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Aldo Vagge, Michele M. Iester, Margherita Cavanna, Adriana Parisio, Carmen Burtolo, Carlo E. Traverso; Evaluation of Ocular Movements in Patients With Dyslexia. Invest. Ophthalmol. Vis. Sci. 2012;53(14):4857.
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to analyze the relationship between dyslexia and eye movements.
22 patients were included in the study: 11 patients have a diagnosis of dyslexia and 11 subjects were used as a control group (normal readers). The age of patients enrolled ranged from 8 to 13 years. All patients underwent careful orthoptic and ophthalmological visit; eye movements were quantified by Ober-2 system. This is a set of goggles with infrared diodes emitting pulsed and light photo-detectors that collect the light reflected from both eyes and a series of software programs used to evoke different types of eye movements like text, pictures, etc. Each patient had to read a text while wearing the Ober goggles. Ocular motility was divided into three phases: stability analysis to while fizating a still target; analysis of tracking saccades; analysis of fixation pauses, speed reading, saccades and regressions through the reading of a text.
the mean age was 9.4 +/- 1.6 (years +/- ) and 9.2 +/- 1.5 for the dyslexic and control group patients respectively. Ophthalmological and orthoptic evaluation did not show statistically significant differences between the two groups. The stability analysis on fixating a still target showed a significant (p<0.001) difference between dyslexic and control group, outlining an increased amount of loss of fixation in dyslexic subjects (5.36 +/- 2.5 and 0.82 +/- 2.1, respectively). Only two patients in the control group presented a fixation loss while none in the study group presented this defect. Also tracking saccades (left and right horizontal axis) and loss of fixation after saccades did not show significant difference. When the reading time was analyzed, a significant (p<0.001) difference was found between the dyslexic subjects and the control group (90+/- 52.0 seconds and 42 +/- 17.3, respectively). When the regression saccades were analyzed, a significant (p<0.001) difference was found between the dyslexic subjects and the control group (52+/- 33.4 seconds and 20.3 +/- 11.3, respectively).
this is the first report of some ocular movement difference between dyslexic and healthy subjects detected with the Ober-2 system . Should our findings be confirmed, this analysis could be added to the work-up of dyslexic patients.
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