This article was originally published in a sponsored newsletter.

Strabismus is one of the most frequent ocular conditions among developmentally normal children.¹Intermittent exotropia (IXT), the most common form of divergent strabismus, is characterized by an exodeviation in which normal binocular alignment is present some of the time with a manifest exotropia at other times.²

One non-surgical treatment option for childhood intermittent exotropia is overminus lens therapy in which patients wear an optical correction that has more minus power than the cycloplegic refractive error.³ The minus lenses promote fusion by inducing convergence and decreasing the magnitude of the ocular misalignment.⁴ The goal of minus lens therapy is to induce enough convergence to promote bifoveal fixation and prevent the occurrence of suppression and amblyopia.⁴

Minus lens therapy can be a useful tool in young children who are not good candidates for vision therapy or surgery. Indeed, 46% experience improved quality of fusion and 26% demonstrate improved quality of fusion and exhibit a quantitative decrease in the angle of deviation.⁴

Minus lens therapy may be a beneficial tool to aid in the treatment of strabismus; however, practitioners must consider its possible effect on myopia progression. Children who have IXT are already at risk of myopia; a population-based study of children who had intermittent exotropia found that 90% of patients were myopic by the age of 20 years.⁵

Oatts highlighted concerns that overminus lens therapy could lead to increasing myopia,⁴ such as the increased accommodative effort that leads to myopia progression.⁶ A recent study conducted by Chen and colleagues also concluded that, after 12 months of overminus lens wear, children ages 3 to 10 years old showed improved distance IXT control. However, 17% of the overminus group had an increase in myopia of more than 1D compared to 1% noted in the control group.⁶

Overminus lens treatment poses a risk of increasing myopia in all children, so clinicians and parents considering overminus lenses as a potential treatment to temporarily improve IXT control should weigh the potential benefit of better eye alignment against the increased risk of myopia progression, particularly in children who already have myopia.³

1. Heydarian S, Hashemi H, Jafarzadehpour E, et al. Non-surgical Management Options of Intermittent Exotropia: A Literature Review. J Curr Ophthalmol. 2020 Jul 4;32:217-225.

2. Cotter SA, Mohney BG, Chandler DL, et al. Three-year observation of children 12 to 35 months old with untreated intermittent exotropia. Ophthalmic Physiol Opt. 2020 Mar;40:202-215.

3. Chen AM, Erzurum SA, Chandler DL, et al. Overminus Lens Therapy for Children 3 to 10 Years of Age With Intermittent Exotropia. JAMA Ophthalmol. 2021 Apr 1;139:464-476.

4. Oatts JT. Intermittent Exotropia. American Academy of Ophthalmology. Available at aao.org/disease-review/intermittent-exotropia-2. Accessed Feb. 1, 2023.

5. Ekdawi NS, Nusz KJ, Diehl NN, Mohney BG. The development of myopia among children with intermittent exotropia. Am J Ophthalmol. 2010 Mar;149:503-537.

6. Hemphill N. Overminus lenses for intermittent exotropia may increase myopia progression. Healio. 2020 Oct 28. Available at healio.com/news/optometry/20201028/overminus-lenses-for-intermittent-exotropia-may-increase-myopia-progression. Accessed Mar. 27, 2023.