Retinal diseases

The diseases of the retina are very diverse. The diseases of the retina are caused by the influence of various factors leading to pathologoanatomical and pathological physiological changes, which in turn determines violations of visual functions and the presence of characteristic symptoms. Among the diseases of the retina are hereditary and congenital dystrophies, diseases caused by infections, parasites and allergic agents, vascular disorders and tumors. Despite the variety of retinal diseases, pathoanatomical and pathophysiological manifestations may be similar for different nosological forms.

The pathological processes observed in the retina include degeneration, which can be genetically determined or secondary, inflammation and edema, ischemia and necrosis, hemorrhages, deposition of hard or soft exudates and lipids, retinoschisis and retinal detachment, fibrosis, proliferation and formation of neovascular membranes, hyperplasia and hypoplasia of pigment epithelium, tumors, angioid bands. All these processes can be identified with ophthalmoscopy of the fundus.

The retina does not have a sensitive innervation, so the pathological conditions proceed painlessly. Subjective symptoms in diseases of the retina do not have any specificity and are associated only with a disruption of function, which is typical for diseases not only of the reticular membrane, but also of the optic nerve. Depending on the localization of the pathological process, the function of central vision, peripheral vision is disrupted, limited loss of visual field (scotoma) is detected, dark adaptation is reduced. There is no pain in retinal lesions.

Ophthalmoscopic picture in diseases of the retina consists essentially of four elements:

1. changes in blood vessels, their walls, caliber, their course in the retina;
2. hemorrhages in different layers of the retina;
3. opacities of normally transparent retina in the form of diffuse, large areas or limited white spots - foci;
4. pigmentation of the retina in the form of small points from and large dark foci.

Inflammatory diseases of the retina (retinitis, retinovasculitis). Inflammatory processes in the retina (retinitis) never proceed in isolation because of close contact between the retina and the choroid. Started as retinitis, the process quickly spreads to the choroid and vice versa, so in clinical practice, in most cases, there are chorioretinitis, retinovasculitis.

Retinal diseases are caused by various endogenous causes, such as:

1. infection (tuberculosis, syphilis, viral diseases, purulent infections, toxoplasmosis, parasites);
2. infectious-allergic processes in the retina (rheumatism, collagenosis);
3. allergic reactions;
4. blood diseases.

Retinovasculitis is divided into primary and secondary. Primary develop in the retina as a result of a general allergic reaction without previous common ocular manifestations.

Secondary - a consequence of some inflammatory process (uveitis). The retina is involved again.

Various etiological factors causing inflammatory changes in the posterior pole of the fundus cause multifocal involvement of the retina and choroid in the pathological process.

Often the main role in diagnosis is played by the ophthalmoscopic picture of the fundus, as there are no specific diagnostic laboratory tests to identify the cause of the disease.

Isolate acute and chronic inflammatory diseases of the retina. To establish the diagnosis is very important anamnestic data. Histologically, the separation of the inflammatory process into acute and chronic inflammation is based on the type of inflammatory cells found in tissues or exudate. Acute inflammation is characterized by the presence of polymorphonuclear lymphocytes. Lymphocytes and plasma cells are detected in chronic nematode inflammation, and their presence indicates the involvement of the immune system in the pathological process. Activation of macrophages and giant inflammatory cells is a sign of chronic granulomatous inflammation, therefore immunological studies are often the main ones not only in establishing the diagnosis, but also in choosing the tactics of treatment.

[1], [2], [3], [4], [5]

Symptoms of retinal diseases

1. Reducing central vision is the main symptom. Patients with a disease of the macula note a violation of central vision, which is confirmed by perimetry (positive scotoma). In contrast, in patients with optic neuropathy, patients do not complain of a change in the visual field (negative scotoma).
2. Metamorphosis (distortion of the perceived image) is a frequent symptom of macular pathology. It is not characteristic for optical neuropathy.
3. The micropsy (reduction of the size of the perceived image in comparison with the actual one) is a rare symptom caused by the "rarefaction" of the foveal cones.
4. Macropsy (increasing the size of the perceived object in comparison with the actual one) is a rare symptom caused by the "congestion" of foveal cones.

Disturbance of color vision is a frequent symptom of the early stage of optic nerve diseases. But it is not typical for light forms of macular pathology.

Vision is reduced, metamorphopsia, macropsia, micropsia, and photopsy are noted.

In peripheral vision - scotoma of different localization. If the focus is located on the periphery, then gimeralopia is characteristic. On the fundus there is always a focus (accumulation of cellular elements). If the focus is localized in the outer layers, in whom a slight deposition of the pigment may occur. If the focus is located in the inner layers, the disc may be involved in the process of the optic nerve (edema, hyperemia).

With the rhinovasculitis, the transparency of the retina is broken, the swelling of the interstitial substance occurs in the zone of the focus. In the preretinal layers, hemorrhages may appear - large, large. This is the so-called "inverted bowl syndrome". If the internal layers of hemorrhage have the form of a stroke, then in the outer layers they are deep - in the form of dots. The appearance of the pigment in the focus zone speaks of chorioretinitis (i.e., the vascular membrane is affected).

If the vessels of the retina are involved, then retinovasculitis occurs.

The inflammatory process of arteries is called arteritis. There are endoarteritis, periarteritis, panvasculitis.

Endoarteriitis - densification of the arterial wall. The lumen of blood vessels is narrowed, the blood flow is slowed down, sometimes full obliteration occurs, there is ischemic edema.

Periarteritis - inflamed clutch (loose accumulation of exudate) around the vessel. It covers the vessel, so it can not be traced in its entire length.

Panarteritis - all walls of blood vessels are affected.

