We want more flexibility and relaxation, especially when traveling. Accordingly, self-tinting lenses can be a great traveling companion.
However, you should bear in mind that most of the UV rays which activate self-tinting lenses are blocked by car windows, meaning that the prescription lenses do not darken as much there. Although PhotoFusion® prescription eyeglass lenses offer a certain protection against glare in cars, we still recommend wearing "real" sunglasses during long journeys with significantly changing light conditions (like through tunnels).
Photochromic prescription lenses also react to temperature differences. That means that self-tinting lenses darken less in bright sunlight when outdoor temperatures are high. As a result, we recommend carrying sunglasses, particularly in southern regions.