Ophthalmology: Neuro-ophthalmology

👁️ The eye as a window -the pupils, eye movements and fundus give vital clues to neurological and systemic disease. A painful Horner syndrome may be a carotid dissection; a third nerve palsy with a dilated pupil may be an aneurysm about to burst; uveitis may be the first sign of sarcoidosis or ankylosing spondylitis. In children, early detection of squint, amblyopia and a white pupil saves sight and lives.
Your four questions for every patient: Which pupil is abnormal -the big one or the small one? Is the double vision binocular, and which nerve or muscle is weak? Is there a systemic disease or drug behind this? In a child -is the red reflex normal, and are the eyes straight?

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Unequal Pupils

• Physiological anisocoria -up to 1 mm difference in about 20% of people; the same in light and dark; normal reactions.
• Key question: which pupil is abnormal?
  • Difference bigger in the dark -the small pupil can't dilate: Horner syndrome, Argyll Robertson pupil, pilocarpine drops, uveitis (with a red eye).
  • Difference bigger in bright light -the large pupil can't constrict: third nerve palsy, Adie pupil, dilating drugs, trauma, acute angle closure.

Pupil	Features
Third nerve palsy	Large pupil with ptosis and a "down and out" eye -urgent (aneurysm)
Adie (tonic) pupil	Young woman; large pupil with poor light reaction, slow constriction to near; reduced knee and ankle jerks (Holmes–Adie). Benign. Constricts with dilute pilocarpine 0.1%.
Pharmacological dilation	Very large, fixed; doesn't constrict with 1% pilocarpine. Ipratropium nebulisers, scopolamine patches, plants (e.g. Datura), dilating drops.
Horner syndrome	Small pupil, mild ptosis, dilation lag in the dark
Argyll Robertson pupils	Small, irregular, both eyes; react to near but not to light ("accommodate but don't react"). Neurosyphilis, diabetes.
RAPD	Pupils equal in size; affected pupil dilates on the swinging light test -optic nerve or severe retinal disease

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Horner Syndrome

• What it is: Damage to the sympathetic pathway to the eye.
• Features:
  • Miosis (small pupil) with dilation lag.
  • Mild ptosis (and slight raising of the lower lid).
  • Anhidrosis (reduced sweating) of the face -if the lesion is before the carotid bifurcation.
  • Apparent enophthalmos.
  • Heterochromia (lighter iris) if congenital.
• Causes -follow the pathway:
  • Central (brainstem, cord): lateral medullary stroke, MS, syringomyelia, tumours.
  • Pre-ganglionic (chest and neck): Pancoast tumour (apical lung cancer -shoulder pain, hand weakness), neck trauma or surgery (thyroid, carotid), cervical rib, central lines.
  • Post-ganglionic (carotid and skull base): carotid artery dissection, cluster headache, cavernous sinus lesions.
• Tests:
  • Apraclonidine drops -the Horner pupil dilates (reversal of anisocoria) -confirms the diagnosis.
  • Acute, painful Horner (neck, face or head pain) -same-day CT or MR angiography of head and neck for carotid dissection (stroke risk).
  • Otherwise imaging along the whole pathway (MRI head and neck, chest imaging for Pancoast tumour).

⚠️ Safety Pearl: A new Horner syndrome with neck pain or headache is a carotid dissection until proven otherwise -image urgently, even in young people after minor neck trauma.

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Double Vision

• Step 1 -cover one eye:
  • Goes away = binocular diplopia: the eyes are misaligned (nerve, muscle, or neuromuscular junction problem).
  • Persists in one eye = monocular diplopia: an eye problem -cataract, astigmatism, dry eye, corneal disease. Not neurological.
• Step 2 -horizontal or vertical?
  • Horizontal -sixth nerve palsy, INO, medial rectus problems (thyroid, myasthenia).
  • Vertical -fourth nerve palsy, third nerve palsy, thyroid eye disease (inferior rectus), skew deviation (brainstem), orbital floor fracture.
• Step 3 -which direction is it worst? Images are furthest apart when looking in the direction of the weak muscle.
• Step 4 -other clues:
  • Pupil involvement; ptosis.
  • Fatigability (myasthenia).
  • Proptosis, lid retraction (thyroid eye disease).
  • Headache, papilloedema (raised ICP), GCA symptoms (over 50).
  • Other cranial nerves (cavernous sinus, brainstem), ataxia.
• Acute binocular diplopia -same-day assessment (stroke, aneurysm, GCA, raised ICP). No driving until resolved or adapted (DVLA).
• Symptom relief -patch one eye (alternate in children to avoid amblyopia), prisms on glasses, botulinum toxin, squint surgery once stable.

