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Andrea R. Carvalho, Miguel Zapata, Laura Distefano, Anna Salas, Carme Macià, Jose Garcia-Arumi; Histological Findings in a Pig Model of Experimental Branch Retinal Artery Occlusion. Invest. Ophthalmol. Vis. Sci. 2011;52(14):5360.
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© ARVO (1962-2015); The Authors (2016-present)
This study was designed to evaluate the retinal damage in time of branch retinal artery occlusion (BRAO). Research was approved by the local institution animal ethical committee and was conducted in compliance with the ARVO statement for the use of animals in ophthalmic and vision research.
In this study 10 hybrid pigs (15Kg) were used to check retinal damage in 60, 90, 120, 180, 240, 300, 360 minutes, 12, 24 and 48 hours after BRAO. Colour fundus photography (CF) and Fluorescein angiography (FA) were performed in all eyes before and after occlusion as well as before euthanasia. Electroretinography (ERG) was done before occlusion and euthanasia following ISCEV protocol. BRAO was obtained by applying diathermy for 5 to 7 seconds in the superior temporal branch artery of the right eye under general anaesthesia. Left eye was used as control. Both eyes were enucleated and fixed in 4% formaldehyde solution, for paraffin inclusion. Serial cuts of 3µ were stained in standard hematoxiline/eosine to evaluate retinal integrity, number of retinal ganglionar cells (RGC), including life and dead cells, nerve fiber layer (NFL) changes, inner retina vascular pattern and correlation of retina and NFL thickness. To check apoptosis deoxynucleotidyl transferase dUTP nick end labelling (TUNEL) was also performed.
Retinal integrity and architecture was maintained in all time points. The number of life RGC decreased after 300 minutes of local ischemia, being > than 25 cells in 40X until 240min. The percentage of died RGC increased to more then 40% of total cells from 300 min to 48 hours time points. TUNEL assay was negative in all samples, which suggested that cells died by necrosis instead of apoptosis. NFL tended to thick with time but thickness measurement was only significative at 24 and 48 hours. NFL also showed vesiculations in all time points. After 300 min vessels were dilated. In the ERG was observed a high intra-individual and interindividual variability (control eye) recorded in the different time points of the study. Therefore, only very extensive damage to the retina might lead to a significant change in the ERG amplitudes.
After 300 minutes of ischemia inner retina presented significant damage in other hand it is possible to maintain some retinal function after this time point as it was observed that only a small area surrounding the lesion were affected.
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