Hi folks I am new to the site. Have been doing a lot of reading and watching Jake’s videos so am getting a pretty good understanding how to reverse a negative diopter sphere prescription. My case is a bit different (maybe a lot different) in that I used to have a mild negative sphere (-1.25) and strong negative astigmatism (-4.5) in both eyes but since my cataract surgery I now have +2.5/-4.5/82 in the left and bit better in the right. I currently have about 20/40 sometimes 20/30 vision so have been without glasses. Close up vision is excellent up to about 90 cm or more. Active focusing has been helping improve my close up even more.
So I am trying to understand the physics of my new prescription. When I had a negative sphere prescription (nearsighted) I understood that the focal point was before my retina thus the need for minus glasses. Given that I had been wearing a minus prescription for 50 yrs for both far and close vision I assume my eye had lengthen. Now that I have what looks to be a strong positive sphere (supposedly farsighted) , I assume the surgeon had tried to match my new cataract lens focal length to my already elongated eye length resulting in ok vision but not 20/20. (As an aside when I wear pin hole glasses I have 20/20 maybe even a bit better.) I don’t quite understand what equivalent sphere means but I know mine is +0.25 when I use the formula which is probably why I have reasonable vision. So assume its my high astigmatism that’s holding me back from 20/20.
Given this long winded story, I’m not sure if progressive diopter reductions in my prescription makes sense or if a plastic cataract lens can even be reshaped by the ciliary muscle. Also with a positive small equivalent sphere, does my eye need to elongate a bit more to match the new lens focal length (higher risk of retinal tear) ? Already had one retinal tear after the cataract surgery which ended up be a blessing in disguise as removing the vitreous solved the serious floater problem in my right eye. A recent flood of floaters in my left eye probably means I will have a tear in that eye at some point. I’ve got to say though, the surgery was easy and so was cataract surgery. If anybody is interested in my experience, would be happy to share.
Anyways, as I mentioned I am working without glasses (nice !) no problem but would love to get to 20/20. Sorry if this sounds like asking for specific advice but its just such a weird situation I find myself in with these new eyes !. I may not even be asking the right questions.