Unit 5 - AION Flashcards
What parts of the optic nerve are affected in posterior optic neuropathy?
- Intra-orbital
- intra-cannicular
- intra-cranial portions of the optic nerve with usually no visible ONH oedema.
What are three common causes of PION
- Face-down spinal surgery
- Radiotherapy
- Hypotension
What are the two main types of AION?
Arteritic and non-artieritic
In what population is Arteritic AION most common?
White woman, mean age 70,
(rare in blacks, hispanics and under 60).
Giant cell arteritis can cause vision loss in other ways to arteritic AION - what are they?
- CRAO
- Cordal ischaemia
What proportion of GCA vision loss is due to arteritic AION?
80%
What are the ocular symptoms of arteritic AION?
Sudden altitudinal, unilateral vision loss. Develops from hours to days.
What are the signs of arteritic AION?
- V/A and colour vision reduced if visual field affects fixation
- RAPD
- Oedematous disc at onset
What 7 non-ocular symptoms may be present in arteritic AION?
- Scalp tenderness
- Frontal, temporal headaches
- Pain on eating
- Patient feels unwell and tired
- Pain and stiffness in upper legs, arms and shoulders worse in the morning
- Weight loss
- Tenderness and prominence of temporal artery
In what proportion of GCA are there only ocular symptoms and no systemic symptoms?
20%
What systemic tests need to be conducted?
- ESR
- Temporal artery biopsy (although negative doens’t rule it out)
- Thrombocytosis
What is the treatment of arteritic AION?
High dose IV steroids followed by oral steroids Taper steroids slowly. Systemic symptoms usually subside within a week
What recovery is there from arteritic AION?
Not much
How often is the second eye affected in arteritic AION?
54-94% without treatment
What are the 7 signs of Non-arteritic AION
- v/a better than 6/60
- altitudinal visual field loss (lower>upper)
- Colour vision loss proportional to v/a loss (unlike in optic neuritis)
- Slight to moderate RAPD
- Small splinter haems around ONH
- Pale ONH
- Contralateral disc is small in diameter with small or absent cup “disc a risk”
What 8 risk factors are there in Non-arteritic AION?
- Hypertension (34-50% of cases)
- Diabetes (5-25%)
- Obstructive sleep apnoea
- Hyperopia
- Optic disc drusen
- Elevated IOP
- Migraine
- Use of phospodiesteras-5 inhibitors (viagra)
What is the prognosis in Non-arteritic AION?
43% gain at least 3 lines, others no change 15% will involve second eye
Optic disc becomes atrophic within 4-6 weeks
What treatment is there for non-arteritic AION?
None
Some recommend asprin to reduce risk of stroke or MI
