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Ultra-high resolution adaptive optics OCT detects retinal capillaries
Invest Ophthalmol Vis Sci. 2011;52(9):6292-6299.
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Ultra-high resolution optical coherence tomography with adaptive optics enables observation of many capillaries proximal to the foveal avascular zone, according to a study.
"The vast majority of capillaries in the retina are likely detectable with [ultra-high resolution adaptive optics] OCT, though increased instrument sensitivity may be required to offset increased scatter when the retina becomes thick and the capillaries are deep. ... Aside from this caveat, [ultra-high resolution adaptive optics] OCT is a promising option for noninvasive mapping of the intricate details of the multilaminar networks of capillaries in the retina," the study authors said.
Ultra-high resolution OCT images from seven patients were compared with entoptic diagrams to assess the technology's potential for detecting individual capillaries. Validation of ultra-high resolution OCT with adaptive optics involved testing for the presence of a foveal avascular zone (FAZ), observing distinct features in the capillary pattern near the FAZ and measuring the zone's size. Three patients lacking an FAZ were included to gauge accuracy.
The OCT observations were consistent with those of entoptic diagrams for all three methods of comparison, with FAZ diameters measured by the two technologies strongly correlated.
The average capillary diameter near the FAZ rim was 5.1 ± 1.4 µm, or 4.6 µm accounting for axial image blur. This measurement was consistent with histology, which placed the average at roughly 4.7 µm.
Capillary depth range increased monotonically with eccentricity and was larger and more variable for patients without FAZ.