Diabetic Retinopathy: Causes

Pathogenesis (disease development)

Diabetic retinopathy will be divided into:

• Nonproliferative diabetic retinopathy (NPDR) – it forms on the retina (retina):
  • Microaneurysms (bulge in the vascular wall of the capillaries) and pinpoint hemorrhages.
  • Exudation of lipids, resulting in so-called hard exudates.

  The disease remains confined to the retina; usually occurs earlier and may progress to the proliferative form

• Preproliferative diabetic retinopathy – the following typical changes occur at this stage:
  • Intraretinal (within the retina) microvascular (affecting small blood vessels) abnormalities (IRMA).
  • Multiple hemorrhages (multiple hemorrhages)
  • Venous abnormalities (caliber jumps, loops).
  • Formation of soft esudates (“cotton-wool foci”) due to capillary occlusions.
• Proliferative diabetic retinopathy (PDR) – advanced stage with the following changes:
  • The retina becomes regionally hypnoxic (lack of oxygen supply).
  • Secretion of angiogenic growth factors (mainly Vascular Endothelial Growth Factor, VEGF), resulting in the development of neovascularization of the retina and iris (iris): rubeosis iridis with the risk of glaucoma (green star). The newly formed vessels bleed easily. This leads to recurrent vitreous hemorrhage, resulting in fibrosis of the vitreous. This, in turn, can lead to traction-related (train-related) amotio retinae (retinal detachment; synonym: Ablatio retinae) as a result.

In addition to the above-mentioned forms occurs in approximately 15% of those affected still the so-called macular edema (water accumulation at the point of sharpest vision), which in turn also leads to severe visual impairment (= diabetic macular edema, DMÖ).

The loss of vision (reduction of visual acuity or deterioration of another visual function) is essentially due to the following vascular changes:

• Pathologically increased capillary permeability.
• Progressive capillary occlusion with ischemia (“reduced blood flow”) and vascular proliferation (“disordered retinal (“belonging to the retina”) vascularization); these lead to late sequelae such as vitreous hemorrhage, tractional retinal detachment (ablatio retinae, amotio retinae) and neovascular glaucoma (glaucoma)

Etiology (causes)

Biographical causes

• Genetic burden from parents, grandparents.
• Gender – male preferred in type 1 diabetes.
• Hormonal factors
  • Hormonal transition during puberty.
  • Degree of hyperglycemia (high blood sugar).
  • Form of diabetes (type 1 or type 2)
  • Disease duration of diabetes mellitus

Behavioral causes

• Nutrition
  • Magnesium deficiency – see micronutrient therapy.
• Consumption of stimulants
  • Tobacco (smoking) (in type 1 diabetes, smoking is clearly a risk factor for retinopathy)
• Therapy of diabetes mellitus – with optimally adjusted glucose serum levels, the disease can be delayed.

Disease-related causes

• Diabetic nephropathy (kidney disease) – risk factor for the development or progression of diabetic retinopathy and/or maculopathy.
• Gestational hypertension (high blood pressure in pregnancy)/pre-eclampsia (4.1-fold).
• Hyperglycemia (“hyperglycemia”) (about 10% of the risk).
• [Hyperlipidemia (elevated blood lipids)] – no longer considered a risk factor according to an international case-control study of 2,535 type 2 diabetes patients.
• Hypertension (high blood pressure)

Laboratory diagnoses – laboratory parameters that are considered independent risk factors.

• HbA1c (elevated)

Other causes

• Hormonal changes during pregnancy