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
Band-shaped keratopathy is caused by – 
Select and explain. 
A. Amyloid, B. Calcium, C. Monopolysaccharide, D. Lipid
B: Calcium
Answer: B: Calcium 
Explanation: Band keratopathy is characterized by the deposition of calcium salts in a band-like pattern in the anterior layers of the cornea.