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
[{'content': "Percentage of endothelial cell loss during Descent's membrane stripping in automated penetrating keratoplasty \nSelect and explain. \nA. 0-5%, B. 10-15%, C. 30-40%, D. 50-60%", 'role': 'user'}, {'content': 'Answer: C \nExplanation: C i.e. 30-40% The incidence of endothelial cell loss in donor tissue of Descemet stripping endothelial keratolplasty is nearly 36%, mainly in the central area of graft. Compared with penetrating keratoplasty, EK involves more donor-tissue manipulation including lamellar dissection and folding, which could potentially damage donor endothelium. On the other hand EK grafts are usually larger (8-9 mm diameter compared with typical PK diameter of 7 - 8mm) and provide a larger reservoir of healthy donor endothelium. However, several recent repos suggest that endothelial cell loss in first few years after EK is similar to that experienced after PK.', 'role': 'assistant'}]