Optic Pits

From EyeWiki



Optic Pits
Classification and external resources
Optic pits: Color fundus photo and corresponding SD-OCT image

Optic pits: Color fundus photo and corresponding SD-OCT image

OMIM 120430
DiseasesDB 31315


Optic Pits (also known as optic nerve pits, optic disc pits, or less commonly optic holes) are congenital defects presumably arising from the failure of fetal fissure closure in embryogenesis.

Disease Entity

History

Wiethe first described the clinical presentation of two optic disc depressions in a 62-year-old female patient in 1882; this entity was later termed “optic disc pit.” Other abnormalities such as nerve head coloboma and enlarged optic nerve head may be seen with the pits.

Etiology

Etiology of optic disc pits is unclear. Congenital optic pits are thought to result from an imperfect closure of the superior edge of the embryonic fissure. Histologically, herniation of a dysplastic retina into the subarachnoid space through a defect in the lamina cribrosa at the pit has also been described.

Risk Factors

Optic pits are rare, occurring in about 1 in 10,000 people with no gender predilection. They can be diagnosed in children or adults. There are no known risk factors. It has been suggested that unilateral pits may be inherited in an autosomal dominant fashion.

Pathophysiology

Pathophysiology of optic disc pits is unclear. Some hypothesize that they occur due to incomplete closure of the optic fissure resulting in a microcommunication between the subarachnoid space and the pit. The communication of Optic Pits and Cerebral Spinal Fluid (CSF) is controversial and Beta-2 Transferrin levels (typically used for CSF detection in leaks from skull fractures) of submacular fluid associated with optic pits has been variable. Many believe that pits are not colobomas. Pits are usually not found close to the optic fissure and are more unilateral than bilateral and only rarely seen with iris or choroidal colobomas. Absence of lamina cribrosa is noted at the site of the pit. Closed optic nerve pits can be associated with meningeal cysts.

Primary prevention

Optic pit formation occurs in utero and there is no known primary prevention.

Diagnosis

The diagnosis of an optic pit is based on morphology of the nerve and is observed via clinical examination. They are usually unilateral, though 10-15% are bilateral. Usually there is only one pit per disc, however, two to three pits have been described in the same optic nerve.

History

Patients are generally asymptomatic and findings are usually incidentally found on routine exam. However, patients may complain of metamophopsia, micropsia, blurred or decreased vision, or a blind spot if the optic pit is associated with a serous detachment.

Physical examination

Optic pits are generally found inferotemporally within the nerve, though up to one-third are central. They appear as a round or oval depression that differs in color from the surrounding disc (grey, yellow or black). The color variation depends on the amount and location of glial tissue in the pit. The size can vary from 0.1-0.7 disc diameters and the depth from 0.3-0.5 diopters. There may associated macular edema, serous macular detachment; schisis or pigmentary changes in the macula.

Signs

A pit can be seen with direct or indirect ophthalmoscopy. For detailed evaluation, slit lamp biomicroscopic binocular examination should be performed.

Symptoms

Pits are often asymptomatic though they can be associated with vision loss from a secondary serous retinal detachment (sometimes referred to as Optic Disc Pit Maculopathy). Occasionally, visual field deficits, arcuate scotoma or an enlarged blind spot, can be detected on perimetry.

Shallow serous macular detachments can be seen in upto three-fourths of eyes with inferotemporal pits. They usually become symptomatic in the 3rd or 4th decade of life though reports in children have been described.

The source of the retinal fluid in optic disc pit maculopathy is controversial; the reports in literature describe it to be vitreous, cerebrospinal fluid, and even in some cases fluid from blood vessels in the pit.

Diagnostic procedures

Spectral-domain optical coherence tomography (SD-OCT) can be used to determine if trace amounts of subretinal fluid exists when it is not apparent clinically. OCT of an optic pit may show a schisis-like separation between the inner and outer retina.

Visual field testing can show an enlarged blind spot as well as a relative central scotoma in the presence of a serous detachment.

Fluorescein Angiography (IVFA) is not particularly useful in diagnosing optic pits though it may be helpful in eliminating other diseases in the differential of serous detachment.

An Amsler grid can be used to monitor the onset of macular involvement of an optic pit with serous detachment.

Laboratory test

The diagnosis of an optic pit is clinical. Though no laboratory test exisits there are studies in progress looking at genetic markers.

Differential diagnosis

Optic nerve coloboma, choroidal and scleral crescent, tilted disc syndrome, circumpapillary staphyloma, hypoplastic disc, and glaucomatous optic neuropathy (which may also lead to a pseudopit). Idiopathic central serous retinopathy and subretinal neovascular membrane are among alternative considerations for serous retinal detachment involving the macula.

Management

No treatment is required for an isolated optic pit.

Medical therapy

There is no medical therapy that is indicated for this structural defect.

