Variability of stereoacuity in intermittent exotropia

Area of Science:

• Ophthalmology
• Pediatric Eye Care
• Vision Science

Background:

• Intermittent exotropia (IXT) is a common childhood strabismus.
• Distance stereoacuity is a key metric for monitoring IXT.
• The day-to-day variability of stereoacuity in IXT patients is not well-established.

Purpose of the Study:

• To investigate the variability of distance and near stereoacuity within a single day in children diagnosed with intermittent exotropia (IXT).

Main Methods:

• A prospective cohort study involving 12 children with IXT.
• Stereoacuity was measured multiple times daily using standard distance and near tests (Frisby Davis, Distance Randot, Frisby, Preschool Randot).
• Variable stereoacuity was defined as a change of two or more log levels between assessments.

Main Results:

• 42% of children exhibited variable distance stereoacuity over the day.
• Variable results were observed in 33% using the Distance Randot test and 42% using the Frisby Davis Distance test.
• Variable near stereoacuity was noted in 22% of participants, with changes sometimes indicating a shift from measurable to unmeasurable stereoacuity.

Conclusions:

• A significant proportion of children with IXT demonstrate substantial fluctuations in stereoacuity within a 24-hour period.
• Isolated stereoacuity measurements in IXT patients may not accurately reflect their typical visual function.
• Clinicians should consider the potential for stereoacuity variability when assessing IXT progression.