Axenfeld Nerve Loop

From EyeWiki

Axenfeld Nerve Loop
An emissary canal through the sclera with Axenfeld nerve loop (arrowhead), which is overlying the pars plana (arrows) (trichrome stain). (Courtesy of Harry H. Brown, MD.[1]

Axenfeld Nerve Loop


  • Intrascleral nerve loops were first described by Axenfeld in 1902[2]. They are a common, incidental finding on slit lamp examination. It is important to recognize this entity as they may be mistaken for intrascleral foreign bodies.

Detailed Description

The term “Axenfeld Nerve Loop” is used to describe intrascleral nerve loops of the long, posterior, ciliary nerves. The ciliary nerve pierces the sclera near the optic nerve and travels within the sclera and suprachoroidal space until it branches at the level of the ciliary body[2]. The nerve loop is an anastomosis of the long ciliary nerve that turns to enter the sclera before turning back again to continue to the ciliary body[3]. The examiner may elicit pain if the loop or overlying conjunctiva are manipulated – as is common when probing for traumatic injury. The loop commonly appears as a grey, white nodule under the bulbar conjunctiva. It may be surrounded by pigment, especially in those with a darker iris. They are typically found a constant distance from the corneoscleral junction, usually within 3-4 mm of the limbus.

Epidemiology/Risk Factors

  • None


  • Pathologic examination would reveal findings consistent with a peripheral nerve.

Differential Diagnosis

  • Nevi
  • Malignant Melanoma
  • Cysts
  • Scleral Foreign Bodies


  • No therapy is needed – this is a natural, anatomic landmark. Several cases have been reported of anterior nerve sheath tumors arising from intrascleral nerve loops[4].


  • Very good.


  1. American Academy of Ophthalmology. Stroma. Accessed Deceneber 3, 2021.
  2. 2.0 2.1 Axenfeld UMT: Ueber intrasklerale. Nevenschleifen. Ber Dtsch Ophthalmol. Ges 30: 134-137, 1902.
  3. Reese AB. Intrascleral nerve loops. Trans Am Ophthalmol Soc. 1931; 29: 148-153.
  4. Chang, Glasgow. Evidence that Anterior Eiscleral Nerve Sheath Tumors Arise From the Axenfeld Nerve Loop. Archives of Ophthalmology 127 (8): 1060. August 2009.
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