You unbox your new photochromic lenses, slip them on indoors, and… nothing. They stay light. Before you assume something's wrong — they're working exactly as designed. Photochromic lenses only change in one place: direct sunlight.
Why they don't darken indoors
Photochromic lenses darken in response to UV light, and UV comes from the sun — not from your lamps. Indoor lighting (LED, fluorescent, incandescent) gives off virtually no UV, so the lenses have nothing to react to. Just as importantly, ordinary glass blocks most UV, which means your lenses also won't fully darken behind a window or a car windshield. None of that is a defect — it's simply how the technology works.
Watch the 30-second testSee a pair of IMINTA Transition lenses go from light to a deep tint the moment they hit direct sunlight — then fade back in the shade. That's exactly what yours will do outdoors. They won't darken indoors or behind glass, and that's completely normal.▶ Watch on YouTube →
How to test your photochromic lenses (the right way)
- Step outside into direct sunlight. A clear, sunny day shows the effect best.
- Wait about 30–60 seconds. You'll watch the lenses deepen to a rich, dark tint.
- Move into the shade or back indoors. Over the next minute or two they'll fade back to a light tint.
- Want a side-by-side? Hold one lens up to the sun and keep the other shaded or covered — then compare. The difference is obvious.
The most common "test" mistake
By far the #1 reason people think their lenses "aren't working" is testing them indoors, in the car, or near a window — all places where UV can't reach the lens. Take them into open sunlight and you'll see them transform.
A couple of things that affect the change
- Temperature: the lenses react faster in warm weather and a little slower in the cold — normal photochromic behavior.
- Behind the wheel: windshields filter UV, so the lenses stay lighter while driving. If yours are also polarized photochromic, the polarization still cuts road glare the whole time.
Want one lens that adapts to the light and kills glare? Read about our polarized photochromic lenses, or find your frame and add Transition lenses →