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Hashemi Eye Care - Neuroscience Institute and Research Center

Optic Nerve Sheath Fenestration

Surgery to create openings in the optic nerve sheath to reduce pressure and protect vision in IIH.

2 min read

Optic nerve sheath fenestration (ONSF) is a surgery that creates small windows (fenestrations) in the covering of the optic nerve. This allows cerebrospinal fluid to drain, reducing pressure on the nerve and protecting vision.

Key Takeaways

  • Protects vision in IIH and papilledema
  • Reduces pressure around optic nerve
  • Done for vision-threatening disease
  • Doesn't treat headaches (usually)
  • Alternative to shunting

When It's Done

  • Rapid or severe vision loss from papilledema
  • Medical treatment not working fast enough
  • Vision-threatening IIH
  • May be done on one or both sides

How It Works

The optic nerve is surrounded by a sheath containing CSF. When intracranial pressure is high, this pressure is transmitted to the nerve. Fenestration:

  • Creates drainage openings
  • Reduces pressure locally around nerve
  • Protects optic nerve from further damage

The Procedure

Before Surgery

During Surgery

  • General or local anesthesia
  • Incision inside eyelid or lateral approach
  • Access to optic nerve sheath
  • Small cuts made in sheath
  • Takes 1-2 hours

After Surgery

  • Eye may be patched initially
  • Antibiotic drops/ointment
  • Avoid straining
  • Usually outpatient

Outcomes

What It Helps

  • Stabilizes or improves vision
  • Protects optic nerve

What It Doesn't Help

  • Headaches (usually)
  • Papilledema in other eye (sometimes)

Risks

  • Double vision (temporary or permanent)
  • Vision loss (rare)
  • Pupil abnormality
  • Bleeding
  • Infection

Compared to Shunting

  • ONSF: treats eyes directly, not headaches
  • Shunt: treats entire system, helps headaches
  • Sometimes both needed
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