Contact Lens Power

If you wear contact lenses, you might be curious about some of the codes and numbers inscribed on the lens packaging. Optometrists prescribe contact lenses with various degrees of power to remedy different vision issues. The Federal Trade Commission imposes rules that make it possible for contact lens users to acquire their contact lens prescription to buy contacts anywhere they pick.

What Is the Power on Contact Lenses?

When you understand what the abbreviations and numbers imply, you will have a better understanding of your individual contact lens prescription.

Contact Lens Power Table
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  1. Discover the fundamental Latin terminology that optometrists use on prescriptions. Ocular dexter or OD describes the right eye and ocular sinister or OS refers to the left eye. If you are amongst the people with the exact same prescription for both eyes, you may see an OU for ocular uterque.
  2. Comprehend the sphere power of your lenses. Sphere power is the main power in the lens to fix either hyperopia, farsightedness, or myopia, nearsightedness. Sphere power is favorable if you are farsighted and negative if you are nearsighted. The unit of measure for sphere power is a dioptor, or D. Contact lens producers make lenses in 0.25 D power increments. The greater the sphere power is from absolutely no, the stronger the prescription.
  3. Consider the cylinder power if your prescription has one. Cylinder power is the power to correct astigmatism. This power also is in diopters and much like sphere power, the greater the number is from absolutely no the stronger the prescription.
  4. Acknowledge the “add” power, if you use bifocal lenses. Include power is an extra restorative power on part of the lens to assist with reading and viewing objects close-up. Add power is always favorable.


Power/Sphere (PWR/SPH): This figure shows whether you are long or short-sighted and how much correction your eyes need. If you are long-sighted your figure will begin with a + (plus sign) and if you are short-sighted it will begin with a- (minus sign). This will be followed by a number that goes up from 0 in measures of 0.25 dioptres, the higher the number the stronger the visual correction needed (this value can be shown on the box as “PWR” or “D”).

Reyus Mammadli (Eyexan Team Leader) / author of the article
Bachelor in biomedical and electrical apparatus and systems. For more than 20 years he has been studying methods to improve health using affordable and safe methods. Collaborates with eye care charity organization of the CCP. Specialization is a vision correction by laser surgery, including LASIK.
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