June 2022
Volume 63, Issue 7
Open Access
ARVO Annual Meeting Abstract  |   June 2022
Defocus influence on cones visibility in peripheral macula imaged with non-adaptive optics OCT
Author Affiliations & Notes
  • Maciej M. Bartuzel
    Institute of Physics, Faculty of Physics, Astronomy and Informatics, Nicolaus Copernicus University in Torun, Poland
  • Patrycjusz Stremplewski
    Institute of Physics, Faculty of Physics, Astronomy and Informatics, Nicolaus Copernicus University in Torun, Poland
  • Alejandra Consejo
    Department of Applied Physics, Universidad de Zaragoza, Zaragoza, Aragón, Spain
  • Marcin Sylwestrzak
    Institute of Physics, Faculty of Physics, Astronomy and Informatics, Nicolaus Copernicus University in Torun, Poland
  • Iwona Gorczynska
    Institute of Physics, Faculty of Physics, Astronomy and Informatics, Nicolaus Copernicus University in Torun, Poland
  • Footnotes
    Commercial Relationships   Maciej Bartuzel None; Patrycjusz Stremplewski AM2M sp. z o.o. sp.k., Code E (Employment); Alejandra Consejo None; Marcin Sylwestrzak None; Iwona Gorczynska AM2M sp. z o.o. sp.k., Code O (Owner)
  • Footnotes
    Support  National Science Centre, Poland, grant No. 2018/31/B/ST7/03138. Universidad de Zaragoza, Fundacion Bancaria Ibercaja, Fundación CAI (CB 4/21)
Investigative Ophthalmology & Visual Science June 2022, Vol.63, 4428 – F0107. doi:
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      Maciej M. Bartuzel, Patrycjusz Stremplewski, Alejandra Consejo, Marcin Sylwestrzak, Iwona Gorczynska; Defocus influence on cones visibility in peripheral macula imaged with non-adaptive optics OCT. Invest. Ophthalmol. Vis. Sci. 2022;63(7):4428 – F0107.

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

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Abstract

Purpose : It is known that in many subjects imaged with OCT systems, the cone photoreceptors can be resolved in the peripheral retina without adaptive optics (AO). However, there are no systematic studies investigating what factors influence the visibility of cones in OCT. We analyze how defocusing of the OCT beam influences the visibility of cones in the peripheral macula when imaged with 5 μm lateral imaging resolution.

Methods : Imaging was performed with SS-OCT in 4 healthy subjects. The accommodation was blocked with Tropicamide. Laser operating at 1.6MHz rate with λ = 1.06μm providing 6μm axial resolution was used. 3D data sets were acquired ~6° nasally from the fovea. The FOV was 5°×5°. Light beam diameter of 6.2mm at the cornea was used providing 5μm nominal lateral resolution at the retina. The beam focus was shifted from the photoreceptor layer in 31 steps over ±312 µm depth. 6 data sets were acquired at each defocus. Cones visibility was calculated from the radially averaged power spectrum (RAPS) of the en face images as the height of a Gaussian peak fitted to the RAPS after subtracting non-periodic component fit. The study was approved by the Bioethics Committee of NCU and adhered to the Declaration of Helsinki.

Results : In all imaged subjects, cones were visible in en face images of the inner/outer photoreceptor segments junction (IS/OS) when the beam was focused at that layer. As expected, the visibility of the cones was decreasing with increasing defocus. Focal shift of ~100μm (~1/3 of the thickness of the retina) causes substantial loss in the cones visibility. Cones visibility is shown as a function of defocus in Fig.

Conclusions : Cone photoreceptors of the peripheral macula can be visualized in non-AO OCT imaging with a nominal transverse imaging resolution of ~5μm provided that the device operator pays attention to the proper focusing of the imaging system. The proposed measure of photoreceptors visibility could be used for determining how much the beam size could be decreased to still resolve photoreceptors within the depth of focus reasonable for the device operator and without paralyzing the accommodation and dilating the pupil.

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

 

Cones visibility in the peripheral macula as a function of defocus. Cones visibility is measured as the height of Gaussian peak fitted to the radially averaged power spectrum of the image. Examples are shown for two different imaged regions (blue and orange).

Cones visibility in the peripheral macula as a function of defocus. Cones visibility is measured as the height of Gaussian peak fitted to the radially averaged power spectrum of the image. Examples are shown for two different imaged regions (blue and orange).

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