Features
• Painful monocular vision loss
• Worse with eye movements
• Decreased colour vision (red desaturation)
• Relative afferent pupillary defect (RAPD)
• Central scotoma common
Associations
• Multiple sclerosis (most common)
• Neuromyelitis optica (consider in severe, bilateral cases)
• Viral infections (rare)
Prognosis
• Spontaneous improvement within weeks in most cases
Features
• Pale optic disc on fundoscopy
• Decreased visual acuity and contrast sensitivity
• Visual field defects vary (central or peripheral)
Causes
• Previous optic neuritis (MS)
• Chronic glaucoma
• Compressive lesions (e.g., tumours)
• Ischaemic optic neuropathy
• Toxic/nutritional (e.g., methanol, ethambutol, vitamin B12 deficiency)
Features
• Bilateral optic disc swelling due to increased intracranial pressure (ICP)
• Preserved visual acuity early
• Transient visual obscurations (seconds)
• Enlarged blind spot
Causes
• Mass lesions (tumour, abscess)
• Idiopathic intracranial hypertension (IIH) — young obese women
• Cerebral venous sinus thrombosis
• Severe hypertension (hypertensive crisis)
Urgency
• Requires urgent neuroimaging to exclude space-occupying lesion before LP
Features
• Sudden painless monocular vision loss
• Altitudinal (sectoral) visual field defect
• Swollen pale optic disc
Causes
• Arteritic: giant cell arteritis (GCA)
o Scalp tenderness, jaw claudication, high ESR/CRP
• Non-arteritic: small vessel disease (diabetes, hypertension)
Management
• High-dose steroids immediately if GCA suspected
Pattern Common Cause
Central scotoma Optic neuritis
Enlarged blind spot Papilloedema
Altitudinal defect AION, branch retinal artery occlusion
Bitemporal hemianopia Optic chiasm lesion (e.g., pituitary adenoma)
Homonymous hemianopia Optic tract, occipital cortex
Quadrantanopia Temporal (superior) or parietal (inferior) lesions
Extra Revision Pearls
• Painful monocular loss clue → optic neuritis; painless → AION, CRAO
• RAPD clue → severe unilateral or asymmetric optic nerve disease
• GCA clue → scalp tenderness, raised ESR, immediate steroids
• Methanol clue → toxic optic atrophy with profound bilateral loss
• Papilloedema clue → bilateral, transient blackouts on bending or straining
• Central scotoma clue → optic nerve head or macular involvement
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Author & Educational Disclaimer
Author:
Dr Phillip Cockrell BM FRCP DipClinEd
Dr Phillip Cockrell is a UK Consultant Physician in Internal Medicine, currently working at Queen Alexandra Hospital, Portsmouth University Hospitals NHS Trust. He has previously worked as a registrar across Intensive Care Medicine, Gastroenterology, Cardiology, Stroke Medicine, Acute Medicine, and Respiratory Medicine.
He has held senior leadership roles including Associate Clinical Director of the Acute Medical Unit, Clinical Director of Internal Medicine, and Chief of Medicine. Dr Cockrell has over 15 years’ experience in postgraduate medical education, having lectured extensively across the MRCP syllabus and contributed to MRCP revision teaching and course development.
Dr Cockrell holds a Bachelor of Medicine (BM), Fellowship of the Royal College of Physicians (FRCP), and a Diploma in Clinical Education (DipClinEd). His teaching approach is based on structured consolidation of complex medical topics to support efficient and effective revision for postgraduate examinations.
Purpose of this content:
The material on this page is intended solely for educational purposes to support revision for the MRCP (UK) Part 1 examination. It reflects examination-relevant principles of internal medicine and is designed to aid learning and pattern recognition.
Medical disclaimer:
This content is designed for postgraduate medical examination revision and does not constitute medical advice, diagnosis, or treatment guidance and must not be used as a substitute for professional clinical judgement, local guidelines, or specialist consultation. Clinical decisions should always be made in the context of individual patient circumstances and current national guidance.
