Optic Atrophy

OPTIC ATROPHY


OPTIC ATROPHY

  • Refers to optic nerve shrinkage from any cause which produces degeneration of axons in the anterior visual system.
  • Optic atrophy is the end result of any pathological process.
  • That damage axons b/w retinal ganglionic cells to lateral geniculate body (LGB).

OPHTHALMOSCOPIC CLASSIFICATION:

1. Primary (simple) optic atrophy

  • Results from the lesions proximal to the disc without antecedent papilloedema.
  • Lesions of optic nerve, optic chiasma, optic tract & LGB cause primary optic atrophy.

Its common cause are:

  1. trauma to the optic nerve or chiasma
  2. demyelinating disorders like multiple sclerosis 
  3. Leber’s hereditary neuritis
  4. toxic amblyopia
  5. tabes dorsalis (Syphilis)
  6. Vitamin B deficiency
  • Optic disc is greyish-white or white (chalky white) with clear margin.
  • Shallow, saucer-shaped atrophic cupping due to degeneration of nerve fibres.
  • Surrounding retina & retinal vessels are normal as the disease process is proximal (behind) the optic disc.

2. Consecutive optic atrophy

  • Occurs following destruction of ganglionic cells secondary to degenerative or inflammatory lesions of choroid or retina.

Its common cause sre:

  1. retinitis pigmentosa
  2. diffuse chorioretinitis
  3. pathological myopia
  4. CRAO
  5. Glaucoma
  • Disc is yellow-waxy in colour & the retinal vessels are attenuated.

3. Secondary optic atrophy

  • Occurs after disc edema.
  • Also c/d postpapilledematous optic atrophy

Its causes are:

  1. Papilloedema
  2. Optic neuritis (papillitis)
  3. Neuroretinitis
  4. Ischemic optic neuropathy
  • Characterised by disappearance of vascularity of disc which causes increase in pallor of disc.
  • Post-neuritic optic atrophy is a secondary optic atrophy which develops as a sequel to long standing papilloedema or papillitis.

4. Glaucomatous optic atrophy

  • Occur in long stannding glaucoma i.e chronic open angle or closed angle glaucoma.
  • There is glaucomatous cupping of optic disc.
  • Abrupt margins of optic disc & normal retinal appearance.

5. Ischemic optic atrophy

  • Due to disc ischemia caused by giant cell arteries, severe hemorrhage, severe anemia.
  • Disc is pale with obliteration of retinal vessels.

6. Toxic optic atrophy

  • Due to chronic retrobulbar neuritis secondary to toxic agents (toxic amblyopia)

Common causes are:

  1. tobacco
  2. ethyl alcohol
  3. methyl alcohol
  4. lead quinine
  5. chloroquinine

O/B of the pathological process, the optic atrophy can be divided into:

1. Ascending atrophy:

  • Acsending optic atrophy (Wallerian degeneration) follows damage at retinal ganglion cell level.
  • Nerve fiber degeneration progress (ascends) from the eye-ball towards the lateral geniculate body.
  • So, consecutive optic atrophy is a type of ascending atrophy.

2. Descending atrophy:

  • Descending (retrograde) atrophy.
  • Occurs when degeneration proceeds from the region of optic tract, chiasma or retrobulbar portion of optic nerve towards optic disc.
  • So, primary optic atrophy is a type of descending atrophy.

3. Cavernous (Schnable’s) optic atrophy:

  • Mucoid degeneration of glia occurs.

Seen in:

  1. chronic simple glaucoma 
  2. methyl alcohol poisoning
  3. high myopia

Exam Important

  • Optic atrophy can be caused by Methyl alcohol poisoning.
  • In optic atrophy pallor of the disc is an index of Loss of vascularty of the disc.
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