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Can bifocals slow myopia progression?
Insights
Bifocal lenses may slow myopia progression in children with esophoria. Myopia worsened faster during school months than summer vacation, suggesting environmental factors influence progression.
Area of Science:
- Ophthalmology
- Pediatric Optometry
Background:
- Retrospective studies suggest bifocals slow myopia progression in children with near point esophoria.
- A prospective study was designed to validate this hypothesis.
Purpose of the Study:
- To investigate the efficacy of bifocal lenses in slowing myopia progression in children with near point esophoria.
- To compare myopia progression rates between single-vision and bifocal lens corrections.
Main Methods:
- Thirty-two children with near point esophoria were randomized into single-vision or bifocal (+1.25 D) lens groups.
- Axial length and refraction were measured every six months for 18 months.
- Twenty-eight children completed the study.
Main Results:
- Myopia progression was similar in both groups for the first 12 months.
- Progression was significantly faster during school months (0.64 D/yr) compared to summer vacation (0.29 D/yr).
- Over 18 months, myopia progressed at 0.57 D/yr with single-vision lenses and 0.39 D/yr with bifocals.
Conclusions:
- Bifocal lenses showed a trend towards slowing myopia progression in this cohort.
- Seasonal variations significantly impacted myopia progression rates, with faster progression during the school year.
- Further long-term studies with larger sample sizes are required to confirm these findings.
Background:
Retrospective studies have suggested that in children with near point esophoria, bifocals can slow myopia progression by about 50 percent. A prospective study was conducted to test this hypothesis.
Methods:
Thirty-two children, all with near point esophoria, were randomly divided into either correction with single-vision or with bifocal lenses containing a +1.25 D and. Axial length and refraction were measured under cycloplegia every 6 months for 18 months. Twenty-eight children completed the study.
Results:
Myopia progressed at an equal rate in both groups for the first 12 months. Progression was much faster during the first 6 months, which was during the school year, than during the second 6 months, which included all of the summer vacation (0.64 D/yr vs 0.29 D/yr). During the last 6 months, myopia progressed rapidly for children in single-vision lenses (0.80 D/yr) but slowly for those in bifocals (0.37 D/yr). A repeated-measure analysis of variance showed that season of the year had a significant effect on myopia progression (p > 0.002) and that the effect differed for the two treatment groups (p > 0.043). Over the whole 18-month study, myopia progressed at rate of 0.57 D/yr for those in single-vision lenses and 0.39 D/yr in those in bifocals (p = 0.26).
Conclusions:
Bifocals seemed to slow myopia progression in these children with near-point esophoria, although a longer-term study with more subjects is needed to confirm this finding. Myopia progressed more rapidly during the school year than during summer vacation.