Intermittent exotropia with a positive Bielschowsky head-tilt test
To investigate the clinical features of patients with intermittent exotropia (IXT) with and without positive Bielschowsky head-tilt test (BHTT), but without superior oblique palsy.Methods
We retrospectively reviewed the charts of 118 patients with IXT. Patients were divided into two groups according to positive or negative BHTT. Associated risk factors for positive BHTT in patients with IXT were analysed. The changes in the BHTT result after surgery were also analysed.Results
Fifty patients showed a positive BHTT, and 68 patients showed a negative BHTT. There were significant differences between the groups with regard to the elapsed time from the onset of IXT, the angle of distance exodeviation, inferior oblique muscle overaction, vertical deviation at the primary position, suppression and stereoacuity (all for p<0.05). Risk factors for a positive BHTT among patients with IXT were the elapsed period since the onset of IXT (OR, 1.034; 95% CI 1.008 to 1.061, p=0.011), angle of distance exodeviation (OR, 1.087; 95% CI 1.015 to 1.165, p=0.017) and near stereoacuity (OR, 1.006; 95% CI 1.001 to 1.011, p=0.029). Horizontal muscle surgery alone, without cyclovertical muscle surgery, resulted in a significant decrease in the number of patients with positive BHTT (p<0.01).Conclusions
A positive BHTT was seen in patients with IXT with larger angle exodeviations, longer elapsed time periods since the onset of IXT and worse stereoacuity. The positive BHTT could be eliminated using horizontal muscle surgery only, without complementary inferior oblique muscle weakening surgery.