I think that is most noticeable when you try to read in different light conditions with and without glasses - my correction for reading is between 1.5 and 2 dioptres but I can read unaided in bright conditions because of the high contrast - as soon as the light levels reduce from that I have to reach for my glasses.
If you artificially reduce your light levels with sunglasses, down goes your contrast.
The main effect of brighter light is to allow/cause the pupils to contract, reducing the effect of off-axis distortions in the lens and cornea. The ultimate limit is diffraction limits in pinhole apertures where the interference of the light causes spreading at the edge of the pinhole. There are gag glasses made that are opaque black plastic for the "lenses" with many small holes for light to pass through. When conditions are bright enough they work quite well.
I guess one could call the problem "contrast" but the real effect is optical aberration / blurring / smearing of the image not being focused on a one-to-one correspondence between the scene and the retina.
I still recall in my 40s standing up in the cube farm from a long day at the computer monitor and noting that everything more than 20 feet or so was a bit blurry, like a fog had rolled in - the lenses were no longer elastic enough to flatten out rapidly when the lens muscles relaxed. Now my lenses appear to be stiff enough the little muscles that should deform them no longer can. At least I can see well enough in the distance, though there is some correctable astigmatism that is annoying. As long as there are no highway eye charts and I have cheap readers to see the speedometer I am still good to drive.
That "adaptation time" in the report is, I think, the time required for the elastic capsule of the lens to change shape as the muscles squeeze or release it. At the age mentioned, I suspect that adaptation time is approaching infinity.