Dystrophy of the eye

Ocular dystrophy includes many degenerative pathologies affecting the cornea - the transparent part of the outer shell, the retina - the inner shell with photoreceptor cells, as well as the vascular system of the eyes.

The most important part of the eye is considered to be the retina, since it is an element of the visual analyzer that perceives light impulses. Although it is really possible to imagine normal vision without a healthy cornea - the light-refracting lens of the eye, providing at least two-thirds of its optical power. As for the blood vessels of the eyes, their far from insignificant role is indicated by the fact that vascular ischemia can provoke a significant deterioration in vision.

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Causes of eye dystrophy

Now, in the same order, let us consider the causes of eye dystrophy.

As is known, there are no blood vessels in the cornea itself, and the metabolism in its cells is provided by the vascular system of the limbus (the growth zone between the cornea and the sclera) and fluids - intraocular and lacrimal. Therefore, for a long time it was believed that the causes of corneal dystrophy - structural changes and decreased transparency - are associated exclusively with disturbances in local metabolism and, partially, innervation.

The genetic nature of most cases of corneal degenerations is now recognized, and they are transmitted in an autosomal dominant manner and manifest at different ages.

For example, the result of mutations in the KRT12 gene or the KRT3 gene, which provide keratin synthesis in the corneal epithelium, is Messmann's corneal dystrophy. The cause of spotted corneal dystrophy is mutations in the CHST6 gene, which disrupts the synthesis of polymeric sulfated glycosaminoglycans that are part of the corneal tissue. And the etiology of dystrophy of the basal membrane and Bowman's membrane type 1 (Reiss-Bücklers corneal dystrophy), granular and lattice dystrophy is associated with malfunctions of the TGFBI gene, which is responsible for the growth factor of corneal tissue.

Ophthalmologists attribute the main causes of the disease to, firstly, biochemical processes in the membranes of its cells, associated with age-related increase in lipid peroxidation. Secondly, a deficiency of hydrolytic enzymes of lysosomes, which contributes to the accumulation of granular pigment lipofuscin in the pigment epithelium, which disables light-sensitive cells.

It is especially noted that such diseases as atherosclerosis and arterial hypertension – due to their ability to destabilize the state of the entire vascular system – increase the risk of central retinal dystrophy by three and seven times, respectively. According to ophthalmologists, myopia (nearsightedness), which causes the eyeball to stretch, inflammation of the vascular membrane of the eye, and high cholesterol play an important role in the development of degenerative retinopathies. The British Journal of Ophthalmology reported in 2006 that smoking triples the risk of developing age-related retinal dystrophy.

After fundamental research over the last two decades, the genetic etiology of many dystrophic changes in the retina has become clear. Autosomal dominant gene mutations provoke excessive expression of the transmembrane G-protein rhodopsin, the key visual pigment of rod photoreceptors. It is the mutations of the gene of this chromoprotein that explain the defects of the phototransduction cascade in pigmentary retinal dystrophy.

The causes of the disease may be associated with impaired local blood circulation and intracellular metabolism in arterial hypertension, atherosclerosis, chlamydial or toxoplasmic uveitis, autoimmune diseases (rheumatoid arthritis, systemic lupus erythematosus), diabetes of both types, or eye injuries. There is also an assumption that problems with blood vessels in the eyes are a consequence of vascular damage to the brain.

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Symptoms of eye dystrophy

Symptoms of corneal dystrophy noted by ophthalmologists include:

• painful sensations of varying intensity in the eyes;
• a feeling of a blocked eye (the presence of a foreign object);
• painful sensitivity of the eyes to light (photophobia);
• excessive lacrimation;
• hyperemia of the sclera;
• corneal edema;
• decreased transparency of the stratum corneum and decreased visual acuity.

Keratoconus is also characterized by itching in the eyes and visualization of multiple images of single objects (monocular polyopia).

