“Cataract” is a term for clouding of the internal lens of the eye. The clouding can occur in a number of different patterns, and cause problems such as blurry vision, glare, trouble reading, and worsening nearsightedness. Surgery involves removal of the clouded lens from the thin capsule that surrounds it, and replacing it with a new lens. It is always done in the operating room by an eye surgeon. Laser can sometimes be used for small parts of the surgery.
With the standard single focus artificial lens implant (monofocal), you can select which of the four zones you want to see without wearing glasses. You must wear glasses if you want to see any of the other zones.
Bifocal lens implants (multifocal) are designed to produce a dual focus, meaning they can focus on more than one distance. With a bifocal lens implant, part of the lens is set for distance focus (zone 1) while part of the lens is then set for reading distance (zone 4). Having bifocal lens implants can significantly reduce your dependence on reading glasses.
Extended focus lens implants provide continuous focus over a range of distances. This lens implant is a good option for patients that want good natural focus without glasses when outdoors and indoors distances, as well as at mid-range distances, like zones 1, 2, and 3.
If the shape of the cornea is imperfect, it creates a natural blur or misfocus called astigmatism. Astigmatism is a refractive error that causes blurry vision. For patients with astigmatism, astigmatism correction can be put into the lens implant instead. This is something easily incorporated into each of the three lens implant categories. Any lens containing astigmatism correction is called a toric lens.