Abstract
Purpose :
Retinitis Pigmentosa (RP) is a group of hereditary diseases that lead to incurable blindness. To determine pathologic features of RP, we examine cone photoreceptors in the macula of RP patients using an adaptive optics（ AO）fundus camera to correlate the results to clinical outcomes.
Methods :
A prospective cross-sectional study. 9 subjects diagnosed with RP underwent ophthalmic test including fundus photography, scanning laser ophthalmoscopy and optical coherence tomography (SLO/OCT), and electroretinography. We imaged fifteen eyes using the rtx1™ flood-illuminated AO camera from Imagine Eyes (Orsay, France). Macular AO images covering an area of 10×10 degrees in a 2.4-mm diameter concentric annular zone (excluding the foveal avascular zone) were subdivided into six annular rings and four quadrants. Cone density (cells/mm(2))and the percentage of cones with six neighbours were measured in total annular zone used a custom automated algorithm.
Results :
The parafoveal cone density was analyzed in six annular zones and four quadrant sectors, corresponding values(C1~C5 mean +/-SD，/mm2 16067±5011.4, 14851.1±4689.6, 14270.3±4360.9, 13845.5±4215.0, 13755±4429.9/mm)（inferior [I], and nasal [N] superior [S], temporal [T] 14071.5±4621.4, 13948.1±4925.6, 14821.1±4863.6, 14595.9±4343.9） were significantly lower (P < 0.001) compared to that of the normal controls. The nearest-neighbour analysis revealed a distribution in the percentage of cones with six neighbours was correlated with the cone density (r2=0.616, p<0.05). Cone density decreased and inter-photoreceptor distance increased with increasing retinal eccentricity from C1 to C5.
Conclusions :
With noninvasive technique of AO, visualization at the cellular level enabled us to observe in vivo changes in the cone photoreceptors of RP patients. In our study, a sparse array of cone photoreceptors with significantly reduced density of the parafoveal annular zone is one of the morphologic features of RP. Imaging data acquired from the AO camera show blurred in some sector, which corresponded to changes in the fundus images and optical coherence tomography.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.