Does anyone know much about cataract lens replacements? (I was surprised I could not find anything in a search of Phys-L archives).
I have one new lens at present (the other eye next week) and have two questions.
1. How can a single tiny lens have more than one focal length? My new lens allows me to see distance objects clearly and also objects close up (this was an added expense over and above the usual distance lens they typically use). I believe (based on the tech person who scheduled the surgery) it is a fresnel type lens but I don’t know much else. The angle I look at things doesn’t seem to matter (so I don’t think it is like a graduated bifocal lens).
2. Why would an insertion at a slight angle work to resolve astigmatism? I would have thought the lens would be circularly symmetric so the angle at which it was inserted should not matter but they tell me they were able to correct about half my mild astigmatism by inserting at 60 degrees (about 2 o’clock when looking from the front). There are asthmatic lens replacements but I did not get that kind of lens.
kyle
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