Abstract
Purpose: :
To evaluate the ability of collagen crosslinkers to stabilize the corneal shape, using an intact globe expansion method (GEM).
Methods: :
Enucleated eyes from 2-3 week old New Zealand White rabbits underwent mechanical debridement of the corneal epithelium. The corneas were then treated with either 1) R/UVA - riboflavin/dextran drops and UVA (370 nm) irradiation, 2) EY - eosin y gel formulation and visible light irradiation (525 nm), or 3) Control - dulbecco’s phosphate buffered saline (DPBS) and no light treatment. Following treatment, eyes were immersed in a DPBS bath at 37 C, and mounted for determination of ocular expansion at an elevated pressure of 35 mm Hg; expansion of cornea and sclera was measured using digital photography.
Results: :
Control eyes typically rupture through failure at the limbus after 6-9 hours of elevated pressure. Both EY and R/UVA eyes demonstrated significantly longer expansion times before rupture (> 15 hours, or no rupture), with failure typically occurring in the untreated sclera. The corneal perimeter (CP - a measure of the profile of the cornea) provides a quantitative descriptor of the corneal expansion. R/UVA and EY corneas resist expansion (CP increases ~0%) while control eyes expand (CP increases ~8%) in the 6 hours before control eye rupture. Within the first hour of elevated pressure expansion, there is significant difference between both R/UVA and Control, and EY and Control; however, there is no significant difference between R/UVA and EY during the experiment.
Conclusions: :
Treatment of the cornea with either EY or R/UVA stabilizes the cornea, increasing resistance to expansion and rupture. Stabilization with EY and R/UVA is indistinguishable with the current testing method, indicating the possibility for equivalent efficacy as treatment modalities.
Keywords: cornea: basic science • sclera • keratoconus