Choosing the right prescription lenses
Prescription swimming goggles come with optical lenses that are usually a reasonably close match to your exact prescription. So, unless you have a very basic prescription, most swimming goggles will not provide the same level of vision as your glasses or contact lenses. However, they will provide more than adequate vision for use in and around a swimming pool. And for most wearers they will be significantly better than nothing at all!
To choose you lenses, follow these simple steps:-
A spectacle prescription is usually written in the following way:
sphere cylinder axis
In order to calculate the goggle lens power you need to take into account two aspects of your prescription
The sphere (or sph) is the main part of your prescription and will be ‘–’ for short-sightedness (myopia) and ‘+’ for long-sightedness (hypermetropia)
The cylinder (or cyl) is the secondary part of your prescription and refers to the amount of astigmatism you have. This is usually a minus (-) number but may occasionally be plus (+) so take careful note what sign the cyl is
The axis is the third part of your prescription and can usually be ignored when selecting prescription goggles
- R -3.00 / -0.50 x 180
- L -2.50 / -1.00 x 180
If you do not have astigmatism in one or both eyes, then your prescription will only have one number, the sph power, which may be written in the form of -3.00 or -3.00 DS (where DS or ds stands for dioptre sphere)
You should base the power you order primarily on the amount of short or long sightedness you have. If you also have a moderate degree of astigmatism (up to around 2.00 cyl), then you should add around half of this to choose the most appropriate lens power. Most swimming goggles come in 0.50 dioptre steps so you may have to select the nearest power. To do this you need to take account of the power and sign (+ve or -ve) of both parts of the prescription
Here are some examples:
-3.00 /-1.00 x 90 - the best power would be -3.50 (-3.00 plus half of -1.00 so -3.00 plus -0.50)
-3.00 /+1.00 x 90 - the best power would be -2.50 (-3.00 plus half of +1.00 so -3.00 plus +0.50)
+4.00 /-1.00 x 90 - the best power would be +3.50 (+4.00 plus half of -1.00 so +4.00 plus -0.50)
+4.00 /+1.00 x 90 - the best power would be +4.50 (+4.00 plus half of +1.00 so +4.00 plus +0.50)
-4.00 /-1.50 x 45 - the best power would be -4.50 (-4.00 plus half of -1.50 so -4.00 plus -0.75 = -4.75, then rounded down to the nearest half dioptre)
Remember to do this simple calculation for each eye as most prescription goggles allow you to select different powers for the right and left lenses.
It's worth bearing in mind prescription goggles can take a bit of getting used when wearing for the first few times and unless you have a very basic prescription, most swimming goggles will not provide the same level of vision as your glasses or contact lenses. However, they will provide perfectly adequate vision for use in and around a swimming pool.
It is important to note that prescription swimming goggles are not for use outside of the swimming pool and especially for driving, operating equipment, or any other use where your normal prescription glasses or contact lenses would be indicated.