Accelerated Corneal Collagen Cross-linking Research Articles

Accelerated corneal collagen cross-linking in pediatric patients: two-year follow-up results.

Purpose. To evaluate the effectiveness and safety of accelerated corneal collagen cross-linking (ACXL) in patients below 14 years of age with progressive keratoconus. Materials and Methods. Thirty eyes of 18 patients with established progressive keratoconus underwent preoperative and postoperative visual acuity assessment, topography, and specular microscopy prior to ACXL and were followed up for 24 months. Results. Mean age of the patients was 12.7 years with ten males and eight females. There was an improvement in the mean postoperative uncorrected distant visual acuity (from 0.76 ± 0.26 to 0.61 ± 0.25; P = 0.005), mean corrected distant visual acuity (from 0.24 ± 0.19 to 0.12 ± 0.12; P < 0.001), mean spherical refraction (from −3.04 DS ± 3.60 to −2.38 DS ± 3.37; P = 0.28), mean cylinder (from −3.63 DC ± 1.82 to −2.80 DC ± 1.48; P = 0.008), and spherical equivalent (from −4.70 D ± 3.86 to −3.75 D ± 3.49; P = 0.15). Three eyes of two patients with vernal keratoconjunctivitis (VKC) showed progression. There were no intra- or postoperative complications. Conclusion. In pediatric patients ACXL is an effective and safe procedure for the management of keratoconus. Optimal management of VKC is important to arrest the progression of keratoconus.

Pulsed Light Accelerated Crosslinking versus Continuous Light Accelerated Crosslinking: One-Year Results.

Purpose. To compare functional results in two cohorts of patients undergoing epithelium-off pulsed (pl-ACXL) and continuous light accelerated corneal collagen crosslinking (cl-ACXL) with dextran-free riboflavin solution and high-fluence ultraviolet A irradiation. Design. It is a prospective, comparative, and interventional clinical study. Methods. 20 patients affected by progressive keratoconus were enrolled in the study. 10 eyes of 10 patients underwent an epithelium-off pl-ACXL by the KXL UV-A source (Avedro Inc., Waltham, MS, USA) with 8 minutes (1 sec. on/1 sec. off) of UV-A exposure at 30 mW/cm2 and energy dose of 7.2 J/cm2; 10 eyes of 10 patients underwent an epithelium-off cl-ACXL at 30 mW/cm2 for 4 minutes. Riboflavin 0.1% dextran-free solution was used for a 10-minutes corneal soaking. Patients underwent clinical examination of uncorrected distance visual acuity and corrected distance visual acuity (UDVA and CDVA), corneal topography and aberrometry (CSO EyeTop, Florence, Italy), corneal OCT optical pachymetry (Cirrus OCT, Zeiss Meditec, Jena, Germany), endothelial cells count (I-Conan Non Co Robot), and in vivo scanning laser confocal microscopy (Heidelberg, Germany) at 1, 3, 6, and 12 months of follow-up. Results. Functional results one year after cl-ACXL and pl-ACXL demonstrated keratoconus stability in both groups. Functional outcomes were found to be better in epithelium-off pulsed light accelerated treatment together with showing a deeper stromal penetration. No endothelial damage was recorded during the follow-up in both groups. Conclusions. The study confirmed that oxygen represents the main driver of collagen crosslinking reaction. Pulsed light treatment optimized intraoperative oxygen availability improving postoperative functional outcomes compared with continuous light treatment.

Evaluation of corneal stromal demarcation line after two different protocols of accelerated corneal collagen cross-linking procedures using anterior segment optical coherence tomography and confocal microscopy.

