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
If the axial length of the eyeball is changed by 1 mm then the power changes by – 
Select and explain. 
A. 1 diopter, B. 2D, C. 3D, D. 4D
C: 3D
Answer: C: 3D 
Explanation: 1 mm change in axial length leads to ametropia of 3D.