Anatomy
The Optic Nerve: Your Eye's Connection to the Brain
The optic nerve is a cable of approximately 1.2 million nerve fibres that carries visual information from the retina to the brain's visual cortex. Damage to the optic nerve — from glaucoma, inflammation, or compression — causes permanent vision loss because nerve fibres cannot regenerate.
Anatomy Overview
The Optic Nerve: Your Eye's Connection to the Brain
Structure & Components
Peripheral vision loss (glaucoma-pattern optic nerve damage)
Central scotoma (optic neuritis affecting central fibres)
Colour vision desaturation (early sign of optic neuritis)
Relative afferent pupillary defect (RAPD) detectable by swinging light test
Sudden, painless visual loss (ischemic optic neuropathy)
Pallor of the optic disc visible on fundus examination
Functions & Physiology
Elevated intraocular pressure compressing nerve fibres (glaucoma)
Inflammation of the optic nerve sheath (optic neuritis — often MS-related)
Ischemia from arteritic or non-arteritic blood vessel disease
Compression by tumours in the orbit or pituitary region
Hereditary optic neuropathies (Leber's disease)
Toxins (methanol, ethambutol) or vitamin B12 deficiency
Key Points
Glaucoma treatment to lower IOP and protect remaining fibres
IV corticosteroids for optic neuritis to speed recovery
Management of underlying systemic diseases (MS, diabetes, hypertension)
Surgical decompression for compressive lesions
Neuroprotective approaches (under active research)
Regular OCT monitoring of retinal nerve fibre layer thickness
Low vision rehabilitation if significant damage has occurred
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