Hard contact lenses are associated with a slower rate of progression of myopia in children compared with soft contact lenses, researchers at Ohio State University report.

However, this effect seems to be related to transient changes in the curvature of the cornea, suggesting that the benefit will not be sustained over time.

Dr. Jeffrey J. Walline and colleagues began the study thinking that the changes induced by the hard lenses could be permanent.

“There have been a few studies indicating they would [lead to permanent change] and a couple that indicated they would not,” he told AMN Health.

To further investigate, the researchers enrolled 116 children, between the ages of 8 and 11 years, in the study, which was published in the Archives of Ophthalmology. Fifty-nine children were randomly assigned to rigid lenses and 57 to soft lenses.

Over the next three years, the change in refractive error averaged -1.56 diopters in the rigid lenses group and -2.19 diopters in the soft lenses group.

The changes appeared to be due to corneal steepening, which was greater in the soft lenses group. The results were not affected by subject age or baseline myopia.

Doctors can advise their patients that hard contact lenses “may slow myopia progression slightly but it’s not going to have a profound effect,” Walline said.

The study also showed that children as young as 8 years old do well with contact lenses and can care for them themselves, he added.

“Now we’re taking a look at contact lens wear during sleep,” he said. “They change the shape of the cornea, so when you wake up you can take out the contact lenses and you can see clearly all day long without glasses or contact lenses.”

SOURCE: Archives of Ophthalmology, December 2004.