Understanding Your Glasses Prescription: How It Works, Explained Simply

Video Transcript

A glasses prescription can look like a wall of numbers and abbreviations. Each part has a simple meaning. First, the two rows. O D means the right eye and O S means the left eye. Some prescriptions simply say right and left instead. The sphere column is the main correction. A minus number corrects nearsightedness, and a plus number corrects farsightedness. The cylinder column is the amount of astigmatism, and the axis, from one to one hundred and eighty, describes the direction that correction sits at. The axis is only an orientation in degrees. A larger axis number does not mean worse vision. The add is extra focusing power for reading, used in bifocals and varifocals. It is usually the same in both eyes. Some prescriptions include prism, which shifts the image to help the two eyes work together. Most do not need it. A glasses prescription is not the same as a contact lens prescription, which needs its own fitting and measurements. Prescriptions also expire, since your eyes can change. This video is for general education only. It is not medical advice. Ask your eye doctor what's right for you.