Corneal crosslinking with genipin, comparison with UV-riboflavin in ex-vivo model

To investigate the efficacy and safety of Genipin and UV-riboflavin crosslinking (UV-CLX) in corneal crosslinking.

Porcine eyes were separated in groups for each crosslinker, genipin 0.25% UV-CLX (clinical crosslinking procedure), glutaraldehyde 0.1% (gold standard crosslinker), and control eyes. Intraocular pressure (IOP) was continuously monitored by a pressure sensor cannulated to the anterior chamber and the volume was changed. The changes in ocular pressure as a function of change of the ocular volume were evaluated. Ocular rigidity was calculated as the exponential of polynomial quadratic fit. Endothelial damage was evaluated in a viability assay with alizarin red staining as the changes in cell counts.

Significant changes in IOP were observed in the globes were the cornea was stiffened with genipin and UV-CLX treatment (volume 200 μl: Genipin 19.4 mmHg, UVCRX 18.8 mmHg, glutaraldehide 23.9 mmHg, versus control 14.7 mmHg, and 400 μl genipin 31.5 mmHg, UV-CLX 26.0 mmHg, glutaraldehide 37.3 mmHg versus control 18.7 mmHg). The mean ocular ridigity coefficient was genipin 0.0078 mmHg/μl, UV-CLX 0.0065 mmHg/μl, glutaraldehide 0.0092 mmHg/μl, and 0.0046 mmHg/μl for control eyes. Endothelial cell damage was 5.9±1.8% (control), 10.3±1.7% (UV-CLX), 9.4±1.5% (Genipin 0.25%), and 40.1±6.2% (glutaraldehide). Some granules were observed in the UV-CLX group. Reduction of keratocites was observed in the UV CRX crosslinking.

Corneal crosslinking was similar between UV-CLX and genipin with minimal toxicity to endothelial cells. Stiffened corneas by any method induced substancially higher IOP elevation when ocular volume is increased.