Damage similar in each eye after sequential ischemic optic neuropathy

1. The magnitude of retinal nerve fiber layer (RNFL) loss was similar in each eye following bilateral non-arteritic anterior ischemic optic neuropathy (NAION). 

2. Visual field loss was similar between the two eyes affected by NAION. 

Evidence Rating Level: 2 (Good)            

Study Rundown: Non-arteritic anterior ischemic optic neuropathy (NAION) occurs when there is loss of blood flow to the optic nerve. It is the most common form of ischemic optic neuropathy, typically causing sudden painless vision loss. Although simultaneous bilateral onset of NAION is extremely rare, sequential involvement of bilateral NAION frequently occurs among the elderly. In this study, the authors investigated whether structural damage and visual outcomes were similar in the two affected eyes following sequential involvement of bilateral NAION. They found that the magnitude of peripapillary RNFL loss was similar in each eye in patients who experienced bilateral NAION. In addition they found that visual outcomes, particularly visual field loss, was similar in the two eyes. An important strength of this study is the relatively high correlation coefficients (r=0.583, r=0.457). However, it is limited by its retrospective nature and small sample size. Although this study is not the first to delineate the correlation in structural damage and visual outcome following bilateral NAION, it reinforces previous findings.

Click to read the study in Current Eye Research

Relevant Reading: Optic Disc and Peripapillary Morphology in Unilateral Nonarteritic Anterior Ischemic Optic Neuropathy and Age- and Refraction-Matched Normals

In-Depth [retrospective cohort]: This was a retrospective study involving 25 patients from two institutions. Patients were included if they had the diagnosis of NAION and had the sequential involvement of NAION in the contralateral eye. NAION was defined as sudden, painless vision loss initially accompanied by optic disc edema and splinter hemorrhages and later replaced by disc pallor. In this study, second eyes were affected by NAION about 3.4 years following the first episode. There were two significant findings: 1) a positive correlation between peripapillary RNFL thickness in the two affected eyes (r=0.583, p=0.002) and 2) a positive correlation between visual fields of the two affected eyes (r=0.457, p=0.042). Additionally, there was a weak, non-significant correlation in visual acuity between the eyes following NAION.

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Image: PD 

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