Distribution differences of macular cones measured by AOSLO: Variation in slope from fovea to periphery more pronounced than differences in total cones

Abstract

Large individual differences in cone densities occur even in healthy, young adults with low refractive error. We investigated whether cone density follows a simple model that some individuals have more cones, or whether individuals differ in both number and distribution of cones. We quantified cones in the eyes of 36 healthy young adults with low refractive error using a custom adaptive optics scanning laser ophthalmoscope. The average cone density in the temporal meridian was, for the mean ± SD, 43216 ± 6039, 27466 ± 3496, 14996 ± 1563, and 12207 ± 1278 cones /mm2 for 270, 630, 1480, and 2070 microns from the foveal center. Cone densities at 630 microns retinal eccentricity were uncorrelated to those at 2070 microns, ruling out models with a constant or proportional relation of cone density to eccentricity. Subjects with high central macula cone densities had low peripheral cone densities. The cone density ratio (2070 : 630 microns) was negatively correlated with cone density at 630 microns, consistent with variations in the proportion of peripheral cones migrating towards the center. We modelled the total cones within a central radius of 7 deg, using the temporal data and our published cone densities for temporal, nasal, superior, and inferior meridians. We computed an average of 221,000 cones. The coefficient of variation was 0.0767 for total cones, but higher for samples near the fovea. Individual differences occur both in total cones and other developmental factors related to cone distribution.

Cones in ageing and harsh environments: the neural economy hypothesis

“…Unlike our previous study in myopes that showed cones surviving in the large peripapillary crescents due to axial elongation causing the RPE to slip away from beneath the retina, these subjects did not have high myopia. Both subjects met our criteria for normal subjects: axial length <26 mm and <3D of spherical error . The width of the scleral crescents was narrow compared with that of most of the myopes that we have studied, but wide enough to permit some visualisation of cones, if present ( Figure ).…”

“…For a set of 36 healthy subjects <35 years of age and with axial length <26 mm, the distribution of cone density is well‐fit by a two parameter model, using the natural logarithm (ln):…”

Retinal explant culture: A platform to investigate human neuro‐retina

“…Although the retina is considered as a single entity, the distribution of different retinal cell types and retinal thickness varies across the retina . Explants obtained from every part of the retina have been successfully maintained in culture for an extended period.…”

“…Although the retina is considered as a single entity, the distribution of different retinal cell types and retinal thickness varies across the retina. 31,111,112 Explants obtained from every part of the retina have been successfully maintained in culture for an extended period. However, for experimental purposes, most studies have chosen para macular regions equidistant from the fovea so that each explant has a relatively uniform distribution of retinal cell types.…”

Introduction to special issue on adaptive optics for vision

“…This approach provides new insights at the highest resolution into both structural retinal architecture and functional vision examined in situ. In this special issue a multimodal adaptive optics retinal imaging system reveals the relations between cone acuity and retinal structure (Baraas, Gjelle, Finstad, Jacobsen, & Gilson, 2017), to investigate the relation of cone density in the fovea and the preferred locus for fixation (Wilk et al, 2017), as well as how the cones of the fovea are packed (Sawides, de Castro, & Burns, 2017) and the inter-relation between foveal and parafoveal cone density (Elsner et al, 2017).…”