ИСТИНА

Posterior fossa tumors (PFC) such as medulloblastoma, astrocytoma, ependymoma affect cerebellum and its connections that are associated with eye movements. Children with PFC also show massive impairments with movement control and cognitive functions. Analysis of saccades and gaze stability could be applicable for evaluation oculomotor system condition and related brain functions. 61 patients with PFC (M=12.80; SD=2.66) and 50 healthy children (M=12.96; SD=2.46) participated in our study. We tested gaze stability, timed visually-guided saccades and visual search in these two groups. Eye movements were recorded with Arrington Research Eye Tracker (60 Hz). We found a significant decrease of gaze stability in patients, presumably related to weak inhibition of intrusive saccades during fixation and unwanted distracting saccades to other stimuli. Further, we revealed a significant amount (20,4%) inaccurate hypermetric saccades in patients in visuallyguided saccades test comparing to healthy children (1,4%). Such hypermetric saccades often adjust by corrective saccades and lead to worse performance and increase a test time. Finally, patients demonstrated increased total execution time, fixations number and scanpath length in visual search test. Overall, patients with PFC show weak oculomotor control and visual processing, apparently because of the lesion in vermal and hemispheric oculomotor centers in cerebellum and wide toxic effects on the brain after cancer therapy. Eye tracking method provides a non-invasive reliable assessment of oculomotor and cognitive functions in such patients