Homozygotes have greatly reduced eyes and reduced ocelli.
eya4/eya1 flies have eyes that are between 1/4 and less than 3/4 normal size. eya4/eya3 flies may be eyeless, or may have eyes that are less than 1/4 normal size. eya4/eya3 females are fertile.
eya4/eyaE3 flies are viable, and have eyes which range from 1/2 to less than normal size. Homozygous flies have eyes which are less than 1/2 normal size. Transheterozygotes in combination with eya1, eya2, eya3, eyaE6, eyaE11, eyaE4, eyaE7, eyaD1, eyaE9 or eyaE2 have smaller eyes than normal. Transheterozygotes in combination with eyaE12, eyaE1, eyaD5, eyacli-IID, eyaE8, eyaE5, eyaE10, eyaD4, eyaZ283, eyaD2, eyaD3, eyaD6 or eyaD7 are eyeless.
Homozygotes have severely reduced eyes. eya2/eya4 heterozygous flies have 3/4 sized eyes.
Ocelli are missing, and the posterior vertical bristles of the head are truncated with frayed ends. Eyes have a variable phenotype, ranging from all eye tissue absent, with cuticle containing occasional hairs or bristles occupying the space normally occupied by the ommatidia, through streaks of red-pigmented cuticle with no eye facets present, to patches of red-pigmented cuticle occupying 10-25% of the wild-type eye area, and 10-25 facets present. Eye discs from late third instar larvae show extensive areas of dead cells. Transheterozygotes with eya1 have reduced eyes with fewer facets than normal and the facets are disorganised. The posterior vertical bristles of the head are truncated with frayed ends.