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| congenital_stationary_night_blindness [2025/11/25 18:47] – Scott Larson | congenital_stationary_night_blindness [2025/12/01 15:52] (current) – Scott Larson |
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| ====== Congenital Stationary Night Blindness ====== | ====== Congenital Stationary Night Blindness ====== |
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| ====Main Features==== | ====Main Features==== |
| * Night Blindness, variable vision loss, largely normal fundus | * Night Blindness, variable vision loss, largely normal fundus |
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| <WRAP round box 100%> | <WRAP round box 100%> |
| | Figure 45.2 Taylor and Hoyt |
| {{::csnb_erg_responses.jpg|}} | {{::csnb_erg_responses.jpg|}} |
| Congenital stationary night blindness. The left-hand column traces (A) show data from a patient with “incomplete” CSNB (iCSNB); the center traces (B) are from a patient with “complete” CSNB (cCSNB); the right-hand column traces (C) are from a representative normal subject. In iCSNB the rod ERG (DA 0.01) is mildly subnormal. The bright flash response (DA 10.0) is electronegative, with a normal a-wave confirming normal photoreceptor function, but a profoundly reduced b-wave. The 30 Hz flicker ERG (LA 30 Hz) is markedly subnormal and clearly shows the delayed double peak characteristically seen in iCSNB. The photopic single flash ERG (LA 3.0) shows marked reduction in the b:a ratio with simplification of the waveform and loss of the photopic oscillatory potentials, shown on ON/OFF response recording (200 ms orange stimulus on a green background) to reflect involvement of both ON (depolarizing) and OFF (hyperpolarizing) cone bipolar cell pathways. The pattern electroretinogram (PERG) is mildly subnormal in keeping with mild macular dysfunction. In cCSNB there is no detectable DA 0.01 response and the profoundly electronegative DA 10.0 ERG confirms the site of the dysfunction to be post-phototransduction. The LA 3.0 response shows a distinctive broadened a-wave and a sharply rising b-wave with a reduced b:a ratio and lack of photopic oscillatory potentials. This appearance indicates marked dysfunction of cone ON bipolar cell pathways but preservation of the OFF pathways. The profoundly negative ON response, with preservation of the ON a-wave and loss of the ON b-wave, accompanied by a normal OFF response is confirmatory. The broadened trough of the 30 Hz flicker ERG with a sharply rising peak is a manifestation of the same phenomenon. The PERG is almost undetectable. Overall, the findings in cCSNB are those of loss of ON pathway function in both rod and cone systems. Michel Michaelides; Graham E Holder; Anthony T Moore, 45, 526-549 | Congenital stationary night blindness. The left-hand column traces (A) show data from a patient with “incomplete” CSNB (iCSNB); the center traces (B) are from a patient with “complete” CSNB (cCSNB); the right-hand column traces (C) are from a representative normal subject. In iCSNB the rod ERG (DA 0.01) is mildly subnormal. The bright flash response (DA 10.0) is electronegative, with a normal a-wave confirming normal photoreceptor function, but a profoundly reduced b-wave. The 30 Hz flicker ERG (LA 30 Hz) is markedly subnormal and clearly shows the delayed double peak characteristically seen in iCSNB. The photopic single flash ERG (LA 3.0) shows marked reduction in the b:a ratio with simplification of the waveform and loss of the photopic oscillatory potentials, shown on ON/OFF response recording (200 ms orange stimulus on a green background) to reflect involvement of both ON (depolarizing) and OFF (hyperpolarizing) cone bipolar cell pathways. The pattern electroretinogram (PERG) is mildly subnormal in keeping with mild macular dysfunction. In cCSNB there is no detectable DA 0.01 response and the profoundly electronegative DA 10.0 ERG confirms the site of the dysfunction to be post-phototransduction. The LA 3.0 response shows a distinctive broadened a-wave and a sharply rising b-wave with a reduced b:a ratio and lack of photopic oscillatory potentials. This appearance indicates marked dysfunction of cone ON bipolar cell pathways but preservation of the OFF pathways. The profoundly negative ON response, with preservation of the ON a-wave and loss of the ON b-wave, accompanied by a normal OFF response is confirmatory. The broadened trough of the 30 Hz flicker ERG with a sharply rising peak is a manifestation of the same phenomenon. The PERG is almost undetectable. Overall, the findings in cCSNB are those of loss of ON pathway function in both rod and cone systems. Michel Michaelides; Graham E Holder; Anthony T Moore, 45, 526-549 |
| * Nystagmus , strabismus | * Nystagmus , strabismus |
| ====Treatment==== | ====Treatment==== |
| * Unordered List Item | * Low vision and adaptive strategies |
| | * Future hopes of Gene Therapy see reference 2 below |
| ====Resources==== | ====Resources==== |
| - [[https://www.clinicalkey.com/#!/content/book/3-s2.0-B9780702082986000457#hl0000441|Taylor and Hoyt chapter 46. Stationary Night Blindness.]] | - [[https://www.clinicalkey.com/#!/content/book/3-s2.0-B9780702082986000457#hl0000441|Taylor and Hoyt chapter 46. Stationary Night Blindness.]] |
| | - [[https://link.springer.com/article/10.1186/s12967-025-06392-8 |Yi Zhang et al. Gene therapy shines light on congenital stationary night blindness for future cures. Journal of Translational Medicine 2025;23 article 392]] |
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| {{tag>inherited_retinal_disease retina}} | {{tag>inherited_retinal_disease retina}} |