Figure 4: Relative change in ERG amplitude versus IOP (mean ± SEM). (a) Positive STR (pSTR, unfilled triangles) and negative STR (nSTR, filled triangles). (b) Photoreceptoral amplitude ( , filled squares),     amplitude ( , open circles), and scotopic OP amplitude (filled circles). (c) Photopic b-wave amplitude (open diamonds) and photopic OP amplitude (filled diamonds). (d) nSTR (filled triangles, thin solid curve),      (open circles, dashed curve), and photoreceptoral     (filled squares, bold curve) are replotted together with their corresponding best-fit cumulative normal functions for comparison. Reprinted from [46] with permission. The Association for Research in Vision and Ophthalmology remains the copyright holder.