Three-dimensional assessment of para- and perifoveal photoreceptor densities and the impact of meridians and age in healthy eyes with adaptive-optics optical coherence tomography (AO-OCT)

Abstract

An adaptive optics optical coherence tomography (AO-OCT) system is used to assess sixty healthy eyes of thirty subjects (age 22 to 75) to evaluate how the outer retinal layers, foveal eccentricity and age effect the mean cone density. The cone mosaics of different retinal planes (the cone inner segment outer segment junction (IS/OS), the cone outer segment combined with the IS/OS (ISOS+), the cone outer segment tips (COST), and the full en-face plane (FEF)) at four main meridians (superior, nasal, inferior, temporal) and para- and perifoveal eccentricities (ecc 2.5° and 6.5°) were analyzed quantitatively. The mean overall cone density was 19,892/mm2 at ecc 2.5° and 13,323/mm2 at ecc 6.5°. A significant impact on cone density was found for eccentricity (up to 6,700/mm2 between ecc 2.5° and 6.5°), meridian (up to 3,700/mm2 between nasal and superior meridian) and layer (up to 1,400/mm2 between FEF and IS/OS). Age showed only a weak negative effect. These factors as well as inter-individual variability have to be taken into account when comparing cone density measurements between healthy and pathologically changed eyes, as their combined effect on density can easily exceed several thousand cones per mm2 even in parafoveal regions.

Mitochondrial decline in the ageing old world primate retina: Little evidence for difference between the centre and periphery

“…There is little evidence for cone loss in the ageing primate retina including humans [ 7 , 25 ], although Reumueller et al found a weak reduction in number, but this was from imaging with adaptive optics [ 41 ]. Panda-Jones et al also noted a small decline in cone numbers in human ageing but the scatter in the data was very large [ 42 ].…”

Multi-modal and multi-scale clinical retinal imaging system with pupil and retinal tracking

“…Recent work on clinical AO-OCT imaging has outlined the importance of high resolution imaging of the retina in three dimensions 42 , 43 . With the instrument we introduce here, commercialization of this technology comes one step closer and possibly triggers a more widespread clinical use of such instruments.…”

Assessment of Detailed Photoreceptor Structure and Retinal Sensitivity in Diabetic Macular Ischemia Using Adaptive Optics-OCT and Microperimetry

“…This would explain why PR signal density and morphology in areas with intact capillary perfusion in the diabetic eyes analyzed in the current study were comparable to a larger sample of healthy subjects recently examined with the same AO-OCT prototype. 25 …”

“…Thus, we could ensure that intra-individual comparison of PR density values, which are known to decrease with increasing distance from the foveal center, were not influenced by a varying extent of foveal eccentricity. 24 , 25 …”

“…AO-OCT imaging was performed with a system developed at the Center for Medical Physics and Biomedical Engineering at the Medical University of Vienna which had been clinically applied before. 23 , 25 , 27 – 29 In brief, the system combines an AO fundus camera and AO-OCT in a compact system by utilizing a deformable mirror (Mirao52-e RC; Imagine Eyes, Orsay, France) and a Shack Hartmann wavefront sensor (Haso First; Imagine Optics, Orsay, France) for AO enhancement. 30 , 31 The OCT system is operated at 840 nm with an A-scan rate of 200 kHz and an axial resolution in the retina of approximately 5 µm.…”