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
Tissue residue the exposure media. In general, tissue residue approaches are used for chemicals that bioaccumulate or for bioaccumulative chemicals. The majority of these substances are organic compounds that are not easily metabolized by organisms and have long environmental persistence. Examples of these chemicals include: polychlorinated dibenzodioxins, furans, biphenyls, DDT and its metabolites, and dieldrin. The use of tissue residues in assessing toxicity and bioaccumulation may also be referred to as the tissue residue-effects approach (TRA), critical body residue (CBR) or tissue residue-based toxicity tests. Historically, aquatic toxicology toxicity tests have focused on water-based approaches where concentration of a toxicant is determined