Some visual effects caused by the beverage kava.

Kava is a drink produced from the plant Piper methysticum and used as a social and ceremonial beverage on many South Pacific islands. Visual functions were measured in one subject following the taking of this drink. A reduced near point of accommodation and convergence, an increase in pupil diameter and disturbance to the oculomotor balance were noted. No changes were recorded in visual or stereoacuity or in ocular refractive error.