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Abstract #18496 Published in IGR 3-3
Optic disc surface compliance testing using confocal scanning laser tomography in the normal monkey eye
Bellezza AJ; Thompson HW; Burgoyne CFJournal of Glaucoma 2001; 10: 369-382
PURPOSE: To determine the effect of acute, experimentally increased intraocular pressure (IOP) on deformation of the surface of the optic nerve head (optic nerve head surface compliance testing) in normal monkey eyes using confocal scanning laser tomography. METHODS: A total of 156 compliance tests was performed on 48 normal eyes of 30 monkeys in three separate studies. Compliance testing involved obtaining confocal scanning laser tomographic images using a 10° and/or 15° and/or 20° scan angle at various times after IOP was raised from 10 to 30 or 45 mmHg. At each point, six images were analyzed to provide a value for a parameter, called mean position of the disc, which was used to express the amount of deformation the surface of the optic nerve head had undergone at that point. Statistical analysis (ANOVA) was performed to evaluate differences in the amounts of deformation in individual eyes at different IOPs and at different compliance testing sessions (studies 1 and 2) and in the two eyes of individual monkeys under the same conditions (study 3). RESULTS: The majority of eyes showed posterior deformation of the surface of the optic nerve head ranging from 15-86 μm as early as ten minutes after IOP was increased from 10 to 30 mmHg. When pressure was increased from 30 to 40 mmHg in a subset of these eyes, most showed additional deformation. Of the 12 eyes for which both 15 and 20° images were obtained at the same compliance test, seven showed larger amounts of deformation in the 20° images. Of the 18 monkeys tested in both eyes, 12 showed some differences and four showed substantial differences between their two eyes. CONCLUSIONS: In the normal monkey eyes, the surface of the optic nerve head deforms rapidly (in as little as ten minutes) in response to increased IOP. The amount of deformation varies between subjects, and even within the two eyes of individual monkeys. Increasing the scan angle from 15 to 20° frequently increases the amount of deformation detected, suggesting that the peripapillary sclera and the optic nerve head may be involved in the deformation in some eyes.
Dr C.F. Burgoyne, LSU Eye Center, 2020 Gravier Street, Suite B, New Orleans, LA 70112, USA
Classification:
2.14 Optic disc (Part of: 2 Anatomical structures in glaucoma)