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
Keratometer is used for ? 
Select and explain. 
A. Corneal thickness, B. Corneal diameter, C. Corneal curvature, D. Distance between cornea and pupil
C: Corneal curvature
Answer: C: Corneal curvature 
Explanation: Ans. is 'c' i.e., Corneal curvature