Modalities of reading acquisition in three siblings with infantile-onset saccade initiation delay (Cogan congenital ocular motor apraxia): A longitudinal study.

This study aims to ascertain the impact of congenital ocular motor apraxia (COMA), alternatively called infantile-onset saccade initiation delay (ISID), on reading acquisition. More specifically, the consequence of defective initiation of horizontal saccades during reading acquisition was investigated. Three siblings (A: male, 11y3m at the first time-point of testing (i.e. T1 hereafter); B: female, 7y3m at T1 and C: male, 5y9m at T1) suffering from ISID were assessed longitudinally over 3 years in various reading tests and their eye movements simultaneously registered. At each time-point, they were compared to control participants matched on reading level. Eye movements during reading tasks were markedly abnormal in children with ISID at the beginning of reading acquisition and their reading scores were poor. With time, the number of fixations, small amplitude saccades and their reading abilities became comparable to those of control children. Despite the abnormal eye movements and difficulties in specifically directing the eyes to the appropriate position, children with ISID do not seem to encounter major difficulties during reading acquisition, although mild delays might be observed during the early stages.