This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Cornea and sclera, Subject name: Ophthalmology
Corneal dystrophies are usually - 
Select and explain. 
A. Primarily unilateral, B. Primarily bilateral, C. c)Primarily unilateral without systemic disease, D. d) Primarily bilateral with systemic disease
B: Primarily bilateral
Answer: B: Primarily bilateral 
Explanation: Corneal dystrophies are inherited disorders in which the cells have some inborn defects due to which the pathological changes may occur with passage of time leading to development of corneal haze in otherwise normal eyes that are free from inflammation or vascularization.Dystrophies occur bilaterally manifesting occasionally at bih. REF:Comprehensive ophthalmology,AK Khurana,6th edition,pg no.124