PHOMS (Peripapillary Hyperreflective Ovoid Mass-Like Structures) are structures observed around the optic disc using Enhanced Depth Imaging OCT (EDI-OCT). They are defined as ovoid, hyperreflective mass-like structures located on Bruch’s membrane1, 2, 4).
The name directly reflects their characteristics.
First described on OCT in 2011, it was initially mistaken for buried optic disc drusen (ODD) 1, 2).
In 2018, Malmqvist et al. of the ODD Consortium analyzed 38 EDI-OCT images and defined PHOMS as a distinct entity from ODD 1, 4).
In 2020, Petzold et al. refined the diagnostic criteria using the Delphi method 2, 4). The current diagnostic criteria are as follows:
The prevalence of PHOMS varies greatly depending on the study population.
PHOMS coexists in 47%–90% of ODD patients1, 4). The current understanding is that PHOMS and ODD coexist but are distinct structures.
PHOMS are peripapillary hyperreflective ovoid structures located above Bruch’s membrane, appearing as homogeneous hyperreflective areas around the optic disc on OCT. ODD (optic disc drusen) are located within the optic disc and have a hyporeflective core with a hyperreflective rim. The two often coexist (47–90% of ODD patients have concurrent PHOMS). For differentiation points using different tests, see also the “Diagnosis and Testing Methods” section.
PHOMS itself is usually asymptomatic1, 2). In the Beijing Eye Study, adults with PHOMS showed no visual function decline.
Rarely, PHOMS-related spontaneous optic disc hemorrhage may occur, and it is sometimes discovered with chief complaints of floaters or asthenopia5).
PHOMS itself usually does not cause vision loss. In the Beijing Eye Study, no visual function decline was confirmed in adults with PHOMS. However, underlying diseases associated with PHOMS (such as IIH, optic neuritis, NAION) may cause vision loss.
It presents with blurring of the optic disc margin and a prominent C-shaped or O-shaped halo on the nasal side2, 4).
EDI-OCT is the gold standard for diagnosing PHOMS 1). The main findings are as follows.
Morphology and Distribution
Shape: C-shaped halo/annular. Present as a continuous structure.
Predilection sites: Nasal and superior regions.
Characteristic appearance: “Ski-slope” or “boot-shaped” appearance.
Size: Mean height 399 μm, mean width 721 μm.
Reflectivity Characteristics
Reflectivity: Uniformly high reflectivity. Similar to RNFL reflectivity.
Internal hyperreflective spots: Present in 93.8% of children.
Location: Strictly located on Bruch’s membrane.
PHOMS is a marker of axoplasmic flow stasis. When axonal transport is impaired, nerve fibers bulge laterally and herniate, becoming visible as PHOMS 1, 2, 4).
PHOMS is a non-specific finding that accompanies various optic nerve diseases. The main associated diseases and their complication rates are shown below.
Yes, there is a relationship. PHOMS is found in 26% of myopic children (aged 6–12 years, ≥1.00D), making myopia an important risk factor. The higher the degree of myopia, the more likely optic disc tilt occurs, and Bruch’s membrane protrusion and nerve fiber bending make PHOMS formation more likely2, 4).
EDI-OCT is the gold standard for diagnosing PHOMS1). Since it is difficult to distinguish from true papilledema using ophthalmoscopy alone, evaluation with EDI-OCT is essential.
PHOMS and ODD often coexist but show different features on each modality.
| Modality | PHOMS | ODD |
|---|---|---|
| Fundus examination | C-shaped/O-shaped peripapillary halo | Crystalline-like structure within the optic disc |
| OCT | Uniform hyperreflective, oval, peripapillary | Hyporeflective core + hyperreflective rim, intra-papillary |
| OCTA | Microvascular network inside | No vascular network |
| Autofluorescence | Usually hypoautofluorescent | Hyperautofluorescent |
| Ultrasound | High echogenicity at retinal level, no shadowing | Deep high echogenicity with posterior shadowing |
PHOMS is a major cause of pseudopapilledema, but it can also coexist with true papilledema. The following points are important for differentiation.
Even if PHOMS is present, it is essential to rule out urgent conditions such as IIH1, 2, 4).
