Background and purpose: Retrospective studies have shown that as many as 15% of patients with pseudostrabismus go on to develop true strabismus. This prospective study was conducted to examine the efficacy of utilizing a modified cover test technique to help identify patients with pseudostrabismus that are likely to progress to true strabismus.
Patients and methods: Fifty-three subjects were included in the study. All were evaluated using prolonged occlusion during cover testing ("occlusive" cover test). The results of this test were analyzed for its ability to predict the development of true strabismus during a mean follow-up period of 11 months.
Results: The occlusive cover test was of value in detecting which subjects would later develop esotropia.
Conclusion: The occlusive cover test should be incorporated into the evaluation of patients suspected of having pseudostrabismus to identify which patients are most at risk of presenting later with true strabismus.
Keywords: modified cover testing; occlusive cover testing; pseudostrabismus; strabismus.