Thus, changes in the reticular membrane arise as a consequence of the destruction of its vessels, especially capillaries. The most common pathological changes in the vessels of the mesh shell are atheromatosis, atherosclerosis, inflammatory changes in the walls of the vessels and dystrophic disorders.

With atheromatosis and atherosclerosis, the walls of the arteries thicken, the lumen narrows, the strip of translucent blood flow becomes thinner, and the white bands (artery walls) expand, the color of blood through the thickened wall appears yellowish (the arteries are like copper wire). The heavily thickened artery walls, especially the third-order arteries, become opaque, the blood current does not shine, they resemble a shiny silver wire. With arteriosclerosis, the walls of the artery thicken, and in the intersection where the artery lays on a vein, the artery compresses the vein and disrupts the flow of blood in it. Atherosclerotic changes in the walls of the vessels are uneven, as a result of which small aneurysms form in the course of the vessels. The capillaries also change, and first they begin to pass into the layers of the retina the uniform elements of blood and plasma, and later completely obliterated,

With pereflebit, the veins are surrounded by gentle opacities in the form of couplings that clothe the vessel in a greater or lesser extent. The outer layers of the vein grow due to inflammatory infiltration with subsequent organization in connective tissue moorings. The caliber of the vein becomes uneven, sometimes the vessel disappears, hiding in the inflammatory infiltration or in the connective tissue of the Schwartz. When the wall of the yen is destroyed, hemorrhages appear in the vitreous, sometimes so significant that ophthalmoscopy is impossible.

Hemorrhages in the mesh shell

Vascular lesions are accompanied by hemorrhages in the mesh shell. Depending on the shape and magnitude of hemorrhages, localization of hemorrhages in the layers of the retina can be determined. When blood is poured out into the outer or middle layers of the retina, the hemorrhage has the form of small circles, since it occupies the space between the glial supporting fibers in the form of columns perpendicular to the retinal plane, which in its plane look like round spots. When the hemorrhages pass from the capillaries to the inner layer - the layer of nerve fibers, the blood is distributed along these fibers and has the form of strokes. Around the central fossa, as well as around the disc of the optic nerve, hemorrhages in the inner layers are located radial bands. Blood from large vessels, the innermost layers of the retina, pours between the retina and the vitreous body in the form of a large (4-5 diameters of the optic disc) round "pool", the upper part of which is lighter due to the accumulation of blood plasma, and the lower part is darker because of the descending Clot with shaped elements, which often forms a horizontal level.

Varieties of retinovasculitis:

1. hemorrhagic - hemorrhages and external circulation in the mesh shell;
2. exudative - the phenomenon of exudation predominates;
3. proliferative - the outcome of angiitis, which are accompanied by a violation of blood circulation (ischemia gives impetus to proliferation - the formation of connective tissue). The forecast is heavy.

Diagnosis of diseases of the retina

1. Visual acuity is the most important test of the state of the macula function, extremely fast in performance. In patients with macular pathology, visual acuity is often lower when using a diaphragmatic orifice.
2. Biomicroscopy of the fundus with a contact or strong convex lens allows a good examination of the macula. Monochromatic light is used for both visual ophthalmoscopy and for detecting the most delicate disorders. The use of green (red) light can detect superficial damage to the retina, folding of the internal border membrane, cystic edema, as well as subtle contours of serous detachment of the yeeroepithelium. The defeat of the pigment epithelium of the retina and the choroid is better revealed in the light of the final part of the red spectrum.
3. The Amsler grid is a test evaluating the state of the central 10 view in the screening and monitoring of diseases of the macula. The test consists of 7 cards, each contains a square with a side of 10 cm:
   • Map 1 is divided into 400 small squares with a side of 5 mm, each of which is perceived at an angle of 1 when the grid is presented from a distance of 1/3 meters;
   • Map 2 is similar to map 1, but has diagonal lines that help to fix the sight to the patient with low vision;
   • Map 3 is identical to map 1, but contains squares of red color. The test helps to detect color vision disorders in patients with optic nerve diseases;
   • A map 4 with chaotically located points is rarely used;
   • map 5 with horizontal lines is designed to identify metamorphopsia in a particular meridian, which allows an objective assessment of such a complaint as difficulty in reading;
   • map 6 is similar to map 5, it contains a white background, and the central lines are denser to each other;
   • The map 7 contains a smaller central grid, each square of which is perceived by an iodine angle of 0.5. The test is more sensitive. Testing is as follows:
   • If necessary, the patient wears glasses for reading and closes one eye;
   • the patient is asked to look directly at the central point with his open eye and report any distortions, fuzzy lines or solid spots in any part of the grid;
   • patients with maculopathy often note that the lines are wavy, whereas in optic neuropathy the lines are not distorted, but often absent or become fuzzy.
4. Photostress. The test can be used to diagnose the pathology of the macula in an unclear ophthalmoscopic picture and in the differential diagnosis of maculopathies and optical neuropathy. The test is performed as follows:
   • correction of visual acuity in the distance is necessary;
   • the patient observes within 10 seconds from a distance of 3 cm the light of a pen-flashlight or an indirect ophthalmoscope;
   • the recovery time after photostress is equal to the time required for the patient to read any three letters from the line read before the test. In norm - 15-30 seconds;
   • then the test is performed on another, supposedly healthy eye and the results are compared.

The recovery time after photostress lengthens compared to the healthy eye with macular pathology (sometimes 50 sec or more), but is not characteristic for optical neuropathy.

5. Pupillary reaction to light in diseases of the macula is usually not disturbed, but with slight damage to the optic nerve, the disturbance of the friendly reaction of the pupils to light is an early symptom.

[6], [7], [8]