Intermediate distance glasses are the best graphics upgrade I've had for ages!

[Angilion]

Gradual aging of my eyesight caught me out on that. I hadn't realised how suboptimal my other glasses had become for chair to monitor distance. Acclimatisation by slow change. Or Goldilocks with glasses - normal glasses were too far, reading glasses were too near, intermediate glasses were just right!

If you're old enough for your eyes to not be as flexible as they once were (>40, roughly, usually) a test might be worthwhile. You can go as far as measuring the distance and having glasses for that exact distance.

In my case it's not as big an upgrade as going from software rendering on a 486 to a Voodoo card, but it's bigger than going from a 1070 Ti to a 7800XT. Money well spent.

 

[Angilion]

what are intermediate distance glasses?

Glasses that properly correct vision at a distance longer than very short distance and shorter than usual distance vision. Usually ~1m. Usually expressed as an offset from the distance vision correction.

As a person gets older, the lenses in their eyes become less flexible and that affects focusing at closer distances. So it's normal for older people (normally starting around 40-45) to need vision correction for very short distances ("reading glasses"), even if their vision isn't defective and they don't need vision correction past very short distances. Older people with defective eyesight will need two lenses - one for their normal vision correction and another for very short distances that's an offset of their normal vision correction. Sometimes an additional lens becomes necessary (or at least useful) as the flexibility of the lenses in their eyes reduces further as they age more, a lens that will correct their vision at an intermediate distance.

You can have multiple lenses in one pair of glasses (varifocals) but results vary. Some people find varifocals more convenient than swapping glasses for different distances (which is an inconvenience). Other people find varifocals disorientating because your focus changes depending on the direction your eyes are looking at. You have to get used to moving your head more and your eyes less. Other people go with contacts for normal distance vision and putting glasses on over the contacts for very short distance vision. Other people go with one pair of glasses for normal distance vision and a bifocal pair with intermediate lens further up and reading lens further down, often called occupational glasses because they can be a good fit to a desk job where you might be moving your vision between a screen that's ~1m away and some paperwork that's much closer. There are options, each with advantages and disadvantages.