PHOMS Are Uncommon in Patients With Optic Neuritis

Peripapillary hyperreflective ovoid mass-like structures (PHOMS) are not a common clinical marker for optic neuritis, according to a retrospective study published in Eye. This finding, which is detectable upon optical coherence tomography (OCT) assessment, is likely to be seen with concomitant optic nerve head edema. 

Investigators included 102 individuals from the Optical Coherence Tomography and Optic Neuritis (OCTON) cohort (Clinicaltrials.gov Identifier: NCT02573792) — a prospective observational study examining anatomical predictive factors of visual and retinal outcome following optic neuritis, in the assessment. The research team reviewed medical files, fundus photographs, and macular and optic nerve head (ONH) OCT images to determine whether ONH edema and PHOMS were common at neuritis presentation.

At the initial presentation, 28.4% of patients had evidence of ONH edema, but no references to PHOMS were found in any patient files. However, 8 patients met the diagnostic criteria for PHOMS.

The patients fitting the criteria for PHOMS (mean age, 34 years; 62.5% women) all had ONH swelling. The optic neuritis etiologies included idiopathic optic neuritis (n=3), clinically isolated syndrome (n=2), multiple sclerosis (MS; n=1), and Lyme disease (n=1).

According to the report, PHOMS resolved in all cases — 75% of participants experienced total resolution within 1 month and the longest persistent case of PHOMS was 8 months. No patients developed PHOMS during the study duration, but 2 participants had peripapillary changes associated with PHOMS.

The etiologies of optic neuritis without PHOMS included MS (54.1%), idiopathic optic neuritis (16.5%), clinically isolated syndrome (13.8%), anti-aquaporin-4 (AQP4) antibody-positive optic neuritis (4.6%), and myelin oligodendrocyte glycoprotein (MOG) optic neuritis (1.1%). Patients with MOG optic neuritis were more likely to present with ONH edema (61.5%) compared with patients with idiopathic optic neuritis (28.5%), clinically isolated syndrome (23.5%), MS (13.3%), or AQP4 antibody-positive optic neuritis (0%).

The study authors suggest a non inflammatory mechanism may be responsible for the pathophysiology of PHOMS and state,  “[w]e found PHOMS to be a rare manifestation in patients with anterior optic neuritis and ONH edema and we suggest that their persistence after the resolution of the ONH edema should lead to a reconsideration of the etiology.”

Study limitations include a small sample size of participants with PHOMS.