A hairy eyeball tumor isn't the worst thing that can happen, believe it or not. Researchers at Tabriz University of Medical Sciences in Iran described the strange case of a 19-year-old man who was born with a limbal dermoid, the scientific name for the hairy eyeball tumor. Over time, the limbal dermoid expanded until it measured 5 mm in diameter, and yes, the tumor actually caused his eyeball to sprout hair, according to a surprising Jan 2, 2013 report from LiveScience via Yahoo! News.
Here's the good news about the teen's hairy eyeball tumor. It's benign, and doctors were able to remove it successfully. Furthermore, the removal of such tumors rarely causes loss of vision in patients. However, the condition sometimes causes astigmatism, which is characterized by blurred vision. The Iranian teen referenced by the Tabriz University of Medical Sciences did experience some vision loss with the tumor along with some mild discomfort.
Medscape Reference describes limbal dermoids as "benign congenital tumors that contain choristomatous tissue (tissue not found normally at that site). . . . they may contain a variety of histologically aberrant tissues, including epidermal appendages, connective tissue, skin, fat, sweat gland, lacrimal gland, muscle, teeth, cartilage, bone, vascular structures, and neurologic tissue, including the brain." Teeth? Bones? Although a hairy eyeball tumor doesn't sound particularly pleasant, they are rare enough that most doctors treat only one or two patients with the condition throughout their entire career.