Congenital Strabismus

Strabismus that appears within the first six months of life is classified as congenital strabismus. During this period, a baby’s eyes may drift inward or outward and may not yet be stable. This instability makes early detection challenging. Additionally, busy clinic conditions and the difficulty of examining infants further complicate diagnosis. Generally, the eye position begins to stabilize around the third month. If parents notice misalignment in the child’s eyes at this stage or later, a thorough evaluation for strabismus is essential.

Clinical Presentation

Parents often overlook or dismiss eye misalignment, assuming it is temporary. However, due to poor cooperation from infants during exams and the possibility of misdiagnosis, all infants with suspected strabismus in the first six months should be carefully re-examined for congenital strabismus.

In most cases, the misalignment exceeds 50 prism diopters, and the patient exhibits cross fixation, where the right eye fixates on the left visual field and the left eye fixates on the right visual field.

A significant proportion of patients have hyperopia, while a smaller number have myopia. The severity of the misalignment does not always correlate with the refractive error. It is also important to note that a +3.0 D prescription is considered normal in infants, and their refractive values naturally change over time.

If the patient has accommodative ability and the prescribed glasses help reduce the strabismus, surgery should only be planned for the remaining misalignment after glasses correction.

Key Diagnostic Signs

• Many infants with congenital esotropia (inward deviation of the eyes) exhibit limited outward eye movementand excessive inward turning.
• If amblyopia (lazy eye) is present, assessing outward movement becomes more difficult. In such cases, special tests like:
  • Doll’s head maneuver
  • Rotation test
    These tests help determine whether the child chooses not to look in a particular direction or has an actual movement restriction.

Using these methods, congenital esotropia can be differentiated from:

• Sixth nerve palsy (a neurological cause of inward eye deviation)
• Duane syndrome (a congenital eye movement disorder)

Amblyopia (lazy eye) is also commonly associated with congenital esotropia and must be treated as early as possible.

In some cases, vertical (upward/downward) deviations may also be present at birth or develop later. These include:

• Dissociated vertical deviation (DVD)
• Inferior oblique overaction

Because these conditions affect treatment plans, they must be distinguished from congenital strabismus during diagnosis.

Compensatory Head Positions

Children with congenital strabismus often adopt compensatory head postures to improve their vision. They:

• Turn their head toward the fixating eye
• May tilt their chin upward or downward
• If nystagmus (involuntary eye movement) is present, adjusting head position helps them control it and achieve clearer vision.

Treatment of Congenital Strabismus

One of the most critical factors in treating congenital strabismus is not delaying surgery. The primary treatment goals include:

1. Correcting eye misalignment
2. Restoring binocular single vision
3. Developing stereopsis (depth perception) early

Timing of Treatment

Waiting until school age for treatment is a serious mistake because sensory impairments become permanent during this period. The recommended treatment timeline is:

• Preferably by 8 months: Botox treatment may be applied.
• By 12 months: Surgical correction is recommended.

If treatment is delayed, irreversible sensory defects may develop. Additionally, delayed surgery can lead to secondary structural changes in the eye, including:

• Muscle fibrosis (hardening and contraction of eye muscles)
• Conjunctival shrinkage
• Tenon’s capsule contraction, restricting eye movement

Differential Diagnosis

Another important factor in congenital strabismus evaluation is ruling out serious conditions like retinoblastoma, a life-threatening eye cancer in young children.

Thus, early detection, accurate diagnosis, and timely treatment are crucial for the successful management of congenital strabismus.