Intracellular Edema.

The macula is predisposed to edema in various retinal conditions, even when the insult is remote from the macula. The various factors that may predispose the macula to edema include high metabolic activity, radial arrangement of the Henle's layer, lack of inner layers at the fovea, and lack of blood supply at the fovea. The edema is most pronounced in the outer plexiform layer (Henle's layer). Alteration in the blood-retinal barrier and ischemia cause disturbances in vascular permeability as well as with the function of Müller cells. K+ ions and aquaporin-4 play an important role in maintaining the dryness of the macula in physiological conditions. Intracellular edema of Müller cells contributes significantly to macular edema. Steroids and anti-VEGF agents reduce intracellular edema, apart from extracellular edema. Therapeutic targets for improving Müller cell function could play a key role in the development of new molecules.