June 2023
Volume 64, Issue 8
Open Access
ARVO Annual Meeting Abstract  |   June 2023
Differences between ON and OFF cortical function in patients with amblyopia
Author Affiliations & Notes
  • Vanna Lam Vy Nguyen
    SUNY College of Optometry, New York, New York, United States
  • Jian Z Jin
    SUNY College of Optometry, New York, New York, United States
  • Carmen Pons
    SUNY College of Optometry, New York, New York, United States
  • Jingyun Wang
    SUNY College of Optometry, New York, New York, United States
  • Jose-Manuel Alonso
    SUNY College of Optometry, New York, New York, United States
  • Footnotes
    Commercial Relationships   Vanna Nguyen None; Jian Jin None; Carmen Pons None; Jingyun Wang Percept, Code C (Consultant/Contractor); Jose-Manuel Alonso None
  • Footnotes
    Support  NIH Grant EY027361
Investigative Ophthalmology & Visual Science June 2023, Vol.64, 532. doi:
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      Vanna Lam Vy Nguyen, Jian Z Jin, Carmen Pons, Jingyun Wang, Jose-Manuel Alonso; Differences between ON and OFF cortical function in patients with amblyopia. Invest. Ophthalmol. Vis. Sci. 2023;64(8):532.

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

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Abstract

Purpose : Evidence from psychophysical studies indicates that amblyopia affects ON more than OFF visual pathways (Pons et al. 2019). This prospective study aims to directly measure the effect of amblyopia on cortical responses driven by ON and OFF pathways with visual evoked potentials (VEP).

Methods : We are recruiting adults (18-60 years) with amblyopia (strabismic, anisometropic, or mixed) and control subjects with binocularly normal-corrected vision. All subjects are screened with Randot Preschool stereoacuity and ATS-EDTRS best-corrected visual acuity (BCVA). To be eligible, amblyopes must have an interocular difference of ≥2 logMAR lines, and controls must have BCVA within 1 logMAR line in both eyes and a stereoacuity of ≤100 arcsec. VEP is recorded with a portable lightweight headset (Wearable Sensing Inc.) that samples the visual cortex with 9 dry electrodes. The visual stimuli presented are checkerboards with half checks equal to the background and half darker or lighter than the background (100% and 50% contrast, viewed through right eye, left eye, or both eyes, 900 trials). Eye fixation is controlled with an eye tracker (Eyelink 1000). The reliability of cortical responses is quantified with a correlation index that selects the 20 stimulus trials generating the strongest responses and measures the average of all possible correlations between trial pairs.

Results : We tested five amblyopic subjects and one control. The amblyopic group had poor or no stereopsis and an average BCVA of 0.28 ± 0.08 logMAR in the amblyopic eye (AE) and -0.04 ± 0.12 logMAR in the fellow eye (FE). The average amplitude of the cortical response was stronger for FE than AE, but the difference did not reach significance (25.4 ± 5.3 vs. 22.7 ± 4.6 microV, p=0.06, Wilcoxon test). The mean correlation index is significantly larger in FE than AE (0.41 ± 0.2 vs. 0.31 ± 0.21, p=0.03, Wilcoxon test). Both FE-AE differences in response amplitude and mean correlation index are larger for light than dark stimuli, but none of the differences reached significance (FE-AE amplitude difference: 3.51 ± 4.28 for light vs. 1.81 ± 5.64 for dark, p=0.31, Wilcoxon test; FE-AE difference in mean correlation index: 0.14 ± 0.16 for light vs. 0.06 ± 0.15 for dark, p=0.15, Wilcoxon test).

Conclusions : Preliminary results are consistent with the hypothesis that amblyopia reduces the strength of ON more than OFF cortical pathways.

This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.

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