Macular edema Macular edema Macular edema occurs when fluid and protein deposits collect on or under the macula of the eye (a yellow central area of the retina) and causes it to thicken and swell (edema). The swelling may distort a person's central vision, because the macula holds tightly packed cones that provide sharp, clear, central vision to enable a person to see detail, form, and color that is directly in the centre of the field of view. The causes of macular edema are numerous and different causes may be inter-related. Cystoid macular edema (CME) involves fluid accumulation in the outer plexiform
Cerebral edema include physical disruption by arterial hypertension or trauma, and tumor-facilitated release of vasoactive and endothelial destructive compounds (e.g. arachidonic acid, excitatory neurotransmitters, eicosanoids, bradykinin, histamine, and free radicals). Subtypes of vasogenic edema include: In cytotoxic edema, the blood–brain barrier remains intact but a disruption in cellular metabolism impairs functioning of the sodium and potassium pump in the glial cell membrane, leading to cellular retention of sodium and water. Swollen astrocytes occur in gray and white matter. Cytotoxic edema is seen with various toxins, including dinitrophenol, triethyltin, hexachlorophene, and isoniazid. It can occur in Reye's syndrome, severe hypothermia, early ischemia, encephalopathy,