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Effect of intraocular pressure on optic disc topography, electroretinography, and axonal loss in a chronic pressure-induced rat model of optic nerve damage.
Invest Ophthalmol Vis Sci. 2002 Sep; 43(9):2969-76.IO

Abstract

PURPOSE

To characterize the effect of intraocular pressure (IOP) on optic disc topography, retinal function, and axonal survival in a model of IOP-induced optic nerve damage in rat.

METHODS

Hypertonic (1.75 M) saline was injected into an episcleral vein of one eye of 49 Brown Norway rats, with the fellow untreated eye serving as the control. During the 1 to 3 months of follow-up, IOP was measured twice weekly in conscious animals with a handheld tonometer, and changes in disc topography and retinal function were monitored with scanning laser tomography and electroretinography (ERG), respectively. Peak IOP elevation in the experimental eye compared with the fellow control eye (peak deltaIOP), integral of IOP elevation over time (deltaIOP integral), and days of IOP elevation were calculated. Axon counts were obtained from electron micrographs of the sectioned optic nerves.

RESULTS

Progressive cupping was found in 9 (56.3%) of 16 eyes with peak deltaIOP of more than 15 mm Hg and in none of 21 eyes with peak deltaIOP less than 15 mm Hg. A strong correlation between deltaIOP integral and progressive cupping was also found, but not with days of IOP elevation. ERG abnormalities (limited to the b-wave) were found in 11 (64.7%) of 17 eyes with peak deltaIOP of more than 15 mm Hg and in 2 (8.7%) of 23 eyes with peak deltaIOP of less than 15 mm Hg. Neither of the other IOP parameters was predictive of ERG damage. The proportion of surviving axons was negatively correlated to both deltaIOP and deltaIOP integral (P <or= 0.001). Progressive cupping was evident only with more than 55% axonal loss. Similarly, ERG results remained mostly within normal limits for low to moderate axonal loss, but were markedly abnormal with more than 70% axonal loss.

CONCLUSIONS

Structural and functional changes in this model are best correlated to peak deltaIOP and not to duration of IOP elevation, suggesting the existence of an IOP-related damage threshold.

Authors+Show Affiliations

Laboratory for Retina and Optic Nerve, Dalhousie University, Halifax, Nova Scotia, Canada. bal@is.dal.caNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

12202517

Citation

Chauhan, Balwantray C., et al. "Effect of Intraocular Pressure On Optic Disc Topography, Electroretinography, and Axonal Loss in a Chronic Pressure-induced Rat Model of Optic Nerve Damage." Investigative Ophthalmology & Visual Science, vol. 43, no. 9, 2002, pp. 2969-76.
Chauhan BC, Pan J, Archibald ML, et al. Effect of intraocular pressure on optic disc topography, electroretinography, and axonal loss in a chronic pressure-induced rat model of optic nerve damage. Invest Ophthalmol Vis Sci. 2002;43(9):2969-76.
Chauhan, B. C., Pan, J., Archibald, M. L., LeVatte, T. L., Kelly, M. E., & Tremblay, F. (2002). Effect of intraocular pressure on optic disc topography, electroretinography, and axonal loss in a chronic pressure-induced rat model of optic nerve damage. Investigative Ophthalmology & Visual Science, 43(9), 2969-76.
Chauhan BC, et al. Effect of Intraocular Pressure On Optic Disc Topography, Electroretinography, and Axonal Loss in a Chronic Pressure-induced Rat Model of Optic Nerve Damage. Invest Ophthalmol Vis Sci. 2002;43(9):2969-76. PubMed PMID: 12202517.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Effect of intraocular pressure on optic disc topography, electroretinography, and axonal loss in a chronic pressure-induced rat model of optic nerve damage. AU - Chauhan,Balwantray C, AU - Pan,Jingyi, AU - Archibald,Michele L, AU - LeVatte,Terry L, AU - Kelly,Melanie E M, AU - Tremblay,François, PY - 2002/8/31/pubmed PY - 2002/9/13/medline PY - 2002/8/31/entrez SP - 2969 EP - 76 JF - Investigative ophthalmology & visual science JO - Invest Ophthalmol Vis Sci VL - 43 IS - 9 N2 - PURPOSE: To characterize the effect of intraocular pressure (IOP) on optic disc topography, retinal function, and axonal survival in a model of IOP-induced optic nerve damage in rat. METHODS: Hypertonic (1.75 M) saline was injected into an episcleral vein of one eye of 49 Brown Norway rats, with the fellow untreated eye serving as the control. During the 1 to 3 months of follow-up, IOP was measured twice weekly in conscious animals with a handheld tonometer, and changes in disc topography and retinal function were monitored with scanning laser tomography and electroretinography (ERG), respectively. Peak IOP elevation in the experimental eye compared with the fellow control eye (peak deltaIOP), integral of IOP elevation over time (deltaIOP integral), and days of IOP elevation were calculated. Axon counts were obtained from electron micrographs of the sectioned optic nerves. RESULTS: Progressive cupping was found in 9 (56.3%) of 16 eyes with peak deltaIOP of more than 15 mm Hg and in none of 21 eyes with peak deltaIOP less than 15 mm Hg. A strong correlation between deltaIOP integral and progressive cupping was also found, but not with days of IOP elevation. ERG abnormalities (limited to the b-wave) were found in 11 (64.7%) of 17 eyes with peak deltaIOP of more than 15 mm Hg and in 2 (8.7%) of 23 eyes with peak deltaIOP of less than 15 mm Hg. Neither of the other IOP parameters was predictive of ERG damage. The proportion of surviving axons was negatively correlated to both deltaIOP and deltaIOP integral (P <or= 0.001). Progressive cupping was evident only with more than 55% axonal loss. Similarly, ERG results remained mostly within normal limits for low to moderate axonal loss, but were markedly abnormal with more than 70% axonal loss. CONCLUSIONS: Structural and functional changes in this model are best correlated to peak deltaIOP and not to duration of IOP elevation, suggesting the existence of an IOP-related damage threshold. SN - 0146-0404 UR - https://www.unboundmedicine.com/medline/citation/12202517/Effect_of_intraocular_pressure_on_optic_disc_topography_electroretinography_and_axonal_loss_in_a_chronic_pressure_induced_rat_model_of_optic_nerve_damage_ L2 - https://iovs.arvojournals.org/article.aspx?volume=43&amp;issue=9&amp;page=2969 DB - PRIME DP - Unbound Medicine ER -