Balance Optics Sunglasses

understanding your prescription

Following a professional eye test with a qualified optometrist (ophthalmic optician), you will be given a written or printed and signed copy of your prescription.

Your prescription will look similar to the following samples:

Your prescription is made of up to three figures (for each eye).  The sphere power (SPH), the cylinder power(CYL) and the AXIS.

Sphere Power (SPH)
SPH  is the main value of the prescription, giving the overall power of the prescription.

Often the prescription may only have a SPH value for example:  +1.25 , or -3.75, in this case  the CYL and AXIS parts will be left as 0.00 or DS (see figure 1). 

Cylinder Power (CYL) and AXIS
The CYL and AXIS values are always supplied as a pair, i.e. if a cylinder is specified it must also have an axis.  They are always written in this order, usually the CYL has a - infront. Rarely it will have a + infront, and it is important that the correct choice is made.

All SPH and CYL powers are specified in (0.25) steps, i.e. the value written after the decimal point will be 0.00, 0.25, 0.50 or 0.75.

The AXIS is an angle between 1 to 180 degrees.  If there is a CYL specified on your prescription, then there will be an accompanying AXIS . Choose from the dropdown menu the figure matching your AXIS. (If the AXIS has a fraction, choose the lowest closest figure- eg. if AXIS is 52½, then choose 52).
For further help with ordering prescription glasses, see How to Order and Entering your prescription.

ADD
If there is an ADD on your prescription, this is the additional power needed for a reading prescription. Ignore this figure as the ADD is not required for sport.

Your PD measurment
The Pupillary Distance, or pd, is the measurement of the distance between the pupils. It is an important factor creatiing  prescription eyewear, and enables the optical centre of the lens to be placed accurately infront of the eye.
More information about your PD measurement

Note: You must accept responsibility for accurately entering your prescription details and providing a ‘PD’ measurement when ordering prescription lenses with balance optics.

Astigmatism
If you have a CYL and AXIS after the SPH number, then you have astigmatism. This is quite an ordinary part of an eye sight prescription, and means that the front of the eye (cornea) and/or lens is rubgy ball shaped rather than perfectly spherical.  This distorts the light coming into the eye. 

Myopia
If your prescription starts with a ‘minus’(-) before the first number e.g. -2.75, then it means you are short sighted (myopic).
Usually things will look more blurred in the distance, but more clearly defined when close to you.

Hyperopia
If your prescription starts with a ‘plus’ (+), before the first number e.g. +2.75  then it means you are long sighted (hyperopic). Usually things  close to you will look more blurred , but more focused for things which are in the distance.  

If you are under 40 years you may not need to wear prescription eyewear for sport if your level of hyperopia is low. Your natural level of focusing (accommodation) may keep images clear with no ill effects.  Ask your optician if they believe you require a correction for your sport (as they have assessed your eyes).