Wide-field optical coherence tomography of the choroid in vivo

To demonstrate high-speed, high axial resolution optical coherence tomography (OCT) at 1060 nm with penetration to the sclera. The clinical feasibility of dense, high-speed sampling for higher levels of detail at the macula and optic nerve head is explored with respect to motion artifacts.

A three-dimensional (3D) OCT system making use of a high-speed camera operating at 47,000 depth scans/s was developed. The 1010- to 1080-nm wavelength band leads to 6.7 microm effective axial resolution and enables the acquisition of retinal and choroidal 130 Megavoxel volumes of human subjects within 7 seconds. Motion artifacts were reduced by numeric postprocessing techniques.

Drift motion artifacts could be suppressed within fields up to 38 degrees x 38 degrees (approximately 1 cm(2)) using acquisition speeds of up to 74 frames/s at 512 x 512 pixel/frame. This isotropic OCT sampling of the human retina in vivo allowed reconstruction of the retinal microvasculature solely on vessel reflectivity, without the use of contrast agents, and revealed three interconnected capillary meshworks. Simultaneously in the choroid, the structure of the choriocapillaris, Sattler's layer, and Haller's layer were differentiated, and the choroidal-scleral interface was clearly delineated in densely sampled narrow- and wide-angle scans (>38 degrees). At the optic nerve head, the 3D fine structure of the lamina cribrosa and the circle of Zinn-Haller were visualized.

OCT almost centered within the 1060-nm water transmission window significantly profits from lower scattering and allows investigation of the retina and choroid at an unprecedented combination of penetration and high speed at high resolution and may provide superior clinical feasibility to commercial 800-nm devices.