Amphetamine, Barbiturates, and Accommodation-Convergence

It has been demonstrated that barbiturates selectively influence eye movement responses in man. They interfere with normal convergence responses¹and abolish the smooth tracking movements.²The latter effect is closely associated with the well-known phenomenon of barbiturate nystagmus.³Accommodation of the eye for near targets seems unaffected by barbiturates.¹ Since there is a well-known accommodation-convergence synkinesis,⁴thought by many to be an invariable characteristic of an individual, it is of interest to describe the changes in the synkinesis during barbiturate intoxication. The possibility that amphetamine might produce changes in the opposite direction was also investigated in the hope that an indication might be had of the neural level at which these influences operate. Materials and Methods Experimental subjects were several normal male students in their early twenties, with no demonstrable intra- or extraocular muscle abnormality, and with no history involving excessive use of any pharmacologic