At the end of your eye examination you will be given a prescription which will probably look something like the example below.
Bloggs Optometrists
23 High Street
Anytown
Tel: 020 123 456
Name of Patient:
Address:
| Sph | Cyl | Axis | Prism | VA | Rdg Add | Near VA | |
| Right Eye | |||||||
| Left Eye |
I have today examined the patient in accordance with the regulations with the following results:
* The prescription above was issued
* No clinical change in prescription was necessary
* No prescription was required
* The patient was refered to a medical practitioner
The next eye examination is recommended in ______ months
Signature of Optometrist______________(Mr JB Bloggs, MCOptom)
Date:________
You can see that the findings for the right eye are presented on the top line and for the left eye on the bottom line. Another way is to show the right eye on one side the form (normally the left) and the left eye on the other side of the form.
A prescription is usually valid for two years, but your optometrist may be recommended that you have your eyes examined more frequently than this, depending on your particular circumstances.
Remember, an eye examination does not only check that your prescription is right for you; it is also a check on the health of your eyes and visual system. Many eye diseases can go unnoticed until it is too late to treat them effectively so it is important to have regular eye examinations even if you feel you can still see well.
The "sph" box for "sphere" represents the amount of long or short light that is present. The larger the number the stronger, and therefore the thicker the spectacle lens will be. Plus lenses are used to correct long sight and minus lenses are used to correct short sight.
The "cyl" box for "cylinder" represents the amount of astigmatism that is present. Astigmatism is caused when the eye is not completely spherical (like a football) its shaped more like a rugby ball. This causes the vision to be distorted for both distance and near objects. The cylinder may be plus or minus regardless of whether the sphere is positive or negative.
The "axis" box represents the orientation of the cylinder (from 0-180 degrees) and is the angle at which the lens is set into the frame.
The "prism" is the correction needed (if any) to align the eyes, so that they are looking straight and working well together. A prism is a lens that bends the path of light without altering its focus.
"VA" stands for visual acuity. This indicates the standard of vision (for each eye) when corrected. It may or may not be included in the prescription and is usually presented as a fraction. In the UK, VA is conventionally measured at 6m, so the numerator is 6 (eg 6/6). In the US, VA is measured at 20 ft (eg 20/20). The larger the denominator, the worse the eye sees, so a VA of 6/12 is half as good as 6/6.
"Rdg add" (reading addition) shows the additional positive power that is needed to enable the eyes to focus for close work. This is usually only needed for patients over 40-45, since focusing ability declines as we get older (presbyopia). If a reading addition is stated, this means you need different spectacle prescriptions for reading and for distance.
"Near VA" represents the smallest sized print that can be read with the prescription. This is usually written as Nx where x is a number representing the print size. N5 is the smallest sized type that you will normally find and N8 is approximately the size of normal newsprint.