There is no specific treatment for PHOMS itself1, 2, 4). The principle of treatment is management of the underlying disease, and PHOMS resolves with treatment of the underlying condition.
| Underlying disease | Time of resolution | Treatment |
|---|---|---|
| Optic neuritis | 75% resolve within 1 month, remaining within 3–8 months | Standard optic neuritis treatment |
| IIH | Resolves with weight loss and acetazolamide | Weight management and oral medication |
| NAION | Resolves in 1–2 months | Observation |
| LHON | Resolves within 12 months | Manage underlying disease |
Aziria et al. (2023) reported a prevalence of PHOMS of 7.0% in a study of 102 cases of optic neuritis 3). After treatment of optic neuritis, PHOMS disappeared within 1 month in 75% of cases, and within 3 to 8 months in the remaining cases.
Regular monitoring with OCT is useful for assessing disease activity and treatment response of the underlying condition 2). Tracking changes in PHOMS allows non-invasive evaluation of papilledema recurrence or changes in disease activity.
Specific treatment for PHOMS itself is not necessary. PHOMS resolves with appropriate treatment of the underlying condition (e.g., idiopathic intracranial hypertension, optic neuritis, non-arteritic anterior ischemic optic neuropathy). However, some underlying causes of PHOMS, such as idiopathic intracranial hypertension, require early treatment, so diagnosis and treatment of the causative disease are the highest priority.
Histopathological findings of PHOMS show S-shaped herniation of swollen and vacuolated axons 2, 4). Positive S100 immunostaining indicates that these structures are of axonal origin 4). Experiments using radioisotopes and electron microscopy have also detected markers of axonal transport stasis 2, 4).
The formation mechanism of PHOMS varies depending on the underlying disease.
ODD
Mechanical compression: Mechanical compression within the optic disc due to calcified deposits (drusen) impairs axonal transport.
Location: The ODD within the optic disc protrudes laterally as PHOMS.
Idiopathic Intracranial Hypertension
Pressure gradient reversal: Reversal of the pressure gradient across the lamina cribrosa impairs axonal transport.
Reversibility: PHOMS regress when intracranial pressure normalizes after treatment of idiopathic intracranial hypertension.
Tilted Disc Syndrome / Myopia
Structural deformation: Protrusion of Bruch’s membrane and bending of nerve fibers mechanically obstruct axonal flow.
Prevalence: PHOMS is observed in 39.5% of children with TDS.
Optic Neuritis
Inflammatory disorder: Disruption of axonal transport due to demyelination and inflammatory cell infiltration.
Course: PHOMS resolves as inflammation subsides.
Borrelli et al. (2021) first reported the presence of a coronal vascular complex within PHOMS using OCTA 6). It was also shown that larger PHOMS (≥500 μm) are associated with lower vascular density. This space-occupying effect is speculated to be the mechanism underlying the reduced vascular density.
It has been proposed that PHOMS may be a precursor stage of ODD. There is a calcium deposition hypothesis suggesting that accumulation of axon-derived substances eventually leads to calcium deposition and transition to ODD (optic disc drusen)1). However, this hypothesis is not yet established at present.
Borrelli et al. (2021) suggested that PHOMS may contain a vascular complex rather than being merely a morphological structure 6). This finding, first visualized by OCTA (optical coherence tomography angiography), has significantly advanced the understanding of PHOMS pathophysiology. Further research is needed on the relationship between PHOMS and optic nerve blood flow.
Wang et al. (2024) reported two cases of spontaneous localized papillary hemorrhage within PHOMS 5). Both were detected with asymptomatic or mild symptoms (floaters, eye strain), and OCTA was useful in identifying the bleeding source from the vascular complex. The mechanism and clinical significance of hemorrhage within PHOMS are currently being elucidated.
The prevalence of PHOMS in multiple sclerosis (MS) patients is reported to be 16%–19.7%, and longitudinal studies are investigating the potential of PHOMS as a noninvasive biomarker for relapse activity and axonal damage 2, 4).
PHOMS is observed in 26% of myopic children and is expected to be used as a biomarker for optic disc morphological changes associated with axial elongation, with potential application in monitoring myopia progression2, 4).
Efforts are underway to utilize PHOMS for monitoring intracranial pressure in IIH. Prospective studies are needed to determine whether changes in PHOMS can serve as an indicator reflecting fluctuations in intracranial pressure2).
