Abstract
Purpose: :
Corneal abrasion previous to corneal collagen cross-linking (UV CCL) is a painful procedure that exposes the cornea to potential risks such as infections and scar formation that could lead to a decrease in corneal transparency. The purpose of this study was to evaluate the effects of an intact epithelium layer in corneal biomechanical changes after UV CCL.
Methods: :
20 New Zealand white rabbits were randomly divided in 2 treatment groups: Group A (n=10) was exposed to UVA-light (370 nm) and riboflavin 0.1 % for 30 min, and group B (n=10) was exposed to the same treatment after epithelium debridement. Central Corneal thickness (CCT), corneal hysteresis (CH), and corneal resistance factor (CRF) were measured weekly for 3 weeks. Six corneas (n=3 per group) were used for histology to determine keratocyte cell density in the superficial medial and deep corneal stroma.
Results: :
Three weeks after UV CCL, CH increased 14.3%in group A and 44.5 %in group B (p=0.04 and p<0.01 respectively). CRF increased 20 % in group A and 232.1 % in group B (p=0.66, and p<0.01respectively). CH and CRF increase was more important in group B at all time points. CH was significantly higher at week 1, and 3 (p= 0.04, and p < 0.01 respectively) and CRF only at week 3 (p< 0.01) when both groups were compared. We did not find a significant CCT variation in group A (p>0.09). On the other hand, group B showed a significant increase in CCT at all time points (p< 0.01).
Conclusions: :
The presence of the corneal epithelial layer does not prevent corneal biomechanical changes to develop after UV CCL, but it seems to significantly diminish CH and CRF changes.
Keywords: cornea: epithelium • wound healing • cornea: basic science