THE CLEAR VISION GUIDE

Read your glasses prescription without guessing

A guide to SPH, CYL, AXIS, ADD and the fitting measurements recorded alongside them.

Clear Lens editorial · Source-based explainer ·

Keep the signs and units

SPH and CYL are lens powers in dioptres; AXIS specifies cylinder orientation in degrees. ADD records additional near power when prescribed. Copy every sign exactly rather than converting a prescription yourself.

Separate prescription and fitting

PD and fitting height help position lenses in the chosen frame. Ask your dispenser to explain whether PD is recorded for each eye or as a total. A glasses prescription is not a contact lens prescription.

Sources & verification

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