Retinal dystrophies: causes, symptoms, diagnosis, treatment

Retinal dystrophy occurs as a result of dysfunction of the terminal capillaries and pathological processes in them.

These changes include pigmentary dystrophy of the retina - a hereditary disease of the retina. Pigmentary dystrophy of the retina is a chronic, slowly progressing disease. Initially, the patient complains of hemeralopia - weakening of vision at night. The first symptoms of pigmentary dystrophy of the retina appear before the age of eight. Over time, the field of vision concentrically narrows, central vision decreases. By the age of 40-60, complete blindness occurs. Pigmentary dystrophy is a slowly developing process in the outer layers of the retina, accompanied by the death of the neuroepithelium. In place of the dead first neuron, pigment epithelial cells grow into the retina for a second time, which grow into all layers. Pigment clusters are formed around the branches of the capillaries, which resemble "bone bodies" in shape. At first, these bodies appear on the periphery of the retina, then their number increases, they are visible in all areas of the retina up to the macular region. From the periphery, this pigmentation spreads to the center over decades. A sharp narrowing of the caliber of the retinal vessels may be noted, they become threadlike. The optic disc changes, acquiring a waxy hue, then optic nerve atrophy develops.

Over time, twilight vision is impaired so sharply that it interferes with orientation even in familiar surroundings, and "night blindness" sets in, with only daytime vision remaining. The rod apparatus of the retina - the twilight vision apparatus - completely perishes. Central vision is preserved throughout life, even with a fairly narrow field of vision (the person looks as if through a narrow tube).

Treatment of pigmentary dystrophy of the retina. The main goal is to stop the spread of the lesion of the terminal capillaries. For this purpose, multivitamins, nicotinic acid 0.1 g 3 times a day are used; preparations of the middle lobe of the pituitary gland (intermediates of 2 drops 2 days a week for 2 months). Medicinal drugs are used (ENCAD, heparin, etc.), surgical interventions are performed - choroidal revascularization. A diet low in cholesterol and purines is prescribed.

Juvenile retinal dystrophy occurs in childhood or adolescence. A gradual decrease in visual acuity is noted, and a central scotoma appears. The disease is genetically determined and often has a familial and hereditary nature. The following main types of juvenile macular dystrophy are distinguished.

Yolk dystrophy of West. Best's disease is a rare bilateral retinal dystrophy in the macular area, which has the appearance of a round yellowish lesion, similar to a fresh egg yolk, with a diameter of 0.3 to 3 diameters of the optic disc. The type of inheritance of Best's disease is autosomal dominant. The pathological process is located in the macular area.

There are three stages of the disease:

• stage of yolk cyst;
• exudative-hemorrhagic, in which a cyst ruptures, and hemorrhages and exudative changes gradually appear in the retina;
• cicatricial-atrophic.

The disease is asymptomatic and is detected accidentally during examination of a child aged 5-15 years. Occasionally, patients complain of blurred vision and difficulty reading small print. Visual acuity varies depending on the stage of the disease from 0.02 to 1.0. The changes are mostly asymmetrical and bilateral.

Decreased visual acuity is usually observed in the second stage, when cysts rupture. As a result of resorption and displacement of the cyst contents, a picture of pseudohypopyon is formed. Subretinal hemorrhages and the formation of a subretinal neovascular membrane are possible, retinal ruptures and detachments are very rare, with age - the development of choroidal sclerosis.

The diagnosis is established based on the results of ophthalmoscopy, fluorescent angiography, electroretinography and electrooculography. Examination of other members of the family may help in diagnosis. There is no pathogenetically based treatment. In case of formation of subretinal neovascular membrane, laser photocoagulation may be performed.

Vitelline vitelliform macular degeneration of adults. Unlike Best's disease, the changes develop in adulthood, are smaller in size and do not progress.

Stargardt disease and yellow-spotted fundus (yellow-spotted dystrophy). Stargardt disease is a dystrophy of the macular region of the retina that begins in the pigment epithelium and is manifested by a bilateral decrease in visual acuity between the ages of 8 and 16.