It should be borne in mind that retinal dystrophy develops gradually and does not show any signs at the initial stages. And the symptoms characteristic of degenerative retinal pathologies can be expressed as:

• rapid eye fatigue;
• temporary refractive errors (hyperopia, astigmatism);
• reduction or complete loss of contrast sensitivity of vision;
• metamorphopsia (distortion of straight lines and curvature of images);
• diplopia (double vision of visible objects);
• nyctalopia (deterioration of vision with reduced light and at night);
• the appearance of colored spots, “flies” or flashes of light before the eyes (photopsia);
• distortions in color perception;
• lack of peripheral vision;
• scotoma (the appearance in the field of vision of areas that are not perceived by the eye in the form of darkened spots).

Central retinal dystrophy (age-related, vitelliform, progressive cone, macular, etc.) begins to develop in people with changes in the PRPH2 gene, which encodes the membrane protein peripherin 2, which provides light sensitivity to photoreceptor cells (rods and cones).

Most often, the disease makes itself known after 60-65 years. According to the American National Eye Institute, about 10% of people aged 66-74 have predispositions to the development of macular degeneration of the eye, and for people aged 75-85, this probability increases to 30%.

The peculiarity of central (macular) dystrophy is the presence of two clinical forms – non-exudative or dry (80-90% of all clinical cases) and wet or exudative.

Dry retinal dystrophy is characterized by the deposition of small yellowish clumps (drusen) beneath the macula, in the subretinal region. The layer of photoreceptor cells in the macula begins to atrophy and die due to the accumulation of deposits (metabolism products that are not broken down due to a genetic deficiency of hydrolytic enzymes). These changes, in turn, lead to distortion of vision, which is most obvious when reading. Most often, both eyes are affected, although it can begin in one eye and the process lasts for a long time. However, dry retinal dystrophy does not usually lead to complete loss of vision.

Wet retinal dystrophy is considered a more severe form, as it causes vision deterioration in a short time. And this is due to the fact that under the influence of the same factors, the process of subretinal neovascularization begins - the growth of new abnormal blood vessels under the macula. Damage to the vascular walls is accompanied by the release of a bloody-serous transudate, which accumulates in the macular area and disrupts the trophism of the retinal pigment epithelium cells. Vision deteriorates significantly, in nine cases out of every ten, loss of central vision is noted.

Ophthalmologists note that in 10-20% of patients, age-related retinal dystrophy begins as dry, and then progresses to an exudative form. Age-related macular degeneration is always bilateral, with one eye having dry dystrophy and the other having wet dystrophy. The course of the disease can be complicated by retinal detachment.

Retinal dystrophy in children

A sufficient spectrum of varieties of degenerative eye pathologies is represented by retinal dystrophy in children.

Central retinal dystrophy in children is a congenital pathology associated with gene mutation. First of all, this is Stargardt disease (juvenile macular form of the disease, juvenile macular degeneration) - a genetically determined disease associated with a defect in the ABCA4 gene, inherited in an autosomal recessive manner. Statistics from the Royal National Institute of Blind People (RNIB) indicate that this disease accounts for 7% of all cases of retinal dystrophy in British children.

This pathology affects both eyes and begins to manifest itself in children after the age of five. It manifests itself in photophobia, decreased central vision and progressive color blindness - dyschromatopsia to green and red.

This disease is currently incurable, as the optic nerve atrophies over time, and the prognosis is generally unfavorable. However, active rehabilitation steps can preserve and maintain a certain level of visualization (no more than 0.2-0.1).

In Best's disease (macular dystrophy of the macula), which is also congenital, a fluid-containing cyst-like formation develops in the central fovea of the macula. This leads to a decrease in central visual acuity (blurred images with darkened areas) while maintaining peripheral vision. Patients with Best's disease often have almost normal vision for many decades. The disease is inherited, and often family members may not know that they have this pathology.

Juvenile (X-linked) retinoschisis - a splitting of the layers of the retina with subsequent damage and degradation of the vitreous - leads to loss of central vision, and in half of the cases, lateral vision. Common signs of this disease are strabismus and involuntary eye movements (nystagmus); the vast majority of patients are boys. Some of them retain a sufficient percentage of vision into adulthood, while in others, vision deteriorates significantly in childhood.

Retinitis pigmentosa includes several hereditary forms of the disease that cause a gradual decrease in vision. It all begins at about ten years of age with complaints from the child about problems with vision in the dark or limited side vision. As ophthalmologists emphasize, this disease develops very slowly and extremely rarely leads to vision loss.