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Third Nerve Palsy

• The third (oculomotor) nerve supplies most eye muscles (medial, superior and inferior recti, inferior oblique), the lid elevator, and the pupil constrictor.
• Features:
  • Ptosis (often complete).
  • Eye "down and out" (lateral rectus and superior oblique unopposed).
  • Dilated, unreactive pupil in compressive lesions.
  • Double vision (if the lid is lifted).
• The pupil rule:
  • Pupil involved (dilated) -compression until proven otherwise: posterior communicating artery aneurysm (often with headache), uncal herniation, tumour. Needs emergency CT angiography (or MRA).
  • Pupil spared -usually microvascular ischaemia (diabetes, hypertension, older age); often painful; recovers within 3 months. Still needs imaging in younger people, incomplete palsies, or if other signs develop.
• Other causes: GCA, cavernous sinus disease (with IV, V1, V2 and VI involvement), midbrain stroke, trauma, pituitary apoplexy.
• Coma with a dilating pupil -tentorial (uncal) herniation: neurosurgical emergency.

⚠️ Safety Pearl: A painful third nerve palsy with a dilated pupil is a posterior communicating artery aneurysm until proven otherwise -CT angiography the same day. A rupture is often fatal.

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Fourth and Sixth Nerve Palsies

• Fourth (trochlear) nerve palsy -weak superior oblique:
  • Vertical double vision, worse looking down and in -trouble going down stairs and reading.
  • Head tilted away from the affected side.
  • Causes: Head injury (the commonest), congenital (decompensates in adulthood -check old photos for head tilt), microvascular.
• Sixth (abducens) nerve palsy -weak lateral rectus:
  • Horizontal double vision, worse looking towards the affected side and at distance.
  • The eye can't abduct (turn out); turns in at rest.
  • Causes:
    • Microvascular (diabetes, hypertension).
    • Raised intracranial pressure -a "false localising sign" (long course of the nerve); check for papilloedema.
    • Tumours (skull base, nasopharyngeal carcinoma, clivus).
    • Trauma; MS; Wernicke's encephalopathy; GCA.
    • Gradenigo syndrome (middle ear infection spreading to the petrous apex) in children.
• Microvascular palsies recover within about 3 months; image if not recovering, in younger people, or with other signs.
• Over 50 -check ESR and CRP (GCA).

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Internuclear Ophthalmoplegia and Myasthenia

• Internuclear ophthalmoplegia (INO) -a lesion of the medial longitudinal fasciculus (MLF) in the brainstem:
  • On looking to one side, the eye on the side of the lesion fails to adduct (turn in), and the other eye shows nystagmus as it abducts.
  • Convergence is usually preserved.
  • Causes: MS (young people, often bilateral), brainstem stroke (older people, one side).
• Ocular myasthenia gravis:
  • Fatigable ptosis and variable double vision -worse at the end of the day; can mimic any nerve palsy.
  • Pupils always normal.
  • Ice pack test -ptosis improves after 2 minutes of cold.
  • Acetylcholine receptor (and MuSK) antibodies; single-fibre EMG; CT chest (thymoma).
  • About half develop generalised myasthenia within 2 years.
  • Pyridostigmine; steroids; immunosuppression.
• Other causes of restricted eye movements:
  • Thyroid eye disease (restriction, especially looking up).
  • Orbital floor fracture.
  • Miller Fisher syndrome (ophthalmoplegia, ataxia, areflexia; anti-GQ1b).
  • Wernicke's encephalopathy (with confusion, ataxia, nystagmus) -IV thiamine now.
  • Mitochondrial disease (slow, symmetrical, no diplopia).
  • Progressive supranuclear palsy (can't look down).
• See the Neuromuscular Disease and Neurological Localisation chapters.

