DEFINITION

• The macula is a small and highly sensitive part of the retina, located roughly in the center of the retina and just temporal to the optic nerve.
• Macular edema occurs due to fluid and protein leaking from blood vessels within the macula causing it to swell and thicken.
• Focal macular edema is caused by foci of vascular abnormalities, primarily microaneurysms, which tend to leak fluid.
• Diffuse macular edema is caused by dilated retinal capillaries in the retina.
• Clinically significant macular edema (CSME) was defined by the Early Treatment Diabetic Retinopathy Study Group (EDTRS)[6] (see Diagnosis section for full definition).