Generation of an acute retinal photoreceptor degeneration model in rabbits.

Purpose: To assess the appropriate dose of sodium nitroprusside for establishing acute retinal photoreceptor degeneration models in rabbits.

Methods: Sodium nitroprusside (SNP) was delivered intravitreously. Sixteen New Zealand White rabbits are divided into four groups randomly: 0.1 mM, 0.25 mM, 0.5 mM SNP intravitreal injection group (experimental groups), and normal saline intravitreal injection group (control group). Assessments included weight, anterior segment photography, fundus photography, Hematoxylin-eosin staining, immunofluorescence, multi-focal electroretinogram (mfERG) and pupillary direct light reflex were performed at baseline and day 28 after injection. The spectral domain optical coherence tomography (SD-OCT) and full field electroretinogram (fERG) were performed at baseline and day 1, 3, 7, 14, 21 and 28 after injection.

Results: No complications and no significant different in weight were found among all groups. No obvious change was found by slit lamp and fundus photography after injection in all groups. In SD-OCT exams, a time-dependent and dose-dependent injury of photoreceptor was found in SNP injection groups (<0.05). The thickness of inner nuclear and plexiform layer was significantly decreased in 0.5 mM group. HE staining and immunofluorescence present the photoreceptor damage at the posterior pole (0.1, 0.25, 0.5 mM groups) and periphery (0.5 mM group). fERG and mfERG showed significant dose-dependent responses depression in SNP injection groups (<0.05). The pupillary direct light reflex in SNP groups declined significantly at day 28 than pre-injection (<0.05).

Conclusions: Sodium nitroprusside of 0.1 mM and 0.25 mM can lead to monolayer photoreceptor degeneration at posterior pole in rabbits and the lesion is stable at 1 month after SNP injection.