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Visual Field Defects

Defect	Where is the lesion?
One eye only	Eye or optic nerve (retina, glaucoma, optic neuritis)
Central scotoma	Macula or optic nerve (optic neuritis, toxic neuropathy)
Altitudinal (upper or lower half of one eye)	Optic nerve ischaemia (AION) or retinal artery branch occlusion
Bitemporal hemianopia	Optic chiasm -pituitary tumour (upper quadrants first), craniopharyngioma (lower first)
Homonymous hemianopia	Behind the chiasm on the opposite side -optic tract, radiation or occipital cortex (usually stroke)
Upper quadrantanopia ("pie in the sky")	Opposite temporal lobe (Meyer's loop)
Lower quadrantanopia ("pie on the floor")	Opposite parietal lobe
Homonymous hemianopia with macular sparing	Occipital cortex (posterior cerebral artery stroke)
Tunnel vision	Advanced glaucoma, retinitis pigmentosa, vigabatrin; also functional

• Homonymous hemianopia usually prevents driving (DVLA field standard).
• See the Neurological Localisation and Pituitary chapters.

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Thyroid Eye Disease

• What it is: Autoimmune inflammation of the orbital fat and eye muscles, usually with Graves' disease (can occur with normal thyroid function or Hashimoto's). Smoking is the biggest modifiable risk factor.
• Features:
  • Lid retraction (white sclera visible above the iris) and lid lag.
  • Proptosis (exophthalmos).
  • Gritty, watery, red eyes; swollen lids; exposure keratopathy.
  • Double vision -restricted movements (inferior and medial recti most often; worse on looking up).
  • Pain behind the eyes and on movement (active disease).
• Sight-threatening (emergency):
  • Dysthyroid optic neuropathy -enlarged muscles compress the optic nerve at the orbital apex: reduced vision, poor colour vision, RAPD.
  • Corneal breakdown from exposure.
  • Treatment -IV methylprednisolone; urgent orbital decompression if no response.
• Course: An active inflammatory phase (6–24 months) then an inactive burnt-out phase.
• Management:
  • Stop smoking.
  • Restore normal thyroid function (avoid hypothyroidism).
  • Radioiodine can worsen eye disease -give steroid cover or choose another treatment if eye disease is active.
  • Mild -lubricants, sunglasses, sleep with head raised; selenium for 6 months.
  • Moderate to severe active -IV methylprednisolone weekly (EUGOGO regimen); mycophenolate; tocilizumab; orbital radiotherapy.
  • Teprotumumab (anti-IGF-1 receptor antibody) -MHRA-approved for moderate to severe disease; NICE appraisal not yet complete. Side effects: hearing loss, high glucose.
  • Inactive phase surgery -in order: orbital decompression, then squint surgery, then lid surgery.
• See the Thyroid Disease chapter.

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Inflammatory and Rheumatic Disease

• Rheumatoid arthritis -dry eye (secondary Sjögren's), episcleritis, scleritis, peripheral ulcerative keratitis (corneal melting -emergency); hydroxychloroquine toxicity.
• Sjögren's syndrome -severe dry eyes and mouth.
• Axial spondyloarthritis (ankylosing spondylitis), reactive and psoriatic arthritis -acute anterior uveitis (HLA-B27); conjunctivitis in reactive arthritis.
• IBD -episcleritis (tracks bowel activity), uveitis, scleritis.
• Sarcoidosis:
  • Uveitis (anterior, intermediate or posterior), often both eyes.
  • Conjunctival nodules; enlarged lacrimal glands; dry eye.
  • Optic neuropathy.
  • Heerfordt syndrome -uveitis, parotid swelling, fever, facial palsy.
• Behçet's disease -hypopyon uveitis, retinal vasculitis (can cause blindness), with oral and genital ulcers.
• SLE -dry eye, cotton wool spots (retinal vasculitis), antiphospholipid-related vessel occlusions.
• GPA (ANCA vasculitis) -scleritis, peripheral ulcerative keratitis, orbital mass (proptosis), blocked tear duct.
• Giant cell arteritis -see the Retina and Visual Loss chapter.
• Juvenile idiopathic arthritis -silent uveitis (no red eye), especially in young girls with oligoarthritis and positive ANA; needs regular slit lamp screening.

