This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Diseases of Cornea, Subject name: Ophthalmology
Most common type of astigmatism in keratoconus is 
Select and explain. 
A. Simple myopia, B. Simple hypermetropia, C. Irregular astigmatism, D. Regular astigmatism
C: Irregular astigmatism
Answer: C: Irregular astigmatism 
Explanation: Keratoconus usually have irregular astigmatism * B/L Non inflammatory ectatic condition of cornea Clinical Presentation * Young females with constantly changing power of glasses with myopia & high cylinder and irregular astigmatism SIGNS IN KERATOCONUS Munson sign Enlarged corneal nerves Oil droplet reflex( on DDO) Rizutti sign Hydrops Fleischer ring