Covering one eye affects how some children read.

The Dunlop Test was used to identify unstable binocular control in a group of 32 mixed-ability children. They were compared with 32 reading age-matched controls. The children were then asked to read two lists of single real words of equal linguistic difficulty: one with both eyes open and the other with the left eye occluded. Only children who failed the Dunlop Test made fewer non-word errors when they read with one eye. This result provides additional support for the theory that unstable binocular control can directly affect how children read. In addition, these findings suggest that this effect must be due, at least in part, to some interaction between the images from the two eyes.