Acute acquired concomitant esotropia associated with myopia: is the condition related to any binocular function failure?

Purpose: To evaluate the sensory motor state, accommodation, and accommodative convergence to accommodation ratio (AC/A) in a cohort of non-amblyopic myopes with acquired concomitant esotropia (Bielschowsky esotropia (BE)). Methods: Refraction, near and far deviation, fusional amplitude (FA), near point of accommodation (NPA), AC/A (gradient method), and stereopsis were measured in a cohort of 26 patients (25 phakic and 1 pseudophakic, age: 14–60 years) with BE, prospectively recruited from January to September 2019 at St. Orsola-Malpighi Hospital, Bologna, Italy. The Pearson’s correlation coefficient was used to correlate distance with near deviation, distance with near divergence FA and angle of deviation with FA (statistical significance: p values < 0.05). Results: Myopia range was 0–17.5 diopters (D) spherical equivalent (mean: 4.4 D). A positive correlation resulted between distance (mean: 23.7 prism diopters/PD, range: 4–40 PD) and near (mean: 23.7 PD, range: 2–45 PD) deviation (p < 0.00001) and between distance (mean: 12.6 PD, range 0–34 PD) and near (mean: 17.0 PD, range 3–36 PD) divergence FA (p < 0.00001). A non-significant correlation resulted between angle of deviation and divergent FA at near (p = 0.07) and distance (p = 0.13) fixation. NPA was within normal limits for age. AC/C ratio range was 0–8 (mean: 3). Twenty-three patients showed Randot stereopsis. Conclusions: BE shows high variability in the age of onset, degree of associated myopia, AC/A, and divergent FA. A little stronger near divergent FA can justify the better compensation at near fixation. These results show that uncorrected myopia, accommodation, and divergence paralysis do not concur with the genesis of BE.