Nearsightedness (myopia) causes blurry vision when looking at distant objects. Approximately 33% of the population in the United States is nearsighted, and some Asian countries report that up to 80% of children are nearsighted. Several studies have examined a variety of methods (including eye drops, incomplete correction (known as 'undercorrection') of nearsightedness, multifocal lenses and contact lenses) to slow the worsening of nearsightedness.
In this review we included 23 clinical investigations of myopia treatments in children. Two studies investigated undercorrection of myopia; twelve studies investigated multifocal spectacles (progressive addition lenses (PALs) or bifocal spectacles); one study investigated bifocal soft contact lenses (BSCLs); one study investigated novel lenses designed to reduce peripheral hyperopic defocus (peripheral vision farsightedness) (i.e. lenses that help to focus peripheral vision as well as central vision); two studies investigated rigid gas permeable contact lenses (RGPCLs); and six studies investigated pharmaceutical eye drops (five of these studies were of anti-muscarinic medications). There was one study that evaluated both multifocal lenses and pharmaceutical eye drops. In all studies the interventions of interest were compared with each other, single vision lenses (SVLs) (spectacles), single vision soft contact lenses (SVSCLs) or placebo. The follow-up period was at least one year for all studies.
The largest positive effects for slowing myopia progression were exhibited by anti-muscarinic medications (eye drops), but they either cause light sensitivity or blurred near vision, and are not yet available for use. Multifocal spectacles including PALs and bifocal spectacles were found to yield a small slowing of myopia progression. Undercorrection of myopia was found to increase myopia progression slightly, while RGPCLs were found to have no evidence of effect on myopic eye growth.
The most likely effective treatment to slow myopia progression thus far is anti-muscarinic topical medication. However, side effects of these medications include light sensitivity and near blur. Also, they are not yet commercially available, so their use is limited and not practical. Further information is required for other methods of myopia control, such as the use of corneal reshaping contact lenses or bifocal soft contact lenses (BSCLs) with a distance center are promising, but currently no published randomized clinical trials exist.
Nearsightedness (myopia) causes blurry vision when looking at distant objects. Highly nearsighted people are at greater risk of several vision-threatening problems such as retinal detachments, choroidal atrophy, cataracts and glaucoma. Interventions that have been explored to slow the progression of myopia include bifocal spectacles, cycloplegic drops, intraocular pressure-lowering drugs, muscarinic receptor antagonists and contact lenses. The purpose of this review was to systematically assess the effectiveness of strategies to control progression of myopia in children.
To assess the effects of several types of interventions, including eye drops, undercorrection of nearsightedness, multifocal spectacles and contact lenses, on the progression of nearsightedness in myopic children younger than 18 years. We compared the interventions of interest with each other, to single vision lenses (SVLs) (spectacles), placebo or no treatment.
We searched CENTRAL (which contains the Cochrane Eyes and Vision Group Trials Register) (The Cochrane Library 2011, Issue 10), MEDLINE (January 1950 to October 2011), EMBASE (January 1980 to October 2011), Latin American and Caribbean Literature on Health Sciences (LILACS) (January 1982 to October 2011), the metaRegister of Controlled Trials (mRCT) (www.controlled-trials.com) and ClinicalTrials.gov (http://clinicaltrials.gov). There were no date or language restrictions in the electronic searches for trials. The electronic databases were last searched on 11 October 2011. We also searched the reference lists and Science Citation Index for additional, potentially relevant studies.
We included randomized controlled trials (RCTs) in which participants were treated with spectacles, contact lenses or pharmaceutical agents for the purpose of controlling progression of myopia. We excluded trials where participants were older than 18 years at baseline or participants had less than -0.25 diopters (D) spherical equivalent myopia.
Two review authors independently extracted data and assessed the risk of bias for each included study. When possible, we analyzed data with the inverse variance method using a fixed-effect or random-effects model, depending on the number of studies and amount of heterogeneity detected.
We included 23 studies (4696 total participants) in this review, with 17 of these studies included in quantitative analysis. Since we only included RCTs in the review, the studies were generally at low risk of bias for selection bias. Undercorrection of myopia was found to increase myopia progression slightly in two studies; children who were undercorrected progressed on average 0.15 D (95% confidence interval (CI) -0.29 to 0.00) more than the fully corrected SVLs wearers at one year. Rigid gas permeable contact lenses (RGPCLs) were found to have no evidence of effect on myopic eye growth in two studies (no meta-analysis due to heterogeneity between studies). Progressive addition lenses (PALs), reported in four studies, and bifocal spectacles, reported in four studies, were found to yield a small slowing of myopia progression. For seven studies with quantitative data at one year, children wearing multifocal lenses, either PALs or bifocals, progressed on average 0.16 D (95% CI 0.07 to 0.25) less than children wearing SVLs. The largest positive effects for slowing myopia progression were exhibited by anti-muscarinic medications. At one year, children receiving pirenzepine gel (two studies), cyclopentolate eye drops (one study), or atropine eye drops (two studies) showed significantly less myopic progression compared with children receiving placebo (mean differences (MD) 0.31 (95% CI 0.17 to 0.44), 0.34 (95% CI 0.08 to 0.60), and 0.80 (95% CI 0.70 to 0.90), respectively).