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 adult cornea: 
Select and explain. 
A. Diameter is 10 mm, B. Diameter is 12 mm, C. Diameter is 14 min, D. Microcornea-diameter < 10mm
D: Microcornea-diameter < 10mm
Answer: D: Microcornea-diameter < 10mm 
Explanation: D i.e. Microcornea - diameter less than 10 mm Horizontal diameter of cornea at bih is 10 mm and the adult size (11.7 mm) is attained by the age of 2 years. Megalocornea is labeled when the horizontal diameter of cornea is of adult size at bih or >13 mm after the age of two yearsQ. In microcornea horizontal diameter is < 10 mm since bihQ (or < 11mm in greatest dimension. Anatomical dimensions of Cornea Corneal diameter (mm) Radium of curvature (mm) Horizontal Veical Anterior surface Posterior surface 11.7 11.7 10.6 11.7 7.8 6.5 Corneal thickness Central Peripheral 0.5 - 0.6 1.2