MAY 19, 2021
This is the first large-scale, randomized clinical trial assessing overminus spectacle therapy for treatment of intermittent exotropia (IXT).
Conducted by the Pediatric Eye Disease Investigator Group (PEDIG) between 2017 and 2019, this study included 386 children aged 3 to 10 years with IXT. Participants were randomized to overminus spectacle therapy (-2.50 D for 12 months, then -1.25 D for 3 months, followed by non-overminus spectacles for 3 months) or to non-overminus spectacle use.
Mean distance control at 12 months was better in participants treated with overminus spectacles than with non-overminus spectacles (1.8 vs. 2.8 points). However, the treatment was associated with increased myopic shift (-0.42 D vs. -0.04 D) and led to early discontinuation of overminus lens therapy in November 2019. By 18 months, the difference in distance control between the overminus and non-overminus arms diminished.
Refractive error was assessed with cycloplegic retinoscopy by an unmasked examiner. Continuous monitoring of patients out to 24 and 36 months would help clarify whether the observed myopic shift is temporary or permanent.
Clinicians and parents should carefully consider initiating overminus spectacles for IXT. Temporary improvement in IXT control should be balanced with the risk of myopic shift.