Many new parents notice that their baby’s eyes occasionally drift inward or outward, an observation that can be concerning. This temporary misalignment, medically known as strabismus, is common in the first few months of life. Most instances of a wandering gaze are a normal part of development and resolve naturally as the infant matures. However, understanding the difference between this temporary stage, a visual illusion, and a persistent medical condition is important.
The Developmental Reason for Temporary Eye Drift
The occasional, fleeting misalignment of an infant’s eyes is directly related to the immaturity of their visual system at birth. A newborn’s brain has not yet learned how to coordinate the six extraocular muscles surrounding each eye simultaneously. This lack of coordination often results in an eye briefly drifting out of alignment.
This temporary drift reflects the developing process of binocular vision, which is the ability to use both eyes together to focus on a single object and perceive depth. The eyes must learn to work as a team to converge on a target, a skill that is not automatic. The eye movements may appear uncoordinated because the brain is still establishing the neural pathways required for precise, conjugate gaze.
Infants are actively learning to focus and track objects in their environment, and this process requires repeated attempts at muscle coordination. Intermittent eye crossing or wandering is expected until the brain fully establishes the necessary control. This phase is considered normal and harmless, often resolving as the child approaches four to six months of age.
Understanding Pseudostrabismus (False Crossed Eyes)
A separate common cause for the appearance of crossed eyes is not related to muscle control but to the baby’s unique facial anatomy, a condition called pseudostrabismus. This term describes the optical illusion where the eyes look misaligned even though they are perfectly straight. It is a frequent source of worry for parents.
The illusion is often caused by a wide, flat bridge of the nose or the presence of prominent epicanthal folds, which are folds of skin at the inner corner of the eyes. These features cover the white part of the eye (sclera) near the nose, making it look like the eye is turning inward. The underlying eye alignment is normal, but the folds obscure part of the eye, creating a deceptive visual effect.
Parents can look for a visual cue to help distinguish this harmless illusion from true misalignment. If a light is shined gently toward the baby’s eyes, the reflection, or light reflex, should appear in the exact same spot on the pupil of both eyes if the eyes are truly straight. In pseudostrabismus, the light reflex is symmetrical, confirming that the eyes are aligned beneath the skin folds.
Pseudostrabismus does not affect vision and typically disappears as the child grows and their facial features, particularly the nasal bridge, become more defined.
True Strabismus: Causes, Timelines, and Treatment
While temporary drift and pseudostrabismus are harmless, true strabismus is a persistent misalignment that requires attention because it can affect vision development. If the eye misalignment is constant or continues past the normal developmental window of four to six months, it is typically classified as true strabismus. This condition means the eyes are pointing in different directions, such as one turning inward (esotropia), outward (exotropia), or occasionally upward or downward.
Risks of Untreated Strabismus
If left untreated, persistent strabismus can lead to a condition called amblyopia, or “lazy eye,” where the brain begins to ignore the visual input from the misaligned eye. This can result in permanent vision loss and a lack of depth perception.
Causes of Strabismus
Causes of true strabismus can be complex, involving issues like poor nerve control of the eye muscles, significant muscle imbalance, or uncorrected farsightedness (hyperopia). Farsightedness can cause the eyes to over-converge when trying to focus.
Diagnosis and Treatment
The diagnosis of true strabismus is typically made by a pediatric ophthalmologist, who will perform a comprehensive eye exam to determine the type and severity of the misalignment. Early intervention is paramount to ensure the brain develops proper connections with both eyes. Treatment options vary and are tailored to the specific cause.
Common treatments include the use of corrective lenses, often prescribed to manage strabismus caused by farsightedness, which reduces the effort needed for focusing. Another approach is patching the stronger, straight eye for a period each day to force the brain to use and strengthen the weaker, misaligned eye. In cases where non-surgical methods are not sufficient, surgery on the extraocular muscles may be recommended to adjust the tension and reposition the eyes for better alignment.