Study of the mechanism of visual function in incomplete type of congenital stationary night blindness

本研究对完全型和不完全型先天性静止性夜盲（CSNB）的视功能机制进行了探讨，结果如下：1.夜盲部位采用全视野光刺激，记录完全型和不完全型先天性静止性夜盲（CSNB）患者及正常人的ERG强度序列。完全性CSNB患者的视杆b波和STR均不可记录，而不完全性CSNB患者的STR可清晰记录，但绝对阈值略有升高。b波刺激阈值未升高，阈值附近b波振幅正常。上述结果提示，完全型夜盲的发病部位可能位于视杆双极细胞内，而不完全型夜盲的发病部位可能位于视杆双极细胞近侧。2.视杆-视锥相互作用暗适应视杆细胞对视锥反应（SRCI）有抑制作用。我们的研究结果表明，SRCI在完全性和不完全性CSNB中均正常，但在某些情况下，SRCI因局限性视网膜功能障碍而缺失。

We studied the mechanism of visual function in complete and incomplete type of congenital stationary night blindness (CSNB) with the following results.1.Locus of night blindnessUsing full-field stimuli with light intensities ranging from near absolute threshold to bright, ERG intensity series from patients with complete and incomplete CSNB and from normal subjects were recorded. Neither the rod b-wave nor the STR was recordable from patients with complete CSNB.In the incomplete CSNB,the STR was clearly recordable, although the absolute threshold was elevated slightly. The b-wave stimulus threshold was not elevated, and the b-wave amplitude near threshold was normal. The peak time of the STR was delayd by approximately 80 msec, whereas that of b-wave was normal.Above results suggest that the locus of the night blindness of the complete type may lie in the rod bipolar cell, while that of incomplete type may lie proximal to the rod bipolar cell.2.Rod-cone interactionDark-adapted rods have a suppressive effect on cone response (SRCI). This phenomenon was applied to analyze the pathological mechanism of CSNB.Our results indicated that SRCI is normal in both complete and incomplete CSNB,but in some cases, SRCI is absent because of localized retinal dysfunction.