This is an interesting topic so I've done a bit of reading to try and understand what's going on. Here's what I've found:
When your distance vision is good, parallel light, which comes from beyond optical infinity (6 meters or farther away), gets focused into your retina. If you are nearsighted (can't see distance well), your eye has too strong an optical power (aka too high a dioptre, aka too short a focal length) so it focuses the image in front of your retina, which makes the image blurry.
(An aside: As mentioned above, distance vision is for parallel light. Light from closer objects is diverging, so you need even more optical power to focus light from a close object onto your retina. The eye has an ability (accomodation) to increase its optical power and thus focus on close objects. But this ability is lost with age, which necessitates reading glasses, which are a positive dioptre, ie an increase in optical power.)
To correct nearsightedness, you get glasses that have a negative diopter (for example a moderate prescription might be -3 dioptre), which weakens the optical power of your eye+glasses, so that the focus of far-away-object light goes from in front of the retina to on the retina.
Ocular adjustments on scope eyepieces have a range of something like plus/minus 2 or 3 dioptres. When the ocular is backed all the way out it's positive dioptre, aka more optical power, so with respect to the reticle it's like looking through a pair of reading glasses. When the ocular is screwed all the way in it's negative dioptre, so with respect to the reticle it's like looking through a moderate strength prescription for nearsightedness.
My problem is I have the ocular adjustment screwed all the way in and it's still not in focus. The solution is I need more negative dioptre applied to my eye, so that I will get good reticle focus somewhere in the middle of the adjustment range of the scope ocular.
One thing to note is that while my prescription is stable, I need to check if it's 100% stable, because my shooting glasses are over a decade old. First thing to try is using the scope with my latest prescription glasses. Also, perhaps the size of the glasses lens (large for my shooting glasses, small for latest prescription pair), or where the light hits the glasses lens, plays a role in actual dioptre change I experience with the (small) 4 mm wide circle of light coming out of the scope.
One backup option is I could try with some cheap over the counter negative dioptre glasses (the opposite of the usual reading glasses you're thinking of), or single-use contacts, with a dioptre even more negative than my prescription.
Another backup option is to go to the optometrist and explain the problem, see if I'm missing anything, whether I need a special extra negative dioptre prescription for use with riflescopes. Or if I need a different prescription for my left eye (dominant) when the right is screwed shut (because closing one eye changes the shape of the other). Is that why some fancy shooters use blinders on their other eye?
