A comparison of multifocal and monofocal intraocular
lens implants used in cataract surgery
(25.09.2013)
(http://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0011863/)
(www.karmayog.org)
Plain
language summary
As people get older, sometimes the
lens of the eye becomes cloudy leading to loss of vision. The cloudy lens or
cataract can be removed, and a replacement lens put in its place. In the past,
the replacement lens had one ‘point of focus’, either in the distance or close
up (‘monofocal’ lens). This meant that glasses were needed for focusing at
other points, for example, for reading. New lenses have been developed that
provide two or more points of focus (‘multifocal’ lenses). These are designed
to avoid the need for glasses. We found 16 trials that randomised over 1600
people to either a multifocal or monofocal lens. People who had multifocal
lenses were less likely to need spectacles. They had the same visual acuity for
seeing in the distance compared to people who had monofocal lenses but had
better visual acuity for near vision. The multifocal lenses had drawbacks:
people with these lenses were more likely to see halos around lights and had
reduced contrast sensitivity (the ability to distinguish an object against a
background which is similar to the object itself). Multifocal 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.
Abstract
Background: Good unaided distance visual acuity is now a realistic
expectation following cataract surgery and intraocular lens (IOL) implantation.
Near vision, however, still requires additional refractive power, usually in
the form of reading glasses. Multiple optic (multifocal) IOLs 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 IOLs.
Objectives: The objective of this review was to assess the effects of
multifocal IOLs, including effects on visual acuity, subjective visual
satisfaction, spectacle dependence, glare and contrast sensitivity, compared to
standard monofocal lenses in people undergoing cataract surgery.
Search methods: We searched CENTRAL (which contains the Cochrane Eyes and
Vision Group Trials Register) (The Cochrane Library 2012, Issue 2),
MEDLINE (January 1946 to March 2012), EMBASE (January 1980 to March 2012), the metaRegister
of Controlled Trials (mRCT) (www.controlled–trials.com), ClinicalTrials.gov (www.clinicaltrials.gov) and the WHO International Clinical Trials Registry Platform
(ICTRP) (www.who.int/ictrp/search/en). We did not use any date or language restrictions in the
electronic searches for trials. The electronic databases were last searched on
6 March 2012. We searched the reference lists of relevant articles and
contacted investigators of included studies and manufacturers of multifocal
IOLs for information about additional published and unpublished studies.
Selection criteria: All randomised controlled trials comparing a multifocal IOL
of any type with a monofocal IOL as control were included. Both unilateral and
bilateral implantation trials were included.
Data collection and analysis: Two authors collected data and assessed trial quality.
Where possible, we pooled data from the individual studies using a random–effects
model, otherwise we tabulated data.
Main results: Sixteen completed trials (1608 participants) and two
ongoing trials were identified. All included trials compared multifocal and
monofocal lenses but there was considerable variety in the make and model of
lenses implanted. Overall we considered the trials at risk of performance and
detection bias because it was difficult to mask patients and outcome assessors.
It was also difficult to assess the role of reporting bias. There was moderate
quality evidence that similar distance acuity is achieved with both types of
lenses (pooled risk ratio (RR) for unaided visual acuity worse than 6/6: 0.98,
95% confidence interval (CI) 0.91 to 1.05). There was also evidence that people
with multifocal lenses had better near vision but methodological and
statistical heterogeneity meant that we did not calculate a pooled estimate for
effect on near vision. Total freedom from use of glasses was achieved more frequently
with multifocal than monofocal IOLs. Adverse subjective visual phenomena,
particularly haloes, or rings around lights, were more prevalent and more
troublesome in participants with the multifocal IOL and there was evidence of
reduced contrast sensitivity with the multifocal lenses.
Authors’ conclusions: Multifocal IOLs are effective at improving near vision
relative to monofocal IOLs. Whether that improvement outweighs the adverse
effects of multifocal IOLs will vary between patients. Motivation to achieve
spectacle independence is likely to be the deciding factor.
Editorial
Group: Cochrane Eyes and Vision Group.
Publication
status: New search for studies and content updated (no change to conclusions).
Citation:
Calladine D, Evans JR, Shah S, Leyland M. Multifocal versus monofocal
intraocular lenses after cataract extraction. Cochrane Database of
Systematic Reviews 2012, Issue 9. Art. No.: CD003169. DOI:
10.1002/14651858.CD003169.pub3. Link to Cochrane