PHOMS

 A

PHOMS are structures seen around the optic nerve head on OCT (optical coherence tomography) scans of the eye. They are not a disease themselves but a sign associated with several optic nerve conditions.

Main causes / conditions associated with PHOMS

1. Optic Disc Drusen

   • One of the most common associations.

   • Calcified deposits in the optic nerve head can cause axonal crowding, producing PHOMS.

2. Papilledema

   • Swelling of the optic disc due to raised intracranial pressure.

   • PHOMS can appear due to axoplasmic flow stasis and compression of nerve fibers.

3. Optic Neuritis

   • Inflammation of the optic nerve.

   • Swelling and disruption of axons may produce PHOMS.

4. Anterior Ischemic Optic Neuropathy

   • Reduced blood flow to the optic nerve.

   • Axonal injury and swelling can lead to PHOMS.

5. Myopia (especially high myopia)

   • Structural crowding or tilt of the optic disc can produce PHOMS-like changes.

6. Crowded or anomalous optic discs

   • Small discs or congenital optic nerve anomalies can cause axonal compression.

7. Other optic nerve disorders

   • Various conditions that disturb axonal transport in the optic nerve may produce PHOMS.

Underlying mechanism

Most researchers believe PHOMS occur due to:

• Axoplasmic flow stasis in optic nerve fibers

• Herniation or bulging of distended axons into the peripapillary retina

Important point

PHOMS are not the same as optic disc drusen, although they are often seen together.

✅ Summary: PHOMS usually occur when there is crowding, swelling, or disruption of optic nerve axons from conditions like optic disc drusen, papilledema, optic neuritis, ischemic optic neuropathy, or high myopia.

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If you want, I can also explain:

• How PHOMS look on OCT

• How to differentiate PHOMS from optic disc drusen

• Whether PHOMS affect vision (this is often what people worry about).