TY - JOUR
T1 - Early Changes in Optic Disc Compliance and Surface Position in Experimental Glaucoma
AU - Burgoyne, Claude F.
AU - Quigley, Harry A.
AU - Thompson, Hilary W.
AU - Vitale, Susan
AU - Varma, Rohit
N1 - Funding Information:
Originally received: April 7, 1995. Revision accepted: August 9, 1995. I Glaucoma Service, Wilmer Institute, Johns Hopkins School of Medicine, Baltimore. 2 LSU Eye Center, Louisiana State University Medical Center School of Medicine, New Orleans. 3 Dana Center for Preventive Ophthalmology, Wilmer Institute, Johns Hopkins School of Medicine, Baltimore. 4 Clinical Trials and Biometry Unit, LSU Eye Center, Louisiana State University Medical Center School of Medicine, New Orleans. 5 Doheny Eye Institute, University of Southern California School of Medicine, Los Angeles. Supported in part by U.S. Public Health Service grants F32EY07047 (Dr. Burgoyne), ROIEY02120 (Dr. Quigley), F32EY06536 (Dr. Varma), P30EYOl765 (Wilmer Institute Core Facility), and P30EY02377 (LSU Eye Center Core Facility) from the National Eye Institute, Bethesda, Maryland; RR04060 (Shared Instrumentation Grant) from the National Institutes of Health, Bethesda, Maryland; a grant from National Glaucoma Research, a program of the American Health Assistance Foundation, Rockville, Maryland; and instrumentation support from the Topcon Corporation. Dr. Burgoyne is the recipient of a Career Development Award (1994-1998) from Research to Prevent Blindness, New York, New York. Presented in part at the ARVO Annual Meeting, Sarasota, May 1994. Each author states that s/he has no proprietary interest in the development or marketing of the Topcon Imagenet System, nor do they receive payment as consultants. Reprint requests to Claude F. Burgoyne, MD, LSU Eye Center, 2020 Gravier St, Suite B, New Orleans, LA 70112-2234.
PY - 1995
Y1 - 1995
N2 - Purpose: To detect changes in the compliance and baseline position (position at the baseline time point of a compliance test) of the monkey optic disc after the onset of chronic experimental glaucoma. Methods: Sixty-six compliance tests were performed on 26 eyes of 13 monkeys. Longitudinal Study. In seven normal monkeys, compliance tests were performed three times in one eye (study eye) and once in the contralateral eye. In the study eye of five of these monkeys, chronic experimental glaucoma was then induced and compliance tests were performed at some or all of the following postglaucoma testing intervals: 1 to 2 weeks, 3 to 4 weeks, 5 to 8 weeks, 9 to 12 weeks, 13 to 18 weeks, and more than 18 weeks after the onset of elevated intraocular pressure (IOP). In the study eye of the remaining two monkeys, the optic nerve was transected, and compliance was tested at 5, 9, and 13 weeks after transection. An analysis of variance (ANOVA) was performed to detect an increase (hypercompliance) or decrease (rigidity) in the compliance of the glaucomatous eyes at each testing interval. A second ANOVA was performed to detect the onset of chronic posterior deformation of the baseline position of each disc. Cross-Sectional Study. In six additional monkeys with pre-existing experimental glaucoma, the glaucomatous study eye was compliance tested at one of the postglaucoma testing intervals used in the longitudinal study. The contralateral normal eye was compliance tested once. These data were then added to the data from the five longitudinally studied monkeys at the appropriate preglaucoma and postglaucoma testing intervals. A third ANOVA was done to compare the compliance of the expanded group of glaucomatous eyes at each postintervention testing interval with the compliance of the 13 normal contralateral eyes. Results: Compliance. In the longitudinally (Pr > F = 0.0005) and cross-sectionally (Pr > F = 0.0001) studied glaucomatous eyes, optic disc compliance increased significantly by 1 to 2 weeks and then returned to a level statistically indistinguishable from normal within 13 to 18 weeks after the onset of glaucoma. In the transection eyes, the optic discs were significantly less compliant (more rigid) at 5 and 9 weeks after transection compared with the discs in either the normal or the glaucomatous eyes (Pr > F < 0.05). Baseline Optic Disc Position. Chronic posterior deformation of the disc was detected in one of three eyes tested 1 to 2 weeks and three of four eyes tested 3 to 4 weeks after the onset of glaucoma (Pr > F < 0.05). Chronic posterior deformation was not detected in the discs of either of the transection eyes at any of the post-transection testing intervals. Conclusion: Changes in optic disc compliance and surface position were detected by digitized image analysis within 2 to 4 weeks of the onset of experimental glaucoma in the monkey eye. These findings are unlikely to be due to axon loss alone, because they did not occur in optic nerve transection eyes (which constitute a model of axon loss in which intraocular pressures remain normal). The results suggest that IOP-related damage to the load-bearing connective tissues of the optic nerve head may occur early in the course of experimental glaucoma.
