What do the "SPH" measurements in a contact lens prescription indicate?

The "SPH" measurements in a contact lens prescription refer to the spherical power needed to correct refractive errors such as hyperopia (farsightedness) or myopia (nearsightedness). This value is crucial as it indicates how strong the lens needs to be to help the eye focus light correctly on the retina, allowing for clear vision.

In a prescription, positive SPH values signify the power needed for hyperopia, while negative SPH values indicate the power needed for myopia. This measure is essential for tailoring contact lenses to the specific visual needs of the patient, ensuring optimal vision correction.