Longitudinal development of PHOMS suggest a novel pathological pathway in MS.

OBJECTIVE: Peripapillary Hyperreflective Ovoid Mass-like Structures (PHOMS) are a new spectral domain Optical Coherence Tomography (OCT) finding. METHODS: Prospective, longitudinal study. Patients (n=212) with MS (n=418 eyes), 59 healthy controls (HC, n=117 eyes) and 267 non-MS disease controls (534 eyes). OCT and Diffusion Tensor Imaging. RESULTS: There were no PHOMS in HC eyes (0/117, 0%). The prevalence of PHOMS was significantly higher in patients with MS (34/212, p=0.001) and MS eyes (45/418, p=0.0002) if compared to HC (0/59, 0/117). The inter-rater agreement for PHOMS was 97.9%, kappa 0.951. PHOMS were present in 16% of patients with relapsing remitting, 16% of patients with progressive and 12% of patients with secondary progressive disease course (2% of eyes). There was no relationship of PHOMS with age, disease duration, disease course, disability or disease modifying treatments. The fractional anisotropy of the optic radiations was lower in patients without PHOMS (0.814) if compared to patients with PHOMS (0.845, p=0.03). The majority of PHOMS remained stable, but increase in size and de novo development of PHOMS were also observed. In non-MS disease controls, PHOMS were observed in intracranial hypertension (62%), ODD (47%), anomalous optic discs (44%), isolated optic neuritis (19%) and optic atrophy (12%). INTERPRETATION: These data suggest that PHOMS are a novel finding in MS pathology. Future research is needed to determine if development of PHOMS in MS is due to intermittently raised intracranial pressure or an otherwise impaired "glymphatic" outflow from eye to brain. This article is protected by copyright. All rights reserved.