Human retinal organoid fluorescent light micrograph. This organoid was made in a laboratory using a patient's cells. Organoids are miniature, simplified versions of organs grown in the laboratory. Scientists are using organoids as part of gene therapy for Leber congenital amaurosis (LCA). This is a rare eye disorder that affects the retina and causes severe vision loss from childhood. Columnar cells (green) are also seen in the outer ring.