How the retina can slow down myopia

"The retina receives a two-dimensional image, which in theory makes depth information ambiguous. However, it manages to extract subtle clues that allow it to determine whether the image is focused in front of or behind it. Understanding how it does this is one of the starting points for our study.’" Olivier Marre.

Myopia occurs when the eye elongates excessively: the image of distant objects is then formed in front of the retina, resulting in blurred distance vision. Research has shown that the retina plays the role of a “conductor,” sending signals that modulate eye growth to maintain sharp focus. But in myopia, this mechanism malfunctions.

In recent years, innovative optical solutions, such as myopia control lenses developed by EssilorLuxottica, have already been able to partly slow down the excessive growth of the eye in children. Their clinical efficacy is proven, but the biological mechanisms explaining how this control works remained poorly understood.

To better understand these mechanisms, Olivier Marre’s team (Institut de la Vision) and EssilorLuxottica’s R&D teams studied how the retina detects whether an image is focused in front of it (which should slow down eye growth) or behind it.

Their study provides a key insight: certain retinal ganglion cells are capable of detecting the focal plane by assessing the sharpness of the image. This discovery strengthens the scientific understanding of the principles underlying current myopia control strategies and could pave the way for new therapeutic approaches.

The secret of retinal ganglion cells

How does the eye manage to regulate its own growth to remain in perfect focus? This remarkable ability is called emmetropization. To achieve it, the retina is able—based on the image it receives through the eye’s optics—to calculate whether the focal plane is in front of or behind it, and then modulate eye growth to bring that focal plane into alignment.

Until now, however, how the retina performed this calculation remained a mystery.

The team showed that some cells achieve this by comparing small variations in light intensity from one point of the image to another, a property known as local spatial contrast. When an image is blurred, these intensity differences become less distinct and are distributed differently across the retina. Ganglion cells can decode this specific “blur signature” and adjust their electrical activity depending on how the blur is projected. This provides a signal the rest of the eye can use to fine-tune its growth.

The retina is therefore not merely a passive “screen”: it acts as an intelligent sensor, capable of deciphering the nature of blur to extract key information. It emits biochemical signals instructing the eye to either grow or slow its growth. If the focusing signal is correct, eye growth stops at the right time. If this mechanism goes awry (for example, under genetic or environmental influence), the eye keeps growing.

This discovery sheds light on a fundamental mechanism of eye growth. By better understanding this cellular “language,” researchers provide a solid foundation for optimizing existing solutions, such as myopia control lenses, and for opening the door to new therapeutic approaches. In the long run, these advances could help better protect younger generations from the global myopia epidemic and reduce the risks of severe visual complications, particularly associated with high myopia (beyond -6 diopters).