However, several companies are taking eye protection even further by developing a sunglass that fully protects the eyes with orbital foam seals, completely preventing UV from reaching the eye.
There may be several other benefits to such an approach, as it also provides protection against another environmental factor: wind!
Cycling downhill or into headwinds at high speeds can provide near hurricane-force wind in the face. In addition to dangers of sunlight and UV, there is evidence that the long-term effects of wind exposure can be damaging to both skin and the eye.
The phenomenon of "windburn" getting more sunburn on a windy day is a common experience and has serious consequences for your eyesight. There is evidence that wind and heat can accelerate the carcinogenic (cancer-causing) effect of UV radiation.
Therefore, protecting the skin around the eyes from both sun and wind can further minimize damage and aging effects from UV exposure.
According to the American Academy of Ophthalmology, pterygia and pingueculae (abnormal growths on the outside surface of the eye that can impair vision) are more common in people exposed to wind and bright sun. Pterygia, sometimes referred to as "triangles" due to their shape, and pingueculae, often a precursor of pterygia, are believed to be associated with microtrauma to the outer surface of the eye from exposure to sunlight and/or dust.
Factors that can contribute to the condition include sunny, sandy, windblown or dusty locations.
Blink rate
Wind also causes us to tear and increase our rate of blinking, in an effort to compensate for the drying effects of continuous wind exposure. While these responses may help to temporarily reduce discomfort, they can reduce our ability to see clearly, compromising peak visual performance. Tearing distorts images by producing numerous optical aberrations. Increased blinking significantly reduces the overall amount of image information, as every blink is in effect a brief visual blackout! Normal blink rates accelerate when wind increases, cutting visual acuity and lowering color perception.
Contact lenses
Another effect of wind can be to dry out and/or displace contact lenses, making clear vision impossible. Even after the wind diminishes, the lens often will not return to its proper position without assistance. The drying effect alone can be extremely discomforting to contact lens wearers, to the point where blinking can start to become painful. Dust and pollen can further degrade the comfort of the contact lenses.
Allergies
According to the American Academy of Ophthalmology, Seasonal Allergic Conjunctivitis, or allergy eyes, is a medical condition in which the eyes respond to allergens (pollen), causing any or all of the following symptoms: swelling, redness, burning and the sensation that something is in the eye. Cycling exposes the eye to a barrage of dust, pollen and exhaust fumes. These elements can be especially discomforting with contact lens wearers, allergy sufferers and people with dry eye syndrome.
Dry eye
It is estimated that 10 million Americans suffer from dry eye syndrome, with allergy sufferers and contact lens wearers at higher risk. Dry eye syndrome is a decline of the quality or quantity of tears bathing the eye. This condition can lead to constant pain from eye irritation and a sandy or gritty sensation. Untreated dry eye can lead to scarring or ulceration of the cornea and thus loss of vision. Sunglasses with foam seals are designed to protect the eyes from wind-borne dust and pollen and can mitigate these conditions.
Several major brands of sunglass companies are engineering glasses that comfortably seals the eye, enhancing visual acuity and protection for individuals in high speed and motion activities sheltering the eyes from wind, dust, snow, pollen and road debris.
I have tested several of these and find them quite comfortable for cycling.
Panoptx Venturi: This sunglass offers the most wind protection with medical grade foam that completely encloses and protects the eye. It has a patented adjustable venting system that controls the amount of wind that reaches the eyes. www.panoptx.com.
Rudy Project Ekynox: This well-known brand in the cycling community offers a foam insert that surrounds the lenses' frame area and comes with removable and interchangeable lenses for cycling in various light conditions. Additional lenses must be purchased separately. www.rudyprojectusa.com.
Zeal Lazor: This performance sunglass comes with a top sweat guard that can serve as a partial wind block. Comes with three interchangeable lenses for varying light conditions and travel case. www.zealoptics.com.