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Denise Valente, Kari V Vienola, Robert Zawadzki, Ravi Sankar Jonnal; Cellular imaging of the retina with an ultrahigh speed areal and tomographic camera and real-time adaptive optics. Invest. Ophthalmol. Vis. Sci. 2020;61(7):208.
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© ARVO (1962-2015); The Authors (2016-present)
A retinal imaging system was implemented for high-speed full-field (FF) swept-source (SS) optical coherence tomography (OCT), incorporating an adaptive optics (AO) subsystem. It has been previously reported that digital aberration correction (DAC) permits visualization of cones with FF-SS-OCT, but only in the parafovea and periphery. By combining AO with FF-SS-OCT this system will be able to resolve all cones and measure functional responses previously reported only in the periphery. With the reference arm blocked, the system is a high speed (kHz) AO fundus camera capable of measuring light-evoked responses through common path interference.
The setup is a Mach-Zehnder interferometer with tuneable source (Superlum BS-840-2-HP) illuminating the retina. The backscattered light is imaged at a CMOS sensor (Photron NOVA S12 Fastcam). In parallel, a deformable mirror (ALPAO DM-97-15) is operated by custom software in closed-loop with a Hartmann-Shack wavefront sensor for real-time aberration correction. Two normal subjects were imaged at locations between the foveal center and 3o.
OCT sensitivity and lateral resolution were measured to be 53 dB and 3 μm, respectively. With closed-loop AO correction, diffraction-limited areal images of the cone mosaic and OCT images of the retina were successfully collected at rates of 1 kHz and 200 Hz, respectively. Cones were laterally resolved in the areal images and resolved in 3D in the OCT images.
The system was demonstrated to be capable of producing multimodal images of the foveal cone mosaic. Future plans include incorporation of a DMD-based visible stimulus channel and modification of the AO system to permit higher speed and dynamic range.Funding: R00-EY-026068 (RSJ); R01-EY-026556 (RJZ).
This is a 2020 ARVO Annual Meeting abstract.
Experimental setup. The dashed-line box shows the Maxwellian illumination with focused beam 3cm away of the cornea. BS: beam splitter; DM: deformable mirror; HS: Hartmann-Shack wavefront sensor.
(a) Areal images with and without adaptive optics; (b) Photoreceptors mosaic at different eccentricities; (c) OCT en face projection of the cone mosaic, 10 motion-corrected volumes averaged. Scale bar: 20μm.
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