Ultraviolet (UV) radiation is a form of electromagnetic energy that is invisible to the human eye, categorized into UVA and UVB rays. UVA rays penetrate deeper into the eye, while UVB rays are responsible for most surface-level damage. UV light exposure occurs even on cloudy days or when indoors near windows, making protection a year-round necessity. UV protection is necessary for daily-wear clear prescription glasses, not just for tinted sunglasses.
The Impact of UV Exposure on Eye Health
The eyes absorb UV radiation, which can lead to both short-term discomfort and long-term biological damage. The effects of UV exposure are cumulative, meaning the damage accrues silently over a person’s entire lifetime. This cumulative exposure increases the risk of developing several sight-threatening conditions later in life.
The cornea is susceptible to a painful condition called photokeratitis, essentially a sunburn on the eye. This temporary but intense exposure can cause redness, blurred vision, and a gritty feeling. The natural lens is also affected by chronic UV exposure.
Exposure to these rays accelerates the alteration of proteins within the lens, which leads to the formation of cataracts. A cataract causes the lens to become cloudy and opaque, progressively hindering vision. Furthermore, long-term UV radiation may contribute to age-related macular degeneration (AMD), a condition that affects the retina and central vision. Protecting the eyes from UV light significantly reduces the risk of these chronic conditions.
How Clear Eyeglasses Provide UV Protection
Standard clear lenses can block UV light through one of two methods: the natural properties of the lens material or an applied coating. The presence of UV protection is not related to the lens color or any visible tint. Lenses that block 100% of UVA and UVB radiation are designated as UV400, meaning they block light up to 400 nanometers in wavelength.
Certain lens materials inherently absorb all UV light due to their chemical composition. Polycarbonate and Trivex lenses, which are commonly used for their impact resistance and light weight, naturally block 100% of UV rays without needing a separate treatment. This built-in protection is a benefit of choosing these materials for everyday eyewear.
Conversely, traditional plastic lenses, such as CR-39, and standard glass lenses do not naturally block the full spectrum of UV light. These materials require an invisible, UV-blocking treatment that is applied to the lens surface during the manufacturing process. This added coating allows these common lens types to achieve the same 100% UV protection standard as the naturally blocking materials. The coating works by incorporating UV-absorbing chemicals that filter the harmful rays before they can reach the eye.
Practical Steps to Verify Your Lens Protection
When ordering new prescription glasses, request 100% UV protection, or UV400, on the lenses. Ask your optician for documentation or a receipt that indicates this feature was included in the final product. Understanding the lens material being used can also provide assurance, as polycarbonate and Trivex materials inherently guarantee this protection.
For existing glasses, the most reliable way to confirm UV protection is to take them to an optical shop. Most opticians have a specialized tool called a UV photometer or UV meter, which measures the exact percentage of ultraviolet light being transmitted through the lens. This test is quick, accurate, and can be performed on clear lenses in seconds.
Beyond the lenses themselves, the style of the frame also plays a role in overall protection. UV light can reach the eyes from the sides, top, and bottom, bypassing smaller lenses. Choosing a frame with larger lenses or a wraparound style helps shield the eyes from this peripheral exposure.