Pathology 3

• Optic neuropathy


  Optic nerve damage
• Optic atrophy


  Retinal ganglion cell axon death that make up the optic nerve
• Causes of optic neuropathy

  • Inflammation
  • Glaucoma
  • Ischaemia
  • Raised intracranial pressure
• Optic neuritis


  Optic nerve inflammation
• Ways optic neuritis is classed


  • According to the portion of optic nerve affected
  • According to cause
• Types of optic neuritis according to portion of optic nerve affected

  • Retrobulbar optic neuritis (posterior portion affected but optic nerve appears normal)
  • Papillitis (anterior portion affected - optic nerve is swollen & hyperaemic)
  • Neuroretinitis (optic nerve head & peripapillary retina affected - optic nerve is oedematous & hyperaemic with macular star)
• Types of optic neuritis according to cause

  • Demyelination
  • Infection
  • Non-infectious causes
  • Parainfectious causes
• Demyelinating optic neuritis


  Nerve fibres lose myelin sheaths
• Demyelinating optic neuritis is present in young patients and associated with multiple sclerosis
• Symptoms of optic neuritis

  • Acute vision reduction in 1 eye
  • Central scotoma
  • Pain around eye & eye movement
  • Vision worse on exercise (Uhthoff phenomenon)
• Signs of optic neuritis

  • RAPD (relative afferent pupillary defect)
  • Decreased colour vision
  • VA changes
  • Reduced light intensity perception
• Urgent referral is required for management of optic neuritis
• Glaucomatous optic neuropathy (Glaucoma)


  Chronic progressive optic neuropathy, mostly associated with high intraocular pressure, shown by retinal ganglion cell death and vision field defects
• Aqueous humour production and drainage

  1. Made in ciliary body

  2. Passes in front of lens

  3. Through pupil

  4. Exits via trabecular pathway OR uveoscleral pathway
• Optic disk


  Optic cup + neuro-retinal rim
• Optic cup


  Hole in doughnut
• Neuro-retinal rim


  Rest of doughnut circle
• ISNT rule


  • Inferior, superior, nasal, temporal
  • Expected thickness = I > S > N > T
• Glaucoma


  Group of conditions that = chronic progressive optic neuropathy
• Types of glaucoma


  • Acquired (open/closed angle)
  • Congenital
• Types of acquired glaucoma

  • Primary open angle glaucoma (POAG)
  • Secondary open angle glaucoma
• Types of closed angle glaucoma

  • Primary
  • Secondary
• Ocular hypertension


  Consistently raised intraocular pressure without optic nerve damage
• Management of ocular hypertension

  1. Monitor if less than 24

  2. Refer routinely to ophthalmologist if over 24
• Primary open angle glaucoma (POAG)

  Progressive, chronic optic neuropathy with open anterior chamber angle, retinal nerve fibre layer and visual field loss, and increased resistance to drainage through meshwork
• Investigations for glaucoma


  • Visual field assessment
  • Slit lamp exam (optic nerve & anterior chamber assessment)
  • Check IOP
  • Fundus imaging
  • OCT
• Types of glaucomatous visual field defects

  • Paracentral scotoma
  • Nasal step scotoma
  • Arcuate scotoma
  • Ring scotoma
• Optic disk changes in glaucoma

  • Notching
  • Asymmetry in C:D ratio between eyes
  • NRR thinning
  • RNFL defects
  • Lamina dot sign (grey dots)
  • Peripapillary atrophy
  • Vascular changes (haemorrhages & BV changes)
• Notching


  Focal & diffuse thinning of retinal nerve fibre layer at optic nerve head
• 1. D ratio asymmetry is an optic disk change in glaucoma
• Retinal nerve fibre layer defects in glaucoma show more red curves/grooves and vision field loss
• Laminar dot sign


  Visible pores/increased size, present in 70% of primary open angle glaucoma
• Peripapillary atrophy


  Early sign of glaucoma damage, with alpha zone (larger & more common in glaucomatous eyes) and beta zone (larger & more common in glaucoma, location correlates with visual field loss)
• Disc haemorrhages


  Splinter/flame shaped haemorrhages, usually show region of visual field damage
• Vascular changes in glaucoma


  • Baring (early sign with NRR thinning and gap between NRR & superficial blood vessels)
  • Bayoneting (double angulation of blood vessels entering optic disk)
• Management of glaucoma


  1. Routine referral

  2. Eyedrops to lower IOP

  3. SLT (Selective laser trabeculoplasty) to improve drainage
• Non-arteritic anterior ischaemic optic neuropathy (NAION)


  Occlusion of short posterior ciliary arteries leading to lack of blood supply and tissue death of optic nerve head
• NAION typically occurs in 40-60 year olds with a "disk at risk"
• Symptoms of NAION


  • Painless monocular vision loss (usually in the morning)
  • VA impairment
  • Colour vision deficiency
  • RAPD
  • Visual field defects
• The optic disk in NAION turns pale over time