Clinical characteristics of intermittent exotropia according to fusional control: findings from the Korean Intermittent Exotropia Study (KIEMS).

PURPOSE

To investigate clinical features of intermittent exotropia (IXT) according to fusional control status from the Korean Intermittent Exotropia Multicenter Study (KIEMS).

METHODS

A total of 2715 IXT participants from the KIEMS dataset were included in this study. We collected age, sex, best corrected visual acuity in LogMAR (BCVA), cycloplegic refraction data, exotropia angle and fusional control status, and near stereoacuity. Exotropia types were classified into basic, convergence insufficiency (CI) and divergence excess (DE) types. Distributions of exotropia type and sex according to fusional control status were investigated. Age, BCVA, spherical equivalents, exotropia angle and near stereoacuity were compared according to fusional control status.

RESULTS

Female to male ratio was 1316 (48.5%) to 1399 (51.5%). Mean age of the participants was 9.4 ± 6.4 years. Mean exotropia angle was 22.5 ± 8.8 and 24.8 ± 9.4 prism diopters at distant and near fixation. Fusional control status was better in CI at distant and DE at near (P = 0.002, 0.021 each). Distant and near exotropia angle were larger in patients with worse distant and near control (P < 0.001). Near stereoacuity was also worse in patients with worse distant and near control (P < 0.001). Good distant control patients had more myopic SE (P < 0.001). Poor near control patients showed worse BCVA and larger BCVA difference (P < 0.001).

CONCLUSION

Fusional control was highly associated with exotropia type and angle, near stereoacuity, and visual acuity. Near fusional control was associated with mean and difference of BCVA in both eyes.