Eye & Vision · Lens Guide
Electrochromic vs photochromic: two ways to change a lens
By the OSAWALLA editorial team · 2026-08-26 · 4 min read
Photochromic lenses darken because UV in sunlight drives a chemical reaction in the lens. You do not control it, and because car windscreens filter UV, they often stay clear indoors in a car.
Electrochromic lenses darken because you applied a small voltage. Half a second, on demand, regardless of UV — which makes them work in a car and let you decide the tint.
If you want the lens to handle itself, choose photochromic. If you want to control it, choose electrochromic.
This article is general information, not medical advice. OSAWALLA devices are wellness products and are not intended to diagnose, treat, cure or prevent any disease. Speak to a clinician about any health concern.
