Question

Advantage and disadvantage of photochromic lenses

Answer 1

Explanation:

There are both advantages and disadvantages to photochromic lenses. The main advantage is that they will darken into a sunglass tint when exposed to U.V. thus removing the need to carry a separate pair of sunglasses for protection against harmful U.V. rays from the sun.

The main disadvantage of photochromic lenses is they do not adjust immediately. It could take up to two minutes for the lenses to adeaquately change from light to dark or vice versa. Another disadvantage for some users is that they will not darken when worn inside vehicles (windscreen/green glass absorbs virtually 100% of UV light). Since they do not darken inside vehicles, they may not be adequate as driving glasses. Another disadvantage is that they become extremely dark when they get cold. This is a big disadvantage for skiers, who need their glasses to lighten when light is dim and flat