This class is about the Basics of optic nerve anatomy, Physiology. Also on optic neruritis,

1. Optic Nerve
• Objectives:
• Anatomy of the optic Nerve
• Physiology of the optic Nerve
• Aetiopathogenesis of optic nerve disorders
• Inflammations of optic
nerve/diagnosis/treatment
• Optic atrophy

2. Anatomy
• Consists of approximately-1.2 million neurons
• Has Four parts; 1) Intra ocular- 1mm
• 2)Intra orbital- 25-30 mm
• 3)Intra canalicular-5-9mm
• 4) Intra cranial – 10-16
mmmmm
• 80% of the fibres arise from the Macula

3. Anatomy
• Blood supply;1) Posteror ciliary artey
• 2) Peripappillary choroidal
vessels

4. physiology
• Axons also take part in the transport of
• Mitochondria,chemicals and proteins from the
neuronal cellbody to the distal terminal.
• Orthograde (eye to the brain)
• Slow component-proteis and enzymes
• Intermediate component-mitochondria and
• Rapid component- organelles

5. Papilledema
• Defined as oedema of the optic discdue to
raised intracranial pressure.

6. Causes of papilledema
• Bilateral:1) Raised intra cranial pressure
• 2)Hypertension
• 3) Diabetic papillopathy
• 4)Grave’s Disease
• 5) Cavernous sinus thrombosis
• Unilateral: 1)Optic neuritis
• 2)Crvo
• 3)Orbital tumours

7. Aetiopathogenesis
• 1) Edema
• 2)inflammation
• 3)Ischemia
• 4)Degeneration
• 5)Trauma
• 6) congenital

8. • Patho-physiology :
• 1) Due to compression of the centrakl retinal
vein
• 2)Blockage of the Axoplasmic flow

9. Clinical features
• Ophthalmoscopically;
• Disc may be Hyperemic swollen with or
without Haemorrages

10. Clinical features
• 1) Transient obscuration of vision
• 2)Blurring of Disc Margins
• 3) Hyperemia of the Disc
• 4) Cup gets filled up
• 5)Veins are dilated
• 6) Disc appears elevated from the surrounding
Retina

11. Clinical features
• 7) Flame shaped Haemorrages on the Disc
• 8)Edema with exudation of macula (Macular Fan)
• 8) Optic disc pallor in late stages(optic Atrophy)

12. Investigations
• 1) Blood pressure – to r/o hypertension
• 2) CT scan of Brain- to r/o any space occupying
lesions
• 3) Visual fields –to document any field defect
• 4) MRI – if CT is normal
• 5) Lumbar Puncture – to r/o infection, tumours

13. Treatment
• 1 )Reduce intra cranial pressure:
• a) Oral Carbonic anhydrase
inhibitor ( Diamox 250 mg TID)
• 2) Decompression
• 3) specific treatment of the cause

14. Differential Diagnosis
• 1)optic Neuritis
• 2) Anterior ischemic optic neuropathy
• 3) Hypermetropia

15. Optic Neuritis
• It is a inflammation of the optic nerve.
• Clinically divided into a) Papillitis
• b) Neuro retinitis and
• c) Retro bulbar neuritis

16. Aetiology
• Demyelinating diseases; Multiple sclerosis
• Neuro Myelitis optica
• Asssociated with infections: Endophthalmitis
• Orbital cellulitis
• sinusitis
• systemic infections
• Immune related: Sarcoidosis, Uveitis
• Metabolic disorders : Diabetes, Anaemia

17. Clinical features
• Sudden drop in vision
• Usually unilateral
• Accompanied by orbital or retroocular pain
• Disturbances of colour vision
• Altered perception of moving objects
• Worsening of symptoms with excercise

18. Clinical features
• Variable degree of vision loss
• Decreased colour vision
• Relative Afferent Pupillary Defect(Marcus-
Gunn pupil)
• Field defects ;a) Relative or Absolute defects in
colour vision b) Central, centero-caecal,
Arcuate, Sectorialor Altitudinal

19. Field Defects

20. Fundus findings

21. Papilledema And Optic Neruritis

22. Differential Diagnosis
• 1)Ischemic optic neuropathy
• 2) Papilledema
• 3) Grade 4 Hyper tensive retinopathy
• 4) Toxic and Metabolic retinopathy

23. Investigations
• Record visual acquity, colour vision
• Pupillary light reflex
• Dilated retinal examination
• Visual fields, VEP
• Complete blood count,CRP,Esr,FTA-ABS,ANA
• MRI brain

24. Treatment
• Treat the primary cause
• Guide lines based on ONTT (Optic neuritis
treatment Trial)
• IV Methylprednisolone 250mg iv over 30-6-
min repeated 6th hourly for 3 days
• Followed by Prednisolone1mg /Kg /day for11
days

25. Possible questions
• 25 year old female presented with complaints of headache & defective vision. On examination of
her fundus, she had bilateral blurring of the disc margins. What is the differential diagnosis of
bilateral disc edema. How would you differentiate
• Papilloedema from papillitis ?
•
• Classify optic neuritis. Describe the clinical features and management of optic neuritis.
• Write the etiology, clinical features and management of papilloedema.
• Classify optic atrophy. Describe the features of different types of optic atrophy
• Enumerate 4 differential diagnosis for bilateral disc edema
• Enumerate 4 differential diagnosis for unilateral disc edema
• How would you differentiate
• Papilloedema from papillitis ?
• What are the field changes in optic neuritis?
• What is Marcus Gunn pupil?
• Give 2 causes for relative afferent pupillary defect.
• Enumerate the features of Horner’s syndrome.
• Draw the visual pathway.
• Draw the pupillary pathway
• Describe the etiology, clinical features and management of AION