Mutant files do not show normal entrainment to temperature cycles but show normal synchronisation to light-dark cycles in assays studying locomotor rhythms. In temperature cycles, the mutant flies are mainly active during the warm phase, do not show the typical transients after transfer to a new temperature regime, and do not anticipate the temperature decrease.

eys³⁹⁵ mutants exhibit a loss of optical isolation of photoreceptor cells. Ultra-structural analysis shows that rhabdomeres and stalk membranes are in close contact in eys³⁹⁵ mutants and individual rhabdomeres are often fragmented. In some ommatidia of eys³⁹⁵ mutants, luminal spaces between stalk membranes are visible but appear devoid of the diffuse matrix seen in wild-type.