity, best spectacle-corrected visual acuity, and maximum keratometry. There were no significant changes in CH in the sham or fellow eye control groups (P(sham) = 0.7; P(FE) = 0.3) or CRF (P(sham) = 0.6; P(FE) = 0.72)., Conclusions: Despite an increase in CRF at one month, there were no statistically significant changes in CH and CRF measurements 1 year after CXL. Development of other in vivo biomechanical metrics would aid in evaluating the corneal response to CXL.

Purpose: To determine the changes in corneal thickness over time after corneal collagen crosslinking (CXL) for keratoconus and corneal ectasia., Setting: Cornea and refractive surgery subspecialty practice., Design: Prospective randomized controlled clinical trial., Methods: Corneal thickness at the apex, thinnest point, and pupil center were measured using Scheimpflug imaging (Pentacam) at baseline and 1, 3, 6, and 12 months after CXL. The treatment group was compared with both a sham-procedure control group and a fellow-eye control group. Associations with clinical outcomes (uncorrected and corrected distance visual acuities and maximum keratometry) were analyzed., Results: The study comprised 82 eyes, 54 with keratoconus and 28 with ectasia after laser in situ keratomileusis. The mean preoperative thinnest pachymetry was 440.7 μm ± 52.9 (SD). After CXL, the cornea thinned at 1 month (mean change -23.8 ± 28.7 μm; P<.001) and from 1 to 3 months (mean change -7.2 ± 20.1 μm, P=.002), followed by a recovery of the corneal thickness between 3 months and 6 months (mean +20.5 ± 20.4 μm; P<.001). At 1 year, apex and pupil-center thicknesses returned to baseline (P=.11 and P=.06, respectively); however, the thinnest pachymetry remained slightly decreased from baseline to 12 months (mean change -6.6 ± 22.4 μm; P=.01). The recovery of corneal thickness was more rapid in ectasia than in keratoconus. There was no association between the degree of corneal thinning at 3 months and clinical outcomes after CXL., Conclusions: After CXL, the cornea thins and then recovers toward baseline thickness. The cause and implications of corneal thickness changes after CXL remain to be elucidated., Financial Disclosure: No author has a financial or proprietary interest in any material or method mentioned. Additional disclosure is found in the footnotes., (Copyright © 2011 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.)

Purpose: To evaluate 1-year outcomes of corneal collagen crosslinking (CXL) for treatment of keratoconus and corneal ectasia., Setting: Cornea and refractive surgery subspecialty practice., Design: Prospective randomized controlled clinical trial., Methods: Collagen crosslinking was performed in eyes with keratoconus or ectasia. The treatment group received standard CXL and the sham control group received riboflavin alone. Principal outcomes included uncorrected (UDVA) and corrected (CDVA) distance visual acuities, refraction, astigmatism, and topography-derived outcomes of maximum and average keratometry (K) value., Results: The UDVA improved significantly from 0.84 logMAR ± 0.34 (SD) (20/137) to 0.77 ± 0.37 logMAR (20/117) (P = .04) and the CDVA, from 0.35 ± 0.24 logMAR (20/45) to 0.23 ± 0.21 logMAR (20/34) (P<.001). Fifteen patients (21.1%) gained and 1 patient lost (1.4%) 2 or more Snellen lines of CDVA. The maximum K value decreased from baseline by 1.7 ± 3.9 diopters (D) (P<.001), 2.0 ± 4.4 D (P = .002), and 1.0 ± 2.5 D (P = .08) in the entire cohort, keratoconus subgroup, and ectasia subgroup, respectively. The maximum K value decreased by 2.0 D or more in 22 patients (31.0%) and increased by 2.0 D or more in 3 patients (4.2%)., Conclusions: Collagen crosslinking was effective in improving UDVA, CDVA, the maximum K value, and the average K value. Keratoconus patients had more improvement in topographic measurements than patients with ectasia. Both CDVA and maximum K value worsened between baseline and 1 month, followed by improvement between 1, 3, and 6 months and stabilization thereafter., Financial Disclosure: No author has a financial or proprietary interest in any material or method mentioned. Additional disclosure is found in the footnotes., (Copyright © 2011 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.)

