It’s a conundrum! Elderly folks’ sensory systems are often not as efficient. Knowing where your body is in space is not as sharp as when younger. This means lifting a leg is more precarious because it’s more difficult to know how much the leg has moved. So the impulse is to keep the foot closer to the ground.
Shuffling might be used by someone with peripheral neuropathy because it’s a bit scary to not be able to feel your feet. Keeping the feet close to the ground keeps the guesswork out of knowing whether your feet are directly under you for the next step.

Wearing trifocals, or even bifocals, might cause someone to have to look down very far, causing the head to be too far tilted forward. Just think, the reading area of eyeglasses is the lowest and the first section to view out of when looking down. But the reading lens isn’t good for looking at the ground, it’s blurry, The visual area of the glasses is at the top and the head has to be turned far down to view through that section.

I’m not a vision specialist, nor a medical professional for the elderly, but I’d advocate for wearing a single lens eyeglass for walking around, and a second pair for reading. Although losing them is then a problem. A conundrum!