Diabetic retinopathy

Diabetes mellitus is a global metabollic syndrome. Its onset includes different vascular complications in the body. In addition, when the illness co-exists with other general conditions (high blood pressure, obesity, high cholesterol), the risk of other eye complications multiplies. 

Diabetes may damage the small blood vessels in the retina, which is the back layer of the eye. This is known as diabetic retinopathy. The retina transforms the light and images entering the eye into nervous signs that are sent to the brain. 

Diabetic retinopathy is a common complication of diabetes mellitus which compromses the retina's function. It is a pathology that appears when the retinal blood vessels deteriorate. The affected veins may become dilated, cause fluid to leak (plasma, lipids and/or blood) and may even become occluded, leaving part of the retina without any blood circulation. All the phenomena occurring because of diabetes may cause gradual damage to the structures of the eyeball, leading to severely deteriorated vision, which without treatment leads to blindness. 

Surprisingly, even in advanced stages, diabetic retinopathy does not always cause eye discomfort. For this reason, diabetic patients should undergo regular eye check-ups.

According to studies, the prevalence of diabetic retinopathy ranges from 6.3% to 26.1% in Spain.

The main risk factors for the development of diabetic retinopathy are:

• Duration of diabetes
• High blood glucose levels 
• High blood pressure 

Thus, the first recommendation for a patient affected by diabetic retinopathy is that they are very disciplined with their general healthcare, diet and weight control and that they follow the guidelines given to them by their endocrynologist.

Diabetes cannot be cured, but good monitoring is already a huge achievement. 

 It is common that diabetic retinopathy does not show any warning signs in its initial phases. In the majority of cases, there are no symptoms until the harm to the eye is very serious. 

A diabetic person's progressingly poor vision usually translates to the presence of liquid accumulating in the central part of the retina (macular oedema). On other occasions, the illness starts with an acute intraocular haemorrhage, the first sign of which is the sudden and very alarming appearance of spots that partially or fully hinder the eyesight. However, it is important to remember that diabetic retinopathy may be present, even in very advanced stages, without there being any sings of visual discomfort. 

The symptoms that usually appear are: 

• Blurred vision
• Floaters
• Slow loss of vision over time 
• Sudden loss of vision 

Early detection and timely treatment significantly improve the visual prognosis of the illness and can prevent progression towards blindness. 

The main diagnostic tests for this pathology are: 

• Fluorescein angiography: After injecting an endovenous contrast solution, the blood flow to the retina is studied.
• Optical coherence tomography (OCT): It retrieves an image of the macular area which is very useful for diagnosis and follow-up on macular oedema.
• Angio-OCT: A test that helps us to find out the degree of blood flow in the macula.
• Ultrasound: Especially useful in the study of intraocular haemorrhages that impede the display of the back of the eye.

Some patients affected by diabetic retinopathy only require regular check-ups on their eye health. 

In other cases, a laser has to be selectively applied to the abnormal veins of the retina to reduce the oedema or even to ischaemic areas (with no blood flow) to prevent the disease from becoming more serious. 

In the most advanced cases, intraocular haemorrhages and/or retinal detachment require intraocular microsurgery techniques (vitrectomy), which we usually perform under local anaesthesia. 

Equally, the intraocular drug injections are very effective in selected cases.