Purpose: To study the long-term visual outcome of primary microtropia.
Methods: A retrospective review was made on 31 patients with primary microtropia with the follow-up period of 5 years or more (5-15 years, mean=9.2 years) seen during 16 years from 1985 to 2000 at Okayama University Hospital. The patients were 16 boys and 15 girls, with the age at the initial visit ranging from 5 to 16 years (mean=9.3 years).
Results: All patients showed anomalous retinal correspondence, peripheral fusion, 10 prism diopters or smaller esodeviation at the initial and final visit. At the initial visit, TNO stereoacuity was absent in 24 patients, 480 seconds in 3, and 240 seconds in 4. The visual acuity was 0.8 or better in both eyes of 16 patients, but 0.7 or worse in 1 eye or both eyes of 15 patients. At the final visit, the 24 patients with the absence of stereoacuity still showed its absence, while stereoacuity remained unchanged or improved in the 7 patients with initial stereoacuity of 480 seconds or better. In the 15 patients with 0.7 or worse visual acuity, it improved to 0.8 or better in 7 patients while it remained 0.7 or worse in the other 8 patients. Poor visual acuity had no relation to the absence of TNO stereoacuity at the initial and final visits.
Conclusion: Patients with primary microtropia could be largely classified into those with the absence of TNO stereoacuity throughout the course of treatment and those with some levels of stereoacuity that had a chance to improve during the follow-up.