# Interocular Suppression and Selective Attention in Amblyopia

> **NIH NIH R01** · SMITH-KETTLEWELL EYE RESEARCH INSTITUTE · 2023 · $516,874

## Abstract

Project Summary
Long-term and chronic visual suppression to the visual input from the non-preferred eye is a key factor in
developing amblyopia, or “lazy eye”, as well as a critical barrier to treat amblyopia. Amblyopia is commonly
caused by misalignment of the eyes (strabismus), chronic optical blur in one eye due to unequal refractive
errors in two eyes (anisometropia), or a mixture of strabismus and anisometropia during early childhood,
affecting about 3% to 5% of the population worldwide. Our long-term goal is to understand how and where
suppression occurs in the brain. We propose that selective visual attention plays a role in visual suppression.
Our hypothesis in the current proposal is that selective visual attention biases competition between eyes and
modulates interocular suppression by selectively facilitating responses from the preferred eye and suppressing
responses from the non-preferred eye along the visual cortical hierarchy. To test our hypothesis, we will use
psychophysics to measure whether valid cueing of the stimulus in the amblyopic eye reduces suppression under
dichoptic viewing in adults with amblyopia, compared with invalid/neutral cueing (Aim 1). In Aim 2, we will
use frequency-tagged EEG source imaging along with behavioral measures of perceptual eye dominance during
binocular rivalry to compare the effects of selective attention and increased contrast to the amblyopic eye on
perception and neural responses. We will simultaneously measure and compare the neural activities along the
cortical hierarchy of both eyes under the states of visual perceptual dominance and suppression in adults with
amblyopia and normal vision. These measures will help determine: 1) how and where the brain suppresses
visually conflicting images in amblyopia; 2) how an increase in bottom-up visual salience by increasing the
contrast input to the amblyopic eye changes the neural representation of the amblyopic eye signal and 3)
whether paying attention to the amblyopic eye has a similar effect on neural activity as increasing contrast to
the amblyopic eye. In Aim 3, we will use frequency-tagged EEG source imaging coupled with visual
psychophysics to measure cortical activity and behavioral performance during a multiple-object tracking task
with moving targets presented to one eye and moving distractors presented to the other eye. This aim will
comprehensively characterize: 1) whether visual attention modulates interocular suppression by selectively
facilitating neural responses from the preferred eye and suppressing responses from the non-preferred eye
along the visual cortical hierarchy (Aim 3a); 2) whether there are differences in attentional modulation
between normal and amblyopic vision, in terms of temporal dynamics (Aim 3b) and attentional resource
availability determined by the number of targets to be tracked (Aim 3c). The proposed studies will
systematically investigate visual perception and neural correlates underlying interocular suppress...

## Key facts

- **NIH application ID:** 10720187
- **Project number:** 1R01EY035346-01
- **Recipient organization:** SMITH-KETTLEWELL EYE RESEARCH INSTITUTE
- **Principal Investigator:** Chuan Hou
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2023
- **Award amount:** $516,874
- **Award type:** 1
- **Project period:** 2023-08-01 → 2027-02-28

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10720187

## Citation

> US National Institutes of Health, RePORTER application 10720187, Interocular Suppression and Selective Attention in Amblyopia (1R01EY035346-01). Retrieved via AI Analytics 2026-05-23 from https://api.ai-analytics.org/grant/nih/10720187. Licensed CC0.

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