About
- Optic nerve ischaemia resulting from vascular compromise commonly in the short posterior ciliary arteries.
- Primarily occurs in middle aged patients with a history of vasculopathy.
- Distinct and must be clinically differentiated from arteritic AION, an inflammatory process most commonly seen in giant cell arteritis.
Aetiology
- Risk factors: Hypertension, diabetes, smoking, obesity, sleep apnoea
- Usually occurs in patients over the age of 50.
- Disc at risk: small optic nerve head, resulting in crowding of the optic cup
- The association with sleeping is thought to be due to relative hypotension during sleep. This further reduces arterial blood flow in vessels that are already narrowed.
Clinical
- The classical presentation is of sudden onset profound visual loss after waking from sleeping.
- Marked reduction in visual acuity, though light perception in the effected eye is usually preserved
- Visual field may be compromised
- Painless loss of vision, unlike in arteritic AION (GCA).
- Fundoscopy shows peripapillary wrinkles with optic disc oedema, there may also be a contralateral disc at risk.
- Ipsilateral relative afferent pupillary defect
Investigations
- It is important to rule out arteritic AION as the absence of pain alone provides insufficient evidence to conclusively rule out an inflammatory aetiology.
- FBC, ESR, and CRP should be ordered for all patients.
- Unlike in central retinal artery occlusion, stroke workup is usually not indicated as the process is thought to be related to hypoperfusion and not embolism.
Management
- No reliable evidence exists for any effective treatment options for NAION but exclude giant cell arteritis, as above.
- Cessation of any potentially causative medications such as PDE-5 inhibitors e.g. sildenafil.
- Ongoing management of vascular risk factors such as smoking cessation advice and optimisation of diabetic control.
- Long term aspirin may be considered, particularly given the patient demographic.
Prognosis
- The visual prognosis is generally poor though there may be some minor improvement in visual acuity in the months following.
- Visual fields does not tend to recover.
References and further reading
- Online Information
- Non-arteritic anterior ischemic optic neuropathy: cause, effect, and management, Berry S, Eye and Brain, 2017; 9: 23-28.