Abstract
Purpose:
To study the effect on the neuroretina and the retinal pigment epithelium (RPE) in albino rabbits with high-resolution real-time spectral domain-optical coherence tomography (SD-OCT) after subretinal injection of isotonic salt solution.
Methods:
Subretinal injections of phosphate buffered salt solution (PBS) or balanced salt solution (BSS) were performed in albino or pigmented rabbits by standard small-gauge vitrectomy. Real-time SD-OCT, infrared confocal scanning laser ophthalmoscopy (IR-cSLO) and blue light fundus autofluorescence (BAF) was done up to 12 weeks following subretinal injection. The effects on morphology were compared to histologic hematoxylin eosin-stained sections of the outer retina and flat-mounts of phalloidine-labeled RPE.
Results:
SD-OCT of the normal albino and pigmented rabbit retina revealed 11 distinct layers including the outer nuclear layer, the ellipsoid zone, the photoreceptor outer segments and the retinal pigment epithelium. Subretinal injection of PBS or BSS resulted in an acute thickening followed by a significant thinning of the outer retinal layers that remained stable for up to 12 weeks post-injection. The thinning involved the loss of the outer segments, the ellipsoid zone and thinning of the outer nuclear layer. IR-cSLO of the subretinal bleb area showed a hyperreflective ring with a hyporeflective margin, whereas analysis of the RPE by BAF revealed areas of both hyper- and hypofluorescence. SD-OCT results were confirmed by histology and on subretinal flat-mounts, which demonstrated photoreceptor loss and disturbed RPE.
Conclusions:
SD-OCT, IR-cSLO and BAF provide detailed morphologic information of the posterior segment in rabbits, making it suitable as a preclinical model. Subretinal injection of isotonic salt solutions cause significant and long-lasting degeneration of the outer retina, suggesting that care should be taken when using this route of administration in treatments of retinal disease.