Complicated cataract

Complicated cataract occurs as a result of exposure to unfavorable external and internal factors. Complicated cataract is characterized by the development of opacities under the posterior capsule of the lens and in the peripheral parts of the posterior cortex. This distinguishes complicated cataracts from cortical and nuclear age-related cataracts. When examining the lens in transmitted light, opacities move in the opposite direction of the eyeball movement. Complicated cataracts are cup-shaped and gray during biomicroscopy, with many vacuoles, and calcium and cholesterol crystals are visible. It resembles pumice. Complicated cataracts begin with color blindness at the posterior edge of the lens, when all colors of the spectrum are visible. Complicated cataracts are most often unilateral. This is explained by the fact that complicated cataracts develop in the diseased eye, where intoxication products are located, which, having entered with the liquid, are retained in a narrow space behind the lens. Therefore, in this case, opacities begin in the posterior parts of the lens.

Complicated cataracts are divided into two subgroups:

1. cataracts caused by general diseases of the body:
   • endocrine diseases, metabolic disorders, starvation, vitamin deficiencies and poisoning from various berries;
   • diabetes. Diabetic cataract develops in 40% of diabetics, often in young people. It is a bilateral, rapidly developing cataract. The most superficial layers swell and become cloudy at the back and front, there are a large number of vacuoles, punctate subcapsular deposits, and water gaps between the lens capsule and the cortex. Following the vacuoles, flocculent opacities appear, reminiscent of a "snow storm". Refraction changes early, unstable myopia is characteristic (it can change during the day). Diabetic cataract progresses very quickly;
   • tetanic cataract is observed in tetanus, convulsions, and water metabolism disorders (cholera, etc.). The course is the same as the previous cataract;
   • myotopic cataract - many opacities, which are localized mainly in the cortex. The zone of separation is always transparent. Shiny inclusions (cholesterol crystals) can form between the opacities in the lens;
   • dermatogenic cataract in scleroderma, eczema, neurodermatitis. At a young age, the affected lens matures very quickly. In the light of a slit lamp, against the background of diffuse opacification, more intense opacities are visible near the poles;
   • endocrine cataract develops with myxedema, cretinism, Down's syndrome. With a lack of vitamin PP in the body, pellagra develops, which also causes clouding of the lens (cataract);
2. cataracts caused by eye diseases.

Metabolic processes in the lens can be affected by changes in other tissues of the eye: pigment dystrophies of the retina, high myopia, uveitis, retinal detachment, advanced glaucoma, recurrent iridocyclitis and chorioretinitis of various etiologies, dysfunction of the iris and ciliary body (Fuchs syndrome). All these diseases cause changes in the composition of the intraocular fluid, which in turn affects the disruption of metabolic processes in the lens and the development of opacities. A feature of all complicated cataracts is that they are usually posterior capsular, since in the area of the retrolental space there is a longer contact of toxic substances with the lens, and there is no epithelium behind, which plays a protective role. The initial stage of posterior capsular cataract is polychrome iridescence under the posterior capsule. Then, opacity appears under the posterior capsule, which has a rough appearance. As the opacity spreads to the periphery, it resembles a bowl; with further slow spread, a complete cataract develops.

An example of a combination of cataracts with a general pathology of the body can be cachetic cataracts, which occur due to general exhaustion of the body during starvation, after infectious diseases (typhoid, malaria, aspes, etc.), as a result of chronic anemia.

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Secondary, membranous cataract and fibrosis of the posterior lens capsule

Secondary cataract occurs in an aphakic eye after extracapsular cataract extraction. It is an overgrowth of the subcapsular lens epithelium remaining in the equatorial zone of the lens capsule.

In the absence of the lens nucleus, the cells are not constrained, so they grow freely, do not stretch. They swell into small transparent balls of different sizes and line the posterior capsule. Under biomicroscopy, these cells look like soap bubbles or caviar grains. They are called Adamuk-Elschnig balls after the scientists who first described secondary cataract. In the initial stage of secondary cataract development, subjective symptoms are absent. Visual acuity decreases when epithelial growths reach the central zone.

Secondary cataract is subject to surgical treatment: discision (incision) of the posterior capsule of the lens is performed, on which the Adamuk-Elschnig balls are placed. Discision is performed by a linear incision within the pupillary zone.

The operation can also be performed using a laser beam. In this case, the secondary cataract is also destroyed within the pupil. A round opening with a diameter of 2-2.5 mm is formed. If this is not enough to ensure high visual acuity, the opening can be enlarged. In pseudophakic eyes, secondary cataract develops less frequently than in aphakic eyes.

Membranous cataracts are formed as a result of spontaneous resorption of the lens after injury, leaving only the fused anterior and posterior capsules of the lens in the form of a thick, cloudy film.

Membranous cataracts are dissected in the central zone with a laser beam or a special knife. If indicated, an artificial lens of a special design can be fixed in the resulting hole.

Posterior capsule fibrosis is a term used to describe the thickening and opacification of the posterior capsule following extracapsular cataract extraction.

In rare cases, posterior capsule opacification may be detected on the operating table after removal of the lens nucleus. Most often, opacification develops 1-2 months after surgery due to the fact that the posterior capsule was not sufficiently cleaned and invisible thin sections of transparent lens masses remained, which subsequently become cloudy. Such fibrosis of the posterior capsule is considered a complication of cataract extraction. After surgery, the posterior capsule always contracts and thickens as a manifestation of physiological fibrosis, but it remains transparent.

The dissection of the clouded capsule is performed in cases where visual acuity is sharply reduced. Sometimes, quite high vision is preserved even with significant opacities on the posterior capsule of the lens. Everything depends on the localization of these opacities. If at least a small gap remains in the very center, this may be enough for the passage of light rays. In this regard, the surgeon decides on the dissection of the capsule only after assessing the function of the eye.