The
most feared diabetic complication is blindness. Fortunately, this is
now very rare in developed countries, but still is a common cause of
blindness elsewhere in the world. Diabetes can damage the light
sensitive part at the back of the eye, the retina. At your clinic
visit, you need to have a thorough retinal examination either by
retinal photography, or by ophthalmoscope having had your pupils
dilated with eye drops first. Ask your doctor what changes if any are
present and how they should be managed. The terminology for these
changes is graded from the early background retinopathy, to the more
severe maculopathy, and most seriously the sight threatening
proliferative retinopathy. Cataract is when the lens at the
front of the eye becomes opaque. High glucose levels cause the changes
in the retina, which leads to blood vessel closure and increased blood
pressure within the retina. There is leakage of blood and blood
products from these small blood vessels, the formation weaknesses of
blood vessels (micro aneurisms), and small haemorrhages within the
retina. This initial phase is classified as background
retinopathy. When this occurs in the most sensitive part of the retina,
the macula, loss of visual acuity follows and may progress to
blindness. This process, (maculopathy), is most frequently seen in
Type 2 diabetes patients who have raised blood pressure, and is
aggravated by smoking. As the damage continues, new thin walled and
fragile blood vessels are formed (proliferative retinopathy). Haemorrhage
from these vessels can cause acute loss of sight, which may clear. Organisation of the haemorrhage causes fibrosis within the retina,
which can cause retinal detachment and blindness. Diabetic retinopathy
can be avoided or the progression can be slowed by having the best
blood glucose control possible, by the use of blood pressure
loweringdrugs, particularly the ACE inhibitors drugs, and with the
early use of laser treatment.