June 2022
Volume 63, Issue 7
Open Access
ARVO Annual Meeting Abstract  |   June 2022
Phase-based optoretinography with clinical-grade OCT using tissue velocity
Author Affiliations & Notes
  • Kari V Vienola
    Department of Ophthalmology and Vision Science, University of California Davis, Sacramento, California, United States
  • Robert J Zawadzki
    Department of Ophthalmology and Vision Science, University of California Davis, Sacramento, California, United States
    Department of Cell Biology and Human Anatomy, University of California Davis, Davis, California, United States
  • Ravi S Jonnal
    Department of Ophthalmology and Vision Science, University of California Davis, Sacramento, California, United States
  • Footnotes
    Commercial Relationships   Kari Vienola None; Robert Zawadzki None; Ravi Jonnal None
  • Footnotes
    Support  R00-EY-026068, R01-EY-033532, R01-EY-026556, R01-EY-031098, P30-EY-012576
Investigative Ophthalmology & Visual Science June 2022, Vol.63, 847. doi:
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    • Get Citation

      Kari V Vienola, Robert J Zawadzki, Ravi S Jonnal; Phase-based optoretinography with clinical-grade OCT using tissue velocity. Invest. Ophthalmol. Vis. Sci. 2022;63(7):847.

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

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Abstract

Purpose : In blinding diseases of the retina, loss of visual function may occur long before structural changes are observed. The emerging field of optoretinography (ORG) promises non-invasive, objective assessment of functional, stimulus-evoked responses in the retina. Here we present a novel ORG approach to facilitate and accelerate ORG applications in the clinical setting.

Methods : The swept-source optical coherence tomography (SS-OCT) system uses a source centered at 1060 nm with a 100 kHz A-scan rate and 100 nm bandwidth (Fig. 1). The beam is scanned horizontally over the retina to acquire a series of B-scans. The stimulus source is a fiber-coupled light emitting diode at 555 nm, configured to deliver 30 ms flash. The system was configured to acquire 250 A-scans over each 2.5° scan, resulting in a B-scan rate of 400 Hz and sampling density of ∼333 mm-1 the retina. Prior to imaging, the subjects were dark-adapted for five minutes. The stimulus flash was delivered after the first 0.25 s of OCT acquisition. A time window of five B-scans (t = 10 ms) was used to do a linear fit of the complex signal over time at each pixel. The angle of the fit to the complex signal reveals local tissue velocity, which was recorded as a function of time relative to the stimulus onset.

Results : The results shown in Fig. 2 used a stimulus power of 42 μW, isomerizing 66% of photopigment in the predominant L- and M-cones in a 1.2° circular region. All three subjects showed reproducible differential velocities (between IS/OS and COST) consistent with the previously reported stimulus-evoked contraction (< 10 ms) and elongation (10-50 ms) phases of the outer segment ORG response.

Conclusions : The results are consistent with previous ORG responses acquired from photoreceptor's outer segments using adaptive optics OCT (AO-OCT). Including time for dark adaptation, imaging, and processing, functional responses can be measured and visualized within ten minutes providing a feasible clinical pipeline for larger scale ORG studies.

This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.

 

Optical layout of the SS-OCT system for ORG measurements.

Optical layout of the SS-OCT system for ORG measurements.

 

Optoretinograms from 3 subjects. The blue line represents the difference between the velocities of IS/OS and COST, averaged over 5-10 trials, with the gray area showing the error (±1 SD). Negative and positive velocities correspond to OS contraction and elongation, respectively. Erratic velocity changes observed after 50 ms are likely due to involuntary, aversive eye movements.

Optoretinograms from 3 subjects. The blue line represents the difference between the velocities of IS/OS and COST, averaged over 5-10 trials, with the gray area showing the error (±1 SD). Negative and positive velocities correspond to OS contraction and elongation, respectively. Erratic velocity changes observed after 50 ms are likely due to involuntary, aversive eye movements.

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