cheiroscope

cheiroscope 

An instrument used in the management of amblyopia, suppression and hand and eye coordination. It consists of presenting a line drawing to one eye (usually the dominant one), which is traced by a pencil or crayon in the field of view of the other eye. The two fields of view are separated by a septum and a small mirror is used to reflect the line drawing. Stereoscopes can easily be adapted into cheiroscopes.
Millodot: Dictionary of Optometry and Visual Science, 7th edition. © 2009 Butterworth-Heinemann