Retinal Inner Nuclear Layer Changes Identified in Patients With NA-ION

Patients with non-arteritic anterior ischemic optic neuropathy (NA-ION) may experience microcystic changes in the retinal inner nuclear layer (INL), according to research published in Ophthalmology Science. These changes may be transient and associated with a transudate of intra and subretinal fluid originating from the optic disc or potentially permanent and related to ganglion cell complex (GCC) thinning, according to the report.

Researchers enrolled patients who were referred to a single center for painless monocular vision loss between 2014 and 2021 (N=34; eyes with NA-ION, 45; healthy eyes, 23; mean age, 60 years; 65.6% men). Patients underwent comprehensive eye exams including best-corrected visual acuity (BCVA) measurement, slit lamp evaluation, and fundus biomicroscopy. Optical coherence tomography (OCT) was used to measure inner plexiform layer and GCC thicknesses. All participants were followed over the course of 1-, 3-, and 6-month follow-up visits. Etiology of vision loss and outcomes in eyes with NA-ION were evaluated and compared with fellow healthy eyes.

A subset of 19 eyes were found to have INL microcystic changes with optic disc swelling. In these eyes, vacuoles were localized to the INL and intra and subretinal fluid was originating from the optic disc.

Among these patients, 3 developed microcystic macular oedema (MMO). Mean INL thickness was 48.9 μm in the affected eye and 45.3 μm in the fellow eye. No significant INL thinning was observed during a follow-up visit conducted 2 to 3 years following the initial assessment.

All eyes with MMO demonstrated GCC thinning at 6 months with a 33.3% loss in the superior hemi-maculae and 31.0% loss in the inferior hemi-maculae. Compared with the entire cohort, eyes with MMO had greater involvement of the superior hemi-macula and greater retinal nerve fiber layer (RNFL) thinning at 6 months.

“In conclusion, our study indicates two causes of MMO in the same patients suffering from NA-AION, one reversible and the other likely permanent,” according to the researchers. “This finding highlights the distinction between genuine edema related to transudation of fluid (here associated with optic disc swelling) and the phenomenon observed in [retrograde maculopathy] related to the degree of RNFL loss.”

Study limitations include a small sample size and an observational design.