June 2021
Volume 62, Issue 8
Open Access
ARVO Annual Meeting Abstract  |   June 2021
Ultrafast adaptive optics for imaging the living human eye
Author Affiliations & Notes
  • Yan Liu
    Indiana University Bloomington, Bloomington, Indiana, United States
  • James Alan Crowell
    Indiana University Bloomington, Bloomington, Indiana, United States
  • Kazuhiro Kurokawa
    Indiana University Bloomington, Bloomington, Indiana, United States
  • Hae Won Jung
    Indiana University Bloomington, Bloomington, Indiana, United States
  • Ayoub Lassoued
    Indiana University Bloomington, Bloomington, Indiana, United States
  • Marcel Bernucci
    Indiana University Bloomington, Bloomington, Indiana, United States
  • Donald Thomas Miller
    Indiana University Bloomington, Bloomington, Indiana, United States
  • Footnotes
    Commercial Relationships   Yan Liu, None; James Crowell, None; Kazuhiro Kurokawa, Indiana University (P); Hae Won Jung, None; Ayoub Lassoued, None; Marcel Bernucci, None; Donald Miller, Indiana University (P)
  • Footnotes
    Support  NEI Grant R01 EY018339, R01 EY029808
Investigative Ophthalmology & Visual Science June 2021, Vol.62, 16. doi:
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      Yan Liu, James Alan Crowell, Kazuhiro Kurokawa, Hae Won Jung, Ayoub Lassoued, Marcel Bernucci, Donald Thomas Miller; Ultrafast adaptive optics for imaging the living human eye. Invest. Ophthalmol. Vis. Sci. 2021;62(8):16.

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      © ARVO (1962-2015); The Authors (2016-present)

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Abstract

Purpose : Adaptive optics (AO) measures and corrects ocular wavefront aberrations, enabling cellular-resolution retinal imaging and stimulation. Most current ophthalmic AO systems correct dynamic aberrations up to 2 Hz, the commonly-known cutoff frequency for ocular aberrations. However, this cutoff is based on measurements acquired in healthy subjects under ideal conditions and thus do not capture many real-life clinical scenarios that induce high temporal frequency aberrations. To investigate, we developed ultrafast AO and evaluated its use with optical coherence tomography (OCT).

Methods : Our ultrafast AO system used (1) a fast Shack-Hartmann wavefront sensor (SHWS) with high spatial sampling and dynamic range, (2) efficient software that minimized data processing time, and (3) discontinuous exposure permitting a higher AO loop gain. The SHWS comprised a 20×20 microlens array that sampled a 6.7 mm eye pupil and a high-speed streaming camera (ORCA-Lightning, up to 342 Hz). A direct slope reconstruction method and an integral controller scheme with a gain of 1 determined the voltages for a deformable mirror (DM, ALPAO DM97-15). Our software processed frames in 0.5 ms. We analyzed AO performance in correcting rapid dynamic aberrations caused by tear film disruptions, eye blinks, displacement of a high-power contact lens, nystagmus, and absence of cycloplegia. Performance was compared to conditions mimicking conventional AO on the same eyes.

Results : The cutoff frequency of our AO system as determined from a power rejection curve measurement was 32.5 Hz, enabling correction of dynamic aberrations more than 16× faster than conventional AO. After AO activation, the RMS wavefront aberration from un-cyclopleged subjects dropped below the diffraction limit within 5 ms, 40× faster than the fastest previously-reported ophthalmic AO system. Unlike conventional AO, ultrafast AO achieved high image quality of cone photoreceptors immediately after an eye blink, even in a late-stage retinitis pigmentosa subject wearing a –8.5 D contact lens. This immediate recovery from blinks enables continuous data acquisition for simple and high-throughput imaging in the clinic. In an eye with nystagmus, ultrafast AO improved the Strehl ratio from 0.37 to 0.81 and produced sharper images of the cone mosaic compared with conventional AO.

Conclusions : Ultrafast AO corrects ocular wavefront aberrations that conventional AO cannot and improves the clinical utility of AO.

This is a 2021 ARVO Annual Meeting abstract.

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