This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Cornea, Subject name: Ophthalmology
Ascorbic acid transpo in cornea is mediated by 
Select and explain. 
A. Carbonic anhydrase pump, B. Na K pump, C. Myoinositol pump, D. Passive diffusion
B: Na K pump
Answer: B: Na K pump 
Explanation: Metabolism of Cornea *Main Metabolic pathway: Aerobic *Ascorbic acid transpo: Na K ATPase > Myoinositol *Cornea becomes edematous due to lactate accumulation that happens during hypoxic conditions such as prolonged contact lens use. *Oxygen is derived from environment & glucose from aqueous humor. *Vitamins and amino acids are also provided by the limbal cappilaries