Optic Pit

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Optic Nerve Pit

Overview:

Optic Nerve Pits were first described in 1882 by Wiethe[1]. Since this time, they have typically been an incidental finding on routine dilated fundus exam. Rarely, they may cause visual field defects or macular changes.

Detailed Description:

A optic nerve pit usually presents itself as a unilateral, solitary, ovoid, grey-white excavation of the optic disc most commonly in the inferotemporal quadrant of the nerve head. 15% of optic nerve pits are thought to occur bilaterally. They may cause arcuate field defects or enlarged blind spot. Vision is typically not affected unless macular involvement is present, either by a serous retinal detachment or cystoid macular edema1. Patients with optic disc pit maculopathy typically initially notice a drop in visual acuity to 20/70 in the affected eye[1].

Epidemiology/Risk Factors:

Optic nerve pits are a rare entity. It is estimated that 1 out of 11,000 thousand people are affected. An even smaller percentage, between 25-75% experience visual symptoms or deterioration[1]. They are thought to occur sporadically. Men and women are affected equally.

Etiology/Pathophysiology:

Optic pits are thought to be a result of incomplete closure of the superior edge of the embryonic fissure[2]. This has been the subject of some debate in the literature. The mechanisms of subretinal fluid accumulation in optic disc pit maculopathy are not well understood. It is thought the fluid may arise from the vitreous cavity, leaking vessels at the base of the pit, the orbital space surrounding the dura, or cerebrospinal fluid from the subarachnoid space[1].

Histopathology:

On microscopic examination, there is usually herniation of the surrounding retina and fibrous tissue into the meninges and adjacent optic nerve.

Differential Diagnosis:

  • Other optic disc anomalies
  • Tilted Discs
  • Scleral Crescent
  • Hypoplastic Disc
  • Glaucomatous disc cupping
  • Central Serous Retinopathy (in the case of optic nerve pit maculopathy)
  • Circumpapillary Staphyloma
  • Nerve head coloboma
  • Morning Glory Anomaly

Management/Treatment:

Should the macula be affected, the treatment is usually surgical. Most commonly, a pars plana vitrectomy is performed, with or without internal limiting membrane peel, with or without endolaser, and gas tamponade.

Prognosis:

Good to poor depending on clinical findings. Asymptomatic optic nerve pits carry a favorable prognosis. Should a patient develop optic disc maculopathy, 80% will progress to a visual acuity of 20/200 or worse. Favorable anatomic and functional results have been reported after surgery with an 87% success rate reported recently in the literature.

Additional Resources

References:

  1. 1.0 1.1 1.2 1.3 Optic disc pit: a review. Source: Graefe's archive for clinical and experimental ophthalmology [0721-832X] Georgalas, Ilias yr:2011 vol:249 iss:8 pg:1113 -1122.
  2. Reed D. Congenital pits of the optic nerve. Clin Eye Vis Care 11 (2): 75-80.
  1. Sandali, Barale, Bui, Belghiti, Borderie, Laroche, Sahel, Monin. Long term results of the treatment of optic disc pit associated with serous macular detachment: a review of 20 cases. J Fr Ophthalmol. 2011 Oct; 34 (8): 532-8.