Abstract
Purpose: :
To determine the changes in corneal properties induced by riboflavin-ultraviolet A (UVA) irradiation using a non-invasive quantitative ultrasound method in a porcine eye model.
Methods: :
Twenty-eight fresh porcine globes were acquired within 24 hours post-modern. The porcine globes were divided into two groups: the collagen-crosslinking (CXL) group (n=14) that were irradiated with UVA after riboflavin application following the standard protocol, and the control group (n=14) that underwent all procedures as the CXL group except UVA irradiation. The corneal properties were measured before and after the treatment in both groups by using a quantitative ultrasound method. [1] Changes in corneal thickness, density and stiffness were examined within each group, and the difference in the changes between the CXL group and the control group was analyzed.
Results: :
Based on the measurements of the quantitative ultrasound method, the initial properties of the corneas in the CXL and the control groups were not different. After riboflavin-UVA treatment, corneal properties were altered in the CXL group. Corneal stiffness showed a statistically significant increase (2.59±0.08 GPa before crosslinking vs 2.70±0.08 GPa after crosslinking; P< 0.01). The speed of sound in corneal tissue was also increased after crosslinking (1557±23 m/s before vs. 1588±22 m/s after; P< 0.001). Corneal thickness changed from 989±79 µm to 1236±67 µm after the riboflavin-UVA procedure (P<0.01). In the control group, corneal thickness increased similarly as in the CXL group from 965±41 µm to 1159±47 µm (P<0.01). There was no significant change for both corneal stiffness (2.58±0.04 GPa vs. 2.57±0.05 GPa; P=0.50) and speed of sound (1552±13 m/s vs. 1552±17 m/s; P=0.87) in the control group. No statistically significant change was observed for corneal density in both CXL and control groups.
Conclusions: :
This study demonstrated that corneal stiffness may be increased by riboflavin-UVA-induced collagen crosslinking, and the non-invasive ultrasound technique was sensitive in detecting this change.[1] Liu J, et al. J Biomech 2007;40:1177-1182.
Keywords: cornea: basic science • keratoconus • cornea: stroma and keratocytes