You refract a patient and their prescription is -2.00 -1.00 x 180. What is the spherical equivalent of this prescription?
Contact Lenses
No
U
C
The spherical equivalent is calculated by taking the sphere and adding 1/2 of the cylinder to the sphere. In this example, the calculation would be: -2.00 + 1/2(-1.00) = -2.50. This is relevant for contact lens fitting because if you are fitting a soft spherical contact lens, you want to start with the power of the lens being the spherical equivalent.
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