Biomechanical Changes of the Cornea after Riboflavin/UVA-induced Collagen-crosslinking
Wollensak G.1, Spörl E.2, Pillunat L. E.2
1Berlin, 2University Eye Clinic Dresden
Purpose: Riboflavin/UVA-induced collagen crosslinking has been successfully used to stabilize the cornea in patients with keratoconus or melting corneal ulcers. The present study was undertaken to evaluate the biomechanical effect of combined riboflavin/UVA-treatment on porcine and human cornea.
Method: Corneal strips from five human enucleated eyes and 20 porcine cadaver cornea were treated with the photosensitizer riboflavin and irradiated with two double UVA- diodes (370 nm, irradiance = 3 mW/cm2) for 30 minutes. After crosslinking, stress-strain measurements of the treated and untreated corneas were performed using a microcomputer-controlled biomaterial tester with a prestress of 5 x 103 Pa.
Results: We found a significant increase of corneal rigidity after crosslinking as indicated by a rise in stress for both treated porcine (by 71.9%) and human cornea (by 328.9 %) and in Young´s-modulus by the factor 1.8 in porcine and factor 4.5 in human cornea. Central corneal thickness in porcine cornea was 850 ± 70 mm and human cornea 550 ± 40 mm.
Conclusions: Riboflavin/UVA induced collagen-crosslinking leads to an increase in mechanical rigidity in porcine cornea and even more so in human cornea. As collagen crosslinking is maximal in the anterior 300
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