Neuro-Ophthalmology

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Neuro-Ophthalmology Fundamentals

Visual Pathways and Ocular Motility

1. The Visual Pathway: Field Defect Mapping

Lesion Location Visual Field Defect
Optic Nerve Monocular vision loss.
Optic Chiasm Bitemporal hemianopia.
Optic Tract/Radiation Contralateral homonymous hemianopia.
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2. Pupil & Motility Pearls

  • Adie’s Tonic Pupil: Dilated pupil with sluggish light response; associated with absent deep tendon reflexes (Holmes-Adie syndrome).
  • Horner Syndrome: Triad of ptosis, miosis, and anhidrosis; results from disruption of the sympathetic pathway.
  • Third Nerve Palsy: “Down and out” eye position; if the pupil is involved, prioritize ruling out an intracranial aneurysm.
  • Internuclear Ophthalmoplegia (INO): Disruption of the MLF; presents as impaired adduction in the ipsilateral eye with nystagmus of the abducting eye—highly suggestive of Multiple Sclerosis (in young patients).

3. High-Yield Diagnostics

A neuro-ophthalmological workup hinges on differentiating between pre-chiasmal (retinal/optic nerve) and post-chiasmal (chiasm/tract/radiation/cortex) lesions. Always check for Relative Afferent Pupillary Defect (RAPD) for objective evidence of optic nerve disease.

For detailed pathway diagrams, pupillary evaluation algorithms, and neuro-ophthalmology question banks, visit mymedschool.org.