Base-In Prism Corrections Provides No Improvement in Intermittent Exotropia

Masked Child Eye Test
Almeria, Spain. family is going to have vision and hearing screening
Presenters reviewed pediatric patients who wore prisms for an 8-week trial.

This article is part of Ophthalmology Advisor’s conference coverage from the 2021 meeting of the American Academy of Ophthalmology, held in New Orleans from November 12 to 15, 2021. The team at Ophthalmology Advisor will be reporting on a variety of the research presented by the ophthalmology experts at the AAO. Check back for more from the AAO 2021 Meeting.


The use of partial base-in prism correction is unlikely to result in meaningful improvement of intermittent exotropia control, according to presenters at the American Academy of Ophthalmology. Researchers evaluated the devices’ use in pediatric patients (ages 3-13) who wore the lenses of an 8-week trial.

Investigators took into account 57 children (mean age 6.6±2.2 years) with intermittent exotropia (16-35Δ at distance, distance control score ≥2 on scale ranging from 0 (phoria) to 5 (constant), and ≥1 episode of spontaneous exotropia). The participants  were randomized to partial BI prism (40% of largest deviation) or refractive correction alone. The study looked at distance control at 8 weeks in children who wore the prescribed glasses

In the prism group vs the nonprism group, mean baseline distance control was measured at 3.4 (n=28) points and 3.5 (n=29) points, respectively. At 8 weeks, the mean baseline control for the prism group vs the nonprism group was 3.6 (n=25) and 3.3 (n=25), respectively, with the adjusted difference of 0.28 points (2-sided 95% CI, −0.38 to 0.94 points). The study found that there was no significant improvement in IXT control over an 8-week period after wearing a partial BI prism correction.

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Morrison DG, Summers AI, Chandler DL, et al. A randomized trial of partial prism correction for children with IXT. Paper presented at: American Academy of Ophthalmology 2021 Annual Meeting; November 12-15, 2021; New Orleans. Abstract PA015.