The pathogenesis of retinopathy is still unclear. From the clinical process and most research results, the disease has always been considered to be mainly caused by the damage of retinal blood vessels, especially microvascular system, and then caused a series of pathological changes of the retina. The disorder of glucose metabolism is the root cause. Aldose reductase was converted into sorbitol and fructose under high glucose concentration, and galactose was converted into vermouth alcohol.
Because sorbitol and citronellol are rarely metabolized in cells and difficult to penetrate cell membrane due to their polarity, the increase of intracellular concentration leads to the increase of osmotic pressure, and the water infiltration into cells causes electrolyte imbalance and metabolic disorder. Lens epithelial cells contain high concentration of aldose reductase, so they are prone to cataract with experimental animals.
Clinical manifestations: most patients with retinopathy have symptoms of polydipsia, polyuria, overeating, fatigue and weight loss. In the early stage of retinopathy, there are no ocular symptoms. The development of the lesions may cause different degrees of visual impairment. If the macular area is involved, there may be central shadow of visual field, central visual loss and (or) visual deformation and other symptoms. Retinal small vessels rupture, a small amount of bleeding into the vitreous, patients can consciously before the dark shadow floating. When a large number of neovascularization bleeding into the vitreous cavity, vision can be seriously lost, only light sense. Retinal vascular occlusion outside the macular area, or proliferative retinopathy, the visual field appears a large area of defects.