What is Sturm's Conoid?

Ans. is 'a' i.e., Distance between two focal points created by differential refractive power of lens or cornea in different meridians o Sturm's Conoid:# It is an optical condition in which the refractive power of lens or cornea is not the same in all meridians, hence two focal points separated by a focal interval are formed which is called the Sturm's Conoid.o Etiology:A) Corneal Causes:# Astigmatism# KeratoconusB) Lenticular Causes:# Lenticonus# Congenital tilting of lens# Index astigmatism