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Xiaolin Wang, Boyu Gu, Jing Lu, Christine A Curcio, Yuhua Zhang; Confocal adaptive optics differential phase contrast (AODPC) ophthalmoscopy. Invest. Ophthalmol. Vis. Sci. 2016;57(12):60. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
To image the living human retina at the cellular level using adaptive optics (AO) assisted phase contrast technique.
A confocal adaptive optics scanning laser ophthalmoscope (AOSLO) was adapted for differential phase contrast (DPC) imaging. The phase change of retinal structure was imaged using the split-detector mechanism. Two system configurations were tested. For configuration 1, the imaging light through the confocal pinhole was relayed to a new point where the light was split into 2 beams and received by 2 photomultiplier tubes (PMTs). For configuration 2, the imaging light was first split at the (eye) pupil’s conjugate plane and each beam was then collected by an achromatic lens which focuses the light through a pinhole that was conjugate to the retina plane and placed in front of a PMT. The light source is a low coherent superluminescent diode with a center wavelength of 840 nm. System performance was evaluated by comparing retinal images acquired with pinholes of different sizes in human subjects in normal chorioretinal health and patients with age-related macular degeneration (AMD).
The confocal AODPC produced clear cone and rod photoreceptor mosaics in both healthy eyes and diseased eyes, even if not clearly visible by AOSLO. It revealed subretinal drusenoid deposits as solid, space filling lesions in the subretinal space in patients with AMD, consistent with histologic findings. Foveal cones were better imaged using smaller pinhole. However, for imaging of retina capillaries and optic nerve fibers, a large pinhole provided improved signal to noise ratio. Robust AO correction for the ocular wave aberration is critical to enhance the phase contrast.
DPC imaging adds new ability to AOSLO. The confocal AODPC retains the technical merits bestowed by the confocal imaging mechanism.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.
Retina imaged with confocal AODPC and compared to AOSLO. A & B are AOSLO and AODPC images of photoreceptors at 0.5° nasal in a normal subject, respectively. Photoreceptors invisible by AOSLO are revealed by the phase change. C & D are AODPC images of photoreceptors at 1° nasal in a normal subject taken with pinholes of 0.75 and 3.75 Airy disc, respectively. E & F are AOSLO and AODPC images of subretinal drusenoid deposits (arrowheads) at of 5° superior to the fovea in a subject with AMD, respectively.
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