Some people claim that reading the doctor’s handwriting is almost an art, not to mention to puzzle out a prescription written by them. And above everything, the prescription is for contact lenses or glasses. To avoid misunderstandings in February 2004, legislation went into effect giving all U.S. consumers the right to a copy of their contact lens prescription and by law these prescriptions are valid for a minimum of one year, or the minimum required by state law, whichever is greater.

As a lens is a medical device and if it's not properly prescribed, you may not see well. More importantly, a poorly fitting lens or one made from a material not well-suited to your eyes could result in discomfort, inflammation, swelling, abrasion, or another problem that could, in rare cases, result in permanent eye tissue damage so even if you already have an eyeglass prescription, you need a contact lens prescription that contains additional information.

When your prescription expires, you won't be able to buy more lenses until you get an updated prescription, phase which involves a checkup by your ECP to be certain that contact lenses aren't adversely affecting your eyes.

So when you finally get in your hand the wanted prescription don’t be surprised if you won’t understand a thing as it is full with abbreviations and numbers. Naturally eye doctors understand and use these standard terms, abbreviations and measurements and after skimming trough the following lines you’ll be an expert too:

- The heading is easy to read as it contains general information about the respective medical center and the names of the patient and his/her doctor

- OS and OD are abbreviations for your left and right eye derived from the Latin „oculus sinister et dexter”. In case your prescription has OU written in the first row, then the same measurement is applied for both eyes.

- Next a serious abbreviations follow attached with numbers such as PWR for refractive power, explaining to you whether you are near or farsighted; BC for the base curve, which the lower it is the steeper is your cornea; DIA for diameters, this being an important measurement expressed in millimeters. This will determine where on your eye the lens will rest and if measured wrong, irritation or abrasion is the result. CYL stands for cylinder, measuring astigmatism; AXIS expressed in degrees shows the orientation of the cylinder; ADD is for Add power and bifocal lenses.

- COLOR is included only if the lens changes or enhances the eye color or is a particular design

- BRAND in the US a specific brand is always indicated.

The prescription will also indicate how often your contact lenses must be replaced and when that particular note expires.