Journal article
Temporary elevation of the intraocular pressure by cauterization of vortex and episcleral veins in rats causes functional deficits in the retina and optic nerve
Experimental Eye Research, Vol.77(1), pp.27-33
2003
DOI: 10.1016/S0014-4835(03)00089-7
PMID: 12823985
Abstract
Purpose. To evaluate visual function in rats with chronic elevation of intraocular pressure (IOP). Methods. Chronic ocular hypertension was induced in the left eye of 14 adult Brown Norway rats by cauterizing 3 vortex veins and 2 major episcleral veins; the right eye served as a non-operated control. A control group ( n=5) was sham operated on the left eye. Prior to surgery, the IOP was measured with a Tonopen, the pupil light reflex (PLR) evaluated with a custom-made computerized pupillometer and electroretinograms (ERGs) were recorded simultaneously from both eyes post surgically: IOP was measured on weeks 1, 3, 5 and 8 post-operatively, pupil light reflexes on weeks 1, 4 and 8 post-operatively, and ERGs on weeks 4 and 8 post-operatively. Sixty five days postoperatively, rats were euthanized and optic nerves and eye globes were prepared for histological analysis. Results. Seven days after surgery 5/14 rats developed significant elevation of the IOP in operated eyes (control eyes: 25·1±0·5mmHg; operated eyes: 34·1±0·6mmHg; mean±SEM; p=0·0004; Paired t-test). Elevation of the IOP was sustained at 3 ( p=0·002) and 5 ( p=0·007) weeks postoperatively. However, IOP values did not significantly differ between control and operated eyes 8 weeks postoperatively ( p=0·192, Paired t-test). Sham operated animals showed no elevation of the IOP 7 days postoperatively. When the ratio between consensual and direct PLR (PLR ratio=consensual/direct PLR; pupil of unoperated eye recorded) was examined in rats which developed elevation of the IOP, preoperative values were 92·2±4% (mean±SEM), 1 week postoperatively 65±4% (significantly different from preoperative values, p<0·05 Repeated Measures ANOVA with Dunnett's Multiple Comparison test, n=5), 4 weeks postoperatively 60·6±3·2% ( p<0·01, n=5). By 8 weeks postoperatively, pupil responses had essentially recovered 75·4±6·9% ( p>0·05, n=5). Rats whose IOP values did not rise after surgery and sham operated rats did not develop pupil deficits 4 weeks postoperatively. Rats with elevated IOP displayed a significant decrease in ERG amplitudes in operated eyes at 4 weeks (a-wave operated/a-wave control (a-wave ratio)=42±14% (mean±SEM); b-wave operated/b-wave control (b-wave ratio)=43±16%) but not at 8 weeks postoperatively (a-wave ratio=88±8·4%; b-wave ratio=82·9±9%). Sham operated and rats whose IOP values remained non-elevated after surgery did not develop ERG deficits 4 weeks after surgery. Histological analysis did not reveal any damage in the eyes of animals with elevated intraocular ocular pressure with the exception of one rat, which still had ERG and pupil deficits at the end of experiment. Conclusions. Development of ERG and PLR deficits are proportional to the elevation of the IOP in the rat model of chronic ocular hypertension. Functional monitoring of the ERG and PLR are useful objective techniques for the detection of retina and optic nerve deficits.
Details
- Title: Subtitle
- Temporary elevation of the intraocular pressure by cauterization of vortex and episcleral veins in rats causes functional deficits in the retina and optic nerve
- Creators
- Sinisa D Grozdanic - Department of Biomedical Sciences, College of Veterinary Medicine, Iowa State University, Ames, IA 50011, U.S.ADaniel M Betts - Department of Veterinary Clinical Sciences, College of Veterinary Medicine, Iowa State University, Ames, IA 50011, U.S.ADonald S Sakaguchi - Department of Zoology and Genetics, Iowa State University, Ames, IA 50011, U.S.AYoung H Kwon - Department of Ophthalmology and Visual Sciences, University of Iowa Hospitals and Clinics, Iowa City, IA 52242, U.S.ARandy H Kardon - Department of Ophthalmology and Visual Sciences, University of Iowa Hospitals and Clinics, Iowa City, IA 52242, U.S.AIoana M Sonea - Department of Biomedical Sciences, College of Veterinary Medicine, Iowa State University, Ames, IA 50011, U.S.A
- Resource Type
- Journal article
- Publication Details
- Experimental Eye Research, Vol.77(1), pp.27-33
- DOI
- 10.1016/S0014-4835(03)00089-7
- PMID
- 12823985
- NLM abbreviation
- Exp Eye Res
- ISSN
- 0014-4835
- eISSN
- 1096-0007
- Publisher
- Elsevier Ltd
- Language
- English
- Date published
- 2003
- Academic Unit
- Iowa Neuroscience Institute; Ophthalmology and Visual Sciences
- Record Identifier
- 9983979920202771
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