Congenital stationary night blindness with negative electroretinogram. A new classification

Area of Science:

• Ophthalmology
• Genetics
• Neuroscience

Background:

• Congenital stationary night blindness (CSNB) is an inherited retinal disorder characterized by reduced vision in low light.
• Previous classifications often rely on electroretinography (ERG) findings and family history.
• The specific pathogenesis and classification of CSNB, particularly negative-type ERG, require further elucidation.

Purpose of the Study:

• To analyze patients with CSNB and normal fundi using detailed electroretinography and psychophysical testing.
• To investigate potential differences in pathogenesis between CSNB subtypes.
• To propose a refined classification for CSNB with a negative ERG.

Main Methods:

• Analysis of 64 patients with CSNB and normal fundi.
• Electroretinography (ERG) including assessment of a and b waves with a bright white stimulus.
• Evaluation of rod electroretinography and/or psychophysical dark adaptation using a specific test target.

Main Results:

• All patients exhibited normal fundi and a normal a wave with a significantly reduced b wave (negative-type ERG).
• Patients were classified into two groups: one lacking rod function (complete type) and another group (9 patients) that could not be classified.
• Differences in refractive error, photopic function, and oscillatory potentials suggest distinct pathogenic mechanisms between the groups.

Conclusions:

• CSNB with a negative ERG and normal fundi can be further sub-classified based on rod function.
• Distinct clinical and electrophysiological findings suggest different underlying pathologies in CSNB subtypes.
• This analysis provides a basis for a new classification of congenital stationary night blindness with a negative ERG.