Biomechanical effects of intraocular pressure elevation on optic nerve/lamina cribrosa before and after peripapillary scleral collagen cross-linking

Ivey L. Thornton, William J. Dupps, Abhijit Sinha Roy, Ronald R Krueger

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Abstract

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 mm Hg (groups 1 and 2) and at each globe's preinflation IOP and 80 mm Hg (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.

Original languageEnglish (US)
Pages (from-to)1227-1233
Number of pages7
JournalInvestigative Ophthalmology and Visual Science
Volume50
Issue number3
DOIs
StatePublished - Mar 1 2009

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Optic Nerve
Intraocular Pressure
Sclera
Collagen
Swine
Pressure Transducers
Riboflavin
Photography
Glutaral
Porifera
Glaucoma

ASJC Scopus subject areas

  • Ophthalmology
  • Sensory Systems
  • Cellular and Molecular Neuroscience
  • Medicine(all)

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Biomechanical effects of intraocular pressure elevation on optic nerve/lamina cribrosa before and after peripapillary scleral collagen cross-linking. / Thornton, Ivey L.; Dupps, William J.; Roy, Abhijit Sinha; Krueger, Ronald R.

In: Investigative Ophthalmology and Visual Science, Vol. 50, No. 3, 01.03.2009, p. 1227-1233.

Research output: Contribution to journalArticle

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abstract = "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 mm Hg (groups 1 and 2) and at each globe's preinflation IOP and 80 mm Hg (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.",
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N2 - 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 mm Hg (groups 1 and 2) and at each globe's preinflation IOP and 80 mm Hg (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.

AB - 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 mm Hg (groups 1 and 2) and at each globe's preinflation IOP and 80 mm Hg (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.

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