An apparatus mounted proximate to or on a base of a slit lamp illumination unit operates to automatically lock or secure the illumination unit in a stationary position after each eye examination and further operates to unlock it just before each examination. The apparatus may take the form of a threaded rod that replaces the conventional thumbscrew. The threaded rod is rotated by a motor, which receives instructions from a controller, both located within a housing. A touch sensor on the housing communicates with the controller to activate the locking or unlocking of the threaded rod and may also provide a signal to a transceiver for powering the illumination unit ON or OFF.