I went the cheap route that works well for me transitioning from pre-dawn, to dawn, to full sunlight. I wear yellow lensed bifocal safety glasses until I switch to brown lensed bifocal safety sunglasses. I can see this would not be a good solution if managing several transitions like traversing through tunnels or tree canopies. The yellow is especially good for me in perceiving contrast and avoiding objects like rocks on gray asphalt.