If with cataract surgery they replace the lens with a mono-focal implant… how can the eye focus? My understanding of the lens was it changed size to alter refraction… how does this work when you replace it?
The natural lens of the eye has usually lost that function long before it gets replaced by the new, artificial intraocular lens implant (IOL). This ability to change focus (called "accommodation") starts to decline even during one's teen years (believe it or not). But its slow, relentless hardening does not usually reach the point to cause a problem with reading until our mid-40s. We call the slow loss of accommodative ability "presbyopia."
there is an "accommodating" IOL available, its ability to magnify print at near
is not typically sufficient to meet most people's needs. There are, however, a
number of different multifocal and trifocal IOLs that can simulate
accommodative ability. But these do not actually work in the same way the eye's
natural lens can change shape through accommodation.
_Written by J. Trevor Woodhams, M.D. - Chief of Surgery, Woodhams Eye Clinic