Anizometropiya is pathology of a clinical refraction of an eye at which the difference of the refracting force between eyeballs exceeds 2 . The disease is shown by a diplopiya, blurring of the image before eyes, decrease in visual acuity, bystry fatigue when performing visual work. Apply a vizometriya, ultrasonography, computer refractometry, perimetry, biomicroscopy, an oftalmoskopiya, a skiaskopiya to diagnosis. Tactics of treatment comes down to correction of visual dysfunction by means of contact lenses, points or to application of surgical methods (eksimerlazerny intrastromalny , implantation of IOL).
Anizometropiya treats group of anomalies of a refraction. According to statistical data, prevalence of pathology in structure of all diseases of an organ of vision makes 17%. It is proved that the difference of force of refraction of eyes at children occurs more often than at adults. At seven-year age the disease is diagnosed for 8% of school students, by ten years this indicator reaches 17%. In the course of a refraktogenez clinical manifestations remain stable only with 38,2% of children, at 25,5% of patients regress of symptomatology is observed, at 36,3% expressiveness of symptoms increases. In the European countries this disease suffers from 1,5% of the population, in China – 4%.
In most cases organic pathology of an organ of vision is the cornerstone of an anizometropiya. Functional changes lead to insignificant increase in a difference of a refraction that is not followed by clinical manifestations. Main reasons for a disease:
- Cataract. The cataract becomes the cause of pathology that is connected with violation of passing of rays of light on optical system and visual dysfunction only of one eye.
- Congenital unilateral miopiya. Short-sightedness – the most common cause of an anizometropiya at children. In some cases after completion of formation of an eyeball the symptomatology is independently leveled.
- Astigmatism. Development of this pathology is often caused by violation of a form of a crystalline lens or a cornea in case of asymmetric changes.
- Unilateral gipermetropiya of high degree. Asymmetrical far-sightedness comes to light at patients more often 40 years in connection with development of glaukomatozny changes are more senior.
- Yatrogenny influence. Violations of a clinical refraction arise in the postoperative period that is caused by carrying out surgical interventions on a crystalline lens, a vitreous body, a retina. It is proved that implantation of intraocular lenses (IOL) up to 18 years conducts to an ametropiya and an anizometropiya at adult age.
At excess of a difference of the refracting force of both eyes more than on 2 dioptries there are disorders of binocular sight. At the long course of a disease the clinic of secondary squint accrues. Normal the image is formed as a single whole with participation of a mesh cover of two eyes and a brain. The different refraction is the reason that the image on a retina is deformed, the patient sees it "indistinct". At the same time the patient kompensatorno limits participation of more visually impaired eye in the act of sight. At the abnormal size of a longitudinal axis akkomodatsionny ability is broken. If the symptomatology is caused by refraction pathology, then the provision of nodal points changes that also complicates formation of the image on an internal cover. Decrease in visual acuity has reversible character as it is caused by an accommodation spasm.
Distinguish the congenital and acquired anizometropiya. The disease can independently develop or to be manifestation of other oftalmopatologiya. According to clinical classification, allocate the following forms of a disease:
- Axial. The cause of this option – pathological change of a long axis of one of eyeballs on condition of an identical refraction.
- Refraction. At this form the longitudinal axis meets standard, however the clinical refraction of one eye is more, than another on 2 and more .
- Mixed. It is characterized by a combination of manifestations of axial and refraction option of a disease.
Distinguish three degrees of expressiveness of an anizometropiya:
- Weak degree – to 3 .
- Average degree – 3-6 .
- High degree – more than 6 .
The main clinical manifestations of an anizometropiya are caused by violation of binocular sight. Distinctions in the refracting force of eyes less than 2 are poorly expressed and in rare instances can lead to insignificant visual discomfort. Application of-point correction provides normal visual acuity. At average degree of a disease patients show complaints to doubling, an illegibility of a contour of images before eyes, decrease in visual functions. Disappearance of symptoms when closing one eye is characteristic of an anizometropiya. Parents often note that the child blinks when reading, viewing the TV or work at the computer.
