To determine the effect of riboflavin–UV-A treatment on the corneal limbal epithelial cells during a corneal collagen cross-linking (CXL) procedure.
Thirty freshly enucleated human cadaveric eyeballs were subjected to a CXL procedure, mimicking the clinical protocol. During the UV-A exposure, one half of the limbus (sector A) was left unprotected, whereas the other half (sector B) was covered by a metal shield. Limbal biopsies from both sectors before and after the procedure were analyzed. Each strip of tissue was divided into 3 segments, for cell count of viable cells, for cultivation on human amniotic membrane (HAM), and for stem cell and differentiated corneal epithelial cell marker studies using reverse transcriptase–polymerase chain reaction.
Compared with the cell count before CXL, there was a statistically significant drop in the mean number of viable cells after CXL in sector A but not in sector B. Biopsies from both sectors before CXL and from sector B after CXL showed good growth on HAM. Biopsies from sector A after CXL showed no growth on HAM. The putative stem cell marker ABCG2 was absent in all samples and p63 was absent in 3 of 10 samples taken from sector A after CXL. All markers were present in all samples from sector B after CXL.
Riboflavin–UV-A treatment can result in damage to limbal epithelial cells, particularly the stem cells. Covering the limbal region with a metal shield effectively prevents this damage.
*L and T Microbiology Research Centre, Vision Research Foundation
†Department of Cornea and Refractive Surgery, Medical Research Foundation, Sankara Nethralaya, Chennai, India.
Reprints: Prema Padmanabhan, Department of Cornea and Refractive Surgery, Medical Research Foundation, Sankara Nethralaya, 41 College Rd, Chennai 600 006, India (e-mail:email@example.com).
Supported by the Department of Science and Technology (DST; 105-2008-P).
The authors state that they have no proprietary interest in the products named in this article.
Received October 18, 2011
Accepted January 3, 2012