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I. Gottlob, F.A. Proudlock, H. Shekhar, Y. Rajabally; Reading in Parkinson’s disease . Invest. Ophthalmol. Vis. Sci. 2004;45(13):2517.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose:Patients with Parkinson’s disease (PD) have hypometric saccades and abnormal smooth pursuit. However, little is known about saccades during reading. We investigated eye movements of patients with PD during reading. Methods:Eye movements of 22 PD patients without clinical frontal lobe involvement (mean age 65.3 years, SD 11 years, 15 males, 8 females, mean Hoehn & Yahr stage 2.1, SD 0.7) were compared to 23 healthy control subjects (mean age 65.2 years, SD 11.8 years, 11 males, 12 females) during two reading tasks. One task consisted of reading 25 lines of standard reading format (A4 text). The other task was reading the same text lengths (7 lines) of an unusual wide reading card (90°). The text was very simple, extracted from a children’s story. Eye movements were simultaneously recorded with a high–resolution infrared eye tracker (Eyelink, Sensomotoric Instruments). The saccadic frequency, number of saccades per line, fixation duration, saccadic amplitude, the % of regressions and the reading velocity were analysed. Results:PD patients had significant increase of fixation duration during reading (mean 0.28 msec, SE 0.01 for A4 text and mean 0.29 msec, SE 0.01 for 90 ° text) than controls (mean 0.24 msec, SE 0.006 for A4 text and mean 0.26 msec, SE 0.007 for 90° text). This caused a significant reduction of saccadic frequency (mean 3.73 Hz, SE 0.12 for A4 and mean 3.56 Hz, SE 0.11 for 90° text) than controls (mean 4.01 Hz, SE 0.11 for A4 and mean 3.94 Hz, SE 0.1 for 90° text). The other reading parameters were similar in PD patients and control subjects. Conclusions:We demonstrated that PD patients have a characteristic reading pattern, remaining longer on each fixation point during reading. This is a novel finding and may be related to bradykinesia.
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