The term «ophthalmologic complications of diabetes mellitus» is of frequent occurrence in popular scientific literature, although the processes taking place in eyes should be more properly called not complications, but ophthalmologic symptoms of this disease.
The reason of deterioration of eyesight in case of diabetes mellitus is the retina pathology – diabetic retinopathy. Diabetic retinopathy is the affection of the retina and its vessels caused by long-term increase of blood sugar. Diabetic retinopathy is dangerous because its signs become evident only in progression of the disease.
Diabetic retinopathy has three consecutive stages: nonproliferative, preproliferative and proliferative.
The main reason of vision deterioration in patients with nonproliferative diabetic retinopathy is edema of the retina central region resulting from changes in the retinal vessels. Long-term edema causes irreversible necrosis of the retina neural elements, which results in decrement in visual acuity.
Research showed that traditional medications (urinatives, angioprotectors etc.) are not effective for prevention and dissolution of liquid accumulation in retina. Practically the only way to fight with this vascular malformation is laser retina coagulation. Laser retina treatment is the "gold standard" in treatment of diabetic retinopathy. This method allows to prevent about 50% of complications, which can result in irrecoverable visual function loss.
However, laser retina coagulation improves vision only in the patients, who have this laser treatment at early stages of edema, when visual elements of the retina are still unaffected. Laser treatment of diabetic retinopathy at late stages is aimed only at the eyesight stabilization. The patients, who underwent laser treatment for macular edema retain stable vision for longer period of time unlike those to whom laser retina coagulation was not provided.
The proliferative diabetic retinopathy is the most severe stage. It is diagnosed when the newly formed vessels (neovessels) are present. These vessels are anomalous both in their location and structure – their walls are thin and brittle. Neovessels cause extensive hemorrhages even against normal blood pressure, moderate physical activity and good compensation of diabetes mellitus».
The next step in the proliferative stage of diabetic retinopathy is formation of fibrous tissue. It has a pronounced ability to contract. This tissue binds itself to the retina and in the course of contraction stretches it, which sooner or later results in retinal detachment. This is the mechanism of development of retinal detachment, typical for diabetes mellitus, - the most complicated as to its surgical treatment and visual prognosis.
Diabetic retinopathy of proliferative stage can develop over a period from 3-4 months to several years. As a rule, the process never stops without intervention. Visual acuity at this stage does not reflect the processes taking place in the retina. As a rule, such pathologic changes occur simultaneously in both eyes.
The newly formed vessels being anomalous by nature develop "by their own laws". Traditional medications have no effect on them. Present-day pharmacology has only few medications accelerating dissolution of intraocular hemorrhages, but neither of them is effective against newly formed vessels.
The only way to fight against neovessels is extensive laser retina coagulation (panretinal laser coagulation), indicated in cases of formation and growth of newly formed vessels.
This method of diabetic retinopathy treatment is used in the world during more than 35 years. It was recommended by the World Health Organization as the only method to reduce the risk of visual loss in case of ophthalmologic complications of diabetes mellitus. Properly performed panretinal laser coagulation is effective in 59-86% of cases and allows for long-term stabilization of the vision.
Laser treatment of diabetic retinopathy will be successful only if the doctor's tactics is correct: modern diagnostics, conformity of the laser treatment technology, obligatory follow-up of the process and additional therapy if needed.
We would like to draw your attention to the fact that regular follow-up by the laser surgeon makes part and parcel of the success, even if the first diabetic retinopathy treatment was effective. Frequency of preventive examinations depends on the type, duration, compensation condition and development of complications of diabetes mellitus.
- diabetes mellitus without changes in the fundus – once a year;
- non-complicated diabetic retinopathy – every six months;
- risk of proliferative stage – every three months.