What makes a prescription? If the eye were a perfect sphere then all we would need to correct vision would be a sphere lens. Though there are many people who can be corrected with a sphere lens many patients require a spherocylindrical lens because they have astigmatism. A spherocylindrical lens is made up of sphere power and cylinder power. Optometrists and ophthalmologists think of spherocylindrical lenses differently. Ophthalmologists think of adding the sphere and the cylinder.

What makes a prescription? If the eye were a perfect sphere then all we would need to correct vision would be a sphere lens. Though there are many people who can be corrected with a sphere lens many patients require a spherocylindrical lens because they have astigmatism. A spherocylindrical lens is made up of sphere power and cylinder power.   Optometrists and ophthalmologists think of spherocylindrical lenses differently. Ophthalmologists think of adding the sphere and the cylinder.