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
Which of the following is the least common corneal dystrophy - 
Select and explain. 
A. Macular dystrophy, B. Lattice type I, C. Lattice type III, D. Granular corneal dystrophy
A: Macular dystrophy
Answer: A: Macular dystrophy 
Explanation: Macula corneal dystrophy is an autosomal recessive dystrophy characterised by appearance of dense grey opacity in the central cornea. The condition results due to accumulation of mucopolysaccharides owing to a local enzyme deficiency. It occurs in childhood (5 to 10 years) and leads to marked defective vision in early life, which usually requires penetrating keratoplasty.Reference:Comprehensive ophthalmology,AK Khurana,4th edition,page no.118