14– 16 The clinical value of imaging the choroid has been shown in a small sample of patients, by using OCT at 1060 nm to demonstrate ChT variation over the field of view in uveal inflammation 17 and to demonstrate an increase in vessel density at the center of choroidal neovascularization in age-related macular degeneration (ARMD). 13 Commercial OCT systems operating at 800 nm have shown choroidal penetration only in thin choroids of myopic subjects, or by imaging limited to two-dimensional (2D) horizontal scans. 11, 12 Histologic studies investigated biological structures with comparable high resolution, but these were limited by preparation artifacts, shrinkage, and lack of blood supply to sustain vasculature volume. 7, 8 Histology of choroidal thickness (ChT) reveals increased ChT that correlates with a higher density of vessels in the superficial choroidal layers in open-angle glaucoma, 9 atrophy of the choroidal capillary structure, 10 and neovascularization in the choriocapillaris. 2 Previously, in vivo investigation of the choroid has been possible with ultrasound and MRI, but with limited resolution. High-resolution, high-speed, three-dimensional optical coherence tomography at 1060 nm (3D 1060-nm OCT) images the retina and, in contrast to OCT at 800 nm, significantly increases choroidal penetration, 1– 6 with less light-scattering by cataract. Compared with 800-nm OCT, it provides superior visualization of the posterior pole in cataractous eyes. This imaging system has the potential of visualizing a novel clinical diagnostic biomarker. The imaging performance of 3D 1060-nm OCT is unique, producing maps that show the variation in ChT over the entire field of view, in relation to axial length. Reduced signal strength in cataractous eyes was found in 65% of the 800-nm OCT images, but in only 10% of the 1060-nm OCT images. Subfoveal ChT was 315 ± 106 μm (mean ± SD), negatively correlated with AL ( R 2 = −0.47, P 24.5 mm showed a larger variation and a thicker ChT superiorly than inferiorly. In 64 eyes, ChT maps displayed a thickness decrease with increasing AL. A further 30 eyes (19 subjects), with cataracts assessed with the LOCS III scale, were imaged with 3D 1060-nm OCT and 800-nm OCT, and visualization of the posterior segment was compared qualitatively. ChT maps between retinal pigment epithelium and the choroidal–scleral interface, were generated and statistically analyzed. 3D 1060-nm OCT was performed over a 36° × 36° field of view with ∼7-μm axial resolution and up to 70 frames/s (512 A-scans/frame). To evaluate the performance and potential clinical role of three-dimensional (3D) 1060-nm OCT by generating choroidal thickness (ChT) maps in patients of different ages with different degrees of ametropia and axial lengths and to investigate the effect of cataract grade on OCT retinal imaging quality.Īxial lengths (ALs) and 45° fundus photographs were acquired from 64 eyes (34 healthy subjects, 19 to 80 years, ametropia +3 to −10 D).
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