Full-field electroretinography in a patient with X-linked juvenile retinoschisis typically shows:

• A Supernormal b-wave amplitude in photopic conditions
• B Reduced a-wave with normal b-wave
• C Prolonged implicit time of the a-wave only
• D Normal a-wave with reduced b-wave, producing an electronegative ERG ✓

Explanation

X-linked retinoschisis affects the Muller cells and inner retina, so the photoreceptor-generated a-wave remains relatively preserved while the bipolar cell-mediated b-wave is markedly reduced, giving a negative (electronegative) ERG configuration. The same waveform occurs in congenital stationary night blindness. In contrast, photoreceptor diseases such as retinitis pigmentosa reduce the a-wave itself, which distinguishes outer retinal from inner retinal dysfunction on ERG interpretation.

Reference: Parsons' Diseases of the Eye, 22nd ed.

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Written and medically reviewed by the StethoPrep medical team.