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Xiaolin Wang, Jing Lu, Boyu Gu, Yuhua Zhang; High speed high resolution anamorphic adaptive optics near-confocal ophthalmoscopy. Invest. Ophthalmol. Vis. Sci. 2018;59(9):733.
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© ARVO (1962-2015); The Authors (2016-present)
To precisely image photoreceptor structure in the living human eye, we present a high-speed adaptive optics near-confocal ophthalmoscope.
A low coherent superluminescent diode (λ=795 nm) was employed to provide the imaging light. A digital micro-mirror device (DMD) was deployed to modulate the imaging light into a line of point sources. A high speed line camera was used to acquire the image and act as a confocal gate. An anamorphic imaging mechanism was designed to increase light collecting efficiency and ensure adequate digitization of optical resolution. The adaptive optics (AO) system consists of a custom Shack-Hartmann wavefront sensor and a deformable mirror with 97 actuators.
In most eyes, AO reduced the wave aberration to 0.05 μm (root mean square). The anamorphic imaging mechanism increased the light collection efficiency by 2.60 times in comparison with symmetric optics thereby significantly improving image brightness and signal to noise ratio. The instrument produced retinal image with cellular level resolution at a rate of 200 frames/second (FPS) with a digitization of 512×512 pixels over a field of view of 1.2°×1.2° (Fig). Cone photoreceptor structure was examined in images acquired at 100, 200, and 800 FPS in 3 human subjects in normal macular health. High speed imaging rendered cone mosaic with improved regularity and measurement repeatability.
The DMD modulated AO high speed ophthalmoscope can acquire a frame of retinal image within a time close to the ‘snap shot’ exposure of the flood-illumination AO-fundus photography thus the artifact induced by rapid and continuous eye motion has been effectively reduced. High speed high resolution retinal imaging offered by this instrument has the potential to expand the functionality of AO ophthalmoscopy from imaging static retinal structure to investigating rapid time-varying functional activities.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.
High speed anamorphic adaptive optics near-confocal ophthalmoscopy. A. Instrument diagram. B. A single frame of retinal image acquired without anamorphic imaging. C. A single frame of retinal image taken with anamorphic imaging at the same retinal location. D. An image taken at the fovea. E. An image taken at the eccentricity of 0.8° nasally. F. An image taken at the eccentricity of 2.4° nasally, revealing cones and surrounding rods. The scale bars represent 50 µm.
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