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
Fleischer ring is characteristic of – 
Select and explain. 
A. Megalocornea, B. Diabetes, C. Chalcosis, D. Keratoconus
D: Keratoconus
Answer: D: Keratoconus 
Explanation: Some guides have also given option c as the answer, which is incorrect.
Some confusion exists between Fleisher rings and kisser- Fleischer (KF) ring. Kayser- Fleischer(KF) rings are caused by copper deposits and are indicative of Wilson's disease, whereas Fleischer rings are caused by iron deposits and are indicative of keratoconus.
Cornea is thin (not thick).
Rigid gas permeable contact lenses (not soft contact lenses) are used.