You have a patient come in for a contact lens fitting. The patient's refraction is -1.00 -0.50 x 180 in both eyes. Which of the following would be the best fit for the patient?
Contact Lenses
No
U
C
The patient in this example has a low prescription with low astigmatism. Often it is best to try just a spherical contact lens and see how the vision will do. Toric lenses work well but are more difficult to fit than spherical contact lenses and are also more expensive. If you are trying a spherical contact lens, you want to a contact lens with a power equal to the spherical equivalent of the prescription. The spherical equivalent is calculated by taking the sphere and adding 1/2 of the cylinder to the sphere. In this case, it would be -1.00 + 1/2 (-0.50) = -1.25. You should try this lens on the patient and test their vision. You also want to over-refract the patient. If the patient likes the vision with the spherical contact lens, you can go with this lens. If the patient thinks that there is a definite improvement with the over-refraction (that includes the astigmatism), you could consider trying the patient in a toric soft contact lens.
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