Clinical features and change in incidence of acute acquired comitant esotropia: a 15-year single-centre study in South Korea

Background/objectives We investigated the clinical features and change in incidence of AACE in South Korea. Subjects/methods We reviewed the medical records of AACE patients who visited the Strabismus Clinic of at a tertiary referral hospital from 2007 to 2021. Clinical features were retrieved, including age at onset, angle of deviation, refractive errors, neuroimaging findings, and treatment outcomes. For each year, the proportion of new AACE patients among all new patients who visited the clinic, and the ratio of new AACE patients to new intermittent exotropia (IXT) patients, were analysed to estimate the incidence of AACE. Results Overall, 59 patients were included in the study. The mean age of the patients was 24.7 ± 9.3 years; the incidence of AACE was highest in teenagers and young adults. No patients had a history of visual occlusion, recent physical or psychological stress, or uncorrected myopia, unlike to classic AACE; moreover, no patients exhibited abnormalities in neuroimaging. There was a significantly increasing trend in the proportion of new AACE patients among all new patients (linear regression analysis, R2 = 0.778, p < 0.001). There was also a significantly increasing trend in the ratio of new AACE patients to new IXT patients (R 2 = 0.803, p < 0.001). Conclusions A new type of AACE, distinct from the classic types, is increasingly common in South Korea; this increasing incidence also appears to be a global phenomenon. Large-scale investigations are needed to define the exact clinical features, incidence, and pathophysiology of this new type of AACE.