Diabetic cataract is a clouding of the lens of the eyeball, which leads to visual dysfunction up to amaurosis. The main symptoms of the disease: the appearance of floating “flies” in front of the eyes, diplopia, visual impairment. To make a diagnosis, such studies as visometry, biomicroscopy, retinoscopy, ophthalmoscopy and ultrasound in A-scan mode are used. Conservative treatment is reduced to the appointment of drugs based on riboflavin, cytochrome-C, nicotinic and ascorbic acids. Surgical intervention consists in cataract extraction and IOL implantation.
ICD 10
H28.0 Diabetic cataract (E10-E14+ with a common fourth sign.3)
General information
Diabetic cataract is a complex of pathological changes in the lens that develop against the background of impaired carbohydrate metabolism in patients with diabetes mellitus (DM). According to statistics, pathology occurs in 16.8% of patients suffering from impaired glucose tolerance. In people over 40 years of age, dysfunction can be visualized in 80% of cases. In the general structure of cataract prevalence, the diabetic form accounts for 6%, and every year there is a tendency to increase this indicator. The second type of DM is accompanied by a lesion of the lens 37.8% more often than the first. Women are diagnosed with the disease twice as often as men.
Causes
The leading etiological factor of diabetic cataracts is an increase in blood glucose levels in type 1 and type 2 diabetes. With insulin-dependent diabetes, the clinical picture of the disease is revealed at a younger age, this is due to chronic hyperglycemia against the background of absolute or relative insulin deficiency. With insulin-dependent diabetes, the interaction of cells with the hormone is disrupted, such changes are more typical for patients of the middle age group.
The risk of developing cataracts directly depends on the diabetic “seniority”. The longer the patient suffers from DM, the higher the probability of formation of lens opacities. A sharp transition from oral tablet forms of hypoglycemic drugs to insulin for subcutaneous administration can become a trigger that triggers a chain of pathological changes. It should be noted that with timely adequate compensation for the dysfunction of carbohydrate metabolism, such disorders can be avoided.
Pathogenesis
It is proved that with an increase in the concentration of sugar in the blood, it is determined in the structure of watery moisture. With decompensation of diabetes, the physiological glycolytic pathway of dextrose assimilation is disrupted. This leads to its transformation into sorbitol. This hexatomic alcohol is unable to penetrate cell membranes, which causes osmotic stress. If glucose values exceed the reference values for a long time, sorbitol accumulates in the lens, which leads to a decrease in its transparency.
With excessive accumulation of acetone and dextrose in the lens masses, the sensitivity of proteins to light increases. Photochemical reactions underlie local opacities. An increase in osmotic pressure leads to excessive hydration and contributes to the development of edema. Metabolic acidosis stimulates the activation of proteolytic enzymes that initiate protein denaturation. An important role in the pathogenesis is assigned to edema and degeneration of the ciliary processes. At the same time, the trophism of the lens is significantly disturbed.
Classification
According to the degree of turbidity, diabetic cataracts are usually divided into initial, immature, mature and overripe. The overripe type is also referred to as “milk”. There are primary and secondary (complicated) forms. Acquired changes in the lens capsule and stroma are attributed to metabolic disorders. There are two main types of disease:
- True. The development of pathology is caused by a direct violation of carbohydrate metabolism. The true type can be observed at a young age. Difficulties in differential diagnosis arise in people after 60 years with a history of diabetes.
- Senile. Structural changes of the lens that occur in elderly patients who have a history of diabetes mellitus. The disease is characterized by a bilateral course and a tendency to rapid progression.
Symptoms of diabetic cataract
Clinical symptoms depend on the stage of the disease. With an initial diabetic lesion, visual functions are not impaired. Patients note an improvement in vision when working at close range. This is due to myopization and is a pathognomonic sign of pathology. With an increase in the volume of opacities, patients complain about the appearance of “flies” or “dots” in front of their eyes, diplopia. There is an increased sensitivity to light. There is a feeling that the surrounding objects are viewed through a yellow filter. When looking at the light source, rainbow circles appear.
