Abstract
High-acuity vision in humans is supported by specialized circuitry between cone photoreceptors and midget retinal ganglion cells at the fovea, thus both cell populations contribute to foveal pit structure. Cone density and foveal structure are known to vary between individuals, but quantitative relationships between cones, ganglion cells, and foveal structure remain poorly understood. We used adaptive optics scanning light ophthalmoscopy (AOSLO) and optical coherence tomography (OCT) to examine relationships between cone density, ganglion cell layer (GCL) topography, and foveal structure in 10 normal subjects (age, mean/SD: 26.2/9.4 years). AOSLO was used to measure cone density, Bioptigen SD-OCT foveal line scans were used to measure GCL topography, and Cirrus HD-OCT Macular Cube scans were used to measure foveal pit depth, diameter, slope, area, and volume. Peak cone density (PCD, 164,829/30,782 cones/mm^2) varied between subjects 1.89-fold, while the sum GCL area under the curve (AUC) in four quadrants (0.350/0.021 mm^2) varied only 1.23-fold, and they were not correlated (r^2 = 0.08). PCD was positively correlated with inferior GCL AUC (r^2 = 0.48) and negatively correlated with the ratio between superior and inferior GCL AUC (r^2 = 0.43). PCD was negatively correlated with foveal pit volume (r^2 = 0.39), diameter (r^2 =0.40), and area (r^2 = 0.38). These findings indicate that relationships between cone density and OCT-based GCL metrics are modest at best, demonstrating a need for more robust methods to characterize cell-level relationships between cones and ganglion cells—and, ultimately, visual acuity—in vivo.