# Effects of wavelength on achieving and maintaining emmetropia

> **NIH NIH R01** · UNIVERSITY OF ALABAMA AT BIRMINGHAM · 2021 · $361,536

## Abstract

During postnatal development when the eye is still growing, an “emmetropization mechanism” uses the
eye’s refractive error to regulate the growth of the scleral shell to match the axial length of the eye to the focal
plane. Despite this, in over 40% of Americans and up to 96% of groups in East Asia, the eye becomes too long
for its own optics and is thus myopic. Even low amounts of myopia raise the risk of developing blinding
conditions and refractive surgery does not change this. Thus, effective strategies to slow eye growth and
reduce the prevalence of myopia are needed.
 Maintenance of emmetropia is a neglected area of research. Most myopic children emmetropize relatively
normally, but then are unable to maintain emmetropia in the longer maintenance phase of emmetropia. Our
research in tree shrews (cone-dominated dichromatic mammals closely related to primates) has shown that
maintaining emmetropia is an active process throughout adolescence. Is the eye becoming too short
(hyperopia) and should increase its growth rate to maintain emmetropia (retinal GO signals are needed), or is it
becoming too long (myopia) and should slow the axial elongation rate to maintain emmetropia (retinal STOP
signals are needed). An important problem is that we do not have a solid understanding of the visual cues
used by the emmetropization mechanism to generate STOP signals that will prevent eyes from becoming too
long. In tree shrews, we have discovered that exposure to narrow-band long wavelength (red) light (which only
stimulates the long-wavelength sensitive, or LWS, cones) seems to generate STOP signals that slow growth
during the maintenance phase of emmetropization.
 In specific aim 1, we will determine the optimal parameters for the red light to generate the maximum
STOP signal with minimal exposure and learn if red-light STOP signals show non-linear summation, similar to
other stimuli that generate STOP signals (myopic defocus or interrupted minus-lens wear).
 In specific aim 2, we will determine if the red light “treatment” can produce consistent STOP signaling over
a long period of time in the maintenance phase of emmetropization. We will also examine if the red light can
counteract the myopiagenic effects of a minus lens in a paradigm similar to that used in myopia-control studies.
 In specific aim 3, we will use both analysis of retinal dopamine, and of gene expression in the retina and
post-retinal signaling cascade, to determine if red-light STOP signals act via the same pathways as other
STOP stimuli (such as recovery from induced myopia), or if the pathways are parallel and novel.
 The knowledge gained from this project will not only generate critical data on the operation of the
emmetropization mechanism during the maintenance phase, but also may result in the development of red
light as a novel anti-myopia therapy.

## Key facts

- **NIH application ID:** 10240464
- **Project number:** 5R01EY028578-04
- **Recipient organization:** UNIVERSITY OF ALABAMA AT BIRMINGHAM
- **Principal Investigator:** TIMOTHY J GAWNE
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2021
- **Award amount:** $361,536
- **Award type:** 5
- **Project period:** 2018-09-01 → 2023-08-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10240464

## Citation

> US National Institutes of Health, RePORTER application 10240464, Effects of wavelength on achieving and maintaining emmetropia (5R01EY028578-04). Retrieved via AI Analytics 2026-05-21 from https://api.ai-analytics.org/grant/nih/10240464. Licensed CC0.

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