Abstract
BACKGROUND/AIMS: The clinical assessment of deviation control at near (30 cm or 1/3 m) and far (5-6 m) does not reflect if and how patients' control changes between these two predetermined test distances. We examine how patients' control varies at 6 fixation distances between the two clinical test distances of 30 cm and 5 m. METHODS: The medical records of 48 patients with basic intermittent exotropia (IXT) were retrospectively reviewed. Patients who had visited the Kindai University Hospital between October 2021 and March 2022 without a prior history of treatments except spectacle correction were included. Eye position was examined with refractive correction using the cover test, and 6 fixation distances at 30 cm, 1 m, 2 m, 3 m, 4 m, and 5 m were tested in increasing order. Control assessed at each fixation distance was classified using the Kushner's method (2019). This study rated the control of a poor or fair level as unfavorable and the control of an excellent or good level as favorable. The distance at which the patient's control deteriorated was analyzed. RESULTS: Of 48, 38 (79%) patients had a favorable baseline control, and 8 of them could maintain a favorable control at all distances. Of the 30 patients who could not maintain the favorable baseline control, 17 (57%) at 1 m, 2 (7%) at 2 m, 6 (20%) at 3 m, 2 (7%) at 4 m, and 2 (7%) at 5 m were observed with a control deterioration. The incidence of control deterioration at 1 m was significantly higher than the incidence at other distances (between 1 and 2, 4, 5 m, p < 0.01; between 1 and 3 m, p < 0.05). CONCLUSIONS: Deviation control in patients with basic IXT was affected by fixation distance and most likely worsened at 1 m. Assessing control at various fixation distances may provide a more comprehensive understanding of patients' actual control.