# Stereopsis and Suppression in Strabismus and Amblyopia

> **NIH NIH R01** · SMITH-KETTLEWELL EYE RESEARCH INSTITUTE · 2022 · $398,205

## Abstract

Abstract
Amblyopia (‘lazy eye’) is a neuro-development disorder of the visual cortex that occurs early in life and affects
about 3% of the population worldwide. Amblyopia is associated with reduced visual acuity and contrast
sensitivity in the non-dominant eye. In addition, the majority of individuals with amblyopia do not have
measurable stereopsis or the ability to perceive depth from binocular information, which negatively impacts
many tasks of daily life including eye-hand coordination and navigation. While studies have shown that about
25% of the amblyopic population does have residual stereopsis, the retinal locus that mediates this function is
unknown. This proposal tests the hypothesis that when stereopsis is present in amblyopia, it is the periphery
and not the central visual field that mediates depth perception. The first aim uses a novel procedure to map
stereopsis in both central and peripheral locations to determine whether residual stereopsis is in fact mediated
by the periphery. Our pilot data suggest that it is the periphery that mediates stereopsis in amblyopia. We will
also determine whether this peripheral stereopsis accounts for fusional vergence, the movement of the two
eyes to fuse monocular images to form a binocular percept. The second aim examines the relation between
residual stereopsis and the documented suppression of the non-dominant eye under conditions of binocular
viewing. We will measure the suppression zone for each individual and relate it to the zone of stereo-deficiency
measured for that same individual. This within-participant comparison is essential to understanding the relation
between suppression and stereo-deficiency in this special group of amblyopic individuals who have residual
stereopsis. This group comprises about 50% of those with anisometropia (unequal refractive error), and about
10-40% of those with strabismus (eye deviation). This study will characterize each observer’s capacity for
stereopsis across the visual field including the periphery, which has been ignored previously. The third aim will
use electroencephalography (EEG) combined with a procedure to localize cortical source that produces the
signals to understand the neural basis of suppression in individuals with and without stereopsis, and how well
the non-dominant eye signal is represented on its own, and in the presence of a stimulus in the other eye, as
well as how the two eyes’ signals are combined at different levels of the cortical hierarchy. If the peripheral
visual field has a significant contribution to stereopsis in amblyopia, our study will establish the importance of
clinically evaluating the potential for stereopsis in the periphery and for training peripheral locations to improve
stereopsis.

## Key facts

- **NIH application ID:** 10539773
- **Project number:** 1R01EY034370-01
- **Recipient organization:** SMITH-KETTLEWELL EYE RESEARCH INSTITUTE
- **Principal Investigator:** Preeti Verghese
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2022
- **Award amount:** $398,205
- **Award type:** 1
- **Project period:** 2022-09-01 → 2026-06-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10539773

## Citation

> US National Institutes of Health, RePORTER application 10539773, Stereopsis and Suppression in Strabismus and Amblyopia (1R01EY034370-01). Retrieved via AI Analytics 2026-05-21 from https://api.ai-analytics.org/grant/nih/10539773. Licensed CC0.

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