At high degree binocular sight is sharply broken. A characteristic symptom of an anizometropiya – increase in a difference in brightness and size of the image (anizeyoniya).-Point correction often is followed by an anizoforiya. The symptomatology of a strabizm appears only when changing the direction of a look. Development of an anizopereskopiya at which convergence is significantly complicated is typical for this form. At long visual loadings there comes the bystry exhaustion, the headache irradiating in nadbrovny arches amplifies.
Earlier an anizometropiya complication – the ambliopiya caused by deliberate restriction of participation of the affected eye in sight. In the absence of timely diagnostics and treatment the meeting or dispersing strabizm develops. Long carrying contact lenses leads to microinjuries of a cornea, a keratit, epitelialny hypostasis, a rubeoz of an iris and a neovaskulyarization of a cornea. The risk of development of infectious and inflammatory diseases of forward department of eyes is increased (conjunctivitis, blefarit, Irit). A specific complication of pathology – an anizoakkomodation which is characterized by different akkomodatsionny ability of eyes.
Often objective signs of an anizometropiya come to light incidentally at ophthalmologic inspection. Patients ask for the help the expert only at average and high degree of a disease. The plan of diagnostics includes:
- Computer refractometry. The technique is applied to definition like a clinical refraction, studying of a ratio of the refracting force to a longitudinal axis.
- To Vizometry. Allows to establish extent of decrease in visual acuity.
- Ultrasonography of an eye. It is used for measurement of a perednezadny axis of an eyeball. Ultrasonography is necessary at turbidity of optical environments for visualization of a vitreous body, a retina and an optical nerve.
- To Oftalmoskopy. During survey of an eye bottom it is possible to study a condition of an internal cover, a disk of an optic nerve.
- Perimetry. An additional method of a research which allows to reveal asymmetric narrowing of the visual field on concentric type.
- Eye biomicroscopy. Inspection of forward department of an eye informatively for definition of an etiology of a disease, identification of the first signs of a secondary inflammation of a cornea, a bulbarny conjunctiva.
- To Skiaskopy of an eye. Shadow test – an alternative method of studying of a clinical refraction which gives the chance to measure a ratio of the perednezadny size to the refracting force of optical system. At persons with an anizometropiya blackout moves towards rotation of an oftalmoskopichesky mirror.
Treatment of an anizometropiya
Etiotropny therapy comes down to elimination of displays of the main disease. Conservative methods of correction of visual acuity are used at patients with easy and average degree of pathology. If the difference in corrective glasses has to exceed 2,5 , surgery is shown. The following techniques are applied to treatment of an anizometropiya:
- Visual acuity correction. For the purpose of correction of visual functions special telescopic glasses which optical system consists from the collective and disseminating lenses can be used. The indication to their application – organic defeat of the visual analyzer. At an anizometropiya of high degree appoint izeykonichesky points. Symptomatic therapy is based on selection of contact lenses. At children's age they are used only in the presence of contraindications to expeditious treatment and-point correction.
- Surgical correction. In the absence of damages of a cornea carrying out an eksimerlazerny intrastromalny keratomilez is effective. Alternative option of keratorefraktsionny surgical correction is implantation of additional IOL. At the same time density of endotelialny cages has to be not below the minimum limits meeting age standards. At patients from miopiy high degree a month before surgery carry out laser coagulation of a retina.
Forecast and prevention
The forecast for life and working capacity favorable. Specific methods of prevention are not developed. Nonspecific preventive measures come down to control of visual acuity and a clinical refraction. Consultation of the ophthalmologist of 1 times in 6 months with obligatory carrying out refractometry and a vizometriya is shown to persons to whom within the last 2 years surgeries in the eyes were carried out. At diagnostics of anomalies of a clinical refraction at children 1 years are more senior it is necessary to carry out timely correction of visual dysfunction for the purpose of prevention of development of squint. At patients 12 months are younger use of special methods of treatment is not shown.