Corneal Wound Repair After Rose Bengal and Green Light Crosslinking: Clinical and Histologic Study

To evaluate corneal wound healing after treatment with a new collagen crosslinking protocol using rose bengal dye and green light (RGX).

One cornea of 20 New Zealand rabbits was de-epithelialized (DE) in an 8-mm diameter circle and, in another group (n = 25), the DE corneas were then stained with 0.1% rose bengal for 2 minutes and exposed to green light (532 nm) for 7 minutes (RGX). The contralateral eyes without treatment acted as controls. The animals were clinically followed including fluorescein staining and pachymetry. Healing events were analyzed after euthanasia at 2, 30, and 60 days. Cell death (TUNEL assay), cell proliferation (5-bromo-2'-deoxyuridine incorporation), and cell differentiation to myofibroblasts (α-SMA labeling) were carried out. In addition, loss of keratocytes and subsequent repopulation of the corneal stroma were quantified on hematoxylin-eosin-stained sections.

Wound closure was slower after RGX (4.4 days) then after DE (3.3 days). Cell death was restricted to the anterior central stroma, and the cellular decrease did not differ significantly between RGX and DE corneas. Cell proliferation in the epithelium and stroma appeared at 2 days. In both DE and RGX corneas, recovery of the epithelium was complete at day 30, although cell repopulation of the stroma was not complete at 60 days.

The healing response in corneas after RGX is very similar to that observed after DE alone, suggesting that, along with its short treatment time and limited effect on keratocytes, RGX displays good potential for clinical cornea stiffening.