ex in vivo bovine eye: a model for retinal research: michael t. tseng, nain liu and norman d....

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217 EX IN VIVO BOVINE EYE: A MODEL FOR RETINAL RESEARCH MICHAEL T. TSENG, NAIN LIU and NORMAN D. RI~)TKE, Departments of Anatomical Sciences and Neurobiology, and Ophthalmology, University of Louisville, School of 5~dicine, Louisville, KY 40292, U.S.A. The neuroretina is an integral part of the sensory system. Its function can be assessed accurately through electroretinogram (ERG). The isolated perfused eye preparation offers the opportunity to study retinal responses without the influence of systemic factors. Toward this end, we have devised a means to resuscitate bovine eyes and examine their responses to stimuli. Specifically, we have tested the effects of intraocular innoculation of purified bacterial collagenase on the structure and function of the retina. The enzyme has been used to facilitate the removal of ectopic growth on the surface of the retina. Minutes after exsanguination, eyes were removed abattoir and were perfused with autologous or heterologous whole blood through the cannulated ciliary artery. Heparinized, oxygenated perfusate was delivered at a rate of 60 ml/h. In the laboratory, eyes were dark adapted for 30 rain prior to experimentation. Photic flashes were delivered by a Grass stimulator placed 5 cm above the eye. The ERG was recorded and analyzed after attaining 6 consecutive stable ERG recordings. Purified bacterial collagenase (120-600 U/ml) was introduced through a 22 guage needle. Responses to the same photic stimuli were recorded after 15 min incubation. It was found that the resuscitated eyes maintained reactivity to photic flashes for 6-8 h; 15 min exposure to 600 U/ml of bacterial collagenase extinguished the ERG response. Cessation of the retinal activity was accompanied by the erosion of the inner limiting lamina as demonstrated by transmission electron microscopy. These data illustrate that a stable, isolated, perfused eye preparation can be used to determine the toxic dose of bacterial collagenase and that such preparations may be used to screen other intraocular innoculants. (Supported in part by a grant from the University of Louisville Graduate School and Advance Biofacture, Inc.)

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Page 1: Ex in vivo bovine eye: a model for retinal research: MICHAEL T. TSENG, NAIN LIU and NORMAN D. REDTKE, Departments of Anatomical Sciences and Neurobiology, and Ophthalmology, University

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EX IN VIVO BOVINE EYE: A MODEL FOR RETINAL RESEARCH

MICHAEL T. TSENG, NAIN LIU and NORMAN D. RI~)TKE, Departments of Anatomical Sciences and Neurobiology, and Ophthalmology, University of Louisville, School of 5~dicine, Louisville, KY 40292, U.S.A.

The neuroretina is an integral part of the sensory system. Its function can be assessed accurately through electroretinogram (ERG). The isolated perfused eye preparation offers the opportunity to study retinal responses without the influence of systemic factors. Toward this end, we have devised a means to resuscitate bovine eyes and examine their responses to stimuli. Specifically, we have tested the effects of intraocular innoculation of purified bacterial collagenase on the structure and function of the retina. The enzyme has been used to facilitate the removal of ectopic growth on the surface of the retina. Minutes after exsanguination, eyes were removed abattoir and were perfused with autologous or heterologous whole blood through the cannulated ciliary artery. Heparinized, oxygenated perfusate was delivered at a rate of 60 ml/h. In the laboratory, eyes were dark adapted for 30 rain prior to experimentation. Photic flashes were delivered by a Grass stimulator placed 5 cm above the eye. The ERG was recorded and analyzed after attaining 6 consecutive stable ERG recordings. Purified bacterial collagenase (120-600 U/ml) was introduced through a 22 guage needle. Responses to the same photic stimuli were recorded after 15 min incubation. It was found that the resuscitated eyes maintained reactivity to photic flashes for 6-8 h; 15 min exposure to 600 U/ml of bacterial collagenase extinguished the ERG response. Cessation of the retinal activity was accompanied by the erosion of the inner limiting lamina as demonstrated by transmission electron microscopy. These data illustrate that a stable, isolated, perfused eye preparation can be used to determine the toxic dose of bacterial collagenase and that such preparations may be used to screen other intraocular innoculants.

(Supported in part by a grant from the University of Louisville Graduate School and Advance Biofacture, Inc.)