|
|
 |
|
Pathology of retina
The retina is a peripheral receptor section of the visual analyzer. It is the true part of a brain, which was removed to the periphery. It covers the whole internal surface of the back side of an eyeball. The retina consist of millions photosensitive cells. Is responsible for perception of the image which is projected on it by means of a cornea and a crystalline lens, and transformation of this image to nervous pulses which then are transferred to the brain. In the brain take place decoding and transformation of subjects into visual images, as we see them.
Various zones of a retina are responsible for the various, specialized functions. In the central zone of a retina is concentrated the greatest amount of photoreceptors (conuses), this zone is called macula. It is responsible for the better sight and allows to distinguish more thin details of subjects. The peripheral side of retina is responsible for peripheral sight. It allows to see all, that is located around of a subject which is fixed by an eye at present. In other words, if we notice road directly before ourselves we notice coming nearer automobiles sideways. There is an insignificant amount of conuses in this zone of a retina, but there’re a lot of sticks.
- Why is the regular survey of an eye grounds necessary?
- It is necessary to carry out regular surveys not only of retina, but also of an eye as a whole. As it has been told, it highly differentiated tissue of an eye which enables us to see the world, as it is. It is located inside an eye and consequently it is impossible to see, how the retina looks without special survey and the equipment. And diseases of a retina which the patient can’t guess, can cause the blindness.
- What are the most frequently retinal illnesses?
- Among illnesses which afflict the retina, the main causes of heavy reduction in sight in industrial developed countries are: the age-specific macular degeneration, diabetic retinopathy, the peripheral degeneration of a retina, infringement of blood circulation in a retina, detachment of retina.
- What is the macular degeneration?
- This is an impairment of the central part of a retina which results to irreversible reduction of visual functions, first of all - visual acuities. A principal cause of macular degenerations is gradual process of ageing of an organism and an eye in particular. Less often as the reason can be the transferred trauma, infectious, inflammatory illnesses of eyes, high short-sightedness, less often - the hereditary reasons. Initial displays consist in " misting ", a curvature of subjects, letters (letters "break"), colors become less bright. With time there is a gradual deterioration of the central sight, in the central part of a field of vision appears more or less transparent spot (central scotoma).
On the one hand the macular degeneration results in significant visual problems, but it is important to note, what even in the heaviest cases this disease does not result in full blindness as paracentral and peripheral sight remains safe. Age-specific (senile) macula degeneration. There are two forms - nonexudative (dry) and exudative (damp) which are connected to age changes of the capillary vessels feeding the retina. At the nonexudative form occurs slow progressing thinning retinas owing to an atrophy of this area on a background of insufficient local blood circulation. The exudative form is complicated by formation of pathological vascular capillaries which form thin "neovascular, membranes ". Walls of these again created vasculars differ by the increased fragility, they easily pass the liquid part of blood.
All this results in a edema and haemorrhages in surrounding retina. Repeated episodes of haemorrhages (hemorrhagies) and subsequent processes of their resorption result in formation in macula a healing tissue. Therefore infringements of the central sight are more expressed at the exudative form.
- How is the diagnosis of macular degenerations determined?
- The diagnosis of macular degenerations can be put during inspection. The ophthalmologist examines the central part of a retina after instillation of the special drops expanding pupils, with the help of special lenses. For early diagnostics are applied additional methods of research: check of colour sensation, the test with grid Amsler, central computer perimetry, fluorescent angiography of vessels of an eye grounds by means of unique Heidelberg retinal angiograp, laser scanning of a retina by means of the first in Ukraine Heidelberg retinal tomograph. These researches allow to specify the diagnosis, the stage of illness, to choose the right tactics of treatment.
- What are the presentations of diabetic retinopathy?
- First DR has asymptomatic course: it does not cause in afflicted persons complaints and it is not found out by traditionally used method of research of an eye grounds, indirect opthtalmoscopy. When there are complaints about reduction of sight, it already testifies to expressed or advanced stages of illness and that time of the most effective medical influence for pathological process is missed. The unique way of preventive maintenance of occurrence and progressing DR is early diagnostics. Regular inspection at the ophthalmologist having conditions and opportunities for detailed research of a condition of your retina will allow to reduce risk of loss of sight because of a diabetes. People, suffering a diabetes of the first type, i.e. taking insulin, risk to lose sight in some times more, than patients with a diabetes of the second type. The at earlier age there is a diabetes, the proceeds DR more hardly, and in the course of time the risk of loss of sight is higher. First attributes of DR, even at the successful control and treatment of disease, arises in some years from the moment of the real beginning of a diabetes.
It’s enough for the patient with a diabetes two annual inspections at the ophthalmologist though in some cases, such as pregnancy or long current of illness, it’s advisable to visit the doctor more often.
The examination, that helps us to appreciate the danger of DR development consist of: the examination of visual sharpness, the widening of the pupil with the help of eye drops, the inwardly-euglenic pressure control and the detailed eye grounds examination with the help of biomicroscope and special lens. The most valuable information may be extracted after the laser scanning of the central retinal part with the For the subsequent comparative estimation of development of disease can be demanded photos of an eye grounds and angiographic research of vessels of a retina - fluorescent angiography by means of unique Heidelberg retinal angiographic.
