What is the SPH value on an eyeglass prescription?
Introduction
When you get an eye exam, the doctor will give you a prescription for eyeglasses or contact lenses. This prescription will include several different measurements, including the SPH value. The SPH value is a measure of the spherical power of the lens that you need to correct your vision. Spherical power is measured in diopters (D). A positive SPH value indicates that you are farsighted, while a negative SPH value indicates that you are nearsighted.
Understanding SPH values
The SPH value is the most important measurement on your eyeglass prescription. It determines the strength of the lens that you need to correct your vision. The higher the SPH value, the stronger the lens will be. The lower the SPH value, the weaker the lens will be.
If you are farsighted, you have difficulty seeing objects that are close to you. A positive SPH value will correct your vision by focusing light on the retina, the light-sensitive tissue at the back of the eye. If you are nearsighted, you have difficulty seeing objects that are far away. A negative SPH value will correct your vision by focusing light in front of the retina.
Other measurements on an eyeglass prescription
In addition to the SPH value, your eyeglass prescription may also include other measurements, such as the CYL value, the AXIS value, and the ADD value. The CYL value measures the amount of astigmatism that you have. Astigmatism is a condition in which the cornea is not perfectly round. This can cause blurred vision at all distances.
The AXIS value measures the direction of the astigmatism. The ADD value measures the amount of magnification that you need for reading or other close-up work. If you are over the age of 40, you may need bifocals or progressive lenses to correct your vision for both distance and near vision.
What Is Sph In Eye Prescription
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