Laser and surgical therapy

It may be possible to repair a serous detachment when associated with a pit. Techniques include laser photocoagulation, which can be applied to the temporal margin of the optic disc in the effort to disrupt the communication between the source (the optic pit) and the collection of fluid under the macula.

Pars plana vitrectomy (PPV) with posterior vitreous detachment with gas tamponade (using gases such as C3F8 or SF6) may be used to treat serous detachment associated with an optic pit. Successful macular reattachment leading to possible improved central vision can be achieved using vitrectomy. The purpose of this is to induce a posterior vitreous detachment (PVD) and help remove vitreous traction. Peeling of the internal limiting membrane may also be employed in addition to removing the vitreous for relieving all tractional components along with peeling of glial tissue in the pit. Use of peri-papillary laser during vitrectomy is controversial. Anatomic success has been reported with or without it.

Another surgical technique is macular buckling. This type of posterior scleral buckle is placed when the pathology only involves macula. Though less commonly used, it is an option for repair that may obviate the lens changes associated with pars plana vitrectomy, and may be considered in younger, phakic patients. More recently, peri-papillary retinotomy. A recently described technique, limited PPV with intraretinal fenestration temporal to the pit has had promising results.

Complications

Given the proximity to the optic nerve and macula, great care must be taken during photocoaguation.

Prognosis

Isolated optic pits have an excellent prognosis and usually have no sequelae. It is unclear how many optic pits develop serous detachments as these instances are symptomatic and therefore seek out the care of an ophthalmologist more frequently than those asymptomatic (reports of up to 50% of cases are from retrospective reviews and most likely subject to selection bias). The visual recovery of a serous detachment from an optic pit is dependent on the chronicity of the detachment and success of the repair. Some serous collections, when associated with traction, may resolve without treatment if the traction resolves (for example with formation of a complete, spontaneous PVD.

Additional Resources

References

  1. Annesley, W, Brown, G, Bolling, J, Goldberg, R, Fischer, D. “Treatment of retinal detachment with congenital optic pit by krypton laser photocoagulation.” Graefe's Archive for Clinical and Experimental Ophthalmology 1987; 225:5.
  2. Brown, G, Tasman, W. Congenital anomalies of the optic disc. Grune & Stratton, New York 1983, p. 31.
  3. Brown, GC, Shields, JA, Goldberg, RE. “Congenital pits of the optic nerve head.” Clinical studies in humans. Ophthalmology 1980; 87:51.
  4. Creel, D. “Clinical Electrophysiology.” http://retina.umh.es/Webvision/ClinicalERG.html
  5. Ferry, AP. “Macular detachment associated with congenital pit of the optic nerve head.” Arch Ophthalmol 1963; 70:346.
  6. Hirakata A, Okada AA, Hida T. “Long-term results of vitrectomy without laser treatment for macular detachment associated with an optic disc pit.” Ophthalmology. 2005 Aug;112(8):1430-5.
  7. Magli A, Greco A, Alfieri MC, Pignalosa B. “Hereditary colobomatous anomalies of the optic nerve head.” Ophthalmic Paediatr Genet. 1986 Aug;7(2):127-30.
  8. Ooto S, Mittra RA, Ridley ME, Spaide RF. Vitrectomy with inner retinal fenestration for optic disc pit maculopathy. Ophthalmology. 2014
  9. Park SC, De Moraes CG, Teng CC, Tello C, Liebmann JM, Ritch R. “Enhanced depth imaging optical coherence tomography of deep optic nerve complex structures in glaucoma.” Ophthalmology. 2012 Jan;119(1):3-9.
  10. Reed D. (1999) Congenital pits of the optic nerve. Clin Eye Vis Care. 1999 11(2):75–80.
  11. Sadun, AA. “Optic Disc Pits and Associated Serous Macular Detachment.” Medical Retina 4th Ed., 2005, Chapter 111.
  12. Slusher MM, Weaver RG Jr, Greven CM, Mundorf TK, Cashwell LF. “The spectrum of cavitary optic disc anomalies in a family.” Ophthalmology. 1989 Mar;96(3):342-7.
  13. Stefko ST, Campochiaro P, Wang P, Li Y, Zhu D, Traboulsi EI. Dominant inheritance of optic pits. Am J Ophthalmol 1997; 124(1):112–113.
  14. Theodossiadis GP, Theodossiadis PG. “Optical coherence tomography in optic disk pit maculopathy treated by the macular buckling procedure.” Am J Ophthalmol. 2001 Aug; 132(2):184-90.
  15. Theodossiadis GP, Theodossiadis PG. “The macular buckling procedure in the treatment of retinal detachment in highly myopic eyes with macular hole and posterior staphyloma: mean follow-up of 15 years.” Ophthalmology. 2005 Aug; 112(8):1430-5.
  16. Wiethe T. Ein fall von angeborener deformität der sehnervenpapille. Arch Augenheilkd. 1882;11:14-19.