Horizontal intracorneal swirling water migration indicative of corneal endothelial function.

PURPOSE To test our hypothesis about whether there is water migration in the horizontal corneal plane and investigate its developmental mechanism. METHODS A fluorescein solution was intrastromally injected into normal and edematous corneas of rabbits, and the movement of the fluorescein solution was observed and recorded over time. RESULTS In normal corneas, the water flow was characterized by a swirling movement from the center to the periphery in the stroma. The fluorescein solution ultimately spread and occupied the entire cornea, indicating horizontal intracorneal swirling of water. In contrast, when the corneal endothelia were injured by intracameral injection of a preservative to create corneal edema, no water migration occurred, suggesting that the integrity of the corneal endothelial function is essential for water migration. The water migration stopped with injection of a sodium-potassium pump inhibitor, indicating that the enzyme is necessary for physiologic water migration in the cornea. With recovery of corneal endothelial function, the water migration began, and focal edema remained in the periphery with no water migration in this edematous area. CONCLUSIONS We report for the first time the presence of horizontal water migration in the cornea in a swirling pattern (i.e., intracorneal swirling migration of water, generated by the pump function in the corneal endothelial cells), which may supplement the conventional concept of development of corneal edema in the vertical plane. This dynamic water circulatory system may be involved in increasing the efficiency of the water transfer in the entire cornea.