One of my best friends from undergrad is very nearsighted with a –8.00sph prescription in both eyes. During the college years, when we would go to the pool or beach, he would go into the water and look out into the distance and be constantly squinting, as he refused to swim with his glasses on and despised wearing contact lenses.
Unfortunately, this happens to many swimmers with glasses prescriptions all over the world; when they go into the water, whether for competition or for fun, they are jumping in without any proper prescription swim goggles. The time has come to help these swimming enthusiasts!
The optics of prescription swim goggles
Before we proceed, we must bring it back briefly to the optics days in either physics or optometry school about Snell’s Law, demonstrated in Figure 1, and its angle of incidence and refraction.
Figure 1
Our human eye was made to provide perfect vision in the air. However, when you place your head underwater your vision will get blurry. The reason this occurs is because of the refractive index differences between air and water. The cornea provides much of the total refractive power of the eye (about two-thirds, and +43D) when exposed to air, so refractive power is lost when air is replaced with water.
Refraction is key to our vision because when light hits the crystalline lens of our eye it will cause light to bend so that it can focus images clearly on our retina. When light either lands behind or in front of our retina this will cause a person to have a myopic or hyperopic prescription. However, when light passes from water to the cornea there is little refraction that occurs so the image will not be in focus until it is behind the retina.
Since water has a refractive index of 1.333333 and air has a refractive index of about 1.0003, as shown in Figure 2, this difference is what causes objects to appear larger and closer underwater.
Figure 2
The solution to getting rid of the blur when underwater is to wear swim goggles or a dive mask. For example, when you put on a dive mask, it has a flat front and back lens surface which helps create an air space in front of the cornea; this allows the normal amount of refraction to occur so we can see clearly.
As seen in Figure 3, below, the mask's flat window separates the eyes from the surrounding water by a layer of air.
Figure 3: Flat masks are used for diving. The mask’s window allows a layer of air to be formed between the wearer’s eye and the surrounding water, which helps bend the light before it enters the eye.
When light passes from the dive mask’s lens into the air, the light will diverge and objects underwater will appear both larger and closer than they actually are—up to 34% larger in saltwater and 25% closer. For those who have a prescription for glasses, these individuals will tend to either wear contact lenses or non-prescription swim goggles while in the water.
Choosing prescription swim goggles
The American Optometric Association, FDA, and CDC do not recommend wearing contact lenses in any type of water environment because of the possibility of acquiring an eye infection due to a microorganism called acanthamoeba, which can wreak havoc on your cornea and can ultimately lead to blindness. However, there are many individuals who will either jump in the pool or ocean and have forgotten to take their contact lenses out or just simply do not abide by the rules.
So for those individuals who care to still swim in contact lenses, it is highly recommended that it is only a daily disposable contact lens with a tight-fitting pair of swimming goggles. Once out of the pool it is recommended to remove those lenses approximately thirty minutes after swim time and not right away. If water from a pool, hot tub, or ocean gets into the eye, the contact lens will ultimately be sucked onto the cornea.
If you try to remove the contact lens immediately once you get out of the water (if the contact lens is stuck on the cornea) you may take the epithelium of the cornea with it which can potentially cause a painful corneal abrasion.
Another option to help remove the contact lens is to apply a preservative-free artificial tear in the eye to help loosen the lens and then the lens can be removed and discarded in the trash or preferably recycled.
Always make sure when you are taking off your contact lens that your hands are completely dry. Another potential option, while in the water, would be scleral lenses or rigid gas permeable (RGP) lenses with a tight-fitting goggle. However, you need to be careful with a rigid gas permeable lens underwater, since the eye absorbs nitrogen and when we descend down into the water nitrogen will slowly escape. When you have the RGP in, the lens will not allow the nitrogen to escape and can cause tiny bubbles to form in between the eye and the lens, which can result in blurry vision.
Also, if the mask or goggles get filled with water the potential of losing the lenses can occur.
Based on the facts stated above, the best option for swimming is to not wear any contact lenses at all and to purchase a prescription pair of swim goggles. These will vary tremendously in quality and size and sometimes it can be difficult to get the actual prescription due to the limitations of the manufacturing process. However, these are typically the ideal solution. Prescription swim goggles will allow you to see who is in front of you, check the pool clock for your splits, and also be able to read what is on the whiteboard.
Getting a pair of goggles that fits properly is hard enough, so when the range is vastly reduced, it can be difficult to find a well-fitting pair. My recommendation would be to start with performance brands rather than leisure brands since they tend to have a better seal. To achieve a better seal, choose goggles designed with a step bevel, which allows the lenses to lock into place with a special edge so water will not seep through. Also, having an adjustable bridge strap will make sure
there is proper spacing of the goggles, allowing for the perfect seal around the eye and also minimizing pressure on the nose.
there is proper spacing of the goggles, allowing for the perfect seal around the eye and also minimizing pressure on the nose.
