<prompt> What is Sturms Conoid?Distance between two focal points created by differential refractive power of lens or cornea in different meridians.Pattern of alignment of rays due to a cylindrical lensMethod of calculating IOL powerTool in Diagnosis of Myopia  <response>: Ans. is a i.e., Distance between two focal points created by differential refractive power of lens or cornea in different meridians o Sturms 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 Sturms Conoid.o Etiology:A Corneal Causes: Astigmatism KeratoconusB Lenticular Causes: Lenticonus Congenital tilting of lens Index astigmatism 