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/cm(2) and energy dose of 7.2 J/cm(2); 10 eyes of 10 patients underwent an epithelium-off cl-ACXL at 30 mW/cm(2) 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.

Transepithelial corneal collagen crosslinking for progressive keratoconus: 24-month clinical results.

PURPOSE: To assess the clinical results of transepithelial collagen crosslinking (CXL) in patients 26 years and younger with progressive keratoconus suitable for epithelium-off (epi-off) CXL. SETTING: Department of Ophthalmology, Siena University Hospital, Siena, Italy. DESIGN: Prospective case series. METHODS: The study included 26 eyes (26 patients) treated by transepithelial (epithelium-on) CXL. The mean age was 22 years (range 11 to 26 years) (10 younger than 18 years; 16 between 19 years and 26 years). Preoperative and postoperative examinations included uncorrected (UDVA) and corrected (CDVA) distance visual acuities, simulated maximum keratometry (K), coma and spherical aberration, and corneal optical coherence tomography optical pachymetry. The solution for transepithelial CXL (Ricrolin TE) comprised riboflavin 0.1%, dextran 15.0%, trometamol (Tris), and ethylenediaminetetraacetic acid. Ultraviolet-A treatment was performed with the Caporossi Baiocchi Mazzotta X Linker Vega at 3 mW/cm(2). RESULTS: After relative improvement in the first 3 to 6 months, the UDVA and CDVA gradually returned to baseline preoperative values. After 12 months of stability, the simulated maximum K value worsened at 24 months. Coma aberration showed no statistically significant change. Spherical aberration increased at 24 months. Pachymetry showed a progressive, statistically significant decrease at 24 months. Fifty percent of pediatric patients were retreated with epi-off CXL due to significant deterioration of all parameters after 12 months of follow-up. CONCLUSIONS: Functional results after transepithelial CXL showed keratoconus instability, in particular in pediatric patients 18 years old and younger; there was also functional regression in patients between 19 years and 26 years old after 24 months of follow-up. mentioned.

Transepithelial corneal collagen crosslinking for keratoconus: qualitative investigation by in vivo HRT II confocal analysis.

PURPOSE: This was a qualitative investigation of corneal microstructural modifications in keratoconic patients undergoing experimental transepithelial crosslinking (TE CXL). METHODS: Ten patients with keratoconus intolerant to gas-permeable rigid contact lenses were enrolled. Corneal thickness was in the range 350-390 µm at the thinnest point measured by Visante AC optical coherence tomography system (Zeiss, Jena, Germany). All patients underwent TE CXL with 0.1% riboflavin-15% dextran solution supplemented with TRIS plus sodium EDTA (Ricrolin TE, Sooft Italia) according to Siena protocol. In vivo Heidelberg retinal tomograph II laser scanning confocal analysis (Rostock Cornea Module, Heidelberg, Germany) was performed with the following follow-up: preoperative and postoperative assessments at 1, 3, and 6 months. The following morphologic parameters were evaluated: epithelium, subepithelial, and anterior stroma nerve plexi, keratocytes apoptosis, stromal changes, and the endothelium. RESULTS: After TE CXL, epithelial cells showed apoptosis, with mosaic alterations gradually disappearing. Keratocytes apoptosis was variable, superficial, and uneven, with a maximum depth of penetration at about 140 µm, measured from the surface of epithelium. Treatment respected subepithelial and stromal nerves that did not disappear. No variation in cell count or endothelial mosaic was observed. CONCLUSIONS: In vivo confocal analysis of corneal modifications induced by TE CXL showed a limited apoptotic affect of this treatment, about one-third of classic epi-off crosslinking procedure. The TE CXL respected sub-basal and anterior stroma nerve fibers, resulting safe for corneal endothelium. According to limited penetration, its mid- to long-term efficacy needs to be determined in different clinical settings related to patient age and keratoconus progression.