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R Daniel Ferguson, Mircea Mujat, Ankit Patel, Ramkumar Ramamirtham, James D Akula, Anne B Fulton; AO-OCT imaging with the Compact Adaptive Optics Retinal Imager. Invest. Ophthalmol. Vis. Sci. 2015;56(7 ):5984.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: To compare adaptive optics (AO) line-scanning ophthalmoscopic (AO-LSO) and AO-OCT images obtainable in normal subjects with diffraction-limited AO correction to those obtained in subjects with poor AO correction/media or with retinal disease using the Compact Adaptive Optics Retinal Imager (CAORI). Preliminary clinical measurements have commenced at Boston Children’s Hospital. We describe some early imaging results in from a study in progress, including in a subject with Stargardt’s disease.
Methods: The AO-LSO has a nominal 3°×5° area mode and the AO-OCT channel has 3° B-scan and raster modes and serves as the AO beacon. We have compared retinal AOLSO and AO-OCT images, at 780nm and 850nm respectively, within 3 degrees of the fovea in 3 normal subjects (males, ages 25 to 40) and one Stargardt’s patients (female, 17 years of age).
Results: Retinal disease can often compromise the contrast and quality of both AO-SLO and AO-LSO images of the photoreceptor mosaic. However, a simultaneously acquired, complementary AO-OCT modality can augment photoreceptor imaging, with indications of whether viable cones exist (or at least exhibit normal reflectance properties) beneath poor media and/or with limited AO-correction. AO-OCT and AO-LSO both show very clear photoreceptor mosaics in normal subjects with near diffraction-limited correction in healthy retinas in AO-OCT B-scans at eccentricities beyond >1°, with typical beaded string appearance of reflections from the IS/OS junction. In the Stargardt’s subject, the AO-LSO has very poor contrast with no evidence of photoreceptors beyond the fovea centralis. AO-OCT shows these layers very clearly, but the appearance of the (still visible) IS/OS junction is much altered, with no discernable signs of wave-guided reflections typical of normal cones. The entire inner retina has flocculated debris and appears hyper-reflective with a dense RPE. This accounts for rapid AO-LSO cone image degradation outside the fovea.
Conclusion: OCT effectively gates out multiply-scattered photons which accounts for it superior contrast in disease retinas; in general, we expect AO-OCT to look better in diseased retinas than AOLSO. CAORI's AO-OCT could be an important high resolution back-up modality in the clinic for imaging photoreceptors and other layers when media are poor.
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