Dynamics of Corneal Swelling With Hypoosmolar Riboflavin After Induction During Corneal Collagen Crosslinking in Patients With Progressive Keratoconus.

PURPOSE: To evaluate the rate of corneal swelling induced by hypoosmolar riboflavin in patients with progressive keratoconus (KCN) with corneal thickness <400 µm after the induction phase using riboflavin with 20% dextran during epithelium-off corneal crosslinking (CXL). METHODS: Prospective, nonrandomized, single-center consecutive case series. Preoperative assessments included tomography, specular microscopy, and hysteresis. After epithelial debridement, riboflavin with 20% dextran (Photrexa Viscous; Glaukos, Burlington, MA) was applied at 2-min intervals during a 30-min induction phase. Eyes that dehydrated to a minimum corneal thickness (MCT) of <400 µm after induction (postinduction pachymetry) were recruited. Hypoosmolar riboflavin 0.146% (Photrexa; Glaukos) was used every 10 s to induce stromal swelling, with pachymetry performed every 30 s until the MCT was ≥400 µm (postswelling pachymetry). Corneal swelling rate was compared with variables using regression analysis. RESULTS: In 31 eyes of 31 patients, mean postinduction pachymetry was 338.4 ± 28.7 µm. Hypoosmolar riboflavin induced a postswelling pachymetry of 413.4 ± 15.0 µm over a mean of 5.2 ± 3.2 min, and the average stromal swelling rate was 10.3 ± 8.7 µm/30 s. All eyes reached a postswelling pachymetry MCT ≥400 µm and no cases were aborted. Eyes with highly severe KCN (Kmax >70 and Belin/Ambrosio enhanced ectasia display final D score >17) experienced quicker swelling (14.4 ± 12.8 µm/30 s and 14.9 ± 12.4 µm/30 s, respectively; P < 0.05 for both). A thicker postinduction pachymetry was moderately associated with a faster rate of swelling (rs = 0.389; P = 0.030). CONCLUSIONS: Hypoosmolar riboflavin 0.146% can be safely employed in thinner corneas, allowing for swelling to ≥400 µm for epithelium-off CXL. Associations between swelling rate, KCN severity, and postinduction pachymetry were determined, allowing for a more accurate prediction of procedure time during CXL.

Oxygen-supplemented and topography-guided epithelium-on corneal crosslinking with pulsed irradiation for progressive keratoconus.

PURPOSE: To investigate the effects of customized topography-guided epithelium-on crosslinking (epi-on CXL) with oxygen supplementation on procedural efficacy and corrected distance visual acuity (CDVA) in patients with progressive keratoconus (KC) at 1 year. SETTING: Private eye clinic, Brisbane, Australia. DESIGN: Retrospective, single-center, nonrandomized case series. METHODS: Topography-guided epi-on CXL using the Mosaic system was performed on patients with progressive KC. Oxygen goggles; transepithelial riboflavin; and pulsed, high UV-A irradiance (1 second on, 1 second off; 30 mW/cm2) were applied to enhance oxygen kinetics and bioavailabilities of riboflavin and UV-A. Guided by baseline topography, a higher UV-A dose (15 J/cm2) was applied to the area of steepest anterior curvature with decreasing fluence (as low as 7.2 J/cm2) toward the outer 9 mm. Postoperative CDVA and maximum keratometry (Kmax) were evaluated. RESULTS: 102 eyes (80 patients) were followed for 11.5 ± 4.8 months. At the latest follow-up, mean CDVA (logMAR), mean K, and Kmax (diopters [D]) improved from 0.18 ± 0.28, 46.2 ± 3.8, and 53.0 ± 5.67 at baseline to 0.07 ± 0.18, 45.8 ± 3.7, and 51.9 ± 5.56, respectively (P < .001). 3 eyes (3%) lost more than 1 CDVA line, and another 3 eyes (3%) had increased Kmax greater than 2 D. 43 eyes were followed for at least 12 months (n = 43): mean CDVA, mean K, and Kmax improved from 0.19 ± 0.33 logMAR, 46.5 ± 3.5 D, and 53.6 ± 5.67 D to 0.07 ± 0.17 logMAR, 46.0 ± 3.5 D, and 52.33 ± 5.49 D, respectively (P ≤ .002). No complications were observed. CONCLUSIONS: Tailoring oxygen-supplemented epi-on CXL with differential UV-A energy distributions, guided by baseline topography, in patients with KC seems to be safe and effective. At 1 year, study reports sustained improved CDVA and corneal stabilization.

