“Your eyes are fully grown at birth.”

It's a common observation that babies (Review) seem to have remarkably large eyes, leading many to believe that our eyes are already fully grown at birth. This striking visual impression is a widespread misconception, as the human eye actually continues to develop and increase in size long after we enter the world.

Scientifically, a newborn's eyeball is far from its adult dimensions. At birth, the average length of a baby's eye is approximately 16.5 millimeters. This means a baby's eyes are roughly two-thirds to three-quarters of their adult size. The eye undergoes a period of rapid growth, particularly during the first two years of life, and then experiences another significant growth spurt around puberty. By early adulthood, typically around 18 to 21 years of age, the eye reaches its full length of about 24 millimeters, although the weight of the lens continues to increase throughout a person's lifetime.

The persistence of this myth likely stems from the disproportionate size of an infant's eyes relative to their still-developing skull and facial features. While the eyes are growing, other parts of the head, such as the nose, jaw, and forehead, experience much more dramatic growth throughout childhood and adolescence (Review). This differential growth makes a baby's eyes appear exceptionally large and prominent, creating the illusion that they are already at their full adult size, when in reality, they are still undergoing a significant developmental journey.