Overview
Congenital stationary night blindness (CSNB) is a clinically and genetically heterogeneous group of non-progressive retinal disorders characterized by impaired night vision from birth. CSNB is classified into complete (cCSNB) and incomplete (icCSNB) forms based on ERG findings, and includes X-linked, autosomal dominant, and autosomal recessive subtypes. Visual acuity is often reduced, and nystagmus and myopia are common associations.
Genetics
Multiple inheritance patterns and causative genes. X-linked forms (NYX, CACNA1F) are most common. Autosomal forms involve TRPM1, GRM6, LRIT3, and others.
| Gene | Locus | Inheritance | Notes |
|---|---|---|---|
| NYX | Xp11.4 | X-linked | Nyctalopin; complete CSNB (cCSNB) |
| CACNA1F | Xp11.23 | X-linked | Calcium channel alpha-1F; incomplete CSNB (icCSNB) |
| TRPM1 | 15q13.3 | AR | Transient receptor potential melastatin 1; AR complete CSNB |
| GRM6 | 5q35.3 | AR | Metabotropic glutamate receptor 6; AR complete CSNB |
| CACNA1S | 1q32.1 | AD | Calcium channel; AD CSNB (Nougaret type) |
Clinical Presentation
Congenital
- Night blindness from birth
- Nystagmus (especially in X-linked forms)
- High myopia
Ongoing (stationary)
- Reduced visual acuity (6/12–6/60)
- Strabismus in some
- Normal fundus appearance
Diagnosis
- ERG: Pathognomonic negative ERG (reduced b-wave with preserved a-wave) in complete CSNB
- Fundus: Usually normal appearance
- Refraction: High myopia common
- Genetic testing: CSNB gene panel (NYX, CACNA1F, TRPM1, GRM6, LRIT3, and others)
Current Research & Treatment
No approved treatments exist for CSNB. The condition is non-progressive, so management focuses on optical correction and low vision support. Research into ON-bipolar cell signaling pathways may yield future therapeutic targets.
Active Clinical Trials
The following active clinical trials are investigating treatments for Congenital Stationary Night Blindness. Trial status and enrollment may change; always verify directly on ClinicalTrials.gov.