NEURO-OPHTHALMOLOGY

Clinical Examination Visual Acuity Colour Vision Visual Fields Pupils

Normal Eye and Optic Disc Cupped disc

The swollen optic disc Papilloedema Papillitis Malignant hypertension Ischaemic optic neuropathy Diabetic optic neuropathy CRVO Intraocular inflammation

25 y.o. female Reduced VA Pain with eye movement Colour desaturation RAPD

65 y.o. male Reduced VA Painless loss of vision Essential hypertension Smoker

The pale optic disc Congenital Secondary to raised ICP vascular retinal disease optic neuritis optic nerve compression trauma Glaucoma

Papilloedema Disc swelling secondary to raised ICP Headache Blurred optic disc margin Disc swelling secondary to raised ICP Headache Worse in the morning Valsalva manouver Nausea and projectile vomiting Horizontal diplopia (VI palsy) Causes Space occupying lesion Intracranial hypertension Idiopathic Drugs Endocrine Severe hypertension Haemorrhages Small optic cup CWS Disc pallor Vessel attenuation

Pupils First Order – Retina to Pretectal Nucleus in B/S (at level of Superior colliculus) Second Order – Pretectal nucleus to E/W nucleus (bilateral innervation!) Third Order – E/W nucleus to Ciliary Ganglion Fourth Order – Ciliary Ganglion to Sphincter pupillae (via short ciliary nerves)

Pupil Constricted (mioisis) Dilated (mydriasis) Sympathetic (pupillodilator) denervation Drugs Pilocarpine Morphine Dilated (mydriasis) Parasympathetic (pupilloconstrictor) denervation Lesion of the third CN Drugs Atropine Cocaine

Horner’s Oculosympathetic paresis Ptosis Miosis Ipsilateral anhidrosis Does not dilate with cocaine 4%

Sympathetic Pathway First Order – Posterior Hypothalamus to Ciliospinal centre of Budge (C8-T2) (Uncrossed in Brainstem) Second Order – Ciliospinal centre of Budge to Superior Cervical Ganaglion Third Order – Superior Cervical Ganglion to dilator pupillae muscle. (Close to ICA and joins V1 intracranially)

CVA Tumour Internal Carotid Dissection Herpes Zoster Otitis Media Tolosa-Hunt Sy. Pancoast bronchogenic carcinoma

Causes of Horner’s pupil Central – B/S lesions (tumours, vascular and MS) Syringomyelia, Lat. Med. Syn., S.C. ca. Preganglionic – Pancoast tumour, Carotid & Aortic aneurysms, Neck lesions/trauma. Postganglionic – Cluster headaches, Nasopharyngeal tumours, Otitis media, Cavernous sinus mass and ICA disease. Miscellaneous – Congenital (brachial plexus injury) Idiopathic.

Afferent & efferent defects Argyll-Robertson pupil Small, irreg Does not react to light Reacts to accommodation Causes syphilis diabetes Miotonic pupil (Adie’s syndrome) Dilated Poor response to light and convergence. Constricts with weak Pilocarpine Holmes-Adie syndrome Reduced tendon reflexes (Knee, ankle) - Orthostatic hypotension

Ocular motility abnormalities Third nerve palsy Double vision Eye turned down & out Ptosis Dilated pupil & headache Compressive lesion Sixth nerve palsy Double vision Eye turned in

Cranial Nerve Palsies Looking straight ahead

Posterior communicating artery aneurysm Chiasma Posterior cerebral artery III CN

Internuclear Ophthalmoplegia Defective adduction of the ipsilateral eye Nystagmus of the contralateral (abducting) eye NORMAL CONVERGENCE Causes Young patients Bilateral Demyelination Older patients Unilateral Vascular, tumours

Myasthenia Gravis Fatigability Double vision Lid twitch Ptosis Normal reflexes & sensation

INVESTIGATIONS MG Anti ACh receptor Ab’s Electromyography Tensilon test Edrophonium blocks acetyl-cholinesterase Beware of cholinergic cardiac effects. Use with Atropine 0.6mg Thoracic CT and MRI to rule out thymoma ACh Anti AChR Ab’s AChR

Localising the lesion Monocular visual field defects indicate lesions anterior to the optic chiasm Bitemporal defects are the hallmark of chiasmal lesions Binocular homonymous hemianopia result from lesions in the contralateral postchiasmal region Binocular quadrantanopias reflect optic tract lesions