During cataract surgery the cloudy, diseased crytalline lens is removed from inside the eye. This would result in a large loss of focusing power if this lens is absent. Before implant lenses were developed cataract surgery patients had to use thick, distorting ("coke-bottle-bottom") glasses or contact lenses. This was very inconvenient because without these corrective lenses the patients could not see well until they were applied.As a result the patients were very enthusiastic for implants to be developed. Hence the "pros" for implant lens are more natural vision, better vision, often improved correction such that patients can often see without glasses more frequently than before surgery. Modern implants are now being developed to correct for astigmatism and the combination of near and far vision without correction.
With modern cataract surgery it is very rare that a patient does not get an implant lens. Rarely do implants cause problems in post-surgical eyes. Extrememly rare are the reports of lens caused infections, irritations, bleeding, pigment dispersion or glaucoma. Patients could have these post-operative problems even without implant lenses. Occasionally an incorrect power of an implant is discovered and the lens can be removed and replaced with another. It is always best that diligent, well-planned and careful surgery be performed to minimize implant or other cataract surgery complications.