Vision and Balance: An Optometric Survival Guide
Michael J. McGovern, O.D., F.A.A.O.
Dizziness and balance problems are some of the most commonly reported complaints in medicine. This
course will provide an overview of the neurophysiology of balance, with particular emphasis on the
three sensory inputs – vestibular, visual and somatosensory. It will provide the primary care optometrist
with a clear understanding of the role vision plays in balance and of the proper optometric evaluation
and management of this patient population.
I. Introduction and Course Goals
II. Definition and clinical examples of dizziness, vertigo and disequilibrium
III. Anatomy of balance
a. Afferent systems
i. Vestibular
ii. Visual
iii. Somatosensory
b. Efferent systems
i. Overlapping and redundant neurological pathways that affect motor responses
of the limbs, trunk and eyes
IV. Vestibular system
a. Inner ear / vestibulocochlear complex
b. Bilateral – petrous portion of temporal bone
c. Labyrinths
i. Bony
ii. Membranous
1. Semicircular canals
a. Dynamic equilibrium
b. Rotational acceleration
c. Position in skull mirrors functional actions of extraocular
muscles (EOM’s)
2. Otoliths: utricle and saccule
a. Static equilibrium
b. Gravitational and linear acceleration
3. Cranial nerve VIII – vestibulocochlear nerve
d. Vestibulo-ocular reflex (VOR)
i. Initiates compensatory eye movements to maintain stable visual-spatial world
when body/head move
ii. Dependent on stable bifoveal image
iii. Uncompensated binocular deviations are commonly associated with symptoms
of vestibular dysfunction
V. Visual system
a. Peripheral visual component - comprised of eye itself, EOM’s, accommodative system
and optical media
b. Central visual component
i. Parvocellular – focal – detail – “what is it?” system
ii. Magnocellular – ambient – spatial orientation – “where is it?” system
1. Contributes to balance, movement, coordination
2. Mainly fibers from peripheral retina
VI. Somatosensory system
a. Mechanoreceptors in skin, joints, muscles – detection of position
VII. Integration of 3 systems in brainstem/cortex
a. Sensory mismatch / conflict
b. Dizziness / balance disorders
VIII. Common causes for dizziness / balance disorders
a. Benign positional vertigo
b. Labyrinthitis
c. Meniere’s disease
d. Acoustic neuroma
IX. Optometric role in evaluation and management of dizzy patient or a patient with a balance
disorder
a. Proper optometric follow up questions to complaints of dizziness and balance disorders
b. Basic testing by primary care optometrist
i. Refractive error, binocularity testing, accommodative testing
c. VOR testing
i. Dynamic visual acuity
d. Proper management
i. Optometric treatment
ii. Referrals
X. Summary