A comparison of multifocal and monofocal intraocular lens implants used in cataract surgery

Cataract, defined as the presence of visually-impairing lens opacity in one or both eyes, is present in 30% of persons of 65 years and over in the UK. Modern cataract surgery is frequently accompanied by the insertion of an implant within the eye known as an intraocular lens. Monofocal intraocular lenses have one point of focus. Monofocal intraocular lenses can be used to give clear point of focus in the distance or close up, but you can only choose one focal point. Glasses provide extra lens power which enables focussing at other points in space, such as close up for reading. Multifocal intraocular lenses were designed to avoid the need for glasses by providing two or more points of focus. This review identified 10 trials, and a further three are pending review, comparing monofocal to multifocal intraocular lenses. Unfortunately near vision and subjective outcomes were poorly assessed in these trials. The distance vision without glasses was similar in both groups. Near vision without glasses, however, was better in the multifocal group and participants in this group were more likely to achieve total freedom from glasses. Multifocal intraocular lenses had drawbacks; they were associated with symptoms of halos around lights, and a reduced contrast sensitivity (the ability to distinguish an object against a background which is similar to the object itself). Thus multifocal intraocular lens implants reduce spectacle dependence after cataract surgery but at the expense of clarity. Ultimately it will be up to the individual to decide which type of lens they would prefer.