Eyes

Question 1

Pupils - definition and causes

Miosis
Mydriasis
Anisocoria

Answer 1

Miosis - constricted pupil - Horner’s syndrome, Pontine lesion, Drugs (opioids, anti-psychotics, anti-histamines, cholinergics)

Mydriasis - dilated pupil - Injury to CN 3, epilepsy, stroke, coning, iritis, drugs (anticholinergis, serotinergics, GABA)

Anisocoria - Uneven pupils - 20% physiological, Horners, uveitis, glaucoma, 3rd nerve palsy.

Question 2

Pupils - definition and causes

Adies pupil
Parinaud pupil
Argyll Robertson

Answer 2

Adies pupil - Lesion in the efferent parasympathetic pathway (cilliary body) . Slowed reaction to light, intact accomodation.
Triad - Loss of reaction to light, decreased tendon reflexes (usually lower limb), hyperhydrosis.

Parinaud pupil (dorsal midbrain)- Loss of vertical upward gaze due to defect in the medial longitudinal fasciculus. Supranuclear therefore still has dolls head reflex.
- convergence-retraction nystagmus = upward nystagmus and retracting globes. 
- pseudo-Argyll Robertson pupils - reduced accomodation. 
Causes - Central: pinealoma, multiple sclerosis, vascular lesions. Peripheral: trauma, diabetes mellitus, other vascular lesions, idiopathic, raised intracranial pressure

Argyll Robertson - Lesion in the midbrain - Dilated pupil - Does not react to light but reacts to accommodation - Neurosyphilis diabetic neuropathy, brain injury, thiamine deficiency, and mitral regurgitation.

Question 3

Absent light reflex, intact accommodation

Answer 3

1. Midbrain lesion (e.g. Argyll Robertson pupil)
2. Ciliary ganglion lesion (e.g. Adie’s pupil)
3. Parinaud’s syndrome
4. Bilateral afferent pupil defects

Question 4

Difference between optic tract and occipital lobe lesion

Answer 4

both cause a hemianopia - Occipital lobe is macular sparing

Question 5

Causes of Papilledema

Answer 5

● Space-occupying lesion (causing raised intracranial pressure) or a retro-orbital mass
● Hydrocephalus (associated with large ventricles)
o Obstructive
o Communicating
▪ Increased formation of CSF – choroid plexus papilloma
▪ Decreased formation of CSF – tumour causing venous compression, subarachnoid space obstruction from meningitis
● Benign intracranial hypertension
o Idiopathic, contraceptive pill, Addison’s disease, nitrofurantoin/tetracycline/vitamin A/steroids
o Lateral sinus thrombosis
● Hypertension (grade IV)
● Central retinal vein thrombosis
● Cerebral venous sinus thrombosis

Question 6

Causes of optic neuropathy

Answer 6

● Multiple sclerosis
● Toxic: ethambutol, chloroquine, nicotine, alcohol
● Metabolic: Vitamin B12 deficiency
● Ischaemia: diabetes mellitus, temporal arteritis, atheroma
● Familial – Leber’s disease
● Infective – infectious mononucleosis

Question 7

Causes of ptosis

Answer 7

WITH NORMAL PUPILS
●	Senile ptosis
●	Myotonic dystrophy 
●	Fascioscapulohumeral dystrophy 
●	Ocular myopathy, e.g. mitochondrial myopathy
●	Thyrotoxic myopathy 
●	Myasthenia gravis 
●	Botulism
●	Fatigue
●	Congenital
WITH CONSTRICTED PUPILS
●	Horner’s syndrome 
●	Tabes dorsalis 
WITH DILATED PUPILS
●	Third nerve lesion

Question 8

Causes of Nystagmus

Answer 8

● Horizontal:
o Vestibular lesion – chronic lesions cause nystagmus to the side of the lesion
o Cerebellar lesion – unilateral disease causes nystagmus to the side of the lesion
o Internuclear ophthalmoplegia – nystagmus is in the abducting eye, with failure of adduction on the AFFECTED SIDE. This is the result of a medial longitudinal fasciculus lesion. The most common cause in young adults with bilateral involvement is multiple sclerosis; in the elderly consider brainstem infarction
● Vertical:
o Brain stem lesion:
▪ Upbeat nystagmus suggests a lesion in the floor of the fourth ventricle
▪ Downbeat nystagmus suggests a foramen magnum lesion
o Toxic – phenytoin, alcohol (may also cause horizontal nystagmus)

Question 9

Causes of unilateral blindness

Answer 9

retinal artery/vein occlusion, temporal arteritis, optic neuritis

Question 10

Causes of bilateral blindness

Answer 10

Sudden: bilat occipital infarct, bilat optic nerve damage (methyl alcohol).
Gradual: glaucoma, cataracts, macular degeneration, vitreous hemorrhage, optic nerve compression.

Question 11

Causes of decreased visual acuity

Answer 11

Corneal: scarring, Vitamin A deficiency
Lens: Refractive error, Cataracts
Retinal: macular degeneration, proliferative retinopathy, RP, retinal haemorrhage, retinal detachment
Neurovascular: Optic neuritis, retinal artery or vein occlusion, papilloedema
Glaucoma
Toxins - mercury/methanol
Amblyopia - Congenital disorder

Question 12

What is Tolosa-Hunt Syndrome

Answer 12

Rare condition due to compressive changes in the orbit from inflammatory granuloma
Features - unilateral III, IV, V, VI palsies - severe headache - eye pain
Periorbital inflammatory changes found in MRI

Question 13

Appearance and causes of optic atrophy

Answer 13

Pale, well demarcated disc on fundoscopy
usually bilateral, causing gradual loss of vision
Acquired - MS - longstanding papilloedema - raised intraocular pressure: glaucoma, tumour - retinal damage: choroiditis, retinitis pigmentosa - ischaemia - toxins: tobacco amblyopia, quinine, methanol, arsenic, lead - nutritional: B1, B2, B6, B12 deficiency
Congenital - Friedreich’s ataxia - mitochondrial disorders

Question 14

Hypertensive eye changes

Answer 14

1. Silver wiring
2. AV nipping
3. flame haemorrhages and soft (cotton wool) exudates, hard exudates.
4. Papilloedema

Question 15

Diabetic eye changes

Answer 15

NON-PROLIFERATIVE
● Haemorrhages:
o Dot haemorrhage into the inner retinal areas
o Blot-haemorrhage into more superficial nerve fibre areas
o Hard exudates have straight edges – leakage of protein and lipids from damaged capillaries
o Soft exudates (cotton wool spots) have a fluffy appearance owing to microinfarcts
o Microaneurysms
o Dilated veins

PROLIFERATIVE
● New vessels
● Vitreous haemorrhage
● Scar formation
● Retinal detachment
● Laser scars (small brown or yellow spots)