Diabetic retinopathy,[1] ([ˌrɛtnˈɑpəθi]) is retinopathy (damage to the retina) caused by complications of diabetes, which can eventually lead to blindness.[2] It is an ocular manifestation of diabetes, a systemic disease, which affects up to 80 percent of all patients who have had diabetes for 10 years or more.[3] Despite these intimidating statistics, research indicates that at least 90% of these new cases could be reduced if there was proper and vigilant treatment and monitoring of the eyes.[4] The longer a person has diabetes, the higher his or her chances of developing diabetic retinopathy/
Signs and symptoms
Diabetic retinopathy often has no early warning signs. Even macular edema, which may cause vision loss more rapidly, may not have any warning signs for some time. In general, however, a person with macular edema is likely to have blurred vision, making it hard to do things like read or drive. In some cases, the vision will get better or worse during the day.
In the first stage which is called non-proliferative diabetic retinopathy (NPDR) there are no symptoms, it is not visible to the naked eye and patients will have have 20/20 vision. The only way to detect NPDR is by fundus photography, in which microaneurysms (microscopic blood-filled bulges in the artery walls) can be seen. If there is reduced vision, fluorescein angiography can be done to see the back of the eye. Narrowing or blocked retinal blood vessels can be seen clearly and this is called retinal ischemia (lack of blood flow).
Macular oedema may occur in which blood vessels leak contents into the macular region can happen at all stages of NPDR. The macular oedema symptoms are blurring, darkening or distorted images with not the same between two eyes. 10 percent of diabetic patients will get vision loss related with macular oedema. Optical Coherence Tomography can show areas of retinal thickening (fluid accumulation) of macular oedema.[6]
On the second stage, as abnormal new blood vessels (neovascularisation) form at the back of the eye as a part of proliferative diabetic retinopathy (PDR), they can burst and bleed (vitreous hemorrhage) and blur vision, because the new blood vessels are weak. The first time this happens, it may not be very severe. In most cases, it will leave just a few specks of blood, or spots, floating in a person's visual field, though the spots often go away after a few hours.
These spots are often followed within a few days or weeks by a much greater leakage of blood, which blurs vision. In extreme cases, a person will only be able to tell light from dark in that eye. It may take the blood anywhere from a few days to months or even years to clear from the inside of the eye, and in some cases the blood will not clear. These types of large hemorrhages tend to happen more than once, often during sleep.
On funduscopic exam, a doctor will see cotton wool spots, flame hemorrhages (similar lesions are also caused by the alpha-toxin ofClostridium novyi), and dot-blot hemorrhages.