Peripapillary Hyperreflective Ovoid Mass-Like Structures (PHOMS)

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Introduction

Peripapillary Hyperreflective Ovoid Mass-Like Structures (PHOMS) are homogenous rounded structures, recently described in the latest studies regarding Optic Nerve Head (ONH) evaluation, that were initially considered a finding in Optic Disc Drusen (ODD). However, the Optic Disc Drusen Studies (ODDS) Consortium, a group of fellowship-trained neuro-ophthalmologists and researchers, elaborated on a recent work using Enhanced-Depth Imaging Optical Coherence Tomography (EDI-OCT) of ODD patients, in which they considered that PHOMS are not unique to ODD or papilledema and should not be used to differentiate these optic nerve head findings.[1] PHOMS is increasingly thought to correspond to axoplasmic stasis and nerve fiber bulging/herniation in the peripapillary region, assuming the shape of a "doughnut" or torus around the ONH.[2]

Historical Background

Previous studies regarding the evaluation of morphologic characteristics of ODD, as visualized using Spectral-Domain Optical Coherence Tomography (SD-OCT), tried to categorize ODD into two types - visible and buried - according to their position related to the ONH. The visible ODD were primarily located inside the disc and were characterized by highly reflective borders with an internal hyporreflective core ("cysts") and RNFL thinning, often existing as multiple lumps, sometimes coalescing into larger aggregates. Buried optic nerve head drusen were located exclusively outside the ONH and were characterized by an amorphous C-shaped mass with relatively less distinct borders.[3]

Etiology

As noted above, the PHOMS on OCT can be seen in multiple clinical situations such as:

  1. Papilledema,[4][5]
  2. Anterior Ischemic Optic Neuropathy (AION),[5]
  3. Central Retinal Vein Occlusion (CRVO),[5]
  4. Optic Neuritis (ON),[5]
  5. Tilted-Disc Syndrome (TDS),[5][6]
  6. Optic Disc Drusen (ODD),[1][3][5][7][8]
  7. Stickler Syndrome,[9]
  8. Nonarteritic Ischemic Optic Neuropathy (NAION),[10]
  9. Myopic Shift[6]


Thus, PHOMS is a non-specific finding that can be related to true disc edema or cases of pseudopapilledema and usually resolves with its underlying condition/etiology.[2]

Definition

ODDS Consortium Recommendations

Malmqvist et al. showed in 2018 that PHOMS were present in 74% of patients with ODD included in their analysis. They stated that, despite their histopathological relationship not being clear, several features appeared to distinguish them from each other:[1]

  • Unlike ODD, PHOMS are hyperreflective without a sharp outer margin or hyporeflective core;
  • PHOMS often lie external to and surrounding large parts of the disc, corresponding to funduscopically recognized pseudopapilledema;
  • PHOMS do not demonstrate autofluorescence;
  • PHOMS are not visible on B-scan ultrasound despite their superficial location;
  • PHOMS can be seen in patients with papilledema without ODD;
  • Histopathology of papilledema suggests that PHOMS might correspond to the lateral bulging or herniation of distended axons into the peripapillary retina.

Thus, PHOMS should not be mistaken for ODD.[1]

Multi-Rater Validation of PHOMS

The number of PHOMS' related papers has increased since the ODDS Consortium Recommendations. A Delphi consensus process to develop a consistent and refined definition of PHOMS focused on three characteristics found on OCT B-Scans:[11]

  1. Location: strictly peripapillary and sitting on top of Bruch’s membrane. Frequently, a gap can be observed in the B-scans of PHOMS aligned through the center of the optic disc;
  2. Effect on adjacent retinal layers: an upward deflection of at least two of the other retinal layers;
  3. Signal appearance: similar to the reflectivity of the retinal nerve fiber and ganglion cell layers.

Diagnostic Modalities

EDI-OCT

Infrared image (a) showing a ring (arrow) temporal to the optic disc, correlating with the exact location of the peripapillary hyperreflective ovoid-like mass structures (PHOMS) edge shown on enhanced depth imaging optical coherence tomography (EDI-OCT) in (c) (arrow). The PHOMS contains small hyperautofluorescent spots seen on fundus autofluorescence (b, encircled), and hyperreflective spots on the infrared images (c, encircled). d Ultrasound B-scan showing a hyperechogenic structure (arrow) at the optic nerve head, correlating with the PHOMS seen on EDI-OCT.
Multimodal Imaging of PHOMS.

PHOMS was first described as a finding on EDI-OCT images of patients with ODD. The resemblance of PHOMS with the histopathology sample of a patient with papilledema (lateral bulging/herniation of RNFL) presented the idea that both findings could be related to axoplasmic stasis.[1]

A retrospective cohort study that analyzed 64 eyes (32 patients, children aged 5-16 years) suspected of having pseudopapilledema (normal RNFL thickness, without disc swelling appearance on fundoscopy) found that 93.8% of eyes with PHOMS exclusively had small hyperreflective foci inside, indicating that it might contain calcium deposits in its composition. This finding supported the thesis that PHOMS and ODD might represent a spectrum of the same disease with PHOMS representing continued axoplasmic stasis leading to extrusion of calcified mitochondria, calcium deposition, and formation of ODD. They also identified a distinct ring sign visible on the infrared images of all cases of PHOMS, corresponding to the edge of the structure as seen in EDI-OCT.[12]

Summary

PHOMS is an OCT finding that is nonspecific and can be seen in a number of optic nerve conditions including ODD and true disc edema. The presence of PHOMS should not be used to diagnose ODD. Clinicians should be aware of the significance and OCT appearance of PHOMS.