In the mature form, visual acuity sharply decreases up to light perception. Patients even lose their objective vision, which makes it much more difficult to orient themselves in space. Quite often, relatives note a change in the color of the patient’s pupil. This is due to the fact that through the lumen of the pupillary opening, the lens is visible, the color of which acquires a milky white hue. The use of eyeglass correction does not fully compensate for visual dysfunction. Both eyes are affected, but the severity of symptoms on the right and left differs.
Complications
The negative consequences of diabetic cataracts are caused not so much by pathological changes on the part of the lens as by metabolic disorders in DM. Patients are at risk of diabetic retinopathy with macular edema. In mature cataracts, laser phacoemulsification is associated with a high probability of rupture of the posterior capsule. Often there is the addition of postoperative inflammatory complications in the form of keratoconjunctivitis and endophthalmitis.
Diagnostics
Examination of a patient suffering from diabetic cataract should be comprehensive. In addition to the anterior segment of the eyes, a detailed examination of the retina is carried out, since with DM there is a high risk of concomitant damage to the inner shell of the eye. It is mandatory to perform laboratory tests such as a blood test for glycated hemoglobin, a glucose tolerance test and blood sugar determination. In most cases, an ophthalmologist’s consultation includes the following instrumental diagnostic procedures:
- The study of visual function. When conducting visometry, a decrease in visual acuity in the distance is detected. When performing work at a distance of 30-40 cm, there is no discomfort. With age, presbyopic changes progress, at the same time, the disease leads to a short-term improvement in near vision.
- Eye examination. During biomicroscopy, spot and floccular opacities located in the surface sections of the anterior and posterior capsules are visualized. Less often, small defects can be detected in the transmitted light, which are localized deep in the stroma.
- Retinoscopy. The progression of the disease causes the formation of a myopic type of clinical refraction. Retinoscopy can be replaced by skiascopy using skiascopic rulers. Additionally, computer refractometry is performed.
- Examination of the fundus. Ophthalmoscopy is a routine procedure in practical ophthalmology. The study is performed in order to exclude diabetic retinopathy and optic nerve damage. With total cataract, ophthalmoscopy is sharply difficult to perform due to a decrease in the transparency of optical media.
- Ultrasound examination. Ultrasound of the eye (A-scan) allows you to measure the anterior-posterior size of the eyeball (PCR) to determine what causes myopization. In diabetic cataract, the PCR corresponds to the norm, with pronounced opacities, the lens is enlarged in size.
Diabetic cataract treatment
When initial changes are detected, the goal of treatment is to achieve tolerant blood glucose values and compensate for diabetes. Normalization of carbohydrate metabolism is possible with a diet, the use of oral antihyperglycemic drugs and insulin injections. Timely appointment of conservative therapy makes it possible to positively influence the dynamics of cataract development, to ensure its partial or complete resorption. At the mature stage, normalization of blood sugar levels is no less important, but it is impossible to achieve even partial restoration of the transparency of the lens with gross opacities.
To prevent the progression of pathology, instillations of riboflavin, ascorbic and nicotinic acids are prescribed. In the immature form, preparations based on cytochrome-C, a combination of inorganic salts and vitamins are used. The effectiveness of the introduction into ophthalmological practice of medicines, the active component of which is a synthetic substance that prevents the oxidation of sulfhydryl radicals of soluble proteins that are part of hexagonal cells, has been proven.
Surgical treatment involves the removal of the lens microsurgically (ultrasound phacoemulsification) followed by implantation of an intraocular lens (IOL) into a capsule. Surgical intervention is performed with severe visual dysfunction. Cataract at the initial stage should be removed if its presence makes it difficult to perform vitreoretinal surgery or laser coagulation of the inner lining in diabetic retinopathy.
Prognosis and prevention
The outcome is determined by the stage of diabetic cataract. In case of timely treatment of the disease at the stage of initial opacities, their complete resorption is possible. With mature cataracts, it is possible to restore lost functions only by surgical intervention. Specific prevention has not been developed. Non-specific preventive measures are reduced to blood glucose control, compliance with a special diet, preventive examination by an ophthalmologist 1 time a year with mandatory biomicroscopy and ophthalmoscopy.
