Bevacizumab for Non-Arteritic Anterior Ischemic Optic Neuropathy (NAION)
Intravitreal bevacizumab is not recommended for treating non-arteritic anterior ischemic optic neuropathy, as the highest quality prospective trial demonstrated no benefit over natural history for visual field, visual acuity, or optic nerve swelling. 1
Evidence Against Bevacizumab Use in NAION
The most rigorous study examining this question was a prospective non-randomized controlled trial that directly compared 1.25 mg intravitreal bevacizumab (17 patients) to natural history (8 controls) over 6 months 1. This study found:
- No significant improvement in mean deviation score on visual field testing (primary outcome, P=0.4) 1
- No difference in visual acuity change (P=0.33) 1
- No difference in optic nerve fiber layer thickness on OCT (P=0.11) 1
- Two cases of recurrent NAION occurred in the bevacizumab group 1
The authors explicitly concluded they would not recommend intravitreal bevacizumab for new-onset NAION based on their findings 1.
Supporting Evidence
A smaller retrospective case series of 5 patients corroborated these negative findings 2. In this series:
- Visual outcomes were consistent with the natural course of NAION 2
- One patient improved slightly, three progressed, and one remained stable on visual field testing 2
- Bevacizumab did not appear to have any dramatic effect on clinical outcomes 2
Current State of NAION Treatment
No proven effective medical or surgical therapy currently exists for NAION 3, 4, 5. Multiple treatment modalities have been investigated without success, including:
- Optic nerve sheath decompression 4
- Standard and megadose corticosteroids 4
- Levodopa and carbidopa 4
- Hyperbaric oxygen 4
- Various neuroprotective agents 4
Clinical Management Algorithm
Since no effective treatment exists, management should focus on:
- Confirm the diagnosis by identifying sudden, painless vision loss with optic disc edema in a patient over age 50 3, 4
- Rule out arteritic anterior ischemic optic neuropathy through ESR, CRP, and clinical assessment, as this requires immediate corticosteroid therapy 4
- Identify and control modifiable vascular risk factors including hypertension, diabetes, hyperlipidemia, and atherosclerosis to prevent fellow eye involvement 3, 4
- Monitor the fellow eye closely, as sequential involvement occurs in a significant proportion of patients 4
- Avoid intravitreal bevacizumab, as it provides no benefit and carries injection-related risks 1
Critical Pitfalls to Avoid
Do not confuse NAION with optic neuritis, which can present similarly but occurs in younger patients, may have pain with eye movement, and responds to corticosteroids 4. The clinical presentation of NAION can diverge from the classic description, making differentiation challenging 4.
Do not miss arteritic anterior ischemic optic neuropathy (giant cell arteritis), which requires immediate high-dose corticosteroids to prevent bilateral blindness 4. Any suspicion warrants immediate ESR/CRP testing and possible temporal artery biopsy.
Do not offer false hope regarding visual recovery, as spontaneous improvement is not the rule, and most patients experience permanent vision loss 4. The disease commonly affects the fellow eye sequentially, and 18% of eyes may become blind following acute angle closure events in related conditions 6.
Why Bevacizumab Was Hypothesized
The theoretical rationale for bevacizumab was to decrease optic nerve edema and resolve a proposed compartment syndrome at the optic nerve head 1. However, this hypothesis was not supported by clinical evidence, and the outcomes matched natural history 1, 2.