Contact lenses that automatically adjust to changing light conditions are available to consumers. These products are often referred to as “transition” style lenses because they mimic the light-adaptive technology found in some eyeglass lenses. They are designed to manage the amount of light entering the eye, helping to reduce the visual discomfort that comes from bright or fluctuating light sources.
How Photochromic Contact Lenses Work
The technology powering these lenses is called photochromic, utilizing specialized molecules embedded within the lens material. The currently available product, ACUVUE Oasys with Transitions Light Intelligent Technology, uses trillions of these molecules that are chemically responsive to light. These molecules are initially in a closed, clear state when the lens is not exposed to bright light.
When exposed to ultraviolet (UV) or high-energy visible (HEV) light, the molecules undergo a structural change, causing them to open up and darken the lens. This chemical reaction happens rapidly, allowing the lens to activate and darken in less than 60 seconds. The photochromic mechanism continuously balances the light entering the eye, rather than turning completely dark like a sunglass.
When the light source is removed, such as when moving from outdoors to indoors, the molecules return to their original closed state. The lens begins to fade back to its clear state. This deactivation process is also quick, taking approximately 90 seconds for the lens to return from its darkest tint to its normal clear appearance.
Light Protection and Lens Performance
These light-adaptive lenses provide eye protection and improve visual comfort across various lighting conditions. The photochromic action reduces the intensity of light that reaches the eye, minimizing the need to squint in bright environments. This helps alleviate visual strain when moving between different light levels. The continuous light management also helps reduce halos and starbursts, which can be an issue during low-light driving at night.
Beyond comfort, the lenses offer health protection by filtering light across the visible and invisible spectrums. The technology blocks 99% of UVB rays and over 90% of UVA rays, offering the highest level of UV protection currently available in a contact lens. They also filter a portion of the blue light emitted from digital screens and bright indoor lighting, which can contribute to eye fatigue.
In practical use, the lenses perform well during outdoor activities, but they do not fully replace sunglasses. Since the lenses only cover the cornea and iris, they leave the surrounding skin and the rest of the eye exposed to UV rays. Furthermore, the light-adaptive feature may not activate fully inside a car because most modern windshields block the necessary UV light required to trigger the photochromic reaction.
Prescription Requirements and Availability
Light-adaptive contacts are regulated as prescription medical devices and require a current, valid prescription from an eye care professional. The process involves a comprehensive eye exam to determine the necessary vision correction and a specific contact lens fitting. The fitting ensures the lens sits correctly on the eye and confirms the light-adaptive feature works appropriately.
The lenses are typically available for various vision needs, including sphere power for nearsightedness and farsightedness, in a two-week disposable format. Because they incorporate advanced technology and are a specialty product, they are often priced higher than standard contact lenses. Pricing varies significantly based on the eye care provider, location, and any insurance coverage a person may have.
Once the eye care professional determines the lenses are a suitable option, they provide the necessary prescription. Consumers can then fill this prescription through their doctor’s office or verified online retailers. A contact lens prescription is generally valid for 12 to 24 months, after which a new eye examination is necessary to ensure continued eye health and accurate vision correction.