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Abstract #22738 Published in IGR 11-1
Biomechanical effects of intraocular pressure elevation on optic nerve/lamina cribrosa before and after peripapillary scleral collagen cross-linking
Thornton IL; Dupps WJ; Roy AS; Krueger RRInvestigative Ophthalmology and Visual Science 2009; 50: 1227-1233
See also comment(s) by Crawford Downs •
PURPOSE: To evaluate the biomechanical effect of intraocular pressure (IOP) elevation on the optic nerve/lamina cribrosa complex (ON/LC) and peripapillary sclera (PS) of porcine eyes before and after localized collagen cross-linking. METHODS: Eighteen porcine globes were divided evenly into three groups. The optic nerves were transected to expose the ON/LC, and each globe was infused through an in-line pressure transducer for direct IOP control. Surface wave velocity, a nondestructive measure of tissue stiffness, was measured across the ON/LC and PS before and after collagen cross-linking at IOPs of 10 and 30 mmHg (groups 1 and 2) and at each globe's preinflation IOP and 80 mmHg (group 3). In group 3, papillary strain was measured by analyzing the displacement of fiducial marks immediately adjacent to the ON/LC by using digital photography. Cross-linking in group 1 was achieved with riboflavin-ultraviolet A (UVA) delivery to the entire ON/LC and PS and, in groups 2 and 3, with an annular sponge soaked in glutaraldehyde (GTA) and applied only to the PS. RESULTS: Native PS was significantly stiffer than the ON/LC across all experiments. Before cross-linking, IOP elevation caused significant stiffening of both the ON/LC and PS. After cross-linking with either technique, IOP elevation stiffened the PS but not the ON/LC region. In group 3, papillary strain during IOP elevation was significantly reduced after PS cross-linking. CONCLUSIONS: Stiffening of the peripapillary scleral ring reduces the biomechanical sensitivity of the ON/LC complex to IOP elevation and may represent a novel mechanism for neuroprotection in glaucoma.
Dr. I.L. Thornton, Cole Eye Institute, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio 44195, USA
Classification:
5.3 Other (Part of: 5 Experimental glaucoma; animal models)
2.3 Sclera (Part of: 2 Anatomical structures in glaucoma)
12.4 Laser trabeculoplasty and other laser treatment of the angle (Part of: 12 Surgical treatment)
11.8 Neuroprotection (Part of: 11 Medical treatment)