# Biomechanical Analysis in Strabismus Surgery

> **NIH NIH R01** · UNIVERSITY OF CALIFORNIA LOS ANGELES · 2021 · $584,907

## Abstract

We propose 3 interrelated aims to define the biomechanics of the eye rotating (extraocular) muscles (EOMs) &
optic nerve (ON) in health & visual disease, understand novel EOM actions, & characterize mechanical effects
that may contribute to severe myopia. We aim to improve treatment of strabismus, misalignment of visual
directions of the eyes; glaucoma & non-arteritic anterior ischemic optic neuropathy (NA-AION), both common
blinding ON diseases; & high axial myopia, an ocular elongation & distortion that has become a worldwide
epidemic & major cause of blindness. We propose a novel & critical nexus linking the EOMs, ON, & structure of
the eye's scleral wall that we will explore using modern imaging & artificial intelligence techniques. Aim I will
clarify the kinematic (motion) properties of the human eye, testing by multipositional magnetic resonance
imaging (MRI) of the eyeball & EOMs the hypothesis that translational (linear) movement contributes importantly
to ocular alignment. MRI will be performed during horizontal convergence & vertical eye rotation in normal
people, & in patients who have common forms of strabismus including convergence insufficiency, eye crossing
(esotropia), & outward ocular deviation (exotropia), both before & after corrective EOM surgery. Clarification of
ocular translation is necessary to understand normal ocular motility and treat its disorders. Aim II will
characterize the mechanical loading on the ON caused by eye movements. We will characterize the
mechanical effects of ON tractional loading on the eyeball during horizontal & vertical eye rotations at 2 scales
in living people, to test the hypothesis that such ON loading deforms it & adjacent retina & blood vessels as
loading translates the eye. We propose that the resulting deformation during eye movements may create
repetitive strain injury contributing to glaucoma, NA-AION, & axial myopia. In groups of subjects with the
foregoing diseases, & in an equal group of matched healthy subjects, we will study mechanical effects of eye
movement within the living eye by imaging its internal micro structure & blood vessels with optical coherence
tomography, & outside the eyeball in the eye socket using MRI. Effects of tethering during eye movement will
be studied ex vivo by precision 3D optical imaging of fresh human eye bank specimens subjected to mechanical
tension on the ON that mimic effects of the eye movements imaged in the living subjects. Aim III will model the
biomechanics of ocular kinematics. The constitutive mechanical properties of the non-muscular ocular & eye
socket tissues will be described by finite element models (FEMs) using modern engineering methods for
computational simulation to predict ocular kinematics, as well as local mechanical strains in the ON & sclera
that may cause glaucoma, NA-AION, & the ocular deformities underlying extreme nearsightedness. We will
determine if FEMs employing normal tissue properties can simulate normal ocular translati...

## Key facts

- **NIH application ID:** 10134346
- **Project number:** 5R01EY008313-31
- **Recipient organization:** UNIVERSITY OF CALIFORNIA LOS ANGELES
- **Principal Investigator:** JOSEPH Louis DEMER
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2021
- **Award amount:** $584,907
- **Award type:** 5
- **Project period:** 1991-01-06 → 2024-04-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10134346

## Citation

> US National Institutes of Health, RePORTER application 10134346, Biomechanical Analysis in Strabismus Surgery (5R01EY008313-31). Retrieved via AI Analytics 2026-05-24 from https://api.ai-analytics.org/grant/nih/10134346. Licensed CC0.

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