Visual development in the erly years of life: milestones and warning signs

11/12/2024

At birth, the human visual system is not fully developed. We are not born “seeing” but with the capacity to learn to see.

A newborn’s visual system is immature and will develop as the cerebral cortex receives appropriate and relatively symmetrical stimuli from both eyes during the first years of life. The first months are particularly crucial, with distinct developmental stages:

• At birth, a baby’s vision is limited to 20-30 cm, perceiving only light and dark sensations. Eye mobility and visual acuity are minimal. Human faces, especially those of parents, attract their attention.
• At one month, the baby progresses from light-dark contrast perception to recognising some colours, such as red and green, and begins to develop the accommodation reflex (focusing ability).
• At 2-3 months, they start to follow moving objects with their eyes.
• From 3 months, stereoscopic (depth) vision begins to develop.
• At 4 months, they perceive a wider range of colours, improve focus, and recognise more faces.
• At 6 months, the baby can fuse the two retinal images of an object, achieving binocular vision. By this stage, they have learned to use both eyes in coordination, stopping the natural infant squinting.
• At one year, distance calculation is effective, and coordination between the eyes, hands, and body improves.
• The development of the visual field reaches adult dimensions by the end of the first year.

Complete visual development will not occur until approximately 8-9 years of age, with the first four years being the most critical period. During this time, the visual system is very vulnerable, so any factor that causes poor vision in one or both eyes may result in amblyopia or “lazy eye”. The possibility of recovering lazy eye is high if diagnosed and treated before the age of 4, but it progressively decreases after this age and becomes almost impossible after 9-10 years. This is why all children should undergo a comprehensive ophthalmological examination by a specialist at 2-3 years of age, even if no symptoms are present.

Warning Signs

There are several signs and symptoms that may indicate the presence of a visual problem and should prompt a visit to an ophthalmologist:

• Vision blurred
• Constant blinking
• Rhythmic eye movements (nystagmus)
• Headache and heavy eyelids
• Frequent eye redness and itching
• Bringing objects too close or being unable to read the board
• Tilting the head to fix the gaze (torticollis)
• Tendency to squint or wink one eye
• White-coloured pupil (leucocoria)

What we do not learn to see in childhood cannot be recovered later in adulthood. Failing to act in time could mean a child has a permanently lazy eye, making early diagnosis vital.

Dr. Idoia Rodríguez Maiztegui, ophthalmologist at the Barraquer Ophthalmology Centre