Prisms only fix diplopia (double vision). If your eyes are slow to change focus, this is not diplopia.
@hunny and meme both:Blurry vision that takes a few seconds to sort itself out is usually very simple in itself, but not quite so easy to fix.
To start. A slow shift from near to distance focus is mostly age related. No, I’m not asking, but somewhere between 40 and 50 would be typical. The normal fix would be bifocal lenses. (But see below)
Next comes something for your GP rather than an optometrist (that’s the person who tests your eyes). A blocked tear-duct, or otherwise inadequate lubrication for the eyeball means that a blink does not clean the surface, but just smears what is there around. If several blinks in rapid sucession remove the blurryness, this is likely the problem.
After that, comes a cataract. If its a big one, the blur will not go away. A tiny one can just make it a bit hard at times, and you might just notice a tiny blurry circle if it happens to drift into the centre of your line of sight (say when looking at a monitor, reading this).
Double vision (diplopia). this is where the two eyes are not quite co-ordinated. This can be the muscles that orient the eyeballs (think of a squint) so that the point in two slightly different directions. It can be the muscles that focus the individual lenses in each eye so that an object is aimed at different parts of each retina. It would be unusual to have both sets of muscles involved.
You can test for diplopia yourself. All you need is a high-contrast target, preferably with a 90 degree angle. You casn look for a second image (somewhat fuzzy and slightly displaced), and check by alternately looking with one eye and the other. If is is more than about 50-70 feet away, and it seems to jump about, you can rule out the muscles that turn the eyeballs in to give you a measure of depth perception from binocular vision. But, you cannot measure diplopia yourself.
Optometrists do not usually like to deal with more than mild cases of diplopia, and generally only vertical displacement. Proper diagnosis and measurement is usually done by a hospital Orthoptics Department. This can take some time (several months, even) and often involves stick-on Fresnel (prism) lenses on your normal (or plain glass) specs. The stick-on Fresnel lens is only about half a mm thick, but comes with one great big disadvantage:
It can so reduce the light getting to the eye as to be a hazard when driving.
When a glass or optical plastic lens is made with a prism form, this does not happen - and your driving licence is not at risk. You could probably get away with a Fresnel stick-on added to a reading area of a bi-focal lens, because you do not normally use that when driving.
Quite simple really - until you look into it (sorry, could not resist that one).