Collagen crosslinking of human and porcine sclera

To develop methods of collagen crosslinking the sclera to increase its biomechanical strength for the treatment of progressive myopia.

Department of Ophthalmology, Technical University of Dresden, Dresden, Germany.

Sagitally oriented scleral strips of 4.0 mm x 8.0 mm were prepared from 5 human postmortem eyes and 50 porcine cadaver eyes and treated with various crosslinking methods including physical crosslinking by combined riboflavin-ultraviolet A (UVA) or rose bengal/white-light irradiation and chemical crosslinking by incubation with glucose, ribose, glyceraldehyde, and glutaraldehyde solutions. Parallel scleral strips from the same eye were used as untreated controls. After crosslinking, stress-strain measurements of the treated and control scleras were performed using a microcomputer-controlled biomaterial tester.

A statistically significant increase in scleral rigidity was found after crosslinking with riboflavin-UVA, with a rise in stress in treated porcine (157%) and human (29%) sclera, and after treatment with glyceraldehyde, with a rise in stress in treated porcine (487%) and human (34%) sclera, and with glutaraldehyde, with a rise in stress in treated porcine (817%) and human sclera (122%) at 8% strain. The other crosslinking methods proved ineffective. The untreated human sclera had a 4-fold higher stiffness than porcine sclera.

Collagen crosslinking induced by riboflavin-UVA, glyceraldehyde, and glutaraldehyde led to a significant increase in biomechanical strength in human and porcine sclera. Using these methods, collagen crosslinking might become a treatment possibility for progressive myopia. Future animal and clinical studies must determine the best application methods and the long-term effects of increased crosslinking on scleral rigidity and prevent potential toxicity or serious side effects.