Corneal collagen crosslinking for keratoconus or corneal ectasia without epithelial debridement.

PURPOSE: Corneal collagen crosslinking (CXL) is a relatively new technique to reduce the progression of keratoconus. The technique can be performed with or without complete debridement of the corneal epithelium. We describe a novel intermediate technique involving mechanical disruption of the epithelium, and evaluate its safety and efficacy. METHODS: The case notes of 128 eyes with progressive keratoconus or iatrogenic corneal ectasia who had undergone CXL using the epithelial disruption technique were retrospectively reviewed. Thin corneas were treated with hypotonic riboflavin. All others were treated with an isotonic solution. Note was made of preoperative and postoperative parameters, including uncorrected visual acuity (UCVA), best spectacle-corrected visual acuity (BSCVA), refraction, endothelial cell count, and corneal tomography. Occurrence of procedure-related complications was recorded. Statistical analyses were performed using the paired sample t-test and Wilcoxon signed-rank test, with a level of P<0.05 being accepted as statistically significant. RESULTS: At 12 months, 41.8% of patients treated with isotonic riboflavin had improved UCVA and 29.7% had improved BSCVA. Only 13.4% lost lines of UCVA and 14.9% lost BSCVA. Of the patients treated with hypotonic riboflavin, at 12 months, 75% demonstrated stability of BSCVA and 25% had stable Kmax. In addition, 25% showed improved visual acuity at 12 months, and 58.3% showed regression of their Kmax. Our rate of short-term complications was comparable to studies using complete epithelial removal. CONCLUSIONS: CXL with epithelial disruption is a safe and effective treatment for keratoconus or iatrogenic corneal ectasia, and may be better tolerated by patients than the epithelium-off technique.

An in depth analysis of histopathological characteristics found in keratoconus.

AIMS: The aims of this study were to re-assess the histopathology of the disease by introducing more modern measuring techniques and to determine if axial stromal thinning, which is the most apparent change, is related to the other alterations observed. METHODS: Recipient keratoconic corneas from 36 patients following corneal transplantation were studied. Haematoxylin and eosin (H&E) and periodic acid-Schiff (PAS) staining were used to identify breaks in Bowman's layer and Descemet's membrane. Thickness of corneal layers was measured by Leica QWin software. Epithelial and stromal thickness were measured in each sample at the periphery of the corneal button and at the area of maximal stromal thinning. The presence of apoptotic cells in Bowman's layer breaks was detected by terminal deoxynucleotidyl transferase mediated dUTP-X nick end labelling. RESULTS: In all 36 corneal samples the central stroma, at the apex of the cone, was thinner than the peripheral. There was a negative correlation between central stromal and central epithelial thickness (p = 0.009). Bowman's layer breaks were found in 92% of corneas. Apoptotic cells were detected at the level of Bowman's breaks membrane. We found a positive correlation between epithelial thickness and the number of Bowman's layer breaks (p = 0.009 for central epithelial thickness and p = 0.003 for peripheral epithelial thickness). Descemet's membrane deformities were observed in 19% of corneas and central stromal thickness of these corneas was significantly less than corneas without breaks (p = 0.006). CONCLUSIONS: There are various different histopathological features associated with keratoconus and some of them are very subtle and not very well studied. Accurate measurements also suggest some correlations between them. Stromal thinning is associated with the number of breaks in Descemet's membrane, but it is the thickening of the epithelium which is associated with breaks in Bowman's layer.