Scuba Diving Masks and Swim Goggles

Swimmers and scuba divers who wear corrective lenses on land often find that their time underwater is enhanced by prescription eyewear designed for wet use. While some require only slight corrections, others find it very uncomfortable to be without good vision at any time, even underwater.

There are several devices for improving vision in the water; however, they often stop short of providing visual acuity rivaling what is possible above ground.

Water itself acts as a magnifier, which is why fish in a tank or other underwater objects sometimes appear larger than they actually are. Most eyeglass prescriptions are designed to either magnify (in the case of farsightedness) or minify (in the case of nearsightedness) what the eyeglass wearer sees. When a prescription swim goggle or dive mask is worn underwater, the visual acuity that the wearer experiences is complicated by the magnification of the water.

Diving masks, which are designed for scuba dives or snorkeling, tend to be large and squarish. They come up high and go across the forehead and dip down low, almost to the bottom of the nose. Rubber often surrounds the outside areas of the mask to fit tightly against the face and provide a watertight seal.

Prescription scuba diving masks work in one of two ways: either the entire lens area is a prescription lens, or the Rx lenses are inserted separately between the mask and the wearer's eyes. If the dive mask comes with prescription lenses, they may be either made specifically to your measurements and correction, or they can come premade in a prescription that is the same for both eyes.

Most people who require visual correction have a similar prescription for both eyes, and a dive mask with a premade Rx that is the same on either side generally gives you adequate vision for reading gauges and maneuvering around underwater. Even though premade prescription lenses do not have any astigmatism correction, most people who have regular glasses that correct for small amounts of astigmatism do not suffer when wearing a spherical (meaning "without astigmatism") correction in the water.

Dive masks that are made with lenses designed specifically to your measurements and prescription are generally more expensive than their premade counterparts. Older scuba masks that allowed these custom lenses to slide into the front sometimes had problems with water leaking in around the lenses, but newer models are pretty watertight.

Diving masks are available both with a prescription and without.

Alternatively, some masks have a fixed lens area in the front, but allow an insert containing the custom-made Rx lenses to slide in behind the front lenses. This method eliminates the possibility of water leaking in around the lenses; however, depending on the depth, temperature and type of water that you will be diving in, fogging may be a bit more problematic with inserts.

One of the benefits of an Rx insert is that if you're a contact lens wearer, you can use the same diving mask both with and without the contacts. If you have the contact lenses in for a dive, there is no need for the prescription insert. When you remove the contacts, you can put the insert into place for a clear underwater experience.
 

It is important to keep in mind that not all contact lenses are suitable to wear during diving. RGPs and the old hard (PMMA) lenses have been known to "dig in" to the eyes below certain depths, because of pressure. Also, soft lenses can collect waterborne organisms, becoming contaminated and causing disease. This can happen in pools as well as fresh- and saltwater bodies. Your prescribing doctor must give specific permission for you to wear the lenses underwater, or damage to the eye can occur.

Swimming goggles are similar to diving masks, but they are smaller and rounder. They also protrude further away from the face than dive masks do. Goggles are designed to protect your eyes from the water, yet to be sleek and unobtrusive at the same time, so as not to interfere with your speed and motion. The rubber that surrounds the goggles is meant to keep water away from the eyes.

Similar prescription options are available for swim goggles as for dive masks. Premade prescriptions that are the same for both eyes are commonly available. Generally, swim goggles are used in a pool setting, where adequate vision is provided by the prefabricated Rx goggles, though custom prescriptions can be fabricated for some models. As with the diving masks, the difficulty with custom-made lenses is the potential for leakage.

The lenses in diving masks and swim goggles are made of glass, acrylic, regular ophthalmic plastic or polycarbonate.