Symptoms
These depend on what level of retinopathy is present. However, patients with any of the categories previously outlined may be completely asymptomatic. This is why the screening services play an important role in identifying those with sight-threatening disease so that they can receive treatment in a timely fashion that hopefully conserves their vision.
Diabetic macular oedema (DMO) may cause reduced central visual acuity. It is the most common cause of reduced visual acuity in type 2 diabetes mellitus.
Proliferative diabetic retinopathy (PDR) may cause floaters or sudden loss of vision, especially if there has been a large vitreous haemorrhage.
Signs
Non-proliferative diabetic retinopathy (NPDR): dots (microaneursyms), a few blots and hard exudates are common. If there are many blot haemorrhages and these are associated with cotton wool spots and venous beading, this signifies more advanced NPDR. The patient may be on their way to developing Proliferative diabetic retinopathy.
Proliferative diabetic retinopathy (PDR): abnormal new blood vessels at the optic disc or elsewhere. These grow as a result of retinal ischaemia because of the diabetes. They may look like a bunch of grapes and grow into the vitreous. A very ischaemic eye may have abnormal blood vessels on the iris as well as at the disc or on the retina. There may be vitreous haemorrhage because these abnormal new blood vessels are fragile and tend to bleed easily.
Diabetic macular oedema (DMO): swelling at the macula. There may be obvious central microaneurysms that are leaking (red dots). There may be a rim of brighter exudates surrounding the central, thickened area.
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