The data of this research are of great value for early retinopathy diagnostics and the duly decision of a question on necessity of laser treatment of progressing DR forms. At the nonproliferative DR form owing to functional infringements in the field of capillary vessels there are small haemorrhages, is formed ampoule-shaped expansion - microaneurysms and adjournment of metabolism products (so-called firm exudates), and also edemas in a retina. This DR form mostly met at older diabetics and in the long term conducts to slow deterioration of sight. Because of this DR form, owing to growing deficiency of maintenance of a retina with oxygen (because of corking capillaries), can develop the second DR form - proliferative which first of all is characterized by formation of new vessels (neovascularization).
They sprout in retina, from retina into the vitreous body and cause a haemorrhage in it and growing deterioration of sight. This transition at a youthful diabetes can take place within several months. At a haemorrhage in vitreous body are formed preretinal membranes which result in the subsequent retinal detachment. Despite of a regularity inspections at the ophthalmologist, patients can assist the doctor and, in due time inform him about change of sight.
Our Clinic has all necessary conditions for duly revealing diabetic retinopathy and its effective treatment. It is only necessary to address in Clinic for inspection and consultations if you know, that you are a diabetic.
- What danger may peripheral degeneration of retina cause?
- The peripheral zone of a retina practically is not visible at usual survey of an eye grounds, because it is behind "equator" of an eyeball.
Unfortunately, in this zone more often develop the dystrophic (degenerate) processes frequently connected with increase of length of an eye, and, as consequence, progressing of short-sightedness and deterioration of blood circulation in a vascular environment in this zone. Here’re the basic preconditions of development of one of the most terrible ophthalmologic diseases – retinal detachment. At progressing dystrophic changes in an eye the struck sites of a retina gradually get thin, here are frequently formed tractions (tension) between changed vitreous body and retina which, influencing for a long time on a nervous tunic of eyeball, form break through which the liquid part of vitreous body acts under a retina, and, raising, detach it. Patients mark thus black strings before the struck eye, and also light flashes.
- How to diagnose a peripheral degeneration of retina?
- There are some kinds of peripheral dystrophies (degenerations), various on a danger’s degree of occurrence of retinal detachment. From them the most dangerous in the plan for development of detachment are:
- trellised dystrophy;
- frosted dystrophy;
- dystrophy as a trace of snail.
On statistics peripheral dystrophies of retina developes itself by short-sighted people (myopes) - in 30-40 % of cases, by suffering a far-sightedness (hypermetropes) - in 6-8 %, by people with normal sight - in 2-5 %.
There’re a lot of reasons of peripheral dystrophies of retina: the predisposition transmitted hereditably, short-sightedness of any degree, inflammatory diseases of eyes, traumas, other diseases of eyes. Here’re some general causes of illness: hypertonic illness, atherosclerosis, diabetes, intoxications, transferred infection, other chronic and sharp diseases of an organism, etc.
Peripheral dystrophies of retina can develop at patients of all age groups, including children.
The basic danger of peripheral dystrophies and occurrence of retinal detachment - is the absence of any symptoms (displays) in initial stages. Frequently patients address to the ophthalmologist when the retinal detachment has reached already the central parts with the typical complaint to sensation of "curtain" before an eye. At this stage of disease can only help the serious surgical operation which not always results in full restoration of functions of an eye.
About presence of dystrophic changes on retina you’ll be informed by the ophthalmologist after careful inspection of an eye grounds during usual ophthalmologic survey and, as a rule, will be recommend to carry out the profound inspection of peripheral zones of retina at the ophthalmologist - expert on laser surgery.
- Can your clinic help at vascular changes on eye grounds?
- Cardiovascular diseases now are named "a problem of a century", they are one of principal causes of incapacitation and death rates, in particular between people of able-bodied age. It is caused by steady growth of an atherosclerosis and the hypertonic illness, resulting to local defeats of an eye grounds.
The thrombosis of retinal veins is one of such defeats. Corking of the central retinal vein meets, basically, at elderly patients, and, as a rule, is limited to one eye. The beginning is sudden and also is accompanied by sharp reduction in sight. A characteristic picture of thrombosis CRV create multiple flameshaped haemorrhages around an edematic disk of an optic nerve. At venous occlusion frequently there is a hypostasis of macular zone that is a principal cause of reduction in the central sight. The adequate blood flow can be recovered at recanalization of thrombosed vessels, or at development collateral circulation and shunts. If the blood flow in the struck vessel is not restored, in the struck area of retina are formed the ischemic zones being the initiator of neovascularization and so often complication of thrombosis of the central retinal vein or its branches is the secondary glaucoma. With the purpose of preventive maintenance of its development is usually applied the panretinal lasercoagulation of retina.
- Impassability of the central artery of retina?
- In the basic of sharp impassability of arteries of nervous tunic of eyeball are such conditions, as a spasm, embolism, arteritis and a thrombosis. Despite of distinction of the reasons causing infringements of blood circulation, clinical displays of all conditions are rather same and characteristic. Disease begins with sudden proof reduction in sight, more often in the morning. Sometimes patients mark harbingers of reduction in sight as flashing, occurrences of sparks, short-term and spontaneously disappearing loss of sight.
As a result of illness on eye grounds develops the typical picture: within several minutes the edema of retina accrues. Last become muddy, getting milky-white color. Against its background becomes the cherry-red stain of central pit of yellow stain. Consequences of sharp necessity CAR is the primary atrophy of an optic nerve, the central secondary degeneration of retina and sharp narrowing of retinal vessels. Effective treatment is possible (medicamentous and laser) at the first hours (in rare cases in the first day) after the beginning of illness.
 top
|
 |
|
