I’m -17D. When I take off my glasses and hold an object at my near focus point, I have incredible clarity, equivalent to a 5x microscope. (I did math based on standard “close inspection” distance, my close inspection distance, and viewing angle. The math also works out using the magnification to diopter formula, that 5x = +16D.)
So I’m struggling a bit with doing subjective refraction and measuring distance to blur with differentials on, partly because nothing is ever as clear as close inspection without my glasses. Maybe what I think of as being half blind is really what everyone else sees all the time. I do have a best corrected visual acuity near 20/20, and the doc seems perfectly happy with me struggling to read text that I’d like to see clearly. (I can read the bottom line of the near vision card in full strength lenses, but it gives me a headache quickly.)
Is this why I’ve always been better at reading than most of my peers? I can actually see those close up letters better than they, and they’re always struggling with near vision the way I do at the board/projection?
So no matter how far I go in EM, I’m never going to see as sharply at distance as I do up close. There just isn’t enough rods and cones in the eye to see the smaller visual angle clearly. I wonder how much of EM is teaching ourselves to be comfortable with that fact so the eye can relax (in shape, not just short term muscular posture) and not tighten down (really stretch out, my English language bias is mixing up metaphors) into super clarity close vision mode…
There was another tidbit that caught my attention, we discussed Bates saying children should spend time straining to read fine print. What he meant is pretty vague, around here we tend to recommend larger fonts that encourage more distance between the eyes and the screen, but perhaps if you keep distance the same and shrink the fonts, then you force the visual cortex to deal with character recognition with fewer rods/cones providing data. Who knows, maybe it even affects the edge detection at the ganglion cell level.
Hrm… I’ve actually found the passage.
He might be discussing bringing a book well within your natural focal range straining you near vision, but back in Bates day, before it was easy to print out super fine test scripts, where would a myope get text too fine to see by bringing it closer? He must be discussing holding the fine print at a distance that causes mild strain? The last bit about straining at text you can’t see sounds a lot like print pushing or AF with just a bit too much challenge to actually clear the text.
I’ve taken a page from the mystics folk who chant mantras about “I can see clearly”… “I have plenty of corrected visual acuity, these glasses are sufficient for this distance, this strain to see small text is not abnormal, I can concentrate on this text and understand it.” I’m not really ready to drop all my crazy font sizes, but I’ve made a few concessions to slow down rather than just scale everything up to where I can scan quickly. Trying to keep my distance from the screen the same. My wide 3-screen setup helps with that, as getting too close to one screen and the others are at different focal distances.
I think I have a touch of convergence issues at near vision, and this is something within my control to focus on making both eyes look at the text and help each other resolve the image a bit better. I don’t think this is AF, I can’t do it monocularly.
I don’t know if this affects low myopes so much, you’d have to be at least -4D to get a noticeable (2X) magnification effect at near vision, but maybe other high myopes can relate.