What is an advantage of using photochromic glass over plastic lenses?

The advantage of using photochromic glass over plastic lenses primarily relates to the durability and longevity of the photochromic properties that glass offers. Photochromic glass lenses have the ability to transition from clear to dark when exposed to UV light, and this functionality can remain effective much longer than their plastic counterparts. While plastic photochromic lenses can deteriorate or lose their transition effect over time due to factors such as wear and environmental conditions, the changeable nature of glass lenses is more resilient.

Lenses that are made from photochromic glass typically maintain their photochromic function over an extended period, making them a more reliable option for those who frequently require adaptability to varying light conditions. In contrast, other materials may not have the same level of durability or might require replacement sooner. This characteristic of sustained efficacy is what makes photochromic glass a preferred option for many individuals seeking lasting performance from their eyewear.

The other options present advantages associated with different lens materials or characteristics, but they do not apply to photochromic glass specifically in the same way that durability and sustained function do.