Anomalies of color sight
Anomalies of color sight are a complex of pathologies of the congenital or acquired genesis, including achromatopsia, daltonism and the acquired insufficiency of color sight. The clinical symptomatology is presented by violation of color perception, decrease in visual acuity, nistagmy. For diagnostics of anomalies of color sight use an elektroretinografiya, an anomaloskopiya, Rabkin's tables, Ishikhar's