Leber's amaurosis is a congenital incurable blindness transmitted in an autosomal recessive manner, i.e., for children to be born with this pathology, both parents must have the mutated RPE65 gene. [More information is available when you click on our publication Leber's Amaurosis].

Retinal dystrophy during pregnancy

Possible retinal dystrophy during pregnancy threatens women with severe myopia (above 5-6 diopters), since the shape of the eyeball is deformed. And this creates the prerequisites for the development of complications in the form of peripheral vitreochorioretinal dystrophies, which can cause ruptures and retinal detachment, especially during childbirth. That is why in such cases obstetricians perform cesarean section.

In pregnant women with myopia - in the absence of complications (gestosis) - the retinal vessels slightly narrow to support blood circulation in the uterus-placenta-fetus system. But when pregnancy is complicated by high blood pressure, soft tissue edema, anemia and nephrotic syndrome, the narrowing of the retinal vessels is more pronounced, and this causes problems with its normal blood supply.

According to ophthalmologists, peripheral dystrophies are most often a consequence of a decrease in the volume of circulating blood in all structures of the eyes (by more than 60%) and a deterioration in the trophism of their tissues.

Among the most common retinal pathologies during pregnancy are: lattice dystrophy with thinning of the retina in the outer upper part of the vitreous cavity, pigment and punctate white dystrophy of the retina with areas of atrophy of the retinal epithelium, as well as dystrophy of the eye vessels with spasms of capillaries and venules. Retinoschisis occurs quite often: the retina detaches from the choroid (without or with a rupture of the retina).

What types of eye dystrophy are there?

If we follow the anatomical principle, we must start with the cornea. In total, according to the latest international classification, corneal dystrophy of the eye has more than two dozen types - depending on the localization of the corneal pathological process.

Superficial or endothelial dystrophies (in which amyloid deposits occur in the corneal epithelium) include basement membrane dystrophy, juvenile Messmann dystrophy (Messmann-Wilke syndrome), etc. Dystrophies of the second layer of the cornea (the so-called Bowman's membrane) include subepithelial Thiel-Behnke dystrophy, Reiss-Boucler dystrophy, etc.; over time, they often extend into the superficial layers of the cornea, and some can affect the intermediate layer between the stroma and the endothelium (Descemet's membrane) and the endothelium itself.

Corneal dystrophy localized in the thickest layer, consisting of collagen fibers, fibro- and keratocytes, is defined as stromal dystrophy, which can vary in the morphology of damage: lattice, granular, crystalline, spotty.

In case of damage to the inner layer of the cornea, endothelial forms of the disease are diagnosed (Fuchs, spotted and posterior polymorphic dystrophy, etc.). However, with the cone type of dystrophy - keratoconus - degenerative changes and deformation occur in all layers of the cornea.

In domestic ophthalmology, retinal dystrophy is divided into central and peripheral by the place of its occurrence, and acquired and genetically determined by etiology. It should be noted that today there are many problems with the classification of retinal dystrophy, which lead to a variety of terminology. Here is just one, but very illustrative example: central retinal dystrophy can be called age-related, senile, central chorioretinal, central chorioretinitis, central involutional, age-related macular degeneration. While Western specialists, as a rule, get by with one single definition - macular dystrophy. And this is logical, since the macula (macula in Latin - spot) is a yellow spot (macula lutea) in the central zone of the retina, which has a depression with photoreceptor cells that convert the effect of light and color into a nerve impulse and send it along the optic cranial nerve to the brain. Age-related retinal degeneration (in people over 55-65 years of age) is perhaps the most common cause of vision loss.

Peripheral retinal dystrophy is represented by such a list of "modifications" that it is quite problematic to provide it in full due to terminological inconsistency. These are pigment (tapetoretinal or pigment retinitis), cone-rod, vitreoretinal Goldman-Favre dystrophy, Leber's amaurosis, Loeffler-Wadsworth dystrophy, white-punctate retinitis (dotted white), etc. Peripheral dystrophy can cause retinal rupture and detachment.

