Macular Edema can be caused from a number of ocular diseases such has vein occlusion, ocular inflammation, post surgical complication, diabetes, hypertension, and many other diseases. What most people will notice is a gradual or even sometimes, sudden changes in vision that does not improve. Essentially the retina becomes filled with fluid that causes it to become irregular in shape, thus losing the ability to detect light evenly. Devices such as the OCT, as shown in the picture, can easily detect macular edema that sometimes can be missed by the naked eye.