Macular degenerationis the deterioration of the macula, which is the central area of the retina. Macular degeneration is the most prevalent eye disease and the most common cause of irreversible blindness in the elderly.
Why do diabetics get macular degeneration?
Macular degeneration when it occurs in diabetic patients is known as diabetic retinopathy. Diabetic retinopathy manifests itself gradually and it occurs as a result of damage to the retina. If left untreated, this eye disease can lead to severe vision loss and blindness.
Initially, the disease manifests as damaged blood vessels and retinal swelling. This leads to macular edema which is characterized by fluid collection in the macula. This macular edema predisposes diabetic patients to macular degeneration. The final stage of diabetic retinopathy is characterized by new blood vessel growth on the retina. These blood vessels can break and bleed into the vitreous humor causing cloudiness and impaired vision. In addition, the vessels may cause scar tissue development, which can lead to retinal detachment and blindness.
What is angiogenesis?
Angiogenesis is the formation of new blood vessels from pre-existing ones. It is important to differentiate angiogenesis from vasculogenesis; a process that also involves the formation of new blood vessels. Vasculogenesis is the process by which primary blood vessels are formed during the early stages of development. In vasculogenesis the vessels form by the differentiation of angioblasts, embryonic cells of mesodermal origin. In adults in response to wound healing, angiogenesis is a normal physiologic event.
There are many triggering events that can induce the process of angiogenesis. During inflammation or hypoxia, cytokines favoring the formation of new blood vessels are conveyed to neighboring established blood vessels. Next, inflammatory cells migrate toward the signal source and matrix metalloproteinases are released causing digestion of collagen fibers present in the basement membrane. This creates a breach through which proliferating endothelial cells can migrate in the direction of the signal source eventually leading to the formation of a newly functional blood vessel. Angiogenesis has also been closely linked to the etiology of macular degeneration in the elderly.
Diabetes Care 23(11):1672-8