Explanation – A second, less common, type of retinal detachments are those termed traction retinal detachments. In this class, there is epiretinal tissue that develops or grows on the surface of the retina. The tissue then exerts traction or “pulling” on the retina yielding this second type of retinal detachment.
Traction retinal detachments may develop in healthy eyes and are seen in cases of idiopathic macular hole and macular pucker (aka ERM). Traction retinal detachments may also occur in diseased eyes as in proliferative diabetic retinopathy and proliferative vitreoretinopathy (PVR).
Epiretinal Membrane (ERM) – In cases of macular pucker (ERM), a thin tissue or “membrane” grows along the surface of the retina. The retina becomes wrinkled or “puckered.” Symptoms include decreased vision and/or distortion. While vision loss is usually mild, there can be more severe cases. The membrane develops as a result of an overproduction of protein from cells that normally inhabit the retina. Surgery may be performed to gently lift or peel the membrane off of the surface of the retina. While vision is usually improved, it may not be restored completely, yet the likelihood of progression is significantly decreased, that is, vision loss is halted. The chance of recurrent growth of the membrane is about 5-10%. Indications for surgery, in my opinion, should be limited to the recognition of loss of vision and the desire for improvement or stabilization.
Macular Hole – A similar situation occurs in cases of idiopathic macular hole. An epiretinal membrane develops on the surface of the retina and stretches a hole in the center of the macula. Such holes are progressive and may lead to significant loss of central vision, but not complete blindness. Surgical repair is possible and is successful about 90% of the time. Occasionally, a second attempt is required to achieve closure of the macular hole. As in many retinal conditions, vision may be improved, but not completely restored.
Diabetic Retinopathy In advanced cases of diabetic retinopathy, neovascular (abnormally vascularized scar tissue) membranes develop on the surface of the retina. The vascularized membranes grow on the surface of the retina similar to ivy growing along the ground. Eventually, this surface tissue starts to pull on the retina leading to retinal detachment. Significant loss of vision is likely if the process is not halted. This is the mechanism by which diabetics may become completely blind.
Proliferative vitreoretinopathy (PVR) is generally believed to be a complication of retinal surgery, usually previous retinal detachment surgery. Significant formation of epiretinal membranes repeatedly pull and tear the retina. Multiple surgeries are often required to gain control of the disease. Visual prognosis is poor despite “successful” surgery and blindness is not uncommon. This is a common complication of penetrating eye trauma.