PURPOSE: To determine the interlamellar cohesive strength (ICS) of porcine cornea before and after collagen cross-linking using riboflavin and ultraviolet A (UVA) irradiation. METHODS: Corneal flaps, 130 μm thick, were created with a microkeratome. Cross-linking was accomplished with 0.1% riboflavin and UVA irradiation for 30 minutes (3 mW/cm, 5.4 J/cm) at a distance of 10 mm. Two experiments were performed. (1) The maximal ICS between corneal flap and the stroma was determined and histological examination was performed. (2) The mean stromal ICS was measured. Untreated eyes served as controls in all experiments. RESULTS: The mean maximum flap-stroma ICS was 0.088 ± 0.046 N/mm in the experimental group and 0.012 ± 0.004 N/mm in the control group (P = 0.009). In experiment 2, incomplete (2 mm long) corneal flaps were used and the mean stromal ICS was 0.750 ± 0.077 N/mm in the experimental group and 0.338 ± 0.046 N/mm in the control group (P < 0.0001). Histological examination showed an irregular ragged separation of the surface in the stromal margin of the cornea with cross-linking, but a smooth separation surface in the cornea without cross-linking. CONCLUSIONS: Collagen cross-linking activated by riboflavin/UVA increases ICS in porcine corneas.
PURPOSE: To determine the interlamellar cohesive strength (ICS) of porcine cornea before and after collagen cross-linking using riboflavin and ultraviolet A (UVA) irradiation. METHODS:Corneal flaps, 130 μm thick, were created with a microkeratome. Cross-linking was accomplished with 0.1% riboflavin and UVA irradiation for 30 minutes (3 mW/cm, 5.4 J/cm) at a distance of 10 mm. Two experiments were performed. (1) The maximal ICS between corneal flap and the stroma was determined and histological examination was performed. (2) The mean stromal ICS was measured. Untreated eyes served as controls in all experiments. RESULTS: The mean maximum flap-stroma ICS was 0.088 ± 0.046 N/mm in the experimental group and 0.012 ± 0.004 N/mm in the control group (P = 0.009). In experiment 2, incomplete (2 mm long) corneal flaps were used and the mean stromal ICS was 0.750 ± 0.077 N/mm in the experimental group and 0.338 ± 0.046 N/mm in the control group (P < 0.0001). Histological examination showed an irregular ragged separation of the surface in the stromal margin of the cornea with cross-linking, but a smooth separation surface in the cornea without cross-linking. CONCLUSIONS: Collagen cross-linking activated by riboflavin/UVA increases ICS in porcine corneas.