Isolated capillary and cavernous hemangiomas of the bulbar conjunctiva are rare and are more likely to represent extension from adjacent structures. The palpebral conjunctiva is frequently involved with an eyelid capillary hemangioma. The presence of diffuse hemangiomatosis of the palpebral conjunctiva or conjunctival fornix indicates an orbital capillary hemangioma. A cavernous hemangioma of the orbit may present initially under the conjunctiva.
Nevus flammeus, a congenital lesion described as a port-wine stain, may occur alone or as part of Sturge-Weber syndrome, associated with vascular hamartomas, secondary glaucoma, and/or leptomeningeal angiomatosis. Some cases result from a genetic mutation coding for the vascular endothelial protein receptor for angiopoietin 1, which controls the assembly of perivascular smooth muscle. Ataxia-telangiectasia is a syndrome of epibulbar telangiectasis, cerebellar abnormalities, and immune alterations.