![]() ![]() There may be other notes on your prescription related to lens design or coatings that your optometrist has specifically recommended to give you the most comfortable vision correction possible. PD also stands for interpupillary distance, the distance from the centre of one eye to the centre of the other eye when measured with the eyes gazing to the distance the prescription was intended for. This may or may not be included on your written prescription. ![]() If you require a different prescription for near vision, this can be noted in two ways: another full listing of SPH, CYL, AXIS or a correction factor called ADD, which refers to the distance a prescription should be changed to achieve the near prescription.Ī small percentage of prescriptions incorporate prism as a way to aid the eyes working together, or to assist in rehabilitation. This number is measured in prism dioptres, or PD, and would be followed by the direction of the base or thickest edge of the prism: BU= base up, BD=base down, BI=base in (toward the nose), and BO=base out (toward the ear). Next up, the numbers. The first number in a prescription is the spherical correction, often abbreviated as SPH. This is a measure (in dioptres) of how powerful the lens needs to be to correct either nearsightedness (noted with a - ) or farsightedness (noted with a + ). The second number is the cylindrical correction. This will only be on a prescription if you have astigmatism. If you do have astigmatism, it requires what is referred to as a cylindrical correction, another term provided on the written prescription. It is not uncommon for the numbers for the right eye to be quite different to the number for the left eye in fact this is the norm. B: As we get older, our eyes lose flexibility and can no longer focus on near objects without readers, bifocals or prescription eyeglasses with appropriate diopter strength lenses. These are Latin abbreviations for the terms oculus dextrus, meaning right eye, and oculus. Other lens recommendations Your eyeglass prescription might also include. First, notice the letters OD and OS on your eyeglass prescription. ![]() The first abbreviations you will notice are the letters OD and OS. These are derived from Latin for Oculus Dexter (OD) for right eye and Oculus Sinister (OS) for left eye. Occasionally, there may be the abbreviation OU, oculus uterque, for both eyes. A: Younger, more flexible eyes can adjust to focus on both near and far objects. What does SPH mean on my glasses prescription The SPH on your glasses prescription stands for sphere. An eye prescription specifies the values needed for your corrective eyewear. The type of Rx glasses may be noted on a prescription, such as DV Distance Vision/nearsightedness and NV Near Vision/reading. Your prescription will indicate how severe your astigmatism is and where the irregular curve appears on your eye. Each optometrist will have their own format for writing a prescription so yours may not look exactly like the one pictured, but all the same information should be there, beginning with your name. ![]()
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