Makindo Medical Notes

Glaucoma is the most prevalent optic neuropathy in adults, characterized by progressive damage to the optic nerve leading to vision loss.

About

• Optic atrophy refers to the atrophy or degeneration of the optic nerve, often as the end result of various pathologies that damage the nerve.
• Glaucoma is a leading cause of optic neuropathy, but multiple conditions may contribute to optic nerve damage.

Clinical Features

• Vision Loss: Gradual loss of visual acuity or peripheral vision, depending on the underlying cause.
• Colour Vision Changes: Colours may appear subtly washed out in the affected eye.
• Optic Disc Appearance: The optic disc may look pale, indicating atrophy.
• Associated Symptoms:
  • Headache, weight loss, or polymyalgia rheumatica (PMR) may suggest giant cell arteritis (GCA).
  • Signs of papilloedema, indicating raised intracranial pressure.
  • Marcus Gunn pupil (relative afferent pupillary defect) in unilateral or asymmetrical optic neuropathy.

Onset Patterns

• Acute (Minutes to Hours): Consider ischemic, inflammatory, or traumatic causes.
• Sub-acute (Few Days): Often due to inflammatory or infectious processes.
• Chronic (Weeks to Months): Includes compressive lesions, heredofamilial and degenerative diseases, indolent inflammation, toxic/nutritional deficiencies, and infiltrative conditions.

Causes of Optic Atrophy

• Neurological Conditions:
  • Idiopathic intracranial hypertension
  • Multiple sclerosis and retrobulbar neuritis
  • Traumatic neuropathy
• Vascular Causes:
  • Ischemic optic neuropathy
  • Chronic papilloedema
  • Temporal arteritis (GCA)
• Hereditary and Degenerative Conditions:
  • Leber’s hereditary optic neuropathy
  • Retinitis pigmentosa
  • Retinal storage diseases (e.g., Tay-Sachs disease)
• Toxic and Nutritional Causes:
  • Toxic neuropathies (e.g., isoniazid, toluene exposure)
  • Tobacco and alcohol-related optic neuropathies
  • B12 or folate deficiency
• Infectious and Inflammatory Causes:
  • Chronic optic neuritis
  • Syphilis
• Other Causes:
  • Radiation neuropathy
  • Glaucoma

Investigations

• Blood Tests:
  • ESR and CRP: Evaluate for temporal arteritis.
  • FTA-ABS and RPR: Screen for syphilis.
  • B12 and folate levels: Assess for hematologic causes.
  • Thyroid function tests: Rule out thyroid-related optic neuropathy.
• CSF Analysis:
  • Opening pressure on lumbar puncture (LP) to evaluate for raised intracranial pressure (after ruling out a mass lesion via imaging).
  • CSF protein and immunoglobulin analysis: Screen for multiple sclerosis or broader CNS processes.
• Imaging:
  • CT/MRI of the orbits and brain: Identify compressive, infiltrative, or structural causes.
• Other Tests:
  • Toxicology screen for exogenous or endogenous toxins.

Management

• Treatment depends on the underlying cause:
  • Glaucoma: Manage intraocular pressure with medications or surgery.
  • Temporal arteritis: High-dose corticosteroids to prevent further vision loss.
  • Nutritional deficiencies: Vitamin supplementation (e.g., B12, folate).
  • Infectious causes: Targeted antimicrobial therapy (e.g., syphilis treatment).
• Rehabilitative support such as low vision aids for irreversible damage.