A battery-powered device with a series of individual flashing light sources [typically consisting of a light-emitting diode (LED)] to treat poor accommodative and vergence facility, convergence insufficiency, and large accommodative lag in non-presbyopic subjects. It is designed as a long metal or plastic bar upon which the lights are mounted at intervals and the patient, placed in front it, tracks the movement of the flashing lights as they rapidly change positon. Some types use alternating red and blue lights making use of the phenomenon of chromatic aberration to gently rock accommodation and convergence of the lens. It is suitable for home-use but may be used in an optometrist's office.