Introduction
(CXL) with riboflavin and (UVA) is a new technique of corneal tissue strengthening by using riboflavin as a photosensitizer and UVA to increase the formation of intra and interfibrillar covalent bonds by photosensitized oxidation. The major indication for the use of CXL is to inhibit the progression of corneal ectasia, such as( KC).
AIM OF THE WORK
To evaluate the corneal endothelial cell changes after CXL in cases of KC and its correlation with CCT immediately before UVA exposure.
SUBJECTS
The study was a prospective interventional study.
Inclusion criteria:
Topographic and tomographic evidence of KC.
Documented clinical worsening.
Minimal corneal thickness >450 μm before epithelial debridement.
Completely clear cornea with the absence of any other ocular or systemic disease.
 Exclusion criteria:
Corneal thickness of ≤ 450 μm at the thinnest point.
History of herpetic keratitis, concurrent corneal infections, or concomitant autoimmune diseases.
Severe dry eye, acute hydrops, severe allergic conjunctivitis, and diffuse central corneal opacity.
Advanced KC.
Glaucoma, cataract, or vitreoretinal disorders.
Pregnancy or lactation.
Results
Our results revealed that endothelial cell count, size, and shape did not decrease after the procedure.
25% of eyes had an increase in corneal thickness (CCT) three months after crosslinking. The subgroup analysis showed a significant correlation between preoperative corneal thickness at the thinnest location immediately before UVA rays exposure and the corneal endothelial parameters (ECD, CV %).
There was a statistically significant difference in the endothelial cell density between those with increased CCT and with decreased CCT postoperative.
CONCLUSIONS
Cornealcross-linkingisusuallysafeonendotheliumincorneasabove450microns.
TheROCcurveshowedthatthecutoffpointofthecornealthicknessmeasuredbyonlinepachymetryimmediatelybeforeUVAapplicationis388μmandbelowthatvaluemoreendothelialdamageresults.