Duchenne muscular dystrophy: negative scotopic bright-flash electroretinogram and normal dark adaptation

Recent reports indicate that most subjects with Duchenne muscular dystrophy (DMD) have a negative scotopic bright-flash electroretinogram (ERG). We performed dark adaptometry in seven patients with the DMD phenotype. Three patients had the negative bright-flash response combined with severely reduced rod-related activity; their mean psychophysical dark-adapted threshold was -5.5 +/- 0.3 (normally -5.4 +/- 0.3) cd.m-2. Two of the three patients were able to sit through the complete test: the profile of their dark adaptation curve was normal. The four other patients had a normal scotopic ERG, and their mean psychophysical dark-adapted threshold was -5.3 +/- 0.3 cd.m-2. One of the four was able to complete the entire procedure, and a normal profile was found. In patients with DMD the dark adaptation measurements are normal despite abnormalities in rod-related ERG activity.