In an eye prescription, "SPH" stands for "sphere," and it represents how long or short-sighted a person is. The SPH value can be positive (+) for long-sightedness or negative (-) for short-sightedness. The higher the number, the stronger the prescription for correcting vision.
The SPH number on a glasses prescription is measured in diopters and indicates the amount of lens needed to bring the vision back to normal. A negative SPH number corrects for nearsightedness, while a positive SPH number indicates a prescription for farsightedness. If the SPH value is 0.00, or noted by Plano, Pl, or an infinity sign, it means that there is no vision distance problem.
In summary, SPH in an eye prescription indicates the spherical correction needed for vision and whether a person is nearsighted or farsighted.