AB - Purpose: To detect changes in the compliance and baseline position (position at the baseline time point of a compliance test) of the monkey optic disc after the onset of chronic experimental glaucoma. Methods: Sixty-six compliance tests were performed on 26 eyes of 13 monkeys. Longitudinal Study. In seven normal monkeys, compliance tests were performed three times in one eye (study eye) and once in the contralateral eye. In the study eye of five of these monkeys, chronic experimental glaucoma was then induced and compliance tests were performed at some or all of the following postglaucoma testing intervals: 1 to 2 weeks, 3 to 4 weeks, 5 to 8 weeks, 9 to 12 weeks, 13 to 18 weeks, and more than 18 weeks after the onset of elevated intraocular pressure (IOP). In the study eye of the remaining two monkeys, the optic nerve was transected, and compliance was tested at 5, 9, and 13 weeks after transection. An analysis of variance (ANOVA) was performed to detect an increase (hypercompliance) or decrease (rigidity) in the compliance of the glaucomatous eyes at each testing interval. A second ANOVA was performed to detect the onset of chronic posterior deformation of the baseline position of each disc. Cross-Sectional Study. In six additional monkeys with pre-existing experimental glaucoma, the glaucomatous study eye was compliance tested at one of the postglaucoma testing intervals used in the longitudinal study. The contralateral normal eye was compliance tested once. These data were then added to the data from the five longitudinally studied monkeys at the appropriate preglaucoma and postglaucoma testing intervals. A third ANOVA was done to compare the compliance of the expanded group of glaucomatous eyes at each postintervention testing interval with the compliance of the 13 normal contralateral eyes. Results: Compliance. In the longitudinally (Pr > F = 0.0005) and cross-sectionally (Pr > F = 0.0001) studied glaucomatous eyes, optic disc compliance increased significantly by 1 to 2 weeks and then returned to a level statistically indistinguishable from normal within 13 to 18 weeks after the onset of glaucoma. In the transection eyes, the optic discs were significantly less compliant (more rigid) at 5 and 9 weeks after transection compared with the discs in either the normal or the glaucomatous eyes (Pr > F < 0.05). Baseline Optic Disc Position. Chronic posterior deformation of the disc was detected in one of three eyes tested 1 to 2 weeks and three of four eyes tested 3 to 4 weeks after the onset of glaucoma (Pr > F < 0.05). Chronic posterior deformation was not detected in the discs of either of the transection eyes at any of the post-transection testing intervals. Conclusion: Changes in optic disc compliance and surface position were detected by digitized image analysis within 2 to 4 weeks of the onset of experimental glaucoma in the monkey eye. These findings are unlikely to be due to axon loss alone, because they did not occur in optic nerve transection eyes (which constitute a model of axon loss in which intraocular pressures remain normal). The results suggest that IOP-related damage to the load-bearing connective tissues of the optic nerve head may occur early in the course of experimental glaucoma.
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U2 - 10.1016/S0161-6420(95)30791-9
DO - 10.1016/S0161-6420(95)30791-9
M3 - Article
C2 - 9098280
AN - SCOPUS:0029559565
SN - 0161-6420
VL - 102
SP - 1800
EP - 1809
JO - Ophthalmology
JF - Ophthalmology
IS - 12
ER -