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OP1.1 | Physiology of Vision, Ocular Optics and Visual Pathway Anatomy — SDL Guide (Part 3)

Management Principles for Visual Pathway Disorders

Management of visual pathway disorders follows the anatomy of the diagnosis. The urgency and modality of intervention depend on whether the cause is inflammatory, ischaemic, compressive, or degenerative.

For optic neuritis, the landmark Optic Neuritis Treatment Trial (ONTT) established that intravenous methylprednisolone (1 g/day × 3 days) accelerates visual recovery but does not improve the final visual outcome compared to oral prednisone in standard dose. All patients with first-episode optic neuritis require MRI brain to assess the risk of subsequent MS: those with ≥2 white matter lesions on MRI have a high 10-year conversion risk (50–80%) and are candidates for disease-modifying therapy.

For pituitary adenoma causing chiasmal compression, the primary management depends on tumour type. Prolactinomas respond to dopamine agonists (cabergoline, bromocriptine), which shrink the tumour pharmacologically and restore vision — surgery is often unnecessary. Non-functioning adenomas and other secreting tumours (GH, ACTH-secreting) generally require trans-sphenoidal surgery (TSS), which directly decompresses the chiasm. Post-operatively, visual fields recover substantially if the damage has not been present for too long (optic atrophy, if established, is irreversible).

For occipital stroke (PCA territory), acute management follows standard ischaemic stroke protocols (thrombolysis if within the therapeutic window, antiplatelet therapy, secondary prevention). There is no specific treatment to restore the lost visual field; however, a small subset of patients benefit from vision restoration therapy (VRT) — structured visual stimulation at the border of the hemianopic field — though evidence remains limited. Patients should be counselled on driving restrictions (homonymous hemianopia disqualifies driving in most jurisdictions until assessed and managed appropriately).

Self-Assessment: Consolidating Your Visual Pathway Knowledge

Before moving forward, use these self-assessment prompts to verify that you can apply the material from this module — not merely recall it. The distinction matters: an examiner asking about a patient with bitemporal hemianopia expects you to reason through the anatomy in real time, not retrieve a memorised label.

Work through the following clinical reasoning exercises without looking at your notes. For each, identify the lesion site, name the most likely pathology, and state what investigation you would request first.

Exercise 1: A 40-year-old man presents with six months of progressive difficulty parking his car (misjudging the driver's-side clearance). On formal perimetry he has loss of the right temporal visual field in both eyes — that is, loss of vision to the right in both eyes. His right pupillary light response is sluggish.

Exercise 2: A medical student notices she cannot see the far left side of the whiteboard. Testing with confrontation confirms she has no vision in the left half of the visual field in either eye, but her visual acuity is 6/6 bilaterally and she has no afferent pupil defect. She had a severe migraine with aura yesterday.

Exercise 3: A 28-year-old woman reports two weeks of periocular pain in the right eye that worsens with eye movement, and colours look 'faded' in that eye. Right VA is 6/36; left VA 6/6. The swinging flashlight test shows a right RAPD.

For each exercise: locate the lesion, explain the visual field defect using the anatomy of the pathway, name the most likely underlying diagnosis, and state what the single most important investigation is. Check your answers against the lesion localisation table in this module. If you cannot confidently complete all three without reference to notes, re-read the relevant sections before proceeding to OP1.2.