Goggles include 3 nose bridges (small/medium/large), which can be easily switched to fit your face, and can fit both adults and children. Without anti-scratch or anti-reflective coatings. Made in China.
Prescription swimming goggles come in standard SPH diopters - minuses only. There are no adjustments for cylinder (astigmatism) in swim goggles.
Prescription Swimming Goggles
(Item No. 1270)
The PD or Pupillary Distance is the distance between the pupils of the eyes, center to center, in millimeters. Most adults have a PD between 54mm and 74mm. A PD should be provided as part of your prescription.
If your most recent eye exam did not include the PD value, but a previous one did, you can use the previous value. PD does not change over time for adults.
An optometrist's PD value is recommended, but you can measure it with help from another person. Have someone hold a ruler just below your eyes and measure the distance in mm from pupil center to pupil center. Focus straight ahead at a distant object.
Do not guess your PD value or try to measure anything on your current glasses - there is no way to measure your PD from them.
Spherical, referring to the refractive correction in the prescription.
The Spherical correction is for near (-) or far (+) sightedness.
If "PL" or "Plano" is written for the SPH on your prescription, the value to be entered is 0.00.
Cylinder, referring to the strength of the correction for the astigmatism in the eye.
It can be either positive or negative.
If there is an OD Cyl value, there must be an OD Axis value. If there is an OS Cyl value, there must be an OS Axis value.
If "DS" or "SPH" or "spherical" is noted in this space on your prescription, you have no astigmatism in that eye and the value to be entered is 0.00.
Axis refers to the angle of the correction for the astigmatism in the eye (if one exists) from 1 to 180.
If there is an OD Axis value, there must be an OD CYL (Cylinder) value. If there is an OS Axis value, there must be an OS CYL (Cylinder) value.
If there is no Cylinder value, or if the Cylinder value is zero, then the Axis value is zero.
The Axis value is often written as 3 digits, which means if your Axis value is 5, it is often written as 005. This Axis value is still 5, regardless of how it is displayed.
PRISM and BASE
A Prism is to try and correct a lazy eye and indicates a more delicate condition, this is included with a prescription to correct some special conditions or some eye disorders (like squints) that require the focused image to move position. The measurement is Prism Dioptre. The value may be as high as 10 and may go up in steps of 0.5 or 1 Prism Dioptres.
Base indicates the direction of the prism, by noting the relative position of its "base" or thickest edge. Four abbreviations are used for prism direction: BU = Base Up; BD = Base Down; BI = Base In (toward the wearer's nose); BO = Base Out (toward the wearer's ear).
The (thickness) Index value refers to the refractive quality of the lens, or the degree to which the lens bends light passing through it. The higher the index, the thinner the lens.
For normal, single vision prescription values we recommend a lens with a low Index of 1.5 or 1.56. For prescriptions less than SPH -4/+3, a higher Index lens will not produce a noticeably thinner lens.
Lenses with Index values of 1.61 and 1.67 are appropriate for stronger prescriptions beyond -4 or +3. Lenses with index values of 1.74 are best suited for prescriptions beyond -6.
Single Vision lenses are the standard eyeglass prescription. These lenses are for one field of vision, whether specifically for distance vision, near-vision reading glasses or somewhere in-between such as computer-distance glasses.
Bifocals are a type of lens designed for people who need both near and farsighted vision correction. Different from single vision lenses, bifocals have two sections in each lens, enabling the user to see clearly at two different distance ranges through one lens.
Like bifocal lenses, progressive multifocal lenses enable the user to see clearly at different distance ranges through one lens. A progressive lens gradually changes power from the top of the lens to the bottom, giving a smooth transition from distance vision to intermediate/computer vision to near/reading vision. Progressive multifocal lenses do not have lines or segments and have the advantage of offering clear vision over a large range of distances, not limiting you to two distances as with bifocal lenses.
Sometimes seen on your prescription as just "NV" or "ADD". "NV" stands for "Near-Vision." This is the reading part of the lens in a bifocal or multifocal prescription, and the number indicates the strength of the overlay on the lens, for reading. It is usually the same number for both eyes, but it may be written only once on your prescription.
Photochromic (Transitional) Lenses
Photochromic (or Transitional) lenses progressively darken outside in sunlight to become sunglasses. Transitional lenses darken according to the amount of sunlight the lenses are exposed to. The shade of the lenses is slightly lighter than regular sunglasses and take a minute or two to transition to the darkened shade. When moved out of the sun, the lenses take a minute or two to return to clear lenses.