How do I read my prescription?
A contact lens prescription is made up of specific data which we require to fill your order. All of this information is available on the packaging of the contact lenses you are currently wearing, or from your optometrist or optician. In most states eyecare professionals are required to provide you with a copy upon request.
Here is the information that we need:
OD = right eye
OS = left eye
Brand name (eg. Acuvue)
Power/Sphere/Rx (a number between -20 and +20)
Base Curve (a number between 8.0 and 10.0)
Diameter (a number between 13.0 and 15.0)
For astigmatic patients, we also need:
Cylinder (a number between -4.00 and +4.00)
Axis (a number between 0 and 180)
Cylinder and Axis are usually separated by "X" and read as "times"
Sample Prescriptions
A regular prescription would look like this:
OS -
Brand name: Acuvue
BC: 8.8
DIA: 14.4
SPHERE: -2.50
OD -
Brand Name: Optima FW
BC: 8.4
DIA: 14.0
SPHERE: -2.75
A prescription for astigmatism would look like this:
OS -
Brand name: Acuvue Toric
BC: 8.8
DIA: 14.4
SPHERE: -2.50
CYL & AXIS: -1.25 X 180œ
OD -
Brand name: Focus Toric
BC: 8.7
DIA: 14.0
SPHERE: -4.50
CYL & AXIS: -0.75 X 95œ
This information may appear complicated but in fact it is very straightforward. Just consult your current contact lens packaging for reference.
What does "full wearing time" or "wearing the lenses successfully" mean?
With a few exceptions, we understand a successful wearer of contact lenses to be a person who puts the lenses in place in the morning after getting up and removes them in the evening before going to bed, without the lenses feeling like foreign bodies that damage the eyes, and who believes that with them one can see just as well as with conventional spectacles. (Exception: curvature of the cornea greater than 1.25 diopters).
How long is the working life of contact lenses?
The working life of contact lenses can vary. It depends on how well the lenses are looked after and on the extent of the patients protein secretions. As a rule it is from two to three years - semi-soft lenses last about one year longer. In the case of new lenses, one does not have to pay the full cost of an adaptation, but only the price for replacement lenses.
What are the symptoms with old lenses?
Even with the best possible care, after a certain time a protein film forms on the surface of the lens. The lens is then no longer as flexible as a new lens. The hygroscopic capacity of the material decreases and the cornea no longer receives sufficient oxygen. The symptoms are manifested by the fact that the lens can no longer be worn for as long as it could at the beginning (slightly red eyes, burning sensation etc. in the evening). The visual acuity is reduced as a result of the film of protein. Often the lens prescription is also no longer correct. Many people believe, wrongly, that when these symptoms appear it means that they can no longer tolerate the wearing of contact lenses. However, the problem is with the lenses, which have been worn for too long, and not with the eye. With new lenses, the comfort for the eyes is restored and the visual acuity is again optimal.
How often should the lenses be checked and the eyes examined?
After you have adapted to wearing the lenses, the eyes and the prescription should be checked once a year.
Can lenses be lost or damaged?
You may lose the lenses if they slip out of your fingers or remain stuck onto your finger when you think you have put them back into their case. Always check whether they are really in the lens-case. The most common cause of damage is if the lenses are not handled properly or if, when they are being put back into the lens-case they become caught between the case and the lid. One can lose or damage the lenses in the first week, after months or years - or never!. The best thing is to insure against loss or damage by taking out a service contract, which is obtainable from our Institute, after you have adapted to the lenses. During the adaptation period it is recommended to check whether your household insurance covers third-party damage (civil liability).
Should one keep replacement lenses?
As with spectacles, one should keep replacement lenses in reserve. This saves a lot of trouble, especially of one is dependent on them. They should be ordered after you have completely adapted to the lenses. With the service contract, replacement lenses are particularly cheap and cost less than replacement spectacles. The details of the service contract will be explained to you after your have adapted to wearing the lenses.
How long does adaptation to wearing the lenses take?
The period of adaptation to the lenses varies from case to case and cannot be precisely predicted. Mostly, however, it is at least two to three months, but longer in difficult cases. What is really important is that you in fact really want to have contact lenses, that you have sufficient patience and also that you do not let yourself be discouraged by minor problems and setbacks. Given sufficient time, a lens that can be worn without problems can be found for almost every eye.
Are there bifocal contact lenses?
Yes, bifocal contact lenses which are especially suitable for people over the age of 45 years (presbyopia) have been available for some time. We shall be pleased to explain the various features of these lenses to you.
Are there coloured contact lenses?
Yes, coloured contact lenses are available. They tone or change the natural colour of the eyes. But as the colours are transparent, the effect is greatest with light-coloured eyes. With dark eyes, on the other hand, the effect is minimal. Also, they should always be worn as a pair because, as with sunglasses, they make everything appear coloured.
Is there an ideal age for wearing contact lenses?
No, there is no ideal age for wearing contact lenses. Our youngest wearer of contact lenses is nine years old and the oldest is eighty-four. As a rule, however, it is easier to adapt to using the lenses at as early an age as possible. Then changes to the prescription are in most cases not so frequent, or not as great as with normal spectacles. |
