The cell types in a typical insect visual system are broadly divided into photoreceptor neurons and support cells. While photoreceptors have been studied extensively, support cell biology remains relatively understudied. Here we focus on a subset of support cells in the adult Drosophila compound eye called Semper cells which cage the photoreceptors. These cells provide multifunctional glial support to photoreceptors and also secrete the lens; hence Semper cells are key constituents of a properly functioning fly eye. One of the best-known markers for Drosophila Semper cells is the homeodomain transcription factor Cut, yet the function of cut in Semper cells has not yet been elucidated. Based on its restricted expression to Semper cells, and its other known functions in sensory cell fate decisions and development, we hypothesize that cut is important for visual system development and/or function. To investigate this, we knocked down cut’s expression in the Semper cells using RNAi. This resulted in flies with rough eyes, suggesting a vital role for cut in eye development. We further characterized cut knock-down eyes for three aspects of ocular development previously shown to be influenced by Semper cells: lens focusing, photoreceptor neural activity, and photoreceptor morphogenesis. In each case, we find major deficiencies in animals lacking cut expression in Semper cells, suggesting a broad role for cut in Semper cell biology. Parallel studies on beetles will establish if cut’s expression and function could be conserved in the lens-secreting cells of other arthropods. Taken together, this study will provide further insights into eye-specific “ancient gene networks” which have been conserved across distant phyla.