Optical coherence tomography measurement of retinal layers above the peripapillary hyperreflective ovoid mass-like structure in true papilloedema and pseudo-papilloedema

BACKGROUND: Discriminating between true papilloedema and pseudo-papilloedema is crucial, as true papilloedema can be both vision- and life-threatening. OBJECTIVES: To test a simple method for differentiating pseudo-papilloedema from true papilloedema in patients with peripapillary hyperreflective ovoid mass-like structures (PHOMS) using optical coherence tomography (OCT). SUBJECTS: 81 patients underwent OCT scanning of the optic nerve head (ONH) and peripapillary region following systematic guidelines. Patients were categorised into two groups: true papilloedema due to idiopathic intracranial hypertension (n = 34) and pseudo-papilloedema due to optic disc drusen (n = 40) or myopic tilted discs (n = 7). METHODS: PHOMS dimensions and thickness of retinal sublayers above PHOMS were measured. The retinal thickness directly above the PHOMS and perpendicular to the internal limiting membrane (the PHOMS UP thickness) was measured. RESULTS: While PHOMS were equal in height and width between groups, the PHOMS UP thickness was significantly larger in the true papilloedema group than in the pseudo-papilloedema group (378 µm ( ± 70 µm) vs 204 µm ( ± 47 µm), P < 0.001). CONCLUSIONS: In this selected cohort of patients with well-defined PHOMS, the significantly larger PHOMS UP thickness in the true papilloedema group supports the hypothesis that this condition involves both intra-axonal and interstitial fluid stasis, while pseudo-papilloedema only involves intra-axonal axoplasmic stasis. A PHOMS UP thickness greater than 300 µm may be suggestive of true papilloedema in this context. PHOMS UP thickness may serve as an additional, simple, rapid, OCT-metric to aid in differentiating pseudo-papilloedema from true papilloedema in patients with PHOMS.