Corneal surface hydration

Corneal surface hydration refers to the physiological state in which the cornea maintains an optimal level of water content necessary for transparency and proper vision. This is not a single molecular target but rather a complex process regulated by several mechanisms: • The tear film, particularly its lipid layer, prevents excessive evaporation from the ocular surface and helps maintain hydration[4]. • The corneal endothelium acts as an active barrier with ion pumps (notably Na+/K+-ATPase) that move fluid out of the stroma into the anterior chamber, counteracting water imbibition into the cornea[1][2]. Damage or loss of endothelial cells impairs this pump function, leading to stromal swelling (edema)[1]. • Tear evaporation contributes significantly to changes in corneal thickness; studies show that during recovery from swelling with eyes open, about 80% is due to osmotic thinning via tear evaporation while only 20% is due to endothelial pumping[2]. Disorders affecting these processes—such as dry eye disease (insufficient tear production/evaporation), endothelial dysfunction (Fuchs’ dystrophy), or exposure-related dehydration—can compromise vision by disrupting normal hydration balance. Because "corneal surface hydration" describes a physiological property rather than a discrete molecule/receptor/protein/gene, it should not be considered a canonical therapeutic target. Instead, therapies aim at modulating underlying mechanisms such as enhancing tear film stability or supporting endothelial cell function.

Enhancement or support of tear film stability to reduce evaporation[4] Stimulation or support of endothelial pump function to remove excess fluid from the stroma[2]