Especially when travelling, we want more flexibility and relaxation. Accordingly, self-tinting lenses can be a great travelling companion.
However, you should bear in mind that most of the UV rays which activate self-tinting lenses are blocked by cars' windscreens, which means that the prescription spectacle lenses do not darken as much there. Although PhotoFusion prescription spectacle lenses offer a certain protection against glare in cars, we still recommend wearing "real" sunglasses during long journeys with significantly changing light conditions (e.g. through tunnels).
Photochromic prescription spectacle 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 in southern countries in particular.