AIM: To compare the results of 4 methods for measuring angle of exodeviation in the three types of intermittent exotropia, including when looking at indoor distance target of 6m, looking at indoor distance target of 30m, looking at outdoor far distance target, after 1h diagnostic occlusion test.

METHODS: Prospective case series study. Sixty-five patients with intermittent exotropia between June 2013 and June 2014 were enrolled in the Department of Ophthalmology, Affiliated Hospital to Qingdao University, included 37 males and 28 females with average age(12.5±6.2)years. All the patients were measured when looking at indoor distance target of 6m, looking at indoor distance target of 30m, looking at outdoor far distance target, after 1h diagnostic occlusion test. Intermittent exotropia was divided into basic type, convergence insufficiency type and divergence excess type, which was based on the different result of between the distance and near measurements. The One-way test was applied to analyze the four methods of measuring angle of exodeviation in the three types of intermittent exotropia. LSD-t test was applied to compare the differences between each two methods in each type.

RESULTS: The distance exodeviations tested with looking at indoor distance target of 6m, looking at indoor distance target of 30m, looking at outdoor far distance target, after 1h diagnostic occlusion test were basic type(45.4±21.0, 55.0±15.0, 64.68±17.7, 68.75±16.6PD), convergence insufficiency type(33.3±14.0, 44.9±12.9, 43.6±11.8, 54.6±11.2PD), divergence excess type(55.6±17.4, 66.3±18.8, 76.9±16.4, 78.1±15.6PD). There were obviously differences between each two methods in each type(basic type F=9.649, P=0.00; convergence insufficiency type F=6.886, P=0.001; divergence excess type F=7.989, P=0.00). Compared with looking at indoor distance target of 30m, looking at outdoor far distance target(basic type P=0.044, divergence excess type P=0.048)and after 1h diagnostic occlusion test(basic type P=0.04, divergence excess type P=0.027)had the statistical difference in the basic type and divergence excess type, and there was no obviously difference between looking at outdoor far distance target and after 1h diagnostic occlusion test(basic type P=0.353, divergence excess type P=0.815). Compared with the other three measurements, 1h diagnostic occlusion test can elicit larger angle of deviation in the convergence insufficiency type.

CONCLUSION: Both measurement with looking at outdoor far distance target and after 1h diagnostic occlusion test can elicit the larger angle of deviation in the basic type and divergence excess type; The measurement with after 1 hour diagnostic occlusion test can elicit the larger angle of deviation in the convergence insufficiency type.