Research

How eyes grow and learn to see

Our eyes are remarkable organs—not just because they let us see, but because they grow and adapt in ways that are still not fully understood. At the Visual Optics Lab Antwerp (VOLANTIS), we study how eyes develop, how they sometimes go off track, and how we can model this process using virtual tools. This research spans from the earliest stages of life to adulthood, combining biological data, mathematical modelling, and clinical insight.

The two phases of eye growth

By analysing the eye shapes of healthy adults and combining it with data from hundreds of paper on changes in the eye during childhood, we discovered that most eye structures grow in two phases.

The first phase of eye development begins before birth, when the eye grows rapidly in a largely automatic, genetically programmed way. This early phase completes around 18 months of age, and brings the eye to a state of mild farsightedness (hypermetropia). This is actually a good thing as it gives the eye room to grow into focus later on.

After birth, the second phase begins. During this “emmetropisation” phase, the eye natural growth process will fine-tuning themselves to achieve clear vision. This is not just passive, pre-programmed growth anymore since the eye uses visual input to guide its development. If the image on the retina is blurry, the eye adjusts its shape to bring things into focus.

Interestingly, while the eye grows in all directions, it doesn’t grow evenly. The cornea flattens, the lens thins and then thickens again, and the axial length increases. These changes must stay in balance to maintain clear vision.

This process is surprisingly robust, but not perfect as not all eyes manage to retain this balance. We found that eyes can be grouped into two categories:

• Regulated eyes, where eye growth is well-coordinated and vision remains stable.
• Dysregulated eyes, where one or more components grow out of sync, leading to near- or farsightedness.

This distinction is clearer when we look at the full biometric profile of the eye—not just its length or refractive error. In fact, two people can have the same eye length but very different vision, depending on how their cornea and lens compensate.

Modelling the eye: SyntEyes

To better understand these differences between individual eyes, we created SyntEyes. This is a family of randomly generated, virtual eyes that simulate the natural diversity in eye shapes, and how this affects vision outcomes. These models are more than just simulations, they are tools for testing hypotheses, designing better lenses, and predicting future vision problems.

Why our research matters

Understanding eye growth and the differences in eye shapes helps us in several ways:

• Personalized eye care: By modelling an individual’s eye, we can predict how it might change and tailor treatments accordingly.
• Better lens design: Our models help optimize glasses and contact lenses for different eye shapes.
• Myopia control: We can identify children at risk of developing myopia and intervene earlier.

The bigger picture

Our work shows that emmetropia — the state of having no refractive error — is not a fixed target but a dynamic balance. It’s the result of a complex interplay between genetics, biology, and visual experience. And while most eyes get close to this balance, many don’t. That is where our models come in: to understand, predict, and eventually guide eye development toward better outcomes.