Variation in rod and cone density from the fovea to the mid-periphery in healthy human retinas using adaptive optics scanning laser ophthalmoscopy

Eye (2016) 30, 11351143 2016 Macmillan Publishers Limited, part of Springer Nature. All rights reserved 0950-222X/16

http://www.nature.com/eye

Web End =www.nature.com/eye

EM Wells-Gray1, SS Choi1, A Bries1,2 and N Doble1

Variation in rod and cone density from the fovea to the mid-periphery in healthy human retinas using adaptive optics scanning laser ophthalmoscopy

LABORATORYSTUDY

Abstract

Purpose To characterize the rod and cone photoreceptor mosaic at retinal locations spanning the central 60 in vivo using adaptive optics scanning laser ophthalmoscopy (AO-SLO) in healthy human eyes.

Methods AO-SLO images (0.7 0.9) were acquired at 680 nm from 14 locations from30 nasal retina (NR) to 30 temporal retina (TR) in 5 subjects. Registered averaged images were used to measure rod and cone density and spacing within 60 60 m regions of interest. Voronoi analysis was performed to examine packing geometry at all locations. Results Average peak cone density nearthe fovea was 164 000 24 000 cones/mm2and decreased to 6700 1500 and 5400 700 cones/mm2 at 30 NR and 30 TR, respectively. Cone-to-cone spacing increased from2.7 0.2 m at the fovea to 14.6 1.4 m at30 NR and 16.3 0.7 m at 30 TR. Rod density peaked at 25 NR (124 000 20 000 rods/mm2)

and 20 TR (120 000 12 000 rods/mm2)

and decreased at higher eccentricities. Center-to-center rod spacing was lowest nasally at 25 (2.1 0.1 m). Temporally, rod spacing was lowest at 20 (2.2 0.1 m) before increasing to 2.3 0.1 m at 30 TR. Conclusions Both rod and cone densities showed good agreement with histology and prior AO-SLO studies. The results demonstrate the ability to image at higher retinal eccentricities than reported previously. This has clinical importance in diseases that initially affect the peripheral retina such as retinitis pigmentosa.

Eye (2016) 30, 11351143; doi:http://dx.doi.org/10.1038/eye.2016.107

Web End =10.1038/eye.2016.107 ; published online 27 May 2016

Introduction

Being the rst element in the photo-transduction cascade that triggers vision, the structure and distribution of photoreceptors have long been of interest to clinicians and vision scientists. Typically, histological studies have been conducted to examine characteristics of the photoreceptor mosaic including total cell count, density, spacing, and size,15 as well as how these parameters vary with factors such as age69

and gender.10 Results of these investigations vary widely, and the differences may, in...