Abstract
Purpose: :
Investigating applications for ultra-high speed optical coherence tomography (OCT) at up to 312.500 depth-scans per second for clinical retinal imaging with focus on high density (1 gigavoxel) and high throughput (<0.5 s/volume) acquisition.
Methods: :
A novel ultra-high speed (UHS) 3D-OCT system was developed around a high-speed CMOS line camera, utilizing 160 nm spectral bandwidth, corresponding to <3 µm effective axial resolution. The variable acquisition speed and sensitivity was utilized to either produce ultra-dense tomographic volumes consisting of up to 1 mega-depth-scans with more than 1000 depth points each, or for undistorted high density sampling within the inter-saccade period.
Results: :
UHS OCT at 800 nm was performed on multiple normal subjects and patients with imaging quality comparable to retinal fundus photography while delivering additional depth information in every transversal position at ultrahigh axial resolution. Isotropic (equidistant in all three spatial directions) sampling of the retina for ~7 s allows reconstruction of retinal fiber topology, microvasculature and individual layers down to the RPE-choriocapillaris interface across a typical 30 40° scan angle that includes the perifovea and the optic nerve head, while simultaneously sampling at the transversal resolution limit across the whole scan. Snapshot-type imaging within the typical 0.4 1 s inter-saccade period was achieved at sampling densities (512x128 depth-scans) of currently available commercial OCT devices, but without distortions by microsaccades.
Conclusions: :
UHS OCT bridges the gap between fundus photography that delivers only flat, but high resolution en-face images and ultrahigh axial resolution OCT that is well established for depth resolved analysis of retinal layers. Ultra-high density OCT combines wide-field imaging with the ability to investigate minute details on the 10 µm scale without the need of rescanning the area of interest. While screening and monitoring applications for a wide range of retinal diseases might profit the significant enhancement in level of detail, snapshot OCT permits to extend the application to subjects with poorer fixation including nystagmus patients without the use of an additional eye-tracker.
Keywords: retina • motion-3D • eye movements: saccades and pursuits