Disc Coloboma

BASICS


DESCRIPTION


• Well defined, white bowl-shaped excavation inferiorly displaced in an enlarged optic disc


• Excavation location reflects position of the embryonic fissure relative to the primitive epithelial papilla


• More involved cases appear as enlargement of the peripapillary area with a deep, central excavation lined by glistening white tissue


• Superior disc typically spared, but occasional involvement of the entire disc occurs


• Defect can extend into the adjacent inferior and nasal choroid and retina


• Iris and ciliary body colobomas can coexist


• Visual acuity is primarily dependent upon integrity of the papillomacular bundle; may be mildly-to-severely decreased


• Visual acuity difficult to predict based on appearance of the disc


• Occur unilaterally and bilaterally with approximately equal frequency


• Occasional orbital cysts can occur with possible communication between the cyst and the excavation


RISK FACTORS


Genetics


• Can be accompanied by CHARGE association (CHD7)


• May arise sporadically or be inherited in an autosomal dominant pattern


GENERAL PREVENTION


Possible genetic counseling and/or prenatal testing (if mutated gene known or syndrome recognized in family)


PATHOPHYSIOLOGY


Neuroimaging demonstrates a crater-like excavation of the posterior globe at its junction with the optic nerve


ETIOLOGY


Thought to result from incomplete or abnormal coaptation of the proximal end of the embryonic fissure


COMMONLY ASSOCIATED CONDITIONS


May be accompanied by multiple systemic conditions such as:


• CHARGE Association


• Walker-Warburg Syndrome


• Goltz Focal Dermal Hypoplasia


• Aicardi Syndrome


• Goldenhar Sequence


• Linear Sebaceous Nevus Syndrome


• Increased risk of acquired visual loss through serous retinal detachment in cases of isolated optic nerve coloboma (versus the typical rhegmatogenous retinal detachments seen in chorioretinal coloboma)


• Microphthalmia may also be present in cases with coexistent chorioretinal involvement


DIAGNOSIS


HISTORY


Congenital defect


PHYSICAL EXAM


• Full ocular examination including careful evaluation of the optic discs and evaluation for concomitant treatable amblyopia


• Systemic examination for other anomalies


DIAGNOSTIC TESTS & INTERPRETATION


Lab


Initial lab tests

None unless associated systemic abnormalities exist


Follow-Up & Special Considerations

Significant risk of acquired visual loss through retinal detachment dictates regular follow up with careful retinal evaluation.


Pathological Findings


Presence of intrascleral smooth muscle oriented concentrically around the distal optic nerve.


DIFFERENTIAL DIAGNOSIS


• Morning Glory Disc Anomaly (funnel-shaped excavation of the posterior fundus that incorporates the optic disc)


• Peripapillary staphyloma (relatively normal appearing disc located in a recess peripapillary excavation)


TREATMENT


MEDICATION


No medical treatment for the primary disorder


ADDITIONAL TREATMENT


General Measures


Impact resistant glasses for protection of the non-involved eye if subnormal visual acuity is demonstrated or suspected in the involved eye, or in cases of bilateral involvement.


Issues for Referral


• Low vision evaluation and support as indicated in cases with significant bilateral involvement


• Retinal surgery for detachment


COMPLEMENTARY & ALTERNATIVE THERAPIES


None proven or indicated


SURGERY/OTHER PROCEDURES


• Amblyopia therapy and strabismus surgery as indicated


• Retinal detachment surgery as indicated


ONGOING CARE


FOLLOW-UP RECOMMENDATIONS


• Regular follow-ups to monitor for evidence of retinal detachment


• As needed for amblyopia and strabismus monitoring and treatment


• Low vision care


Patient Monitoring


• Patient concerns about appearance if significant strabismus is present


• Monitor for possible development of acquired loss of vision from retinal detachment


PATIENT EDUCATION


• Possible genetic counseling in cases with family history of the condition


• Low vision intervention in patients with significant bilateral involvement


PROGNOSIS


• Broad range of best corrected visual acuity


• Relatively high risk of subsequent retinal detachment


COMPLICATIONS


Retinal detachment


ADDITIONAL READING


• Brodsky MC, Baker RS, Hamed LM. Pediatric Neuro-Ophthalmology. New York: Springer, 1996:53–55.


• Brown G, Tasman W. Congenital Anomalies of the Optic Disc. New York: Grune & Stratton, 1983:128–141.


• Nucci P, Mets MB, Gabianelli EB. Trisomy 4q with morning glory disc anomaly. Ophthalmic Paediatr Genet 1990;11(2):143–145.


• Pollack S. The Morning glory disc anomaly; contractile movement, classification, and embryogenesis. Doc Ophthalmol 1987;65: 439–460.


CODES


ICD9


377.23 Coloboma of optic disc


CLINICAL PEARLS


• Work to maximize visual potential, especially in bilateral cases. Difficult to predict eventual best corrected visual acuity based on the appearance of the optic disc.


• Use of a high plus lens to equalize the image size of the iris through spectacle lenses can help to provide a more normal appearance in patients with associated microphthalmia.


• Major ophthalmic concerns include protecting the better seeing eye, monitoring the involved eye for possible treatable overlying amblyopia and strabismus, and monitoring for acquired loss of vision in the involved eye from retinal detachment.


• Significant associated systemic abnormalities include CHARGE association.


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Nov 9, 2016 | Posted by in OPHTHALMOLOGY | Comments Off on Disc Coloboma

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