Purpose. To evaluate the depth of corneal stromal demarcation line using AS-OCT and confocal microscopy after two different protocols of accelerated corneal collagen cross-linking procedures (CXL). Methods. Patients with keratoconus were divided into two groups. Peschke CXL device (Peschke CCL-VARIO Meditrade GmbH) applied UVA light with an intended irradiance of 18.0 mW/cm2 for 5 minutes after applying riboflavin for 20 minutes (group 1) and 30 minutes (group 2). One month postoperatively, corneal stromal demarcation line was measured using AS-OCT and confocal microscopy. Results. This study enrolled 34 eyes of 34 patients (17 eyes in group 1 and 17 eyes in group 2). The mean depth of the corneal stromal demarcation line was 208.64 ± 18.41 μm in group 1 and 240.37 ± 18.89 μm in group 2 measured with AS OCT, while it was 210.29 ± 18.66 μm in group 1 and 239.37 ± 20.07 μm in group 2 measured with confocal microscopy. Corneal stromal demarcation line depth measured with AS OCT or confocal microscopy was significantly deeper in group 2 than group 1 (P < 0.01). Conclusion. The group in which riboflavin was applied for 30 minutes showed significantly deeper corneal stromal demarcation line than the group in which riboflavin was applied for 20 minutes.

Accelerated corneal collagen cross-linking for progressive keratoconus

Purpose: To evaluate the efficacy of accelerated corneal cross-linking (CXL) procedure for progressive keratoconus.Materials and methods: Twenty-three eyes of 23 patients undergone accelerated CXL procedure were evaluated preoperatively and postoperatively at 1st, 3rd and 6th month for uncorrected distant visual acuity (UDVA), best corrected distant visual acuity (CDVA), spherical error, cylindrical error, spherical equivalent (SE), keratometric values and thinnest corneal thickness (TCT) values with corneal topography by Scheimpflug camera and endothelial cell density (ECD).Results: The mean UDVA was improved from 0.97 ± 0.41 logarithm of minimal angle of resolution (logMAR) to 0.76 ± 0.45 logMAR at the 6th month after CXL (p = 0.332). The mean CDVA was improved from 0.49 ± 0.30 logMAR to 0.34 ± 0.22 logMAR at the 6th month after CXL (p = 0.026). The mean sphere was decreased from −4.47 ± 4.1 diopter (D) to −3.79 ± 3.86 D and the mean cylinder was decreased from −5.60 ± 2.2 D to −4.55 ± 1.98 D and the mean SE was decreased from −7.22 ± 4.48 D to −6.36 ± 4.34 D at the 6th month after CXL (p = 0.128, p = 0.002 and p = 0.045, respectively). Flat keratometry, steep keratometry, mean keratometry and maximum keratometry were significantly reduced at the 6th month after CXL (p = 0.025, p < 0.001, p = 0.004 and p = 0.03, respectively). TCT and ECD were not changed significantly the 6th month after CXL (p = 0.135 and p = 0.082, respectively).Conclusion: Accelerated CXL procedure was effective to stabilize progression of keratoconus with significant reduction in topographic keratometric values and significant increase in CDVA in 6 months.

Outcomes of a New Microwave Procedure Followed By Accelerated Cross-linking for the Treatment of Keratoconus: A Pilot Study

To analyze the initial data obtained in a group of patients treated with microwave keratoplasty followed by accelerated corneal collagen cross-linking (CXL) for the correction of keratoconus. Prospective, nonrandomized clinical study including six eyes from four patients treated with microwave thermal keratoplasty followed by accelerated CXL. Refractive, topographic, anterior aberrometry, and corneal biomechanics outcomes were analyzed during 6-month follow-up. Immediately after the procedure, a significant reduction of >7.00 diopters (D) was observed in mean keratometry (P=.02). Uncorrected distance visual acuity increased from 0.92±0.52 logMAR (Snellen 20/160) preoperatively to 0.47±0.19 logMAR (Snellen 20/60) postoperatively (P=.05). No statistically significant change was found in corrected distance visual acuity (P=.28). Corneal higher order aberration decreased from 1.89±0.90 to 1.51±0.65 μm and corneal primary coma aberration decreased from 1.45±0.68 μm preoperatively to 0.84±0.23 μm postoperatively (P>.10). No statistically significant changes were found in the biomechanics variables (P=.40). A significant regression of the effect was assessed in keratometry at the end of follow-up (P=.03). The Keraflex procedure may have the ability to improve refractive status in patients who suffer from keratoconus, as well as induce corneal remodeling to a more anterior regular surface. However, the current treatment regimen is not sufficient to maintain the flattening effect achieved and significant regression occurs.