Preserving Little Eyes a Little Longer

Nearsightedness in some children might slow down with no line bifocal lenses

(RxWiki News) Children's eyes continue to undergo changes as they grow, often worsening if they are nearsighted. But there may be a way to slow that downhill trend for certain kids.

A recent study has found a small but noteworthy slowing down of nearsightedness progression in children who wore lenses with a gradation of power instead of lenses with all one power across the entire lens.

"Have your child's eyes checked annually."

David Berntsen, an assistant professor at the University of Houston's College of Optometry, led a study to compare the effectiveness "progressive addition lenses" in nearsighted children.

Progressive addition lenses, also known as no-line bifocals, adds lens power correction to glasses moving from the top to the bottom of the lens.

Dr. Berntsen's team tracked 85 children, aged 6 to 11 years old, during a two-year period. Each child was given either normal single-vision lenses or no-line bifocals for their myopia, or nearsightedness.

Over the next two years, Dr. Berntsen's team observed and tested the children and interviewed their parents regarding the children's outdoor activities and close work, like reading and using the computer.

What they found was that the nearsightedness of children wearing no-line bifocals did not tend to get worse as much as the children wearing only the single-vision lenses.

The slow-down difference was small but large enough to be considered more than a coincidence or explained by other factors in the study.

Dr. Berntsen cautions that no-line bifocals are not necessarily right for all nearsighted children, nor does these study results mean that giving any nearsighted child no-line bifocals will slow down their increasing nearsightedness.

"While the small effect found in the group of children wearing bifocal spectacles does not warrant a change in clinical practice, we found the beneficial effect was still present for at least one year after children stopped wearing no-line bifocal lenses," Dr. Berntsen said.

"For any treatment that reduces myopia progression in children to be useful, the effect of the spectacles or contact lenses must persist after children stop wearing them," he said. "The fact that the small treatment effect from our study was still present one year after discontinuing the treatment is promising. The results suggest that if newer optical designs currently being investigated do a better job of slowing myopia progression, the effects may be expected to persist and decrease how nearsighted the child ultimately becomes."

Dr. Berntsen's team hoped to learn from this study why no-line bifocals might slow nearsightedness progression, and they have interpreted the data to mean that it has to do with lenses that are designed to change blur in an eye's peripheral vision.

The study was published online June 5 in the journal Investigative Ophthalmology and Visual Science. The research was funded by a grant from the National Institutes of Health National Eye Institute, by Essilor of American, Inc. and by the American Optometric Foundation Ezell Fellowship program.

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Review Date: 
June 6, 2012