Photochromic Lenses
AR and Photochromic Lenses

Because anti-reflective (AR) coatings block some UV light, they can affect photochromic performance. Generally, applying an AR coating to any photochromic lens will increase the light transmittance in both the clear and darkened states. Exact percentages vary depending on which coating is used. However, the average gain in transmittance of a photochromic lens in its clear state is approximately four percentage points when an AR coating is used.

While AR coatings can slow the rate of darkening, the difference to the wearer is minimal. The slight loss of darkening ability during the day is balanced at night, when the slightly clearer AR-coated lens helps by allowing more light to reach the eye.

Here are some examples: In-mass plastic lenses with AR have 90% light transmittance in the clear state. Imbibed lenses with AR have 89%. To compare� Clear CR-39 is 92% and Polycarbonate is 90%. In the darkened state, photochromic lenses would be a couple percentage points lighter with AR.

 

Transmittance with AR
In-mass clear state with AR Imbibed clear state with AR Clear CR-39 without AR Polycarbonate without AR	90% 89% 92% 90%
In-mass and imbibed % taken from manufacturer literature. Clear CR-39 and Polycarbonate taken from Spectral Transmittance of Lens Materials published by the Optical Laboratory Association, March 1998.