Subretinal Fluid in NAION

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Using spectral-domain OCT, researchers ob­served subretinal fluid in the macula in a substantial number of patients with nonarteritic anterior ischemic optic neuropathy (NAION).¹ The findings, consistent with earlier studies, confirm that NAION is not just an isolated optic nerve process but is associated with reti­nal abnormalities that may contribute to vision loss.

“Documenting the presence of subfoveal fluid is important since it can be associated with reduced visual acuity, which is classically preserved in nonarte­ritic AION, as well as in papilledema,” said Thomas R. Hedges III, MD, at Tufts University School of Medicine and the New England Eye Center (NEEC) in Boston.

In previous OCT studies, NEEC researchers observed the presence of subretinal fluid in patients with pap­illedema, and they subsequently saw fluid in patients with NAION.² This latest study, using higher-resolution OCT, affirms those findings.

Findings. For this study, 20 patients (25 eyes) diagnosed with NAION between 2013 and 2017 were evaluated using SD-OCT. All patients presented within four weeks of symptom onset; five had a history of NAION in the fellow eye. NAION was diagnosed on the basis of typical clinical presentation, including, among other findings, painless sudden vision loss and altitudi­nal visual field defects accompanied by swelling of the optic disc with hemorrhages.

Peripapillary subretinal fluid was present in 16 eyes (64%). Of those, subretinal fluid extended into the macula to produce subfoveal edema in four eyes (16%). About one month after initial presentation, the sub­foveal fluid resolved in three of these eyes, and visual acuity (VA) improved in two. VA declined in one eye and remained unchanged in another.

Other retinal findings included intraretinal cysts and hyperreflective dots. However, their significance is unclear, the researchers said.

Looking for vitreoretinal changes. OCT revealed a variety of vitreopapillary interface abnormalities, but their presence does not suggest that the vitreous plays any role in the pathogenesis of AION, Dr. Hedges said. Specifically, there was no evidence of a primary role for vitreopapillary traction (VPT) in the presence of optic disc edema. What’s more, neither of the two asymp­tomatic patients with optic disc swelling had VPT.

Treatment implications. Dr. Hedges stressed the im­portance of these findings in treatment trials of NAION, where determining which patients have subfoveal fluid in different treatment groups is critical to interpreting the results. “The reduction in central vision sponta­neously resolves in most patients, which can be helpful for prognosis,” he said. “It will be important to under­stand what is being treated, the optic neuropathy or the secondary effects on the retina.”

—Miriam Karmel

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1 Molaie AM et al. J Neuro-Ophthalmol. Published online April 26, 2021.

2 Hedges TR et al. Arch Ophthalmol. 2008;126:812-815.

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Relevant financial disclosures—Dr. Hedges: None.

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