Glasses prescription glossary
Enter any fields printed on a glasses prescription to get a plain-language explanation of the abbreviations and notation. The decoder does not evaluate or change the prescription.
Leave fields blank if they are not on the prescription. PL or plano is accepted for zero lens power.
OD means the right eye and OS means the left eye. SPH is spherical lens power, CYL is cylinder lens power, and AXIS is the orientation of cylinder correction. ADD is extra plus power for near work in multifocal prescriptions. PD is the pupil distance used to position lenses.
The values alone cannot confirm eye health, explain every symptom, or show whether a prescription is current. This page does not interpret prism, base direction, contact-lens parameters, or visual acuity, and it never recommends changing lens power. Ask the prescriber or dispensing optician about unclear or missing fields.
Contact lens prescriptions include lens-specific measurements such as base curve and diameter, and higher powers may require vertex-distance conversion. Do not use glasses values to order contact lenses unless a licensed eye care professional has issued them for that purpose.
These tools provide general education only. They do not diagnose an eye condition, replace a comprehensive eye exam, or provide a prescription for glasses or contact lenses.
Maintained by the AstigmatismTest.com Editorial Team. Last reviewed and updated . The team checks the method, limits, and wording against the references below; this byline does not claim review by a licensed clinician. Read our editorial policy.