Abstract
Purpose :
The biomechanical impacts of supplemental oxygen and epithelial presence during high-fluence UVA corneal crosslinking were investigated using Optical Coherence Elastography (OCE).
Methods :
A total of 80 fresh New Zealand White rabbit eyes received in pairs were stabilized to room temperature and 15 mmHg intraocular pressure (IOP), and treated with Ultraviolet A (UVA) crosslinking KXL iLink system. Eyes were separated into three treatment groups. All groups received a fluence of 10 J/cm2 at an irradiance of 30 mW/cm2 with 1s:1s pulsing for 11 minutes 6 seconds. Eyes in Groups 2 and 3, with the epithelium intact, received trans-epithelial (epi-on) riboflavin solutions. The epithelium was removed for eyes in Group 1 which received a 10-minute soak of a riboflavin solution. Eyes were placed in chambers to prevent dehydration during IOP stabilization and treatment time. Eyes in Group 3 received supplemental oxygen maintained at a >90% level. Eyes in Group 1 and 2 received air supply at the same flow rate as supplemental oxygen rate for Group 3. An in-house built OCE was used to scan eyes twice immediately before and after UVA treatment to obtain average shear moduli, which were later used in paired and unpaired t-test analyses. The repeatability of scans provided a means to exclude eyes that were not stabilized. The order of eyes receiving treatment, the chambers used for treatment, and the order of running different arms were randomized.
Results :
A significant change in shear modulus pre/post UVA treatment was observed in all groups. The increase in Group 3 (31%) was found to be significantly higher than both Group 1 (17%) and 2 (18%) (p<<0.0001). No significant difference was found between changes in shear moduli in Groups 1 and 2 (p=0.6).
Conclusions :
The oxygen enriched epi-on procedure significantly outperformed both epi-off and epi-on high-fluence procedures without supplemental oxygen. Adding supplemental oxygen to the epi-on procedure resulted in a significant boost in the induced biomechanical changes, around a 100% extra increase in shear modulus, compared to other procedures without supplemental oxygen. Furthermore, the presence of the epithelium did not adversely affect crosslinking efficacy for the normoxic procedures.
This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.