Peripapillary hyperreflective ovoid mass-like structure (PHOMS): prevalence, risk factors, and development over time in Danish myopic children.

Background: On optical coherence tomography (OCT) scans of the optic nerve head, peripapillary hyperreflective ovoid mass-like structures (PHOMS) are sometimes seen as a sign of axonal distension. The phenomenon has been reported more frequently in myopic subjects. We investigated PHOMS-prevalence in a myopic pediatric cohort, associated risk factors, and PHOMS development over 18 months during low-dose atropine treatment.

Methods: In this post hoc analysis of an investigator-initiated, placebo-controlled, randomized clinical trial, 97 6- to 12-year-old myopic participants were randomized to 0.1% atropine for 6 months, then 0.01% for 18 months (N = 33), 0.01% for 24 months (N = 32) or placebo for 24 months (N = 32). Primary outcome was presence of PHOMS. Secondary outcome was mean nasal PHOMS diameter measured on OCT B-scan. Outcomes were reported at baseline, 6, and 18 months. Logistic regression and linear mixed modelling were performed.

Results: PHOMS were present in 26% of participants (n = 25), and 52% (n = 13) had bilateral presentation. Optic disk tilt (OR = 10.81; 95% CI, 3.58-32.58 [P < 0.001]) and longer axial length (AL) (OR = 2.06; 95% CI, 1.02-4.17 [P = 0.04]) increased the risk of having PHOMS. Greater increase in nasal peripapillary choroidal thickness over time was associated with smaller PHOMS diameter at 18 months (P = 0.05).

Conclusions: PHOMS were common in our cohort of children with myopia. Longer AL increases the risk of, but not size of, PHOMS. The diameter of PHOMS seemed stable over time and unaffected by low-dose atropine.