Introduction
Caused by the occlusion of the short posterior ciliary artery due to inflammation
- As well as the circle of Zinn-Haller
- As the circle is two semi-circular arteries, vertical hemianopias are common
Has systemic associations most of the time:
- Giant cells arteritis, a granulomatous vasculitis affecting walls of medium and large sized arteries in the body. This can affect the aortic arch, which is fatal.
- Predominantly affects older people, around ages 70-80 years
- Has a gender bias, affecting females more
- Has swollen tender temporal arteries
Dead Giveaways
The biggest giveaway is Px history.
Otherwise, it is in the fundus image, VF testing and RNFL analysis
Fundus:
The ONH is significantly more pale, and a lot less defined. Can be compared to the fellow eye if it hasn't been affected yet. Cotton wool spots may be seen, and cilioretinal artery can be occluded
Perimetry:
Vertical hemianopia, which is very typical of both AIONs. Though this doesn't distinguish between the AIONs, is a strong indicator towards AION
RNFL, GCL analysis:
OD thicker than OS Relatively speaking, the OD RNFL is significantly thicker compared to the left eye, and to the norms. This is a good indicator of acute AAION. RNFL also has a hitched appearance
In the chronic phase, RNFL actually shows generalised atrophy and thinning
This consequently leads to optic disc cupping, which is seen in a lot of conditions
diagnostic features
Signs and Symptoms:
Severe acute vision loss (<6/60)
RAPD is present
Preceded by transient vision loss
Associated symptoms include:
Jaw claudication
Headaches
Scalp tenderness
Myalgia
Constitutional symptoms
ON cupping may occur in the chronic stage
Vision loss is irreversible due to arterial involvement, but treatment is necessary to prevent fellow eye involvement.
Treatment is usually corticosteroids, but recommends emergency attention.