Myopia is an imbalance between growth of the eyeball and development of the crystalline lens, new research finds. Photo: Donald Mutti, O.D., Ph.D.

A new study finds that myopia develops in children when the crystalline lens stops adapting to the eye’s continued growth, according researchers at The Ohio State University College of Optometry.

The new research, published in the March issue of Optometry and Vision Science, indicates this breakdown occurs about a year before myopia actually occurs.

Lead author Donald Mutti, O.D., Ph.D., and his colleagues found that in children without myopia, the lens grew thinner and flatter to maintain normal vision as the eye grew. But in children who became nearsighted, the lens stopped changing in response to eye growth.

“What this work is trying to show is that it’s not just about the length of the eye—it’s how the length of the eye relates to the rest of the eye,” Dr. Mutti says. “The onset of myopia is really the sudden occurrence of an imbalance between the growth of the eye and the development of the crystalline lens.”

To determine this, the researchers analyzed repeated measurements of vision and eye growth from 732 children ages six to 14. This data was collected over several years for the Collaborative Longitudinal Evaluation of Ethnicity and Refractive Error (CLEERE) study, so they were able to look at the children’s eyes before, during and after the onset of nearsightedness.

They believe that the ciliary muscle, which controls accommodation, may also play a role. While current treatments for myopia target the back of the eye, these findings could suggest a different direction for the future. “If the ciliary muscle is involved in becoming myopic, there might be treatments [developed] aimed at enabling the muscle to respond to increases in the size of the eye,” Dr. Mutti says.

To that end, Melissa Bailey, O.D., Ph.D., one of Dr. Mutti’s colleagues at OSU, is currently conducting studies in which she is imaging the ciliary muscle to find out how it develops in children.

Mutti DO, Mitchell GL, Sinnott LT, et al. Corneal and crystalline lens dimensions before and after myopia onset. Optom Vis Sci. 2012 March;89(3):251-62.