Diabetic Retinopathy

Diabetic Retinopathy is a complication of diabetes, a disease that affects the blood vessels and in particular the microvascularisation. It is the leading cause of blindness, avoidable in the population between 20 and 64 years of age.

It is known that one of the most important factors is the duration of diabetes, so 10 years after the diagnosis of diabetes, about 25 to 50% of diabetics already have some degree of Diabetic Retinopathy and 15 years after the diagnosis, this percentage rises to 75 to 90%.

Type 1 diabetes develops in children, adolescents or young adults due to alterations in the pancreas, possibly due to autoimmune changes. Type 2 diabetes is associated with obesity, poor diet, physical inactivity, ageing and insulin resistance. This type represents 90% of all cases.

Diabetic Retinopathy is a condition characterised by the weakening of the retinal capillaries, due to alterations caused by abnormal glucose metabolism, because there are defects in the production and use of insulin by the organism, leading to chronic hyperglycaemia in the individual.

The metabolic changes lead to retinal capillary dilatation and tortuosity, which in turn leads to retinal dysfunction. The retina reacts by creating new vessels, with abnormal locations and characteristics, due to the metabolic changes that cause difficulties in blood flow. These are more fragile than the normal ones and when they rupture they cause haemorrhages or strokes, which cause the retinal complications are sometimes so severe that they lead to loss of vision.

The existence of neovessels in more than 1/3 of the retina, pre-retinal or vitreous haemorrhages are considered high risk signs.

Most frequent complications arising from Diabetic Retinopathy

• Vitreous haemorrhage, if small, the patient will only notice floaters. In the most serious cases of massive haemorrhage vision is completely lost. The loss of vision is not always permanent as the blood may be reabsorbed and if there is no significant damage to the retina, vision may return to the previous situation.
• Retinal detachment caused by scar tissue stimulated by neovessels, which can pull on the retina detaching it causes flashes and areas of non vision and later severe vision loss.
• Glaucoma because the neovessels grow in the area of the iris near the angle creating difficulty in the excretion of aqueous humour with a very significant increase in ocular pressure.

Diabetic Retinopathy, in its proliferative phase, the phase in which neovessels grow, can lead to blindness due to inherent complications.

Diabetic macular oedema can appear at any stage of Diabetic Retinopathy, being the most frequent cause of vision loss and must be treated by an ophthalmologist.

Non-proliferative Diabetic Retinopathy corresponds to an initial phase of the disease, where there may be no reduction in visual acuity and the lesions are few and scattered. This is a crucial stage, as far as diagnosis is concerned, and finding it early allows the situation to be controlled, preventing the patient from having significant loss of sight.

The appearance of symptoms in Diabetic Retinopathy signifies the existence of already evolved lesions. The most common symptoms are complaints related to decreased visual acuity, visual flashes and, in more serious situations, partial or total loss of vision.

The main risk factors for developing Diabetic Retinopathy are:

• The evolution time
• Poor disease control, with high mean hyperglycaemias
• High blood pressure
• High cholesterol
• Pregnancy
• Tobacco use

The incidence of Diabetic Retinopathy continues to increase globally and is expected to double by 2030, becoming a major public health problem.

In Diabetic Retinopathy, early diagnosis is fundamental to avoid partial or total loss of sight. It is recommended that they have an ophthalmology consultation annually.

In this consultation the doctor will look for signs of macular oedema, the condition that usually causes loss of visual acuity.

A pregnant diabetic should be observed every three months and be followed for up to a year after delivery, as very high hyperglycaemias during pregnancy can cause injury.

During the consultation, it may be necessary to place drops to dilate the eyes to allow a better visualisation of the ocular fundus. In addition, it may be advisable to carry out some diagnostic tests, such as OCT or even Fluorescein Angiography, which facilitate both the diagnosis and the therapeutic decision, as well as to evaluate the progression of the disease.

There is no cure for Diabetic Retinopathy, as it depends directly on the alterations caused by a systemic pathology.

There is no cure for Diabetic Retinopathy, as it depends directly on the alterations caused by a systemic pathology, and once installed there is no possible definitive cure, only some control over the consequences.

The best therapy is the metabolic control of diabetes, over time, because we know that the longer the diabetes lasts the more likely it is to develop retinopathy complications.

The existing treatments are only aimed at controlling complications. The most frequent treatments are:

• Anti-VEGF (anti-vascular endothelial growth factor) medication via intravitreous injections, these drugs delay the growth of neovessels by blocking the growth factor;
• Laser photocoagulation, to treat and destroy the neovessels and exclude less important areas of the retina, the periphery, sacrificing part of the visual field so that the existing vascularisation is sufficient to maintain the irrigation of the tissues of the central part, and therefore their function. Thus, the stimulus for the creation of neovessels is reduced, preventing the progression of the disease and blindness, through coagulation and subsequent tissue healing.
• Vitrectomy; the use of vitreous surgery in cases of prolonged haemovitreous (as blood too long in contact with the retina promotes the formation of neovessels), and also in cases of proliferative retinopathy to remove areas of vitreoretinal traction causing or potentially causing localised retinal detachments. The removal of the vitreous can bring about a calming of the proliferation, which is very favourable to the stabilisation of the disease.