How to read your contact lens prescription:
A contact lens prescription is not the same as a spectacle
or eyeglass prescription. The contact lens prescription
that your optometrist or eyecare professional writes
for you, contains information that relates the size
and shape of the lens to your eyes.
A typical contact lens prescription might look like
this:
| Eye |
Power
(Sphere) |
Base
Curve (BC) |
Diameter
(D) |
| OD (Right) |
-1.50 |
8.8 |
14.0 |
| OS (Left) |
-2.00 |
8.8 |
14.0 |
|
Power (sphere) refers to the strength
of your contact lenses which is given as a '+' (far-sighted)
or a '-' (near-sighted) number. This number may sometimes
be different for each eye.
Base Curve (BC) refers to the amount
of curvature a contact lens has. This number has a decimal
point and is usually between 8.1 and 9.3. Base curve
numbers are usually the same for both eyes.
Diameter (D) refers the diameter of
your contact lens. This number has a decimal point and
is usually between 13.6 to 14.8. The lens diameter is
usually the same for both eyes.
If you are wearing Bifocal contact
lenses, then you will have two lens powers for each
eye. The first number will be a '+' or a '-' number
while the second will be the power of the "Add"
which is a '+' number.
An example prescription would look like:
| Eye |
Power |
Add |
BC |
D |
| OD |
-2.50 |
+1.00 |
8.8 |
14.0 |
| OS |
-2.00 |
+1.50 |
8.8 |
14.0 |
|
Note that the power of an 'add' can be different for
each eye.
If you have astigmatism, your contact
lens prescription will include a 'Cylinder' and 'Axis'
number for each eye. This means you have been fitted
with a Toric contact lens.
An example prescription would look like:
| Eye |
Power |
Cylinder |
Axis |
BC |
D |
| OD |
-2.50 |
-0.75 |
110 |
8.6 |
14.0 |
| OS |
-2.00 |
-1.00 |
070 |
8.6 |
14.0 |
|
The cylinder will have a '-' or '+' sign in front
of it and the axis will be a number between 0 degrees
to 180 degrees. |
