Structural and vascular characteristics of PHOMS in pediatric pseudopapilledema

To evaluate the structural and vascular characteristics of peripapillary hyperreflective ovoid mass-like structures (PHOMS) in pediatric pseudopapilledema and to investigate their relationship with retinal nerve fiber layer (RNFL) thickness and optic nerve head parameters. This retrospective study included 38 pediatric patients with pseudopapilledema (with or without optic disc drusen [ODD]) and 36 age- and sex-matched healthy controls. Structural optical coherence tomography (OCT) and OCT angiography (OCTA) parameters were analyzed, including global and sectoral RNFL thickness, ganglion cell complex (GCC) metrics, Bruch’s membrane opening (BMO) diameter, choroidal vascularity index (CVI), radial peripapillary capillary (RPC) density, and macular vascular parameters. In PHOMS-positive eyes, maximum PHOMS diameter was measured on enhanced depth imaging OCT. Group comparisons were performed using generalized estimating equations. Correlation analysis was conducted to evaluate associations between PHOMS size and structural or vascular parameters. In GEE analyses including all PHOMS-positive eyes (n = 40) and healthy control eyes (n = 72), global RNFL thickness was significantly greater in PHOMS-positive eyes (111.68 ± 22.68 vs. 97.55 ± 8.54 μm, p < 0.001). BMO diameter was significantly larger (p = 0.001) and FAZ area significantly smaller (p = 0.001) in PHOMS-positive eyes. Although RPC density differed between groups (p = 0.045), no consistent differences were observed in GCC thickness, CVI, or other OCTA-derived vascular parameters. Maximum PHOMS diameter showed a significant positive correlation with global RNFL thickness (r = 0.526, p = 0.010). In eye-level analyses including ODD-positive, ODD-negative, and healthy eyes, RNFL thickness differed significantly among groups (p < 0.001), whereas no consistent differences were observed in vascular or ganglion cell parameters. The findings of this study suggest that PHOMS in pediatric pseudopapilledema are predominantly associated with structural optic nerve head alterations. Although differences were observed in selected OCTA-derived parameters, no uniform pattern of microvascular change was identified. The observed association between PHOMS size and RNFL thickness is consistent with the concept of localized axonal crowding and remodeling at the optic nerve head. Further longitudinal studies with larger cohorts are required to clarify the clinical significance of these findings. What is known • Peripapillary hyperreflective ovoid mass-like structures (PHOMS) are increasingly recognized in association with optic disc drusen, myopia, and elevated intracranial pressure, but their structural and vascular characteristics in pediatric pseudopapilledema remain incompletely defined. What is new • PHOMS in pediatric pseudopapilledema were associated with increased RNFL thickness, larger BMO diameter, smaller FAZ area, and lower RPC density. Maximum PHOMS diameter showed a positive correlation with RNFL thickness. While selected structural and vascular differences were observed, no consistent pattern of widespread microvascular alteration was identified.