What Does SPH Mean on an Eyeglass Prescription?
SPH, short for sphere, is the main correction in your glasses. It tells the lab how much power your lens needs to focus light correctly.
Minus numbers: nearsighted
A negative SPH (for example −1.50) corrects myopia. Distant things look blurry; close things look sharp. The bigger the number, the stronger the correction.
Plus numbers: farsighted
A positive SPH (for example +1.25) corrects hyperopia. Close things are harder to focus, and your eyes may feel tired when reading.
How strong is my prescription?
As a general guide: up to ±2.00 is mild, ±2.25 to ±5.00 is moderate, and above ±5.00 is strong. Strong prescriptions benefit from thinner lens materials.
Units
SPH is measured in diopters and changes in steps of 0.25.
Frequently asked questions
Can SPH be different in each eye?
Yes, it is very common to have a different power in each eye.
What if SPH says 0.00 or plano?
That eye needs no sphere correction, although it may still have CYL for astigmatism.
Related guides
This guide is for information only and does not replace an eye exam. If you have eye pain, sudden vision loss or flashes of light, see a doctor right away.