19 Sep What is the Macula?: Macular Diseases
The macula is the most sensitive portion of the retina. The retina is the inside lining of the eye capturing light and sending to our brain to give us vision. Like a sandwich, the retina has several layers.
Diseases of the macula may be classified by the layer of the retina they affect.
Symptoms of Macular Diseases
Macular diseases, such as epiretinal membranes, macular holes, macular edema and macular degeneration, affect central vision. Symptoms can include decreased vision and/or distortion and you can’t distinguish (or at least I can’t) one disease from another based on symptoms…they are all the same.
Diseases on the Surface of tbe Macula
The more common is the macular pucker, aka epiretinal membrane (ERM). This is a sheet of protein which forms on the surface of the retina. Imagine the retina is the hamburger paddy. The epiretinal membrane would be the cheese on top of the paddy.
The ERM can microscopically wrinkle the underlying macula causing changes in the vision.
Removal of the membrane with vitrectomy often remedies the situation. The underlying retina is healthy.
Macular Diseases Involving the Retina
Often the macular tissue itself is affected. In our sandwich analogy, the retina is the meat itself.
Anything causing macular edema affects the actual retinal tissue (meat patty) and therefore vision. Common causes of macular edema? Vascular occlusions (BRVO and CRVO) and diabetic retinopathy.
A macular hole develops after the retina is stretched. There is actually an absence of tissue causing the hole. (If you took a piece of balloon, poked it with a pin and then stretched the balloon apart, you’d see the resultant pinhole…enlarged by the stretching. Same thing happens with macular holes).
Macular edema may be treated with medicines or laser. Macular holes are treated with surgery.
Diseases Underneath the Macula
The most common are wet and dry macular degeneration. Macular degeneration affects the layer of cells feeding the rods and cones. Without functioning rods and cones (the two types of cells allowing us to “see” light and color) we have no vision.
Macular degeneration principally attacks the RPE layer by permanently damaging theses cells. This would be the lower layer of cheese underneath the patty.
There is presently no accepted treatment for dry macular degeneration. Eye injections of anti-VEGF are one helpful treatment for the wet form.
What Does This Mean?
The macula is a small 2 mm x 2 mm area of the retina producing our useful vision. Thus, “macular” becomes an adjective when describing various disease affecting this region.
Only the ERM involves healthy retinal tissue and, hence, the best prognosis. The retina is the healthiest compared to the other situations.
The treatments available for most of the “macular” diseases are not necessarily successful at fully restoring vision. When the diseases affect the tissue itself, either the retina or the layer underneath, some degree of permanence may be expected.