Patients with intermittent exotropia and exophoria plus ortho subjects underwent measurement of saccadic reaction times (SRTs) to compare those occurring in one eye and those occurring with alternating cover tests (ACTs). Twenty-five subjects were studied. Results for the intermittent exotropia group showed SRTs for ACT task of 227.3±69.9ms, and for normal task of 185.4±54.1ms. Results for the exophoria group showed SRTs for ACT task of 198.45±45.3ms, and for normal task of 178.2±34.6ms. Results for the ortho group showed SRTs for ACT task of 224.2±46.5ms, and for normal task of 200.7±37.8ms. The ACT task results were significantly prolonged in all groups. In each group a significant increase in SRTs occurred for the ACT task compared to normals. Further increase was seen for the strabismus group compared to ortho. The authors propose that the influence of occlusion of the re-fixating eye on the release of fixation attention may cause the lag of response.

Saccadic reaction times in alternating cover.
Shinomiya Y, Yamada T, Suzuki K, et al.
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Fiona Rowe (Prof)

Institute of Population Health, University of Liverpool, UK.

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