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Infection and the Eye

• HIV:
  • CMV retinitis -when CD4 is under 50: floaters and field loss; "pizza pie" appearance (white necrotic retina with haemorrhages). Treat with valganciclovir or IV ganciclovir, plus antiretroviral therapy.
  • Herpes zoster ophthalmicus in young people (test for HIV).
  • HIV microvasculopathy (cotton wool spots); Kaposi sarcoma of the lids or conjunctiva.
  • Immune recovery uveitis after starting antiretrovirals.
• Toxoplasmosis -the commonest cause of posterior uveitis: a white focus of retinochoroiditis next to an old pigmented scar ("headlight in the fog"). Treatment if near the macula or optic disc (e.g. co-trimoxazole, or pyrimethamine-based regimens).
• Syphilis -"the great imitator": any type of uveitis, optic neuritis, Argyll Robertson pupils. Test everyone with uveitis of unclear cause.
• TB -uveitis, choroidal granulomas.
• Infective endocarditis -Roth spots (haemorrhages with white centres), conjunctival haemorrhages, endogenous endophthalmitis.
• Candida bloodstream infection -endogenous endophthalmitis (fluffy white lesions); eye examination recommended.
• Toxocara -children with puppies: a white retinal mass (mimics retinoblastoma).
• Herpes simplex and zoster -keratitis, uveitis, acute retinal necrosis (severe).
• Chlamydia -adult inclusion conjunctivitis; trachoma (the world's leading infectious cause of blindness).

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Other Systemic Clues in the Eye

Condition	Eye sign
Wilson's disease	Kayser–Fleischer rings (brown copper ring at the edge of the cornea); sunflower cataract
Marfan syndrome	Lens dislocation (upwards), high myopia, retinal detachment
Homocystinuria	Lens dislocation (downwards)
Myotonic dystrophy	"Christmas tree" cataract, ptosis
Neurofibromatosis type 1	Lisch nodules (iris hamartomas), optic nerve glioma
Sickle cell disease	Proliferative retinopathy ("sea fan" new vessels), vitreous haemorrhage; hyphaema complications
Down syndrome	Keratoconus, cataract, Brushfield spots, squint, blocked tear ducts
Hyperlipidaemia	Xanthelasma; corneal arcus (under 50 suggests familial hypercholesterolaemia); lipaemia retinalis
Hypercalcaemia	Band keratopathy (calcium across the cornea)
Hyperviscosity (myeloma, Waldenström's, polycythaemia)	Dilated, "sausage-shaped" veins, haemorrhages, vein occlusion
Leukaemia and severe anaemia	Retinal haemorrhages (Roth spots), cotton wool spots
Pre-eclampsia	Visual disturbance, serous retinal detachment, cortical blindness (PRES)
Albinism	Pale iris (light shines through), nystagmus, poor vision
Ehlers–Danlos / osteogenesis imperfecta	Blue sclera
Fabry disease	Corneal whorls (cornea verticillata)
Tay–Sachs and similar storage diseases	Cherry-red spot at the macula

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Drugs That Harm the Eye

Drug	Eye effect and action
Hydroxychloroquine	Retinal toxicity (bull's-eye maculopathy, permanent). Keep dose at 5 mg/kg/day or less (actual body weight). RCOphth: yearly screening (OCT and fields) after 5 years, or after 1 year if extra risk (eGFR under 60, tamoxifen, higher doses).
Ethambutol	Optic neuropathy -check acuity and colour vision at baseline; stop if vision changes.
Steroids (any route)	Cataract (posterior subcapsular), glaucoma, central serous chorioretinopathy, worsened herpes keratitis.
Amiodarone	Corneal deposits (vortex keratopathy -usually harmless); optic neuropathy (rare); thyroid eye disease via thyroid effects.
Tamsulosin and alpha-blockers	Floppy iris syndrome during cataract surgery -tell the surgeon.
Topiramate	Acute bilateral angle closure and sudden short sight, usually in the first month -stop the drug, urgent ophthalmology.
Anticholinergics, antihistamines, tricyclics	Blurred near vision; angle closure in narrow angles; dry eye.
Vigabatrin	Permanent concentric field loss -field monitoring.
Sildenafil and PDE-5 inhibitors	Blue-tinged vision; NAION (rare).
Digoxin (toxicity)	Yellow vision (xanthopsia), blurred vision.
Bisphosphonates	Uveitis, scleritis, conjunctivitis (rare).
Isotretinoin	Dry eye, poor night vision, raised intracranial pressure (with tetracyclines).
Checkpoint inhibitors	Uveitis, dry eye, myasthenia, thyroid eye disease.
Semaglutide and rapid glucose lowering	Early worsening of diabetic retinopathy; NAION reported very rarely.
Chloramphenicol drops	Very rarely linked to aplastic anaemia (theoretical; widely used safely).
Pentosan polysulfate	Pigmentary maculopathy (long-term use).

