Abstract

Purpose: To evaluate the natural history of near exophoria in a large cohort of healthy young adults.

Design: Retrospective study.

Participants: Young adults evaluated at the Israeli Air Force Aeromedical Center (IAF AMC) between 2018 and 2023.

Methods: Participants with ≥6 prism diopters (PD) of exophoria at near during their initial assessment were categorized as having exophoria. Eligibility required at least two ophthalmologic evaluations with a minimum interval of one year between the first and last visits. Assessments included ocular alignment, refraction, stereoacuity, and visual acuity.

Main outcome measure: Change in exophoria over time and factors associated with its progression.

Results: Among 23,092 examined subjects, 14,409 (62.4%) exhibited some degree of near exophoria, and 5326 (23%) met the threshold of ≥6 PD. Of these, 369 subjects (1.6%; mean age 27.4 ± 15.6 years; 93% male) met inclusion criteria. At baseline, mean near exophoria was 7.49 ± 2.06 PD (range 6-22 PD). At the final follow-up, the mean exophoria was 7.56 ± 3.08 PD (range 2-18 PD), representing a non-significant change (P = .680). Myopia was the only factor significantly associated with an increase in exophoria over time. Stereoacuity remained consistently high throughout the study period, regardless of exophoria magnitude.

Conclusion: In this large sample of healthy young adults, near exophoria remained stable over time, with no clinically significant progression observed. However, individuals with myopia demonstrated a greater likelihood of exophoria progression. Despite this, stereoacuity was preserved across all participants, including those with marked exophoria.