This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Ophthalmology
Pterygium is: 
Select and explain. 
A. Vascular anomaly, B. Connective tissue proliferation, C. Inflammatory condition, D. Associated with Vit. A deficiency
B: Connective tissue proliferation
Answer: B: Connective tissue proliferation 
Explanation: A pterygium is a proliferation of fibrovascular tissue on the surface of the eye, which extends onto the cornea. The etiology of pterygium is incompletely understood. However, chronic UV exposure is accepted as a causative agent. Treatment options: Pterygia are usually treated only when they interfere with vision. The standard therapy is surgical removal. Pterygia affect astigmatism and are associated with increased rates of macular degeneration; however, it is unclear whether treatment reduces this risk. Eyes with a pterygium or previous pterygium surgery (but not pinguecula) have a higher risk of incident late age-related maculopathy (ARM) (OR 3.3, 95% CI 1.1-10.3) and early ARM (OR 1.8, 95% CI 1.1-2.9). Ref: Chumley H. (2009). Chapter 11. Pterygium. In R.P. Usatine, M.A. Smith, H. Chumley, E. Mayeaux, Jr., J. Tysinger (Eds), The Color Atlas of Family Medicine.