# Neural mechanisms underlying photophobia and dry eye

> **NIH VA I01** · MIAMI VA HEALTH CARE SYSTEM · 2022 · —

## Abstract

It is estimated that 19% of US veterans have dry eye (DE), of which painful ocular symptoms are a common
manifestation. These can include sensations of dryness, burning, and extreme sensitivity to light (i.e.,
photophobia). The symptoms interfere with activities of daily living including driving and reading. Photophobia,
in particular, is one of the most distressing symptoms as its occurrence results in high morbidity without effective
treatment. Individuals most severely affected become prisoners in their own homes due to intolerance to even
small amounts of light. Even in less severe cases, most individuals have significant functional limitations and
often require sunglasses in and outdoors. A knowledge gap exists with regards to the mechanism that underlie
these painful sensations, thus limiting the ability to target appropriate treatment strategies. Our overall hypothesis
is that photophobia is an indicator of central pathologic plasticity of 1) trigeminal pathways, and 2) their interaction
with melanopsin pathways. To test this hypothesis, in aim 1, we define peripheral and central neural responses
to light in individuals with chronic ocular pain and photophobia as compared to controls. In aim 2, we examine
the contribution of different pathways to photophobia by blocking corneal afferent drive (to assess trigeminal
pathways) and intrinsically photosensitive retinal ganglion cell (ipRGC) drive (to assess melanopsin pathways).
In Aim 3, we determine the effect of neural blockade with botulinum toxin injection on photophobia. This study is
greatly needed, as a critical barrier to progress in the field is the lack of information on neural pathways that
underlie disease. The data generated can be used to improve the rehabilitation of ocular pain and increase
function and quality of life in veterans and non-veterans alike.

## Key facts

- **NIH application ID:** 10425233
- **Project number:** 5I01CX002015-03
- **Recipient organization:** MIAMI VA HEALTH CARE SYSTEM
- **Principal Investigator:** Anat Galor
- **Activity code:** I01 (R01, R21, SBIR, etc.)
- **Funding institute:** VA
- **Fiscal year:** 2022
- **Award amount:** —
- **Award type:** 5
- **Project period:** 2020-04-01 → 2024-03-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10425233

## Citation

> US National Institutes of Health, RePORTER application 10425233, Neural mechanisms underlying photophobia and dry eye (5I01CX002015-03). Retrieved via AI Analytics 2026-05-22 from https://api.ai-analytics.org/grant/nih/10425233. Licensed CC0.

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