# Neural mechanisms that detect defocus in the retina

> **NIH NIH R21** · UNIVERSITY OF CALIFORNIA BERKELEY · 2022 · $240,750

## Abstract

PROJECT SUMMARY
A sharp retinal image is essential for accurately encoding the visual world. The focal
length of the eyes' optics can be adjusted within a fraction of a second to bring object of
interest into sharp focus, a process called “accommodation”. On longer timescales, hours
to months, a sharp retinal image is made possible when the axial length of the eye grows
to match the refractive power of the optics, a process called “emmetropization”. In order
to respond appropriately, accommodation and emmetropization require the retina to
detect the sign and magnitude of image defocus. It is well established that the major
optical cue that signals the sign of defocus is longitudinal chromatic aberration (LCA).
LCA is due to the stronger refraction of short than long wavelength light. The identity of
the neurons in the retina that detect LCA signals, and how they relay the signals to the
down-stream mechanisms that control eye growth and accommodation, remains one of
the great outstanding puzzles in sensory neurobiology. This proposal aims to identify the
retinal neurons that respond to LCA. We will use multi-photon calcium imaging to
simultaneously measure responses from tens to hundreds of neurons within an area of
retina under photopic adaptation levels. Patterned, chromatic images will be used to
identify candidate defocus neurons. The somas of the neurons will then be targeted for
single-cell whole-cell recordings to measure in detail the receptive field properties and to
recover the morphology. We will also measure responses to natural scenes rendered with
and without LCA calculated for the optics of the eye. Identification LCA-sensitive neurons
will lay the groundwork for future studies aimed at determining how these retinal
neurons ultimately control accommodation and emmetropization. These insights may
also provide clues as to the origin of the mysterious, continuing increase in the prevalence
of myopia and perhaps lead to development of mitigative strategies.

## Key facts

- **NIH application ID:** 10527088
- **Project number:** 1R21EY033549-01A1
- **Recipient organization:** UNIVERSITY OF CALIFORNIA BERKELEY
- **Principal Investigator:** William Rowland Taylor
- **Activity code:** R21 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2022
- **Award amount:** $240,750
- **Award type:** 1
- **Project period:** 2022-09-30 → 2024-08-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10527088

## Citation

> US National Institutes of Health, RePORTER application 10527088, Neural mechanisms that detect defocus in the retina (1R21EY033549-01A1). Retrieved via AI Analytics 2026-05-28 from https://api.ai-analytics.org/grant/nih/10527088. Licensed CC0.

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