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
True about anatomy of adult cornea –a) Horizontal diameter is 12 mmb) Horizontal diameter is 10 mmc) In megalocornea diameter is > 12mmd) In microcornea diameter < 10mme) Vertical diameter > Horizontal diameter 
Select and explain. 
A. b, B. ad, C. ac, D. ab
B: ad
Answer: B: ad 
Explanation: Anterior and posterior surfaces have same horizontal (transverse) diameter 11.7 (;12) mm, while the vertical diameter of anterior surface (10.6 mm) is about 1 mm less than the posterior surface (11.7 mm).
In micro cornea diameter is <10 mm and in mega cornea diameter is >13 mm