A recent study published in Ophthalmology explored peripapillary hyperreflective ovoid mass-like structures (PHOMSs) in a broad range of neurologic disorders to evaluate their prevalence, location, volume, and potential association with intracranial pressure (ICP).
Give me some background first.
PHOMSs are bright oval reflective formations that appear on optical coherence tomography (OCT) scans near the optic nerve head.
While initially thought to be linked only to optic disc drusen (deposits in the back of the eye), researchers have since found them in conditions like:
- Intracranial hypertension (IH)
- Multiple sclerosis (MS)
- Neuromyelitis optica spectrum disorders (NMOSD)
Go on …
Although their exact role isn’t fully understood, experts believe they may be caused by disrupted fluid drainage in the eye, pressure differences across the optic nerve, or a buildup of material within nerve fibers.
Given their potential diagnostic value, this study aimed to characterize PHOMSs across a range of neurologic disorders.
Now, talk about the study.
This monocentric, retrospective, cross-sectional study analyzed PHOMSs prevalence, volume, location, and intensity across five neurologic conditions using spectral-domain OCT imaging.
The goal: To assess disease-specific differences and their possible association with ICP.
Who was included in the study?
A total of 537 patients (1,032 eyes) were included, with exclusion criteria of significant refractive error (> ±5 diopters [D]) or existing ophthalmic comorbidities.
These five cohorts of neurologic conditions were as follows:
- Cohort 1: Neuroimmunologic diseases (NID)
- n = 237
- Cohort 2: Epilepsy
- n = 153
- Cohort 3: Movement disorders (MD)
- n = 44
- Cohort 4: Intracranial hypertension (IH)
- n = 13
- Cohort 5: Inborn errors of metabolism (IEM)
- n = 90
And the findings?
The study found PHOMSs in 7% of examined eyes with the highest prevalence in IH (54%).
- PHOMSs were mostly located in the nasal region (65%), while temporal placement was rarely seen.
Talk about the size of these PHOMS.
Patients with IH had significantly larger PHOMSs (median: 0.23 mm³) compared to those with epilepsy (0.05 mm³), MD (0.02 mm³), and NID (0.03 mm³).
Interestingly: PHOMS size decreased with age (p = 0.003) in non-IH patients but showed no link to BMI.
Structurally PHOMSs had reflectivity similar to the optic nerve, higher than the outer nuclear layer, but lower than total retinal layers.
- They were also correlated with peripapillary retinal nerve fiber layer (pRNFL) thickness and Bruch’s membrane opening minimum rim width (BMO-MRW).
- However, there was no found association between PHOMS volume and BMO surface.
The take home.
These findings suggest a significant correlation between PHOMSs and IH—possibly due to chronic axoplasmic stasis or increased translaminar pressure gradients.
Importantly: There was no found link to BMI in this study which challenged previous weight-related notions.
The negative correlation with age (excluding patients with IH) suggests PHOMs may shrink over time as diseases progress.
- As such, their correlation with pRNFL thickness and BMO-MRW may affect OCT scan interpretations in neuro-ophthalmology.
Any limitations to note?
A few, including:
- The study’s cross-sectional design prevented the determination of cause and effect
- The small sample size for IH patients limited the findings’ generalizability
- Differences in disease duration, severity, and treatment history could have influenced the results
- A lack of long-term data made PHOMSs progression unclear
Expert opinion?
The investigators concluded that PHOMSs may be a useful marker for IH, highlighting their importance in OCT-based eye exams that assess the nervous system.
Further: They suggested longitudinal studies, ICP correlation analysis in non-IH conditions, and histopathologic evaluations may help to further clarify PHOMSs pathogenesis.
Take home.
PHOMSs are observed in multiple neurologic conditions, with IH patients exhibiting the largest volumes.
Their pathogenesis likely relates to ICP changes, and their impact on OCT parameters demands attention in clinical and research settings.
- For the future: Prospective, multi-center studies are essential to determine their utility as a biomarker for ICP-related pathology.