Osmotic pressure is a critical internal environmental factor that maintains cellular homeostasis. Alterations in osmotic pressure can disrupt the equilibrium of water and solutes within cells, thereby impacting their core functions. In the visual organ, the stability of the osmotic pressure within the internal environment, specifically in substances like tear fluid and aqueous humor, holds paramount significance for sustaining the morphology and functionality of corneal epithelial cells, trabecular meshwork cells, among others. Recent research findings have indicated that osmotic pressure serves as a crucial regulator in modulating the activity levels, inflammatory responses, and barrier functions of ocular cells. A comprehensive investigation into the effects of osmotic pressure on ocular cells is essential for understanding the pathogenesis of ocular diseases and exploring novel therapeutic strategies. This review provides an overview of the ocular osmotic pressure environment, its effects on ocular cells,