Multifocal versus monofocal intraocular lenses after cataract extraction

Good unaided distance visual acuity is now a realistic expectation following cataract surgery and intraocular lens implantation. Near vision however still requires additional refractive power, usually in the form of reading glasses. Multiple optic (multifocal) intraocular lenses are available which claim to allow good vision at a range of distances. It is unclear whether this benefit outweighs the optical compromises inherent in multifocal intraocular lenses.

The objective of this review is to assess the effects of multifocal intraocular lenses, including effects on visual acuity, subjective visual satisfaction, spectacle dependence, glare and contrast sensitivity, compared to standard monofocal lenses.

We searched the Cochrane Central Register of Controlled Trials - CENTRAL (which includes the Eyes and Vision Group trials register) on the Cochrane Library (Issue 1 2002), MEDLINE (1966 to March 2002) and EMBASE (1980 to February 2002). The reference lists of relevant articles were searched. Investigators of included studies and manufacturers of multifocal intraocular lenses were contacted for information about additional published and unpublished studies.

All randomised controlled trials comparing a multifocal intraocular lens of any type with a monofocal intraocular lens as control were included. Both unilateral and bilateral implantation trials were included.

Data were collected and trial quality assessed. Where possible, statistical summary measures were calculated, otherwise data was tabulated.

Eight trials were identified. There was significant variability between the trials in which outcomes were reported. Unaided distance acuity was similar in multifocal and monofocal intraocular lenses (Peto Odds Ratio (OR) 1.21, 95% Confidence Interval (CI) 0.75 to 1.96). There was no statistical difference between multifocal IOLs and monofocals with respect to the proportion of participants achieving 6/6 best corrected visual acuity (Peto Odds Ratio 1.43, 95% CI 0.99 to 2.09). Unaided near vision was improved with the multifocal intraocular lenses. Total freedom from use of glasses was achieved more frequently with multifocal than monofocal IOLs (OR for spectacle dependence 0.15, 95% CI 0.11 to 0.22). Adverse effects included reduced contrast sensitivity and the subjective experience of haloes around lights.

Multifocal intraocular lenses are effective at improving near vision relative to monofocal intraocular lenses. Whether that improvement outweighs the adverse effects of multifocal intraocular lenses will vary between patients, with motivation to achieve spectacle independence likely to be the deciding factor.