What is the reading prescription for a -4.25 sph with an add power of +2.00?

To determine the correct reading prescription for a patient with a distance prescription of -4.25 spherical and an add power of +2.00, it's essential to understand how the add power affects the distance prescription.

The add power is specifically intended for near vision tasks, helping to create a suitable reading prescription from an existing distance prescription. When you have a distance prescription of -4.25, it indicates that the patient requires a correction for distance vision. To find the reading prescription, you need to add the add power to the distance prescription because the add is a positive value meant to correct for near vision.

In this case, you would take the distance prescription of -4.25 and add the +2.00 from the add power. This calculation can be shown as follows:

-4.25 + 2.00 = -2.25 sph.

This result indicates that the patient’s reading prescription should be -2.25 spherical. The adjustment allows for clear vision at reading distances, acknowledging the added requirement for near vision due to presbyopia or other conditions.

The option indicating a reading prescription of -2.25 sph reflects the correct interplay between the original distance correction and the add power.