How We Calculate The Lens Powers You Require

The power of the lens is calculated by combining a proportion of the CYL value and the full SPH value. If the number is then between two available powers the lower one is normally selected in order to avoid eye strain.

Please note that trials have shown that the eyes usually take a short time to become adjusted to the goggles. Also in some cases, particularly for more complex prescriptions, the lenses may not provide the same precise level of correction as your glasses but the visual correction achieved is quite suitable for swimming.