Abstract
Abstract: :
Purpose: In schizophrenia saccadic abnormalities have been described. An excessive distractibility has been demonstrated in the antisaccade task. However, little is known about saccades during reading. We investigated eye movements of patients with schizophrenia during reading. Methods: Eye movements of 17 schizophrenic patients (by DSM4 criteria with a total PANSS score between 31 and 115) were compared to an age-matched group of 17 normal subjects 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, Sensomotorik Instruments). The reading velocity and number of saccades per line were analysed. Results: Schizophrenic patients read significantly slower (mean gaze velocity 5.3°/sec, SD 1.5 for A4 and 4.6°/sec, SD 1.37 for 90° text) than controls (mean gaze velocity 7.4°/sec, SD 2.3 for A4; and 7.1°/sec, SD 1.9 for 90° text). Schizophrenics made significantly higher number of saccades (mean per line 17.9, SD 4.4 for A4; and mean 57.5, SD 16.1 for 90 ° text) as compared to controls (mean per line 11.6, SD 3.2 for A4; and mean 40.1, SD 13.4 for 90 ° text). The higher number of saccades was due to significantly smaller saccades in schizophrenic subjects (mean amplitude 2.21°, SD 0.34° for A4; and mean 2.25°, SD 0.37° for wide text) than in control subjects (mean amplitude 2.96°, SD 0.86° for A4; and mean 3.13°, SD 0.7° for wide text). Schizophrenic subjects did not show increased frequency of saccades or increased numbers of reversed saccades. Conclusion: We demonstrated that schizophrenic patients have a characteristic reading pattern, reading slower and using a higher number of smaller saccades. Eye movement control during reading may have diagnostic value in schizophrenia. Abnormalities in reading might be associated to educational problems in schizophrenia.
Keywords: eye movements • reading • neuro-ophthalmology: diagnosis