Finally, dystrophy of the eye vessels, which can affect the ophthalmic artery and the central retinal artery branching off from it, as well as the veins and venules of the eyes. At first, the pathology manifests itself in microscopic aneurysms (expansions with bulging walls) of extremely thin blood vessels of the retina, and then can progress to proliferative forms, when neovascularization begins in response to tissue hypoxia, that is, the growth of new, abnormally fragile blood vessels. They themselves do not cause any symptoms, but if the integrity of their walls is damaged, serious problems with vision arise.

Diagnosis of eye dystrophy

In ophthalmological clinics, diagnostics are carried out using such methods and techniques as:

• visocontrastmetry (determination of visual acuity);
• perimetry (visual field examination);
• campimetry (determination of the size of the blind spot and the location of scotomas);
• functional testing of the central visual field using the Amsler grid;
• color vision testing (allows you to determine the functional state of the cones);
• dark adaptation testing (provides an objective picture of rod function);
• ophthalmoscopy (examination and assessment of the condition of the fundus);
• electrooculography (provides an idea of eye movements, retinal potential and eye muscles);
• electroretinography (determination of the functional state of various parts of the retina and visual analyzer);
• fluorescein angiography (allows visualization of the blood vessels of the eye and detection of the growth of new blood vessels and leakage from existing vessels);
• tonometry (measurement of intraocular pressure);
• Ultrasound of the internal structures of the eye in two projections;
• optical layer-by-layer tomography (examination of the structures of the eyeball).

To diagnose corneal dystrophy, it is necessary to examine the cornea using a slit lamp, use pachymetry (to determine the thickness of the cornea), skiascopy (to determine the refraction of the eye), corneotopography (to determine the degree of curvature of the corneal surface), and confocal biomicroscopy.

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Treatment of eye dystrophy

Symptomatic treatment of corneal dystrophy includes medications to improve the trophism of its tissues:

Taufon - 4% eye drops based on taurine, which helps restore tissue damaged by degenerative changes in the cornea. They should be instilled under the conjunctiva - 0.3 ml once a day, the course of treatment is 10 days, which is repeated after six months. Taufon in the form of an injection solution is used in more severe cases.

Drops Sulfated glycosaminoglycans (Balarpan) due to the content of a natural component of the corneal stroma activate its regeneration. Prescribed two drops in each eye in the morning and evening - for 30 days. Oftan Katahrom drops, consisting of adenosine (a component of ATP), nicotinic acid and the enzyme cytochrome oxidase, stimulate intra-tissue energy exchange and restoration of the damaged cornea; the dosage recommended by doctors is three times a day, 1-2 drops by instillation, that is, into the conjunctival sac (tilting the head back and slightly pulling the lower eyelid).

In addition, magnetophoresis is used with Vita-Yodurol drops, which contain, in addition to nicotinic acid and adenosine, magnesium and calcium chlorides.

Treatment of retinal dystrophy

At first, treatment with drugs is aimed at stimulating local blood circulation - to improve tissue nutrition (the drops listed above are prescribed).

For example, such treatment of pigmentary dystrophy of the retina is carried out twice a year, but, according to experts, most often it does not give the desired effect. The last word remains with ophthalmological microsurgery: operations are carried out to transplant a longitudinal flap of one of the six oculomotor muscles into the vascular membrane of the eye.

Treatment of retinal dystrophy localized in the macular region should take into account not only the etiology of the disease and concomitant and aggravating diseases of a particular patient, but also the form of the pathology - dry or exudative.

Treatment of dry retinal dystrophy accepted in domestic clinical practice can be carried out with antioxidant drugs. One of them is Emoxipin (in the form of 1% and eye drops and injection solution). The solution can be injected through the conjunctiva or into the periorbital area: once a day or every other day, the maximum course of treatment lasts a month.

In the treatment of retinal dystrophy with drugs that neutralize free radicals and prevent damage to cell membranes, the antioxidant enzyme superoxide dismutase is used, which is part of the drug Erisod (in the form of a powder for making drops). These drops should be prepared in distilled water and instilled for at least 10 days - two drops three times a day.

Wet retinal dystrophy is treated with photodynamic therapy. This is a combined non-invasive method aimed at stopping the neovascularization process. For this purpose, the patient is intravenously injected with the photosensitizing agent Visudin (Verteporfin), which, after activation by a cold red laser, causes the production of singlet oxygen, which destroys the rapidly proliferating cells of the walls of abnormal blood vessels. As a result, the cells die, and a hermetic blockage of the newly formed vessels occurs.

