Transient eye closure and ocular preference in patients with intermittent exotropia

Area of Science:

• Ophthalmology
• Neuroscience
• Vision Science

Background:

• Intermittent exotropia is a common strabismus characterized by outward deviation of the eyes.
• Transient eye closure (TEC) is a compensatory mechanism observed in some patients with exotropia, particularly under bright light.
• Understanding the factors influencing TEC, such as ocular dominance and control of deviation, is crucial for managing this condition.

Purpose of the Study:

• To investigate the association between sensory and motor ocular dominance and the occurrence of transient eye closure (TEC) in patients with intermittent exotropia under bright light.
• To differentiate TEC patterns based on the level of fusion control in intermittent exotropia.

Main Methods:

• A prospective study included 40 patients (aged 7-40 years) diagnosed with intermittent exotropia.
• Ocular dominance was assessed using the hole-in-the-card and Worth 4-Dot tests.
• Transient eye closure (TEC) and outward eye deviation were evaluated under bright light conditions, with patients categorized into good, fair, and poor control groups based on exodeviation fusion control.

Main Results:

• Transient eye closure (TEC) was observed in 58% of patients (23 out of 40) under bright light.
• Among patients with good and fair control, 56% showed TEC in their dominant eye.
• In the poor control group, 63% closed their nondominant eye, often after an initial outward deviation was noted.

Conclusions:

• In intermittent exotropia with TEC under bright light, a tendency exists for dominant eye closure in patients with good fusion control.
• Conversely, patients with poor control frequently exhibit spontaneous outward deviation preceding TEC of the nondominant eye.
• These findings highlight distinct patterns of TEC related to ocular dominance and the degree of motor control in intermittent exotropia.