A spectral-domain optical coherence tomographic analysis of Rdh5-/- mice retina

Abstract

To investigate the longitudinal findings of spectral-domain optical coherence tomography (SD-OCT) in relation to the morphologic features in Rdh5 knockout (Rdh5-/-) mice. Materials and methods The mouse retina was segmented into four layers; the inner retinal (A), outer plexiform and outer nuclear (B), rod/cone (C), and retinal pigment epithelium (RPE)/choroid (D) layers. The thickness of each retinal layer of Rdh5-/mice was longitudinally and quantitatively measured at six time points from postnatal months (PM) 1 to PM6 using SD-OCT. Age-matched C57BL/6J mice were employed as wild-type controls. The data were statistically compared using Student's t-test. The fundus appearance was assessed, histologic and ultrastructural examinations were performed in both groups. Results Layers A and B were significantly thinner in the Rdh5-/mice than in the wild-type C57BL/6J mice during the observation periods. Layers C and D became thinner in the Rdh5-/mice than in the wild-type mice after PM6. Although no abnormalities corresponding to whitish fundus dots were detected by SD-OCT or histologic examinations, the intracellular accumulation of low-density vacuoles was noted in the RPE of the Rdh5-/mice by electron microscopy. The photoreceptor nuclei appeared less dense in the Rdh5-/mice than in the wildtype mice. Discussion The results from the present study suggest that although it is difficult to detect qualitative abnormalities, SD-OCT can detect quantitative changes in photoreceptors even in the early stage of retinal degeneration induced by the Rdh5 gene mutation in mice.

Sub-cellular level resolution of common genetic variation in the photoreceptor layer identifies continuum between rare disease and common variation

“…Additionally, rare variants within RPB3 cause recessive retinal dystrophy and high myopia [35]. Much of the retinoid cycle occurs in the supporting RPE layer, for example RDH5 is almost exclusively expressed in this layer [36], showing that one does not need gene expression in a cell type to impact its structure.…”