Ophthalmologists use drugs to treat exudative macular degenerative pathologies that block the VEGF-A (Vascular Endothelial Growth Factor) protein, which is produced by the body for the growth of blood vessels. Drugs such as Ranibizumab (Lucentis) and Pegaptanib sodium (Macugen) suppress the activity of this protein.

Which are injected into the vitreous body of the eye 5-7 times during the year.

And intramuscular administration of the synthetic adrenal cortex hormone Triamcinolone acetonide helps to normalize catabolism in connective tissue, reduce the level of cell division of membrane proteins and stop infiltration in wet retinal dystrophy.

Laser treatment of retinal dystrophy

It should be borne in mind that laser treatment cannot restore normal vision, since it has a different purpose - to slow down the progression of the disease and minimize the risk of retinal detachment. And it is still impossible to revive dead photoreceptor cells.

Therefore, this method is called peripheral preventive laser coagulation, and its principle of action is based on the coagulation of proteins of the retinal epithelial cells. In this way, it is possible to strengthen pathologically altered areas of the retina and prevent the separation of the inner layer of light-sensitive rods and cones from the pigment epithelium.

This is how peripheral retinal dystrophy is treated using laser coagulation. And laser therapy for dry dystrophy is aimed at removing deposits formed there from the subretinal zone of the eye.

In addition, laser photocoagulation seals choroidal neovascularization in macular degeneration and reduces the growth of leaky blood vessels, preventing further vision loss. This treatment leaves a scar that creates a permanent blind spot in the visual field, but this is much better than having a permanent blind spot instead of vision.

By the way, you shouldn't use any folk remedies for retinal dystrophy: they won't help anyway. So don't try to treat yourself with an infusion of onion peel with honey or compresses with a decoction of chamomile and nettle...

Vitamins and nutrition for retinal dystrophy

The "right" vitamins are very important for retinal dystrophy. Experts include all B vitamins (especially B6 - pyridoxine), as well as ascorbic acid (antioxidant), vitamins A, E and P.

Many eye doctors recommend taking vitamin complexes for vision containing lutein - a carotenoid of natural yellow enzymes. Not only does it have strong antioxidant properties, but it also reduces the formation of lipofuscin, which is involved in the development of central retinal dystrophy. Our body cannot produce lutein on its own, so it must be obtained from food.

Nutrition for retinal dystrophy can and should help fight, and best of all, prevent eye dystrophies. For example, spinach, parsley, green peas, broccoli, pumpkin, pistachios, and egg yolk contain the most lutein.

It is important to include fresh fruits and vegetables in sufficient quantities, healthy unsaturated fats from vegetable oils and whole grains in your diet. And don’t forget about fish! Mackerel, salmon, sardines, herring contain omega-3 fatty acids, which can help reduce the risk of vision loss associated with macular degeneration. These acids can also be found in… walnuts.

Prognosis and prevention of eye dystrophy

The prognosis for eye dystrophy – due to the progressive nature of this pathology – cannot be considered positive. However, according to foreign ophthalmologists, retinal dystrophy itself will not lead to complete blindness. In almost all cases, some percentage of vision, mainly peripheral, remains. It is also necessary to take into account that vision can be lost, for example, with a severe form of stroke, diabetes or trauma.

According to the American Academy of Ophthalmology, in the United States, only 2.1% of patients with central macular degeneration have lost their vision completely, while the rest have some peripheral vision. And despite successful treatment, macular degeneration can recur over time.

Prevention of eye dystrophy is a healthy lifestyle. Dystrophy of the retina of the macula of the eye is promoted by the consumption of large amounts of animal fats, high cholesterol levels and metabolic disorders in the form of obesity.

The role of oxidative stress of retinal cells in the development of its dystrophy is convincingly demonstrated by the increased rate of development of pathology in smokers and those exposed to UV radiation. Therefore, doctors advise their patients to quit smoking and avoid exposure of the cornea to intense sunlight, i.e., wear sunglasses and hats.

It is useful for older people to visit an ophthalmologist once a year, especially if there is a family history of eye dystrophy - retinal, corneal or vascular.