Abnormal threshold ERG response in X-linked juvenile retinoschisis: Evidence for a proximal retinal origin of the human STR

1. We recorded the scotopic threshold response (STR) and a-wave of 4 affected males and 6 obligate female carriers of X-linked juvenile retinoschisis (XLJR). Since the pathology of XLJR affects the proximal retina, one motivation of this study was to use this retinal dystrophy to study human ERG components from the proximal retina. 2. We found that: (1) the STR is reduced or absent in males with XLJR, whereas the a-wave can remain unaffected; (2) from this we deduced that the a-wave ″threshold″ for normal subjects is near-1 log scot. td-s and that the negative ERG wave below this intensity is the STR; (3) the rod driven oscillatory potentials (OPs), were also reduced in XLJR males to approximately the same extent as the STRs; (4) unfortunately, the STR was not sensitive for detecting carriers of XLJR since STR amplitudes remained normal for the 6 obligate female carriers whom we tested. 3. Since the STR of XLJR affected males was greatly reduced or absent, whereas a-wave amplitudes were within normal range, this study confirmed our suspicion that the human STR originates post-synaptic to the photoreceptors.