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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.
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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: • Reduced visual acuity. • Visual field defects. • Dyschromatopsia. • Diminished light brightness sensitivity.
Visual field testing • It is part of the basic ophthalmic examination. • Each eye must be examined separately. • Confrontation field testing. • Amsler Grid. • Perimetry.
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).
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: Neurological causes: Horner’s syndrome. A light–near dissociation. Relative afferent pupillary defect. Adie’s pupil. Argyll Robertson pupil. Coma. • Posterior synechiae. • Intraocular surgery. • Blunt trauma (traumatic mydriasis). • Drugs: • Topical • Systemic
Horner’s syndrome Signs: Causes: Because of its extended course the sympathetic pathway may be affected by a multitude of pathologies: Syringomyelia. Disease of the lung apex. Neck injury, disease or surgery. Cavernous sinus disease. • 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).
Papilledema due to raised intracranial pressure History: 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. • Young female. • Obscurations of vision. • Headache. • Nausea. • Diplopia. • neurological symptoms. • history of head trauma suggesting a subdural hemorrhage.
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 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.
