The electroretinogram response of flies carrying ninaC^I1501E in a ninaC⁵ background is abnormal. The flies show a delay of approximately 1 second upon cessation of the intense light stimulus before the response begins to return to baseline. Once the response termination has started, the mutant flies return more slowly than normal to the dark state. Often, a small repolarisation occurs coincident with cessation of the light stimulation, followed by the delay before full repolarisation. The mutant flies do not show a prolonged depolarisation phenotype.

Intracellular electrophysiological responses of photoreceptor cells in flies carrying ninaC^I1501E in a ninaC⁵ background are abnormal. There is a significant delay in termination of the photoresponse. There is no significant defect in adaptation.

Flies carrying ninaC^I1501E in a ninaC⁵ background do not show retinal degeneration.