Changes in Exodeviation after the Monocular Occlusion Test in Adult Patients with Intermittent Exotropia and Its Association with the Level of Control.

PURPOSE

We investigated the changes in ocular deviation after the monocular occlusion test in adults with intermittent exotropia and evaluated its association with the level of control.

METHODS

We retrospectively enrolled adults (aged ≥18 years) with intermittent exotropia who visited our clinic between September 2015 and May 2019. Patients with basic intermittent exotropia with a distant deviation within 10 prism diopters (PD) of the near deviation were included. The largest ocular deviations obtained before and after 1 hour of monocular occlusion were compared. The level of control was measured using the LACTOSE (Look and Cover, then Ten seconds of Observation Scale for Exotropia) control scoring system.

RESULTS

Forty-six consecutive adult patients (28 males, 18 females; mean age, 34.3 years) were enrolled. The mean ocular deviation was 36.3 PD (range, 18 to 5 PD) at distant fixation and 38.5 PD (range, 18 to 80 PD) at near fixation, which increased significantly to 38.5 PD (p = 0.043) and 41.1 PD (p = 0.011), respectively, after monocular occlusion. The mean ocular deviation increased ≥5 PD in 14 (30.4%) and 15 (32.6%) patients at distant and near fixation, respectively. The level of control was measured in 30 patients. A higher degree of near control was significantly associated with an increase of ≥5 PD in near fixation after the test (p = 0.009 for a near control score ≤2).

CONCLUSIONS

The monocular occlusion test may help to determine the largest ocular deviation in adults with intermittent exotropia. Approximately one-third of patients exhibited an increase in ocular deviation ≥5 PD. Patients exhibiting good control were more likely to manifest an increase in the ocular deviation.