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Intermittent central suppression and reading efficiency: A correlation study

1 May 2002


Purpose: It has been suggested that non-strabismic intermittent central suppression (ICS) may interfere with reading efficiency (RE). If during brief moments of suppression vergence posture changes, during the transition from suppression to non-suppression there may be a brief moment of diplopia and/or confusion until the eyes realign with the reading material. If this were true, it is likely that ICS would have a deleterious effect on oculomotor performance during reading. The purpose of the current study was to explore a possible correlation between ICS and eye movements during reading.

Method: 70 professional students ranging in age from 21 to 37 were tested for suppression tendencies with a modified diamond target on the Borish Vectographic Nearpoint Card 11. The number of intermittent suppression episodes as well as the total time of suppression was measured. The subjects' eye movements were then measured using the Taylor Visagraph 11, a system that quantifies a number of specific eye movement characteristics during a reading task. Subjects who exhibited no suppression were assigned to the control group and those who exhibited any suppression were assigned to the experimental group.

Results: No statistically significant (PC. 05) difference was found between the experimental group (N) and the control group (NB) on any of the eye movement characteristics. Additionally, no statistically significant correlation was found between time of suppression or number of suppression episodes, and any individual eye movement characteristics.

Conclusions: The current study found no correlation between ICS and RE. It should be noted that the sample size was small and the subjects were normal, high achieving adults. Also, many of the subjects in the experimental group exhibited minimal suppression tendencies. Future studies should attempt to include more subjects with greater suppression tendencies.


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