Coloboma is collective term encompassing any focal discontinuity in the structure of the eye, and should not be confused with staphylomas, which are due to choroidal thinning.
Most commonly colobomas are due to failure of closure of the choroidal fissure posteriorly. Typically colobomas are bilateral, small and are not accompanied by other deeper abnormalities. It occurs along the inferomedial aspect of the globe and optic nerve 2.
- CHARGE syndrome
- agenesis of the corpus callosum
- Jacobsen syndrome
- Treacher-Collins syndrome: rare
- Roberts syndrome: rare
- Gorlin-Goltz syndrome: rare
- morning glory syndrome: optic nerve head coloboma with associated midline structural abnormalities of the brain and skull
- coloboma with a cyst (microphthalmia with cyst): results from the proliferation of the embryonic retina with potential extrusion of the vitreous posteriorly into the cyst (thus microphthalmia). The cyst may become discontinuous from the eye, be larger than the eye, and may cause proptosis
On CT or MRI, the affected globe is usually small 2 with a focal posterior defect in the globe with vitreous herniation 3. A retrobulbar fluid-density cyst may be present 3.
- 1. Barkovich AJ. Pediatric neuroimaging. Lippincott Williams & Wilkins. (2005) ISBN:0781757665. Read it at Google Books - Find it at Amazon
- 3. Harnsberger HR, Glastonbury CM, Michel MA et-al. Diagnostic Imaging: Head and Neck. Lippincott Williams & Wilkins. (2010) ISBN:1931884781. Read it at Google Books - Find it at Amazon
- Haaga JR, Boll D. CT and MRI of the whole body. Mosby. (2009) ISBN:0323053750. Read it at Google Books - Find it at Amazon