[Recording system for the scotopic threshold response]

The scotopic threshold response (STR) is a newly investigated component of the electroretinogram. Since the STR reflects post-photoreceptoral processing in the retina at intensities near absolute threshold, the STR would be a useful index to evaluate the rod pathway in the proximal retina. A conventional ERG setup, however, involves difficulties in STR recording. Therefore we constructed a new recording system for the purpose. The characteristics of the apparatus are as follows: 1) A diffusing sphere provides full-field stimuli ranging from a very dim light near absolute threshold to a very bright light. 2) A remote-control system for changing filters is used to avoid breakdown of the dark-adapted status. 3) A software artifact rejection routine is used to exclude responses influenced by eye movements and blinks. Using the apparatus we have examined the human STR and generally confirmed the previous findings.