In the macular area, speckling appears, and a "metallic sheen" is formed in the lesion. The disease was described by K. Stargardt at the beginning of the 20th century as a hereditary disease of the macular area with a polymorphic ophthalmoscopic picture, which includes "bronzed bronze", "bull's eye", choroidal atrophy, etc. The "bull's eye" phenomenon is ophthalmoscopically visible as a dark center surrounded by a wide ring of hypopigmentation, which is usually followed by a ring of hyperpigmentation. There is a rare form of yellow-spot dystrophy without changes in the macular area. In this case, multiple yellowish spots of various shapes are visible between the macula and the equator: round, oval, elongated, which can merge or be located separately from each other. Over time, the color, shape and size of these spots can change. All patients with Stargardt disease have relative or absolute central scotomas of varying sizes depending on the spread of the process. In yellow-spotted dystrophy, the visual field may be normal in the absence of changes in the macular region.

Most patients experience changes in color vision such as deuteranopia, red-green dyschromasia, etc. In yellow-spotted dystrophy, color vision may be normal.

There is no pathogenetically proven treatment. Wearing sunglasses is recommended to prevent the damaging effects of light.

Vitelline-spotted dystrophy of Franceschetti is characterized by the presence of yellowish foci in the posterior pole of the fundus. Their shape is varied, the size - from point to 1.5 diameters of the optic nerve disc. Sometimes the disease is combined with Stargardt dystrophy.

Involutional retinal dystrophies have two forms: non-exudative ("dry") and exudative ("wet"). The disease occurs in people over 40 years of age. It is associated with involutional changes in Bruch's membrane, choroid and outer layers of the retina. Foci of dyspigmentation and hyperpigmentation gradually form due to the death of pigment epithelial cells and photoreceptors. Disruption of the processes of retina release from the constantly renewing outer segments of photoreceptors leads to the formation of drusen - foci of accumulation of retinal membrane metabolic products. The exudative form of the disease is associated with the occurrence of a subretinal neovascular membrane in the macular region. Newly formed vessels growing through cracks in Bruch's membrane from the choroid into the retina cause repeated hemorrhages and are sources of lipoprotein deposits in the fundus. Scarring of the membrane gradually occurs. At this stage of the disease, visual acuity is significantly reduced.

In the treatment of large patients with this pathology, antioxidant drugs, angioprotectors, and anticoagulants are used. In the exudative form, laser coagulation of the subretinal neovascular membrane is performed.

Hereditary generalized retinal dystrophies

Photoreceptor retinal dystrophies differ in the type of inheritance, the nature of the visual impairment and the picture of the fundus depending on the primary localization of the pathological process in various structures: Bruch's membrane, retinal pigment epithelium, in the pigment epithelium-photoreceptor complex, photoreceptors and inner layers of the retina. Retinal dystrophies of both central and peripheral localization can be a consequence of mutation of the rhodopsin and periphyrin gene. In this case, the symptom that unites these diseases is stationary night blindness.

To date, 11 chromosomal regions are known that contain genes whose mutations cause the development of retinitis pigmentosa, and each genetic type of retinitis pigmentosa is characterized by allelic and non-allelic varieties.

Hereditary peripheral retinal dystrophies In these forms of retinal dystrophy, the optically inactive part of the retina near the serrated line is affected. Not only the retina and choroid are often involved in the pathological process, but also the vitreous body, which is why they are called "peripheral vitreochorioretinal dystrophies".

Hereditary central retinal dystrophies

Central (macular) retinal dystrophies are diseases localized in the central part of the retina, which are characterized by a progressive course, a typical ophthalmoscopic picture and have similar functional symptoms: decreased central vision, impaired color vision, decreased cone components of ERG.

The most common hereditary retinal dystrophies with changes in the pigment epithelium and photoreceptors include Stargardt disease, yellow spotted fundus, and Best's vitelliform dystrophy. Another form of macular retinal dystrophy is characterized by changes in Bruch's membrane and retinal pigment epithelium: dominant drusen of Bruch's membrane, Sorsby's dystrophy, age-related macular degeneration, and other diseases.

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