In a small preliminary study supported by the National Eye Institute (NEI), researchers have found that children who wore bifocal eyeglasses had a slightly slower progression of myopia, or nearsightedness, than children who wore traditional single-vision eyeglasses. These findings appear in the August 2000 issue of Optometry and Vision Science.
The randomized trial was conducted with 82 children between ages six and 12, all of whom had myopia and a condition called esophoria, which is a tendency for the eyes to cross while reading. A minority of all myopic children have esophoria. The researchers found that, after 30 months, the children wearing bifocals had slightly reduced progression of myopia compared with the control group that wore regular eyeglasses.
The results of this study are not definitive and support the need for future research. The researchers conclude that their findings "seem to fall short of what might be considered a substantial benefit" and "do not justify the unequivocal recommendation" of bifocals for all myopic children with esophoria. According to the authors, modest benefits of bifocal use "need to be weighed against the increased cost and the attitude of the parent and child towards bifocals."
Myopia commonly appears between ages 8 and 12 years and can progress rapidly during this time. The authors point out that a reduction in the development of myopia in young children might lead to a reduction in the final amount of myopia as adults. Less severe myopia would result in corrective eyeglasses that are not as strong; better vision when the eyeglasses are not worn; and perhaps lesser risks for retinal detachment and certain eye diseases, all of which are associated with increasing degrees of myopia.
Identifying risk factors for myopia and evaluating promising treatments for preventing its onset or slowing its progression are among the research objectives of the NEI. The Institute is supporting a multicenter, randomized, controlled clinical trial to evaluate whether progressive lenses slow the progression of nearsightedness in children as compared with single vision eyeglasses. This study, called the Correction of Myopia Evaluation Trial, is following more than 400 children with myopia in both eyes. Results from this study are expected to be released in 2002.