Multifocal contact lenses (MFCLs), normally used in aging eyes, can slow the progression of myopia in children, according to results of the Bifocal Lenses In Nearsighted Kids (BLINK) study.*
“These lenses are believed to work by focusing some of the light directly on the retina, which enables children to see clearly, and focusing some of the light in front of the retina, which acts as a signal to slow eye growth,” said BLINK study chair, Jeffrey J. Waline, OD, PhD, associate dean for research at the Ohio State University College of Optometry (USA).
“If the eye continues to grow at the normal rate when light focuses in front of the retina, then vision continues to get worse. Therefore, the eye slows its growth so vision doesn’t get worse at the same rate,” he added.
These results highlight the exciting discovery of the option to control the development of nearsightedness in children, a condition that can increase the risk of cataracts, glaucoma and retinal detachment later in life if left untreated. Slowing myopia progression could decrease the risk of these sight-threatening complications.
BLINK for Children
Myopia is the most common ophthalmic condition in the world with an estimated 34% of the world population being affected. Half of the world’s population is expected to be myopic by 2050, with 10% of the population being highly myopic.
If untreated, myopia can inhibit academic performance in children. Visual impairment among preschool children is estimated to increase by 26% by 2060, with uncorrected refractive error comprising 69% of cases.
When a child has myopia, their eyeball is slightly longer than normal from front to back and images are focused at a point in front of the retina instead of directly on the retina. When this happens, objects at a distance seem blurry and unclear — and the higher the power added, the further in front of the retina the lens focuses peripheral light.
By comparison, single vision glasses and standard contact lenses, traditionally used to correct myopic vision, focus peripheral light to a point behind the retina, which encourages eyeball growth.
Several other advances in the treatment of nearsighted children include eye drops (such as atropine) which have previously been found to help slow the progression of myopia, but Dr. Walline said that multifocal contact lenses appear to provide better slowing of eyeball growth.
“While these contact lenses do not slow myopia progression, on average, as much as atropine eye drops, they do provide better slowing of eye growth (on average). Eye length is highly related to vision-threatening complications in adulthood, so that may be a very important factor when determining the best option for myopia control for young children,” he explained.
The study examined whether high add power contact lenses provided better slowing of myopia progression and eye growth than medium add power contact lenses and single vision contact lenses.
Almost 300 myopic children, aged between 7 to 11 years old, took part in the study, conducted at Ohio State and the University of Houston, USA, and funded by the National Eye Institute, part of the National Institutes of Health.
At baseline, the children required -0.75 to -5.00 diopters of correction to achieve clear distance vision.
The children were randomly assigned to wear single vision contact lenses or multifocal lenses, the outer lenses of which were either high add power (+2.50 diopters) or medium add power (+1.50 diopters).
The results? Children in the high add multifocal contact lens group saw the slowest progression in their myopia: Only the high add power contact lenses significantly reduced the rate of myopia progression over three years compared with medium add power multifocal and single vision contact lenses.
Mean myopia progression, as measured by changes in the eye prescription required to correct distance vision, was -0.60 diopters for the high-add group, -0.89 diopters for the medium-add group, and -1.05 diopters for the single-vision group. The multifocal lenses also slowed eye growth.
The three-year adjusted eye growth was .42mm for the high add group, .58mm for the medium-add group, and .66mm for the single-vision group.
“When fitting soft multifocal contact lenses for myopia control, the strongest add power that provides children with clear vision ought to be used, and that add power is almost always the highest add power available (+2.50 diopters). Also, the parents of all myopic children should be educated about myopia control,” noted Walline.
According to Walline, the contact lenses are safe to be used by children.
“Children have repeatedly been shown to be able to independently wear and care for soft contact lenses. In fact, they typically have fewer problems than college-age students. These lenses also provide clear vision and freedom from glasses, so the benefits outweigh the small risks that are associated with any contact lens wear,” he said.
“This study shows that if fitting soft multifocal contact lenses for myopia control, optometrists ought to use the high-add power. Ultimately, this provides another option for myopia control in young children, and enforces the fact that parents of myopic children need to be educated about the benefits of myopia control,” Dr. Walline concluded.
*Walline JJ, Giannoni AG, Sinnott LT, et al. A Randomized Trial of Soft Multifocal Contact Lenses for Myopia Control: Baseline Data and Methods. Optom Vis Sci. 2017;94(9):856-866.