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Eye Tumours

• Choroidal melanoma (uveal melanoma):
  • The commonest primary intraocular tumour in adults; often found on routine examination (pigmented mass), or blurred vision, flashes, field loss.
  • Spreads to the liver (check LFTs, liver imaging).
  • Treated at specialist centres -plaque brachytherapy, proton beam radiotherapy, or removal of the eye.
  • Metastatic disease -tebentafusp (for people with a specific HLA type).
  • Choroidal naevi are common and benign; monitored for change.
• Metastases to the eye -overall the commonest intraocular tumour (breast and lung cancer).
• Vitreoretinal lymphoma -older people with "uveitis" that doesn't respond to steroids; linked to CNS lymphoma.
• Eyelid tumours -basal cell carcinoma (most), squamous cell carcinoma, sebaceous carcinoma, melanoma, Merkel cell carcinoma.
• Conjunctival tumours -squamous cell carcinoma (HIV, sun exposure), melanoma, lymphoma (salmon-pink patch).
• Orbital tumours -lymphoma, cavernous haemangioma, meningioma, optic nerve glioma (NF1), lacrimal gland tumours, metastases. Present with proptosis, double vision or visual loss.
• Retinoblastoma -children (see below).

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Squint and Amblyopia

• Squint (strabismus) -the eyes point in different directions:
  • Esotropia (turns in), exotropia (turns out), hyper- or hypotropia (up or down).
  • Concomitant (non-paralytic) -the angle is the same in all directions; common in children; often from long sight.
  • Incomitant (paralytic) -varies with gaze; nerve palsy or restriction; needs investigation.
• Tests:
  • Corneal light reflex (Hirschberg) -reflections should be in the same place in each pupil.
  • Cover test -cover the straight eye; the squinting eye moves to take up fixation.
  • Red reflex; acuity.
• Pseudosquint -wide nasal bridge and epicanthic folds make the eyes look turned in; light reflexes are symmetrical.
• Normal -intermittent squint can be normal in the first 3 months of life.
• Amblyopia ("lazy eye"):
  • Reduced vision in an eye that is otherwise healthy, because the brain didn't get a clear image during development.
  • Causes -squint, unequal glasses prescription (anisometropia), blocked vision (cataract, ptosis).
  • Treat early -best results before age 7–8, when the visual system is still developing.
  • Treatment -glasses first; then patching the good eye or atropine drops to blur it.
• Refer any child with a persistent squint; urgently if sudden onset, with a poor red reflex, headache, or other neurological signs (tumour, raised ICP).
• Squint surgery -to straighten the eyes (cosmetic and to help binocular vision).

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White Pupil and Retinoblastoma

• Leukocoria -a white pupil (often first seen in a flash photograph) or an absent red reflex.
• Causes:
  • Retinoblastoma -must be excluded.
  • Congenital cataract.
  • Retinopathy of prematurity; Coats disease; toxocara; persistent fetal vasculature; retinal detachment.
• Retinoblastoma:
  • The commonest eye cancer of childhood -usually under 5.
  • RB1 gene (chromosome 13). Bilateral or family history = heritable (germline) form -also a lifelong risk of other cancers (osteosarcoma, soft tissue sarcomas), especially after radiotherapy.
  • Features: White pupil, new squint, red painful eye, poor vision, family history.
  • Referral (NICE NG12) -absent red reflex: refer urgently (within 2 weeks) for assessment for retinoblastoma. A new squint or change in vision: urgent if there is a family history of retinoblastoma.
  • Treatment at the national centres (London and Birmingham) -chemotherapy (IV or intra-arterial), laser, cryotherapy, plaque radiotherapy, or eye removal. Survival in the UK is over 95%.
  • Genetic testing and screening of siblings and offspring.
• Congenital cataract -found at the newborn and 6–8 week red reflex checks. Needs surgery within weeks to prevent dense amblyopia. Causes: genetic, infection (rubella, CMV, toxoplasmosis), galactosaemia, Down syndrome.