However, not many labs have the capacity to create these designs for swim goggles so you would have to check with your lab to see if they have these step bevels or if they can create prescription swim goggles.
For swimming goggles, Hilco is one of my favorite companies and does very well with its custom-made designs. Once you open an account with them to acquire the frames, you can then choose to have the lenses made by Hilco or done in your own lab. Their Leader xRx Rx-Ready brand is one of the best in the industry and offers hypo-allergenic silicone eye seals, a strap with adjustable nose bridges, and two different size options. Their unique leakproof lens, which is dependent on the bevel design, provides leakproof performance. The prescription power range is +20.00D to -20.00D to -4.00 cyl.
However, you do not want to prescribe any cylinder prescription in a swim goggle because, when you are in the water, you will ultimately feel dizzy and your surroundings will seem warped. Therefore, when prescribing prescription swim goggles, you would want to do a spherical equivalent similar to what you would do with contact lenses.
For example, if you have a prescription -3.00 -1.00 x 180 OU in the swim goggle, you would prescribe -3.50sph OU. When you have a high prescription of -8.00sph OU in glasses, you would keep the same prescription (-8.00sph OU) for the swim goggle prescription, as opposed to giving -7.50sph OU. The reason for keeping it the same is when you are underwater things will appear more magnified, so it already takes into account for vertex distance.
Another company who offers other options of swim goggles is RecSpecs by Liberty with their Shark and Frogeye products. All of their frames include a clear single vision prescription lens and can be upgraded to progressives. Do not forget if the patient has mild astigmatism, we can do the spherical equivalent for their swim goggles.
If patients choose to not purchase through the actual office, my recommendation would be to visit this website called safetygearpro.com, which offers the aforementioned Leader xRx Rx-Ready. The site has styles for both adults and juniors with four different color options and prescription ranges from +10.00 to -10.00 sphere and cylinder power ranging up to -6.00 cyl. Many other websites like amazon and swimoutlet or swim shops will have prescription swim goggles, but those typically do not have cylinder powers, which again we do not want to incorporate. Often sphere prescription will be unavailable or sold out.
When it comes to tints in a swim goggle, clear and light tinted lenses is what is recommended. If you have a mirrored or dark tinted lens while swimming outdoors they are great for blocking the sun rays. However, they can dim the surroundings or have some impact on your peripheral vision.
Strict Goggle Etiquette
If you really feel the need to wear contact lenses while swimming, you can get around it by being vigilant with your goggles. That means making sure there is a good seal on them before you get in the water, and not removing or adjusting them until you finish your post-swim shower.
Best features for prescription swim goggles:
- Anti-fog treatment (Keep out of direct sunlight when not wearing because this can cause the coating to degrade faster)
- Anti-Reflective
- 1.59 Index Polycarbonate Lens
- Polarized lenses
- Built-in UV protection
- Soft silicone gaskets
Note:
Recreational Lap Swimmers do better with larger lenses for better peripheral awareness and more padded frames.
Competitive Swimmers should choose a frame with a low profile
Although overlooked by many practitioners, the reality is that millions of contact lens wearers swim and dive without removing their lenses and without experiencing adverse consequences. We need to accept the fact that patients will continue to wear contact lenses while swimming or in the water and, as eyecare practitioners, we need to educate them on the appropriate considerations of daily disposable contact lenses, proper hygiene, disinfection, and ocular physiology in order to enhance the recreational water enthusiast's underwater experience.
Always remember to prescribe or recommend a prescription pair of swim goggles, as it is the best alternative we have!
Bonus feature
Sports performance vision is crucial to the specific sport that we play. On television, we often see performance bikes that enable people to compete and train with each other from the comfort of their own home. In the swimming world, there are open water swimming goggles that can track mileage and have GPS and an electronic compass built in the goggles. This helps athletes or recreational swimmers with a 15% performance improvement and keeps them on course; most swimmers will tend to zig-zag during open water.
Both OnCourse and Form Swim give guided workouts, real-time metrics, and even video tutorials. The Form Swim workout categories include endurance, power, recovery, sprint, technique, and test sets. Both of these companies have been seen in Men’s Health and the Wall Street Journal.
Author Tip: Even though Hilco does a wonderful job, I personally use HT OptiLab which is located in Brooksville, Florida. Contact: Joe Perez Phone: 352-345-4349. Email: htoptilab@gmail.com.
