1. OPTIC NEUROPATHIES Anatomy of optic nerve Clinical features
3. Special investigations
4. Optic neuritis
Retrobulbar neuritis
Papillitis
Neuroretinitis
5. Anterior ischaemic optic neuropathy (AION)
6. Leber hereditary optic neuropathy

2. Anatomy
The optic nerve is the second of twelve paired cranial nerves but is considered to be part of the central nervous system .
composed of retinal ganglion cells axons and Portort cells
Most of the axon of the optic nerve terminate in the lateral geniculate nucleus from where information is relayed to the visual cortex.
Its diameter increases from about 1.6 mm within the eye, to 3.5 mm in the orbit to 4.5 mm within the cranial space

3. The optic nerve component lengths are :
1 mm in the globe, 24 mm in the orbit, 9 mm in the optic canal and 16 mm in the cranial space before joining the optic chiasm.
partial decussation occurs and about 53% of the fibers cross to form the optic tracts.

4. Signs of optic nerve dysfunction
Reduced visual acuity
Afferent pupillary
conduction defect
Dyschromatopsia
Diminished light
brightness sensitivity

5. Applied anatomy of afferent conduction defect
Anatomical pathway
Signs
Equal pupil size
Light reaction
- ipsilateral direct is absent or diminished
- consensual is normal
Near reflex is normal in both eyes
Total defect (no PL) = amaurotic pupil
Relative defect = Marcus Gunn pupil
3rd

6. Visual field defects Central scotoma Centrocaecal scotoma Altitudinal
Nerve fibre bundle

7. Optic disc changes Normal Swelling Optico-ciliary shunts Atrophy
Papilloedema
Retrobulbar neuritis
Papillitis and neuroretinitis
Early compression
AION
Optico-ciliary shunts
Atrophy
Postneuritic
Optic nerve sheath meningioma
Compression
Occasionally optic nerve glioma
Hereditary optic atrophies

8. Special investigations
MRI
Visually evoked potential
Orbital fat-suppression techniques in
T1-weighted images
Assessment of electrical activity of
visual cortex created by retinal
stimulation

9. Classification of optic neuritis
Retrobulbar neuritis
(normal disc)
Papillitis (hyperaemia and
oedema)
Neuroretinitis (papillitis
and macular star)
Demyelination - most
common
Viral infections and
immunization in children
(bilateral)
Cat-scratch fever
Lyme disease
Sinus-related (ethmoiditis)
Demyelination (uncommon)
Lyme disease
Syphilis
Syphilis

10. 1-Retrobulbar neuritis,in which the optic disc appearance is normal,at least initially , because the optic nerve head is not involved.It is the most frequent type in adults and is frequently associated with multiple sclerosis.
2-Papillitis,it is characterized by variable hyperaemia and oedema of the optic disc.
It is the most common type of optic neuritis in children.
3-Neuroretinitis is characterized by Papillitis with macular star.It is the least common type of optic neuritis and is most frequently associated with varial infections and cat-scratch fever.Other causes include syphilis and lyme disease and resolve within 6-12 months.

11. by definition , papilloedema is swelling of the optic nerve head
by definition , papilloedema is swelling of the optic nerve head. Secondary to raised intracranial pressure. It is nearly always bilateral , although it may be asymmetrical. All other causes of disk oedema in the absence of raised intracranial pressure are referred to as ‘disk swelling ,and usually produce visual impairment. All patient with papilloedema should be suspected of having an intracranial mass unless proved otherwise.however not all patients with raised intracranial pressure will necessarily develop papilloedema .

12. Non-arteritic AION Presentation Acute signs Late signs
Age years
Altitudinal field defect
Eventually bilateral in 30% (give aspirin)
Acute signs
Late signs
Pale disc with diffuse or sectorial oedema
Resolution of oedema and haemorrhages
Few, small splinter-shaped haemorrhages
Optic atrophy and variable visual loss

13. FA in acute non-arteritic AION
Localized hyperfluorescence
Increasing localized
hyperfluorescence
Generalized hyperfluorescence

14. Superficial temporal arteritis
Presentation
Age years
Scalp tenderness
Headache
Jaw claudication
Polymyalgia rheumatica
Superficial temporal arteritis
Acute visual loss
Special investigations
ESR - often > 60, but normal
in 20%
C-reactive protein – always
raised
Temporal artery biopsy

15. Histology of giant cell arteritis
Granulomatous cell infiltration
High-magnification shows
giant cells
Disruption of internal elastic lamina
Proliferation of intima
Occlusion of lumen

16. Arteritic AION
Affects about 25% of untreated patients with giant cell arteritis
Severe acute visual loss
Treatment - steroids to protect fellow eye
Bilateral in 65% if untreated
Pale disc with diffuse oedema
Few, small splinter-shaped haemorrhages
Subsequent optic atrophy

17. Leber hereditary optic neuropathy
Maternal mitochondrial DNA mutations
Presents
Typically in males - third decade
Occasionally in females - any age
Initially unilateral visual loss
Fellow eye involved within 2 months
Bilateral optic atrophy
Signs
Disc hyperaemia and dilated capillaries
(telangiectatic microangiopathy)
Vascular tortuosity
Swelling of peripapillary nerve fibre layer
Subsequent bilateral optic atrophy