Return sweep latency in reading with a paralyzed eye.

The study concerned the distribution of directional control of eye movement in reading. With the paralysis of the right eye, progressive movements of the left eye were possible, but regressive movements were cancelled, being observed as drift. Base-out prism placed over the non-paralyzed eye allowed for the re-establishment of regressive movements. The results for this subject were explained on the basis of a large retinal error marker having been established. With the paralysis of one eye, base-out prisms reduce that error.