References

  1. Jump up to: 1.0 1.1 1.2 1.3 1.4 Malmqvist L, Bursztyn L, Costello F, Digre K, Fraser JA, Fraser C, Katz B, Lawlor M, Petzold A, Sibony P, Warner J, Wegener M, Wong S, Hamann S. The Optic Disc Drusen Studies Consortium Recommendations for Diagnosis of Optic Disc Drusen Using Optical Coherence Tomography. J Neuroophthalmol. 2018 Sep;38(3):299-307. doi: 10.1097/WNO.0000000000000585. PMID: 29095768.
  2. Jump up to: 2.0 2.1 Fraser JA, Sibony PA, Petzold A, Thaung C, Hamann S; ODDS Consortium. Peripapillary Hyper-reflective Ovoid Mass-like Structure (PHOMS): An Optical Coherence Tomography Marker of Axoplasmic Stasis in the Optic Nerve Head. J Neuroophthalmol. 2021 Dec 1;41(4):431-441. doi: 10.1097/WNO.0000000000001203. PMID: 33630781.
  3. Jump up to: 3.0 3.1 Lee KM, Woo SJ, Hwang JM. Morphologic characteristics of optic nerve head drusen on spectral-domain optical coherence tomography. Am J Ophthalmol. 2013 Jun;155(6):1139-1147.e1. doi: 10.1016/j.ajo.2013.01.024. Epub 2013 Mar 19. PMID: 23522355.
  4. Wibroe EA, Malmqvist L, Hamann S. OCT Based Interpretation of the Optic Nerve Head Anatomy and Prevalence of Optic Disc Drusen in Patients with Idiopathic Intracranial Hypertension (IIH). Life (Basel). 2021 Jun 19;11(6):584. doi: 10.3390/life11060584. PMID: 34205357; PMCID: PMC8234108.
  5. Jump up to: 5.0 5.1 5.2 5.3 5.4 5.5 Malmqvist L, Sibony PA, Fraser CL, Wegener M, Heegaard S, Skougaard M, Hamann S; Optic Disc Drusen Studies Consortium. Peripapillary Ovoid Hyperreflectivity in Optic Disc Edema and Pseudopapilledema. Ophthalmology. 2018 Oct;125(10):1662-1664. doi: 10.1016/j.ophtha.2018.04.036. Epub 2018 Jun 8. PMID: 29891127.
  6. Jump up to: 6.0 6.1 Lyu, I.J., Park, KA. & Oh, S.Y. Association between myopia and peripapillary hyperreflective ovoid mass-like structures in children. Sci Rep 10, 2238 (2020). https://doi.org/10.1038/s41598-020-58829-3
  7. Ahn YJ, Park YY, Shin SY. Peripapillary hyperreflective ovoid mass-like structures (PHOMS) in children. Eye (Lond). 2022 Mar;36(3):533-539. doi: 10.1038/s41433-021-01461-w. Epub 2021 Mar 17. PMID: 33731891; PMCID: PMC8873397.
  8. Teixeira FJ, Marques RE, Mano SS, Couceiro R, Pinto F. Optic disc drusen in children: morphologic features using EDI-OCT. Eye (Lond). 2020 Sep;34(9):1577-1584. doi: 10.1038/s41433-019-0694-6. Epub 2019 Nov 19. PMID: 31745329; PMCID: PMC7608464.
  9. Khatib TZ, Safi A, Nixon TRW, Georgoulas S, Montesano G, Martin H, Richards AJ, McNinch A, Poulson AV, Alexander P, Snead MP. Peripapillary Hyperreflective Ovoid Mass-Like Structures in Stickler Syndrome. Ophthalmol Retina. 2024;8(10):1013-1020. doi:10.1016/j.oret.2024.05.008
  10. Wang W, Liu J, Xiao D, Yi Z, Chen C. Features of Peripapillary Hyperreflective Ovoid Mass-Like Structures in Nonarteritic Anterior Ischemic Optic Neuropathy Patients and Normal Controls. Transl Vis Sci Technol. 2024;13(1):7. doi:10.1167/tvst.13.1.7
  11. Axel Petzold, Valerie Biousse, Lulu Bursztyn, Fiona Costello, Alison Crum, Kathleen Digre, Clare Fraser, J. Alex Fraser, Bradley Katz, Neringa Jurkute, Nancy Newman, Jette Lautrup-Battistini, Mitchell Lawlor, Petra Liskova, Birgit Lorenz, Lasse Malmqvist, Jason Peragallo, Patrick Sibony, Prem Subramanian, Robert Rejdak, Katarzyna Nowomiejska, Valerie Touitou, Judith Warner, Marianne Wegener, Sui Wong, Patrick Yu-Wai-Man & Steffen Hamann (2020) Multirater Validation of Peripapillary Hyperreflective Ovoid Mass-like Structures (PHOMS), Neuro-Ophthalmology, 44:6, 413-414, DOI: 10.1080/01658107.2020.1760891
  12. Mezad-Koursh D, Klein A, Rosenblatt A, Teper Roth S, Neudorfer M, Loewenstein A, Iglicki M, Zur D. Peripapillary hyperreflective ovoid mass-like structures-a novel entity as frequent cause of pseudopapilloedema in children. Eye (Lond). 2021 Apr;35(4):1228-1234. doi: 10.1038/s41433-020-1067-x. Epub 2020 Jul 2. PMID: 32616868; PMCID: PMC8115042.
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