Eyeglass and contact lenses prescriptions can contain components and abbreviations that may be harder to decipher. Here are some of the common abbreviations and what they mean:
- OD: or oculus dexter refers to your right eye
- OS: or oculus sinister refers to your left eye
- SPH: is the sphere and refers to the lens power required to help correct your vision. A (-) negative
indicates nearsightedness and (+) positive indicates farsightedness - CYL: is the cylinder and refers to how much astigmatism you have if any. Astigmatism is caused
by a cornea or lens that has a different shape than normal and multiple focal points.
Astigmatism is very common. - AXIS: a number between 1 and 180, indicates exactly where the astigmatism appears on your
eye - ADD: stands for the additional lens power needed to make it easier for you to read. This is seen
on prescriptions for reading glasses or the lower portion of bifocal/progressive lenses - BO, BI, BU, BD stand for base out, base in, base up, and base down. These refer to the position
of the prism on eyeglasses that correct double vision
For contact lenses you may see additional information such as the brand, mode of wear, and BC +
DIA.
- BC: The base curve is the measurement that indicates the curvature and shape of your contact
lenses. This is taken when the steepness or flatness of your cornea is measured. - DIA: The diameter is the measurement of the length that your contacts need to be to
completely cover your cornea.