purpose. To evaluate rod photoreceptor and postreceptor retinal function in pediatric patients with achromatopsia (ACHR) and blue cone monochromatism (BCM) using contemporary electroretinographic (ERG) procedures.

methods. Fifteen patients (age range, 1–20 years) with ACHR and six patients (age range, 4–22 years) with BCM were studied. ERG responses to full-field stimuli were obtained in scotopic and photopic conditions. Rod photoreceptor (S rod, R rod) and rod-driven postreceptor (log σ, V max) response parameters were calculated from the a-wave and b-wave. ERG records were digitally filtered to demonstrate the oscillatory potentials (OPs); a sensitivity parameter, log SOPA 1/2, and an amplitude parameter, SOPA max, were used to characterize the OP response. Response parameters were compared with those of 12 healthy control subjects.

results. As expected, photopic responses were nondetectable in patients with ACHR and BCM. In addition, mean scotopic photoreceptor (R rod) and postreceptor (V max and SOPA max) amplitude parameters were significantly reduced compared with those in healthy controls. The flash intensity required to evoke a half-maximum b-wave amplitude (log σ) was significantly increased.

conclusions. Results of this study provide evidence that deficits in rod and rod-mediated function occur in the primary cone dysfunction syndromes ACHR and BCM.