# Horton_Admin_Supplement_EY029703

> **NIH NIH R01** · UNIVERSITY OF CALIFORNIA, SAN FRANCISCO · 2024 · $209,893

## Abstract

Project Summary
 Approximately 2% of children in the United States have strabismus, a condition in which the eyes are not
aligned properly. As a consequence, stereovision may be lost and the deviated eye is at risk for reduced vision
from amblyopia. There are many other potential consequences, including reduced eye-hand coordination,
diminished quality of life, employment discrimination, social prejudice, and psychological distress. The goal of
this project is to investigate the most common form of strabismus, intermittent exotropia. A translational
approach is used that combines a prospective, longitudinal observational study of patients with intermittent
exotropia to define its natural history and clinical features along with analysis of data from a parallel set of
laboratory studies in nonhuman primates. Aim 1 will focus on the problem of defining the severity of intermittent
exotropia. Patients wear tracking glasses that record the fixation point of each eye within the visual scene while
they go about their normal daily activities. This technology makes it possible to measure the “occurrence rate”
of exotropia – defined as the percentage of time that an ocular deviation is present. This data will enable eye
doctors to identify which patients have a stable versus a progressive form of intermittent exotropia. The latter
group may need surgery to re-align their eyes, but there is currently no consensus regarding the criteria for
recommending surgery, in part because it has not previously been possible to quantify the occurrence rate. The
project will also stratify patients into the 3 recognized subtypes of intermittent exotropia (basic, convergence
insufficiency, divergence excess) to probe the relationship between fusion loss and vergence demand. Insights
from that correlation could also influence surgical planning. Successful introduction of ambulatory eye tracking
into pediatric eye care would thus have a major impact on the management of intermittent exotropia. Aim 2 will
explore the contingent of retinal ganglion cells that projects to the superior colliculus, a brainstem center
controlling eye movements. Experiments have been performed in monkeys, injecting a retrograde tracer into
the superior colliculus to label these cells. A different retrograde tracer has been injected in the lateral geniculate
nucleus in the same monkeys. The data from these animals will be analyzed to determine the percentage of
ganglion cells which is double-labeled, signifying that the cells send a branching axon to both targets.

## Key facts

- **NIH application ID:** 10932049
- **Project number:** 3R01EY029703-05S1
- **Recipient organization:** UNIVERSITY OF CALIFORNIA, SAN FRANCISCO
- **Principal Investigator:** JONATHAN C HORTON
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2024
- **Award amount:** $209,893
- **Award type:** 3
- **Project period:** 2019-02-01 → 2025-01-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10932049

## Citation

> US National Institutes of Health, RePORTER application 10932049, Horton_Admin_Supplement_EY029703 (3R01EY029703-05S1). Retrieved via AI Analytics 2026-06-14 from https://api.ai-analytics.org/grant/nih/10932049. Licensed CC0.

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