Flash-electroretinography (FERG) were used to assess retinal function in vivo.

The green, blue, grey and black tracings indicate wild-type (LAB22; ABCA4^+/+) unaffected dog, a heterozygous (LAB6; ABCA4^+/-) dog, and two homozygous (LAB4 and LAB3; ABCA4^-/-) affected dogs, respectively. Black arrows in A, B and C indicate 3 cd/m²/s-flash stimuli and the red line in D indicate 0.02 cd/m²/s-flash stimuli and scales show amplitude on the y-axis (μV) and time in ms on the x-axis for each type of response. (A) A dark-adapted, mixed rod-cone response. (B) Light-adapted cone transient responses (C) and cone flicker response at 30 Hz. Note that the affected dog had a delayed response to the stimuli. (D) The dark-adapted rod responses monitored during one hour in an affected (LAB3) and a wild-type female (LAB22).