Abstract
Purpose:
This study aimed to evaluate the anatomical and functional changes of rabbit retina after intravitreal injection of sodium iodate (SI) and thus to investigate a monocular retinal degeneration model of rabbits.
Methods:
Twenty adult female New Zealand white rabbits were divided into 4 groups and each group underwent a monocular intravitreal SI injection with one of four doses (0.1 mg, 0.2 mg, 0.4 mg, 0.8 mg). Before and after injection, both eyes of the rabbits underwent examination including fundus photography, swept-source optical coherence tomography (OCT), and electroretinography (ERG). Light microscopy and transmission electron microscopy (TEM) were performed after enucleation.
Results:
No significant change was observed in the fundus among all groups except that of 0.8 mg-group which showed attenuation of choroidal vessels. ERG showed an acute reduction of b-wave with gradual recovery, but 0.8 mg-group showed an irreversible extinguishment. A-wave amplitude was also decreased in 0.2 mg- and 0.4 mg-group, with complete recovery in the 0.2 mg-group (P = 0.698) but partially in the 0.4 mg group (P = 0.002).<br /> In lower-dose (0.1 mg and 0.2 mg) groups, no significant changes were observed both in OCT and post-mortem histopathologic examination. In higher-dose (0.4 mg and 0.8 mg) groups, swelling of ganglion cell layer and splitting of internal limiting membrane were observed in OCT at early phase. At day 28, inner retina was relatively preserved but photoreceptor was disappeared in 0.4 mg-group. In 0.8 mg group, the entire retina was destroyed.
Conclusions:
The retinal destruction after intravitreal SI injection was dependent on injection dose and post-injection time. The retinal damages were reversible at low doses (0.2 mg), but irreversible at high doses. At a certain dose (0.4 mg), outer retina was selectively ablated and inner retina was relatively preserved.<br /> This model would be useful in evaluating the effectiveness of the electrical retinal stimulation in different stages of the retinal degeneration.