The prescription you receive whenever you visit your ophthalmologist contains all the information that you need when you are placing order for a pair of contact lenses. They are important and ensure that the lenses you get for yourself are safe and provide clear vision.
So, you should always ask for a copy of prescription when you go for an eye exam and fitting.
Well, you're good if you are looking for a pair of disposable contact lenses as some online stores like ContactLenses4US provide you a wide range of multifocal Toric lenses and disposable contact lenses without prescription as well.
Then again, there is no harm in getting your eyes examined and obtaining a prescription because:
- Your regular eyeglass prescription doesn't work when you are looking for a pair of contact lenses as they sit on your eye whereas an eyeglass is 12mm away from it and regular soft lenses do not work on astigmatism which your doctor might try to work on by changing the power of your lenses.
- Moreover, it contains information about after how long you should replace your lenses- usually, a year after of the fitting.
- The contact lenses prescription also contains the information about the size of the lens.
- Lenses are more complicated than they seem because at times, you might have regular prescription for one eye and a Toric or Bifocal one for the other, varying up to brands and type as well.
Here is how you can read your contact lenses prescription explained by decoding the codes and terms mentioned in the below example:
OD is the abbreviation used for the right eye, whereas, OS is for left. OU is another abbreviation used for both the eyes.
PWR/Power or SPH/Sphere is used to define how much corrections each of your eyes needs if you are long-sighted or short-sighted. The prescription begins with a +' sign if you are long-sighted and a -' sign if you are short-sighted. It is measured in Dioptres rising from 0 to 0.25 and so on. The bigger the value, higher correction is required.
Base Curve/BC is usually a number between 8 and 10 millimetres or written as words such as flat, medium, or steep. It defines the lens curve that will fit your eyes well.
DIA or the Diameter defines the width of your lenses and ranges between 13 to 15 millimetres.
Prescription for Correcting Astigmatism
Cylinder/CYL. Increasing in the measures of 0.25, Cylinder is always a minus figure falling between +4 and -4. It determines the degree of Astigmatism and correction required.
Axis/AX. When your eye doctor will provide you a prescription to correct astigmatism (or faulty curvature of the eye), he/she will define the angle of correction through the degree of Axis ranging between 0 and 180 degrees.
Prescriptions for Presbyopia
Addition/ADD. When you are having trouble with near vision, the addition will tell you a number between .50 and 3.00 to correct your vision.
Dominant/D. In case you have a multifocal or bifocal vision, your ophthalmologist will use this to define which eye is dominant and which is non-dominant through D' and N' respectively.
Also, ensure that the brand is mentioned in the prescription because the BC in one brand doesn't mean the same in another.