This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Lens, Subject name: Ophthalmology
All of the following are required for IOL power calculation before surgery except - 
Select and explain. 
A. Biometry, B. Keratometry, C. SRK Formula, D. Corneal topography
D: Corneal topography
Answer: D: Corneal topography 
Explanation: Intraocular lens power calculation :- Which requires Keratometry (K), Axial length of eyebal or Biometry (L) and aconstant (A). It is calculated by SRK formula:- Power of IOL = A-2*5L-0*9K (Ref: Fedorov SN, Kolinko AI. Estimaion of optical power of the intraocular lens. Vestn Oftalmol 1967; 80:27-31)