Updated: January 20, 2026
A contact lens prescription contains specific abbreviations and measurements required to order the correct lenses. These values ensure each lens matches the power and shape of your individual eyes.
- OD stands for Oculus Dexter which refers to the right eye.
- OS stands for Oculus Sinister which refers to the left eye.
- PWR or SPH indicates the refractive power in diopters with a minus sign for nearsightedness and a plus sign for farsightedness.
- BC and DIA represent the base curve and diameter which are measurements in millimeters that define the fit and size of the lens.
- CYL and AXIS are required for astigmatism correction while ADD is used for multifocal or bifocal lenses.
Contact lens prescriptions must include a specific brand or manufacturer. These details are not the same as a glasses prescription and require a separate fitting.
Disclaimer:Â This information is for general informational purposes only and is not a substitute for professional advice, diagnosis, or treatment.
References:
Gomes JAP, et al. TFOS DEWS II iatrogenic dry eye report (pubmed.ncbi.nlm.nih.gov/28736340/). 2017.
Morgan PB, et al. International Trends in Daily Disposable Contact Lens Prescribing 2000 to 2023 (pubmed.ncbi.nlm.nih.gov/38951051/). 2024.
Wolffsohn JS, et al. CLEAR, Evidence-based contact lens practice (pubmed.ncbi.nlm.nih.gov/33775384/). 2021.
