KERA (keratocan) is a keratan sulfate-containing proteoglycan essential for corneal stromal transparency and structural integrity. As a component of the extracellular matrix, KERA functions alongside lumican and mimecan to maintain corneal transparency during development and throughout life 1. The protein is expressed by keratocytes (corneal stromal fibroblasts) and contributes to proper collagen fibril organization within the stromal matrix 2. KERA expression is tightly regulated through conserved promoter elements involving cell-type-specific transcriptional factors 1. Mutations in KERA cause cornea plana 2, an autosomal recessive disorder characterized by corneal flattening and transparency defects. The importance of keratocyte-derived matrix components is underscored by studies showing that disruption of stromal cell signaling pathways (such as TGFβR2 in keratocytes) results in reduced collagen fibril density, corneal thinning, and corneal ectasia 3, phenotypes that parallel corneal dystrophies involving KERA. Clinically, understanding KERA function is relevant for corneal transplantation approaches and regenerative medicine strategies. Recent advances in differentiating keratocytes from human pluripotent stem cells, identified by KERA expression, offer potential therapeutic applications for corneal damage and visual impairment 2.