Low Angle Ring Illumination Stereomicroscopy (LARIS) Method for High-Contrast Imaging of <em>Drosophila</em> Compound Eyes

The compound eyes of <i>Drosophila</i> are widely used to gain valuable insights into genetics, developmental biology, cell biology, disease biology, and gene regulation. Various parameters, such as eye size, pigmentation loss, formation of necrotic patches, and disorientation, fusion, or disruption of ommatidial arrays, are commonly assessed to evaluate eye development and degeneration. We developed an improved imaging method named low-angle ring illumination stereomicroscopy (LARIS) to capture high-contrast images of the <i>Drosophila</i> compound eye. Different optical alignments were tested to capture the fly compound eye image under the stereomicroscope; the highest contrast with minimal reflection was achieved through the LARIS method. The images captured using LARIS clearly showed ommatidial fusion, disorientation, and pigmentation loss, which were hardly visible with a conventional imaging method in the degenerating compound eyes of <i>Drosophila</i>. In addition to its research applications, this protocol is cost-effective due to the low expenses associated with supplies and equipment. We anticipate that LARIS will facilitate high-contrast imaging of the compound eyes in <i>Drosophila</i> and other insects. Key features • Low-angle ring illumination stereomicroscopy (LARIS) is an improved optical alignment for high-contrast imaging of <i>Drosophila</i> compound eyes. • LARIS is a simple, inexpensive, and robust method with additional advantages over existing SEM methods to capture high-contrast microscopic images of the <i>Drosophila</i> eye. • LARIS can be easily implemented across laboratories and used as a low-cost teaching/research tool.