Purpose: To assess the outcomes of conductive keratoplasty (CK) for patients with complications related to LASIK or photorefractive keratectomy (PRK)., Design: Retrospective, noncomparative, interventional case series., Participants: Sixteen eyes of 15 patients were treated using CK after complications of initial LASIK or PRK surgeries. Five cases are described in detail., Intervention: Rehabilitative CK was performed., Main Outcome Measures: Uncorrected visual acuity (UCVA) and best spectacle-corrected visual acuity (BSCVA), refractive error, keratometry, topography analysis, and a subjective assessment of visual quality., Results: After CK treatment, there was a mean improvement in UCVA of 2 lines; 1 eye lost >1 line of UCVA. Best-corrected visual acuity improved or remained the same in 12 of 15 eyes; no eyes lost >1 line of BSCVA. There was a mean reduction in astigmatism of 54%. Videokeratography generally demonstrated improved quality of the corneal optical surface, and patients reported a reduction in optical symptoms such as glare and halo., Conclusions: Conductive keratoplasty may give improved corneal optics and vision in patients with complications of LASIK or PRK. This application of CK offers an alternative in cases in which further flap manipulation or laser treatments are contraindicated.

Purpose: To determine the incidence and risk factors for laser in situ keratomileusis (LASIK) retreatment and to present a novel retreatment technique., Design: Retrospective noncomparative consecutive case series., Participants: Two thousand four hundred eighty-five eyes (1306 patients) underwent LASIK surgery for myopia, hyperopia, or astigmatism using either the Summit Apex Plus or the Alcon LADARVision excimer laser systems. Only retreatments for residual refractive error were included., Main Outcome Measures: Prevalence and incidence of retreatments were determined. Potential risk factors for retreatment, including age, gender, and attempted correction, were assessed. Refractive error and a ratio of residual sphere to cylinder in retreated eyes were also analyzed., Results: Of the total cohort studied, 288 eyes of 233 patients underwent one retreatment, and 3 eyes of 3 patients required two retreatment procedures. The overall 1-year incidence of retreatment was 10.5%. The average length of time between initial treatment and enhancement was 7.3 +/- 6.4 months; 85% of retreatments took place within 1 year. Two hundred eighty-five of the 288 retreatments were accomplished using a manual flap lift approach; 3 eyes required a repeat microkeratome cut. Higher initial corrections and residual astigmatism were associated with a significantly higher rate of retreatment. Patients older than 40 years were at greater risk for retreatment. There was no gender difference., Conclusions: Higher initial corrections, astigmatism, and older age are risk factors for LASIK retreatment. Most LASIK flaps can be lifted using the manual technique described up to 3 years after initial surgery.

Purpose: To determine changes in higher-order aberrations (HOAs) after corneal collagen crosslinking (CXL). Setting: Cornea and refractive surgery practice. Design: Prospective randomized controlled clinical trial. Methods: Corneal and ocular HOAs were measured and analyzed using the Pentacam device and Ladarwave aberrometer, respectively, at baseline and 12 months after CXL. Results: Ninety-six eyes (64 keratoconus, 32 ectasia) of 73 patients had CXL. A fellow-eye control group comprised 42 eyes. The mean preoperative total anterior corneal HOAs, total coma, 3rd-order coma, and vertical coma were 4.68 μm ± 2.33 (SD), 4.40 ± 2.32 μm, 4.36 ± 2.30 μm, and 4.04 ± 2.27 μm, respectively. At 1 year, the mean values decreased significantly to 4.27 ± 2.25 μm, 4.01 ± 2.29 μm, 3.96 ± 2.27 μm, and 3.66 ± 2.22 μm, respectively (all P<.001). There were no significant changes in posterior corneal HOAs. The mean preoperative total ocular HOAs, total coma, 3rd-order coma, trefoil, and spherical aberration were 2.80 ± 1.0 μm, 2.60 ± 1.03 μm, 2.57 ± 1.03 μm, 0.98 ± 0.46 μm, and 0.90 ± 0.42 μm, respectively. At 1 year, the mean values decreased significantly to 2.59 ± 1.06 μm, 2.42 ± 1.07 μm, 2.39 ± 1.07 μm, 0.88 ± 0.49 μm, and 0.83 ± 0.38 μm, respectively (all P=.01). After CXL, HOAs were significantly improved compared with the control group. Changes in HOAs were not statistically associated with an improvement in visual acuity or most subjective visual symptoms, however. Conclusion: Corneal and ocular HOAs decreased after CXL, suggesting an improvement in corneal shape. Financial Disclosure: Dr. Hersh is medical monitor for Avedro, Inc. No author has a financial or proprietary interest in any material or method mentioned. [ABSTRACT FROM AUTHOR]