Transition lenses can change its color according to surrounding light conditions. The company claims that Transition lenses can darken in bright conditions so that they can provide enough UV protection as well as sunglasses do. This advocated feature of Transition lenses actually attracts a large group of customers, because they think that separate sunglasses are needless.

Transition lenses can provide UV 400 protection, which is sufficient in most states of USA. But these lenses can not replace sunglasses in some aspects. For example, Transition lenses do not fight against high energy visible (HEV) light. In the violet band from 380 to 530 nm in the visible spectrum, high energy visible light is high-frequent and commonly referred to as the near UV range. There is a high occurrence of HEV light from pools, sidewalks and sand.

HEV protection from sunglasses is important for ordinary people, especially for younger children because their eye lenses are thought to transmit more HEV light than adults. Without proper protection, HEV light may lead to age-related macular degeneration, which has been proved by quite a few studies. Only special HEV sunglasses can filter out the near UV range. Currently, only polarized sunglasses can offer protection against HEV light.

In addition, Transition lenses will not darken when the wearer is in a vehicle with UV protected windshield. In this case, Transition lenses are too clear to provide continual protection against glare and eyestrain. In this consideration, Transition lenses behind vehicle windshield are even less helpful than regular sunglasses.

Always coupled with small frames that only cover the intermediate eye area and little of the surrounding area, Transition lenses only offer normal eye protection against UV light. Most sunglasses provide a larger coverage that can protect the fragile skin and still block various angles of sunlight. In this way, sunglasses offer extended protection against harmful rays.

In conclusion, eyeglasses with transition lenses are a good choice for people who need to regularly move from indoors to outdoors or vise versa. But for those spending an extended amount of time outdoors, sunglasses are irreplaceable.