Abstract
Purpose :
Genetic models of retinal degenerative disorders in larger animals are difficult to be acquired and still have not been firmly established yet. This study tested to develop and characterize the outer retinal degeneration induced by intravitreal injection of a sodium iodate (SI) after vitrectomy in the canine.
Methods :
In preliminary experiment, the left eyes of 3 female mixed breed dogs were repeatedly received increasing dose of the intravitreal SI injection to develop the outer retinal degeneration 2 weeks after vitrectomy. Spectral-domain optical coherence tomography (OCT) and infrared fundus photography (IR-FP) and electroretinography (ERG) were performed at baseline and 1, 2, 4 and 6 months after intravitreal injection to decide outer retinal degeneration. Histological examinations with hematoxylin and eosin (H&E) stain were performed between one and six month after final injection. In the second efficacy study, based on the preliminary results, 1.2mg SI/0.05ml was injected into the either eye of 6 canines 2 weeks after vitrectomy. IR-FP, OCT, and ERG were performed at baseline and 1, 2, 4 and 6 months after intravitreal injection and histology were performed at 3 or 6 months after injection.
Results :
In preliminary experiment, in first dog, after two times of 0.4 mg SI injection followed by 1.0 mg SI injection, severe retinal atrophy of the whole retina was induced in the OCT. In the second dog, after two times of 0.8 mg SI injection, severe retinal atrophy of the whole retina was induced in the OCT. in the third dog, after single 1.2mg SI injection, outer retinal degeneration was induced. In the second efficacy study, all 6 eyes showed diffuse outer retinal degeneration in OCT and loss of both cone and rod response in ERG. Histological examination also showed the loss of outer nulclear layer and photoreceptor layer.
Conclusions :
Vitrectomized canine model with intravitreally injected 1.2mg dose of SI could induce the outer retinal degeneration effectively and degree of retinal degeneration can be evaluated through in-vivo ophthalmic examination.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.