Oxygen-supplemented transepithelial-accelerated corneal crosslinking with pulsed irradiation for progressive keratoconus: 1 year outcomes.

PURPOSE: To investigate the effects of combining oxygen supplementation with enhanced UV-A light and increased riboflavin permeability in improving the efficacy of epithelium-on crosslinking (epi-on CXL). SETTING: Private eye clinic in Brisbane, Queensland, Australia. DESIGN: Retrospective single-center nonrandomized uncontrolled longitudinal cohort case series. METHODS: Transepithelial CXL was performed on keratoconic eyes. Applications of an oxygen goggle and pulsed UV-A irradiation (1 second on, 1 second off) were used to enhance oxygen kinetics during epi-on CXL. Additional procedural modifications included the use of benzalkonium chloride and high UV-A irradiance level (30 mW/cm 2 ) to improve the stromal bioavailability of riboflavin and UV-A. The main efficacy outcomes were the changes in mean corrected distance visual acuity (CDVA) and safety over 12 months. Additional refractive and keratometry (K) outcomes were also observed. RESULTS: 53 eyes (38 patients) were included in this study. 12 months postoperatively, mean CDVA improved from a mean of 0.18 ± 0.2 at baseline to 0.07 ± 0.1 logMAR ( P < .0001). No statistically significant change was observed in maximum K (Kmax) and mean K, which were respectively 51.7 ± 5.8 diopters (D) and 46.4 ± 3.85 D at baseline and 51.2 ± 5.7 D ( P = .152) and 46.0 ± 3.84 D ( P = .06) 12 months postoperatively. Only 3 eyes experienced an increase of more than 2 D in Kmax; however, none of these eyes experienced a CDVA loss. There were no reported infections, corneal scarring, or other severe adverse effects. CONCLUSIONS: Performing supplemental oxygen epi-on CXL with accelerated, pulsed UV-A irradiation in conjunction with riboflavin permeability enhancers resulted in improved CDVA ( P < .0001) and stable keratometry up to 12 months postoperatively with a good safety profile.

Corneal collagen cross-linking: a review of 1-year outcomes.

PURPOSE: To review outcomes of corneal collagen cross-linking (CXL) for keratoconus (KC) or ectasia in a cornea subspecialty practice. METHODS: Results from controlled clinical trials at a single site cornea subspecialty practice, including 104 eyes (66 KC and 38 ectasia). Outcomes and the natural course of changes in postoperative parameters including maximum keratometry (KMax), uncorrected visual acuity (UCVA), and best-corrected visual acuity (BCVA) over 12 months are reviewed. In addition, corneal topography indices, wavefront higher-order aberrations, and the natural history of wound healing after CXL are discussed. Characteristics associated with CXL outcomes are reviewed as well. In predicting treatment outcomes for KMax and BCVA, the preoperative patient characteristics examined were gender, age, disease group, cone location, thinnest pachymetry, UCVA, BCVA, and KMax. RESULTS: At 1 year, an average of 1.7 diopter (D) flattening in KMax was found. Mean BCVA improved slightly more than 1 line (from 0.35±0.24 to 0.23±0.21 logMAR). All postoperative parameters similarly follow a trend of worsening between baseline and 1 month, and improvement thereafter. More specifically, quantitative improvements are typically seen at 3 months and may continue between 3 and 12 months. A review of baseline patient characteristics indicated that (1) eyes with preoperative KMax of 55 D or steeper were 5.4 times more likely to gain 2 D or more of KMax flattening at 1 year after CXL, and (2) eyes with preoperative BCVA of 20/40 or worse were 5.9 times more likely to gain 2 or more Snellen lines at 1 year after CXL. Conversely, no baseline characteristic was found to correlate with treatment complications of continual topographic steepening or loss of vision. CONCLUSIONS: Corneal collagen cross-linking seems to be effective in decreasing progression of KC, with improvements in optical measures in many patients. Postoperative parameters discussed within this review followed a seemingly reproducible trend in their natural course over 12 months. Generally, the trend observed was immediate worsening between baseline and 1 month, resolution at approximately 3 months, and improvement thereafter. In predicting outcomes after CXL, no patient characteristics showed correlations with negative treatment outcomes such as loss of vision or continual topographic steepening. However, steeper KMax (≥55 D) and poorer BCVA (≤20/40) at the time of treatment correlated with better postoperative KMax and BCVA outcomes at 1 year, respectively. These outcome predictors should be considered when offering CXL to patients with KC or postoperative corneal ectasia.