If you have diabetes, an excellent pair of sunglasses is almost as essential to your care plan as your blood-sugar monitor. That may seem like an overstatement, but here’s the truth: Uncontrolled diabetes is the biggest threat to vision for Americans under age 65, leading to problems like cataracts, swelling (diabetic macular edema), and diabetic retinopathy. Know what exacerbates all those complications? Sunlight. "Harmful ultraviolet (UV) light can damage many critical structures of the eye, such as the cornea, lens, and retina. Diabetics are at higher risk, as their ability to repair UV damage is weakened," says Frank Siringo, M.D., a retina surgeon at Omni Eye Specialists Denver in Colorado.
So we're clear, yeah? UV-blocking sunglasses are non-negotiable. Here's a checklist of what to consider when picking your pair:
Lens Material: Polycarbonate
Polycarbonate plastic blocks 100% of UVA and UVB rays without the need for any additional coating (they're also lightweight and shatterproof). Even if you opt for a different material, making sure your sunglasses are UV-protected—look for the label "UV400"—is still your number-one priority, says Dr. Siringo.
Lens Color: Your Choice
The harmful portion of the light spectrum is not in the visible wavelengths, so the intensity of the color of your lenses does not correlate with the amount of protection your eyes receive, says Alan B. Shnay, O.D., an optometrist in Calumet City, IL. In other words, dark lenses don't block more UV than lighter ones. Darker lenses do, however, allow the pupil to dilate, letting in more light. If the lenses do not block UV, then more of this harmful light will enter the eye.
That said, the lens color can affect one's comfort level. Dr. Shnay often recommends brown or grey tints if the patient has cataracts, which tend to develop sooner in people with diabetes. "Cataracts decrease contrast sensitivity, and these tints help to minimize the effects of that loss," he says.
Polarized Lenses? Yes!
Polarized lenses don't protect against UV rays, but they do minimize glare, which can be particularly uncomfortable for people with diabetic eye disease. Patients who have had laser treatment for diabetic retinopathy often have particular difficulty with glare and may benefit greatly from polarized lenses, says Dr. Siringo. You can also opt for anti-reflective coating and/or mirrored lenses for further glare protection. If you spend a lot of time outdoors or on the road, the extra investment is worth it. (And don't forget to throw on a wide-brimmed hat to block any stray light.)
Photochromic Lenses? Maybe
Transitions-brand photochromic lenses, which change from clear inside to dark outside in the presence of sunlight, are completely UV-protective. However, in people with cataracts or diabetic macular edema, they may not be the best choice, says Dr. Schnay. Even at their clearest, there is a slight reduction in light transmittance, which can adversely affect night driving in those patients. Plus, when driving on a sunny day, the lenses tend not to darken much, since the windshield blocks most of the UV light that cause them to change color. If you're not sure if they're right for you, discuss your options with your doctor.
Best Shape: The Bigger the Better
Dr. Shnay says wrap-around sunglasses offer the most complete protection for the entire ocular surfaces, including lids. But some prescription wrap-arounds increase distortion due to the extra curve of the lens.
One reliable choice: "Oakley sunglasses can be made with a limited Rx range and won't have too much, if any, distortion," he says. Otherwise, just choose a frame with the most coverage you’re comfortable with—and a style that suits you!