Neuro-ophthalmology Dr. Abdullah Al-Amri Ophthalmology Consultant

Content Optic nerve and visual pathway. Visual field testing. Ocular autonomic pathways. Pupillary reactions Ocular motor cranial nerves. Ocular motility testing.

Optic nerve and visual pathway The optic nerve begins anatomically at the optic disc but physiologically and functionally within the ganglion cell layer that covers the entire retina. The optic nerve is surrounded by a sheath formed by the dura, arachnoid and pia mater continuous with that surrounding the brain.

Signs of optic nerve dysfunction: 1.Reduced visual acuity. 2.Visual field defects. 3.Dyschromatopsia. 4.Diminished light brightness sensitivity.

Visual field testing It is part of the basic ophthalmic examination. Each eye must be examined separately. 1.Confrontation field testing. 2.Amsler Grid. 3.Perimetry.

Confrontation field testing

Perimetry

Color vision testing

Ocular autonomic pathways Movements of the pupil are controlled by the parasympathetic and sympathetic nervous systems. The pupils constrict (miosis) when the eye is illuminated (parasympathetic activation, sympathetic relaxation) and dilate (mydriasis) in the dark (sympathetic activation, parasympathetic relaxation).

Sympathetic Pathways

Parasympathetic Pathways

Pupillary reactions Pupils should be examined while patient is looking at distance. Both pupils should be round and equal in size at first inspection. Swinging-flashlight test is the most valuable test for optic nerve dysfunction. Abnormal test called Relative Afferent Pupillary Defect (RAPD). (Marcus Gunn Pupil)

Causes of anisocoria Ocular causes: Posterior synechiae. Intraocular surgery. Blunt trauma (traumatic mydriasis). Drugs: i.Topical ii.Systemic Neurological causes: Horner’s syndrome. A light–near dissociation. Relative afferent pupillary defect. Adie’s pupil. Argyll Robertson pupil. Coma.

Horner’s syndrome Signs: Interruption of the sympathetic pathway. A small pupil on the affected side. A slight ptosis on the affected side. Lack of sweating on the affected side. Heterochromia (congenital Horner’s). Causes: Because of its extended course the sympathetic pathway may be affected by a multitude of pathologies: I.Syringomyelia. II.Disease of the lung apex. III.Neck injury, disease or surgery. IV.Cavernous sinus disease.

The swollen optic disc

Papilledema due to raised intracranial pressure History: Young female. Obscurations of vision. Headache. Nausea. Diplopia. neurological symptoms. history of head trauma suggesting a subdural hemorrhage. Signs: The optic disc is swollen. No spontaneous venous pulsation of the central retinal vein. A large blind spot will be found on visual field testing. Abnormal neurological signs may indicate the site of a space-occupying lesion.

Optic neuritis Inflammation or demyelination of the optic nerve results in optic neuritis. An acute loss of vision. Pain on eye movement. Other neurological symptoms to suggest a diagnosis of demyelination (multiple sclerosis). Signs: Reduced visual acuity. Reduced color vision. Relative afferent pupillary defect (RAPD). Central scotoma on field testing. A normal disc in retrobulbar neuritis. A swollen disc in papillitis.

Ocular motor cranial nerves

Ocular motility testing Eye movement should always be examined, especially if the patient has a complaint of double vision or if any neurologic disease is suspected. All nine ocular positions should be examined carefully.

Third cranial nerve palsy

Fourth cranial nerve palsy

Sixth cranial nerve palsy

Questions