Adult flies with tinc^{dsRNA.Scer\UAS} expression driven under the control of Scer\GAL4^GMR.PY (which becomes active in all differentiating ommatidial cells posterior to the morphogenetic furrow), have abnormal eyes with disorganised and fused ommatidia. Inner tangential sections show abnormalities of the photoreceptor cells, wherein most of the cells are collapsed or split. tinc^{dsRNA.Scer\UAS} expression, under the control of Scer\GAL4^ey.PH or Scer\GAL4^GMR.PY, during the earlier stages of eye development does not affect the differentiation of the photoreceptor cells. Abnormalities associated with tinc^{dsRNA.Scer\UAS} expression occur in later developmental stages. In the wild-type eye, 40 hours after puparium formation, the eight elav-positive photoreceptor cells are arranged in a circle within an ommatidium. In contrast, in the tinc^{dsRNA.Scer\UAS} eye (driven by Scer\GAL4^GMR.PY), the patterning of the photoreceptor cells is irregular. Some ommatidia are found to be fused to adjacent ones, and the spatial patterning of the photoreceptor cells is disturbed. The pigment and cone cells of flies expressing tinc^{dsRNA.Scer\UAS} under the control of Scer\GAL4^GMR.PY are also arranged in a disorganised pattern compared to wild-type. Some cone cells and primary pigment cells show deformed shapes. These phenotypes are almost completely suppressed by the introduction of the tinc^Scer\UAS.cHa transgene.