⚠️ Safety Pearl: Take a parent's concern about a "white eye in photos" seriously -examine the red reflex and refer urgently if it is absent or abnormal.

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Retinopathy of Prematurity

• What it is: Abnormal blood vessel growth in the immature retina of premature babies; can cause retinal detachment and blindness.
• Risk factors: Low gestational age and birth weight; high or fluctuating oxygen levels; sepsis.
• Screening (UK guideline): Babies born before 31 weeks or weighing under 1,501 g -dilated eye examinations on the neonatal unit from a few weeks after birth.
• Treatment: Laser to the peripheral retina, or anti-VEGF injection.
• Prevention: Careful oxygen targeting in neonatal care.
• Long-term -higher risk of short sight, squint, amblyopia; follow-up.

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Other Childhood Eye Problems

• Vision screening:
  • Newborn and 6–8 week checks -red reflex (cataract, retinoblastoma).
  • Orthoptist screening at age 4–5 -amblyopia and squint.
• Blocked tear duct (congenital nasolacrimal duct obstruction) -watery, sticky eye from birth; usually clears by 12 months; massage; probing if persistent.
• Congenital glaucoma -large eyes (buphthalmos), cloudy cornea, watering, photophobia. Urgent referral -surgery.
• Non-accidental injury -retinal haemorrhages (many, in several layers, extending to the periphery) in a baby with unexplained brain injury suggest abusive head trauma. Follow safeguarding procedures; ophthalmology examination with photographs.
• Periorbital and orbital cellulitis -see the Red Eye and Eye Emergencies chapter.
• Nystagmus in infancy -may be idiopathic or a sign of poor vision (albinism, congenital cataract, optic nerve problems) or brain disease; refer.
• Myopia in children -increasingly common; more time outdoors helps prevent it; low-dose atropine drops and special lenses can slow progression.
• Allergic eye disease and conjunctivitis -common; see the Red Eye chapter.

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Drug Reference Table

Drug	Key points
Apraclonidine drops	Confirms Horner syndrome (Horner pupil dilates).
Pilocarpine 0.1% / 1%	0.1% constricts an Adie pupil; 1% fails to constrict a pharmacologically blocked pupil.
Pyridostigmine	Ocular myasthenia; diarrhoea, cramps.
Thiamine IV (Pabrinex)	Wernicke's encephalopathy with ophthalmoplegia -give before glucose.
Methylprednisolone IV	Active moderate to severe thyroid eye disease (weekly regimen); dysthyroid optic neuropathy.
Selenium	Mild thyroid eye disease for 6 months.
Teprotumumab	Anti-IGF-1R antibody for moderate to severe thyroid eye disease; hearing loss, high glucose.
Valganciclovir / ganciclovir	CMV retinitis; low white cells.
Atropine 1% drops	Amblyopia treatment (blurs the good eye).
Hydroxychloroquine	Keep to 5 mg/kg/day or less; yearly retinal screening after 5 years (1 year if high risk).
Ethambutol	Baseline acuity and colour vision; stop if vision changes.

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Spot the Diagnosis

Clue	Diagnosis
Small pupil, mild ptosis and neck pain after a chiropractic manipulation	Horner syndrome from carotid dissection
Horner syndrome, shoulder pain and wasted hand muscles in a smoker	Pancoast tumour
Ptosis, eye down and out, dilated pupil, severe headache	Posterior communicating artery aneurysm
Ptosis, eye down and out, normal pupil, diabetes	Microvascular third nerve palsy
Double vision going downstairs after a head injury	Fourth nerve palsy
Can't abduct both eyes, headache worse lying down	Sixth nerve palsies from raised ICP
Young woman, failure of adduction with nystagmus of the other eye	INO (MS)
Ptosis worse in the evening, normal pupils	Ocular myasthenia
Large pupil, slow to react, absent ankle jerks, young woman	Holmes–Adie syndrome
Fixed dilated pupil after ipratropium nebulisers	Pharmacological mydriasis
Small irregular pupils that react to near but not light	Argyll Robertson pupils (neurosyphilis)
Proptosis, lid retraction, falling colour vision	Dysthyroid optic neuropathy -emergency
Hypopyon uveitis with oral and genital ulcers	Behçet's disease
Floaters with CD4 count 30	CMV retinitis
Brown ring at the edge of the cornea with tremor and abnormal LFTs	Wilson's disease
Tall man with upward lens dislocation	Marfan syndrome
Bilateral sudden blurred vision 2 weeks after starting topiramate	Drug-induced angle closure
Yellow vision and nausea on digoxin	Digoxin toxicity
White pupil in a toddler's photos	Retinoblastoma -urgent referral
Absent red reflex at the 6-week check	Congenital cataract
Multilayer retinal haemorrhages in a baby with a subdural haematoma	Abusive head trauma

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Exam-style Scenarios

1. A 42-year-old woman has a sudden severe headache and drooping of the right eyelid. The right eye is down and out and the right pupil is 7 mm and unreactive.
Answer: Third nerve palsy with pupil involvement -posterior communicating artery aneurysm.

• Emergency CT and CT angiography; neurosurgical referral.
• If subarachnoid haemorrhage: nimodipine, BP control, coiling or clipping.

2. A 38-year-old man has had left neck pain since a gym session 2 days ago. His left pupil is small and the left lid droops slightly.
Answer: Painful Horner syndrome -carotid artery dissection.

• Same-day CT or MR angiography of the head and neck.
• Antiplatelet (or anticoagulant) treatment per stroke team; look for TIA or stroke signs.

3. A 52-year-old smoker with Graves' disease has bulging eyes and now reduced vision and colour vision in the right eye with a right RAPD.
Answer: Dysthyroid optic neuropathy.

• Urgent ophthalmology; IV methylprednisolone.
• Orbital decompression if no rapid response.
• Stop smoking; keep thyroid function normal; avoid radioiodine without steroid cover.

4. A woman has taken hydroxychloroquine 400 mg daily for lupus for 6 years. She weighs 58 kg and has never had eye screening.
Answer: At risk of hydroxychloroquine retinopathy.

• Dose is about 6.9 mg/kg/day -above the 5 mg/kg limit; review dose with rheumatology.
• Refer for retinal screening now (OCT and fields), then yearly.

5. A mother says her 18-month-old's left eye "glows white" in photographs. The child has also developed an inward squint on that side.
Answer: Suspected retinoblastoma.

• Examine the red reflex; urgent ophthalmology referral (within 2 weeks; sooner per local pathway).
• Treatment at a national retinoblastoma centre; genetic testing (RB1) and sibling screening.

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Key Points

• Anisocoria worse in the dark -small pupil abnormal (Horner); worse in light -large pupil abnormal (third nerve, Adie, drugs).
• Painful Horner syndrome = carotid dissection until proven otherwise; Horner with arm symptoms in a smoker = Pancoast tumour.
• Monocular diplopia is an eye problem (often cataract); binocular diplopia is a nerve, muscle or junction problem.
• Third nerve palsy with a dilated pupil = aneurysm until proven otherwise -CT angiography the same day.
• Fourth nerve: vertical diplopia going downstairs, head tilt; sixth nerve: can't abduct -consider raised ICP.
• INO: MS in the young, stroke in the old. Myasthenia: fatigable ptosis, normal pupils.
• Thyroid eye disease: stop smoking; radioiodine can worsen it; optic neuropathy needs IV steroids and decompression.
• Uveitis can be the first sign of HLA-B27 disease, sarcoid, Behçet's, syphilis, TB or lymphoma.
• Hydroxychloroquine: 5 mg/kg/day or less; yearly retinal screening after 5 years.
• Topiramate can cause bilateral angle closure; vigabatrin causes permanent field loss; tamsulosin affects cataract surgery.
• Amblyopia must be treated early (glasses, patching or atropine) -refer any persistent squint.
• Absent red reflex or white pupil in a child -urgent referral for retinoblastoma or cataract.
• Screen premature babies (under 31 weeks or under 1,501 g) for retinopathy of prematurity.

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Guidelines and Further Reading

• The Royal College of Ophthalmologists: Hydroxychloroquine and chloroquine retinopathy -recommendations on monitoring
• EUGOGO and British Oculoplastic Surgery Society guidance on thyroid eye disease
• NICE NG12: Suspected cancer -recognition and referral (retinoblastoma)
• RCOphth and RCPCH: UK screening guideline for retinopathy of prematurity
• Public Health England / NHS: Newborn and infant physical examination (NIPE) and child vision screening
• DVLA: Assessing fitness to drive (diplopia and visual fields)
• BNF -for current doses

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