As an ophthalmologist there is no reason that heart surgery should change someone's refraction.
fully agree ... but most people don't think about the anatomy of the eye they just think about how they perceive vision. Now what (as you go on to mention) may well be at work is the operation of the muscles.
Some drugs may alter focusing while they are being used but this is infrequent and usually temporary.
which focus the lens. What I've read (some time ago actually and I've forgotten the source) is that two things are at work here.
- the lens hardens over time and its ability to deform lessens
- as the lens looses its ability to deform it places greater strain on the muscles attempting to pull it into shape
What I see here is that if something triggers a situation where the muscles don't keep straining and thus strength training they may take a time to get back to that strength. Indeed we know that as we age muscles are indeed harder to "rebuild" after a period of enforced rest (either by injury or illness).
I did a lot of reading when I was recovering from my surgery not least about my eyes because I found it a lot harder to read my computer screen when I got back to it. I began then using glasses at my work, +1.5 diopters, and found that worked for a while, but then I found this was eventually also resulting in eye strain and went up gradually (over a few years) to +1.75
I'm sure that you'll now be nodding and saying,
well yes, but this is a very common progression of presbyopia statistically speaking, and at your age that's likely. I don't disagree, but this may well have been exacerbated by the surgery and the down time and the complete relaxation of those muscles for a much longer period. It could also have resulted in the
Crystalline lens deforming (or re-conforming) to a relaxed state (after some consecutive days of not being under pressure) which required even more effort to reform it.
This (also from my readings) is as I understand it the explanation often given for why we see (based on the dissection and examination of many eyes over the years) a build up in muscle size to around middle age and then a steady decline in the muscle size after that (and the adoption of eyeglasses is often fingered in that cycle from what I've read).
Of what I've read R.A. Weale is the only document I kept (other readings were likely from books because where I worked in IT for some time just happened to be at a University Library) and may indeed be considered flawed now.
So what I'm saying is that we anticipate a decline, but when its a smooth line we frequently don't notice it. However when there is a noticeable decline attributable to an event we tend to focus our attention on that. I often say that decline is best modelled by a reduced scaling function on a sawtooth pattern. It may go up or down but overall the line of best fit is a decline (not unlike this simplification).
Best Wishes
