Which of the following is the least common stromal type of corneal dystrophy?
High-Yield Explanation
Among the options given in the question, macular dystrophy is least common type of stromal corneal dystrophy. It is an autosomal recessive disorder which occur due to a systemic inborn error in keratan sulphate metabolism. It is fuher classified into three types namely type I, I A, II depending on the presence or absence of keratan sulphate in the serum and cornea. It occur in children and they usually present with defective vision in early life. Normally, the principal glycosaminoglycans in the cornea are keratan sulphate and dermatan sulphate. They play a in corneal hydration and has a substantial role in maintaining the homeostasis of the cornea. Ref: Ocular Periphery and Disorders By Darlene A. Da, Page 230; Ophthalmology By A.K Khurana, 4th Edition, Page 117-8; The Biology of the Eye By Jorge Fischbarg, 2006, Page 94; Cornea By Edward J. Holland, 2005, Page 907