What should one look for in a patient's prescription to identify presbyopia?

To identify presbyopia in a patient's prescription, one should look for the presence of ADD power. Presbyopia is a condition commonly associated with aging where the eye's ability to focus on near objects decreases due to a loss of elasticity in the lens. In the case of individuals with presbyopia, eye care professionals often prescribe a bifocal or multifocal lens, which necessitates the addition of an "ADD" power for near vision.

The ADD power indicates the additional magnification needed for reading or other close work, which helps compensate for the reduced near vision associated with presbyopia. Thus, when reviewing a prescription, the presence of ADD power is a clear indicator that the patient is experiencing difficulties focusing on close objects, characteristic of presbyopia.

On the other hand, the presence of a cylinder and axis refers to astigmatism correction, while plus sphere power might be common in hyperopic prescriptions but does not specifically indicate presbyopia. Lastly, zero power readings do not provide any relevant information about the focusing ability at different distances. Therefore, the ADD power is the most defining characteristic for identifying presbyopia.