Went to the optometrist yesterday, because I had a pseudo-blind spot appear in my view that turned out to be related to a new cotton wool spot in my right eye. As part of the exam, I got those pupil dilation drops (and an anesthetic right before them). It had been at least 10 years (possibly 15) since I got them last. Got a big clue as to how active focus works, or more specifically, how it does not work.
I’d mentioned my eye improvement process to the optometrist. At the end she had me check my vision, which puzzled me a bit, as I know one’s prescription is much worse with medically dilated pupils vs regular eye exam pupils and lighting. At first she put up a view, and I was unable to clear the view, but the view was obviously too strong (which I complained about). She acquiesced to my complaints and put weaker lenses in, that I had no problem reading. Turned out they were -4.0 (my prescription she determined for me two years earlier were 5.0s). Given that my eyes were fully dilated I suspect my prescription in dark opto office settings is about -3.25D, which aligns well with my personal measurements.
But I digress. What struck me is that I should have been able to clear the line with a diopter or two too strong prescription. I couldn’t I tried. It was close enough to being legible but nothing I did could clear it. Later I did some research, and what did I find? That the drops (or maybe the anesthetic applied before them) inhibits the normal accommodation reflex. In other words, it interfered with the ability to accommodate via the ciliary muscle in the usual way to see close up.
Why do I bring that up? Because before that part of the exam, after my eyes had fully medically dilated, I was playing around and found that I could active focus normally. No problems whatsoever improving the (crummy) view with active focus. I could look at something a bit far with too weak (with the drops) view, then clear it, then relax it back to blur again.
So I realized the next day (today) that that’s a big clue to the active focus mystery (what exactly is it). It’s obvious (to me) that active focus does not involve the ciliary, or anything near the pupil area. My eye muscles in the area were all misbehaving (due to the medication), yet I was able to active focus at will, and to the usual degree.
I have my guesses as to what active focus is (and this experience helps confirm that for me), but do others have some ideas as to why I couldn’t near focus at all with those eye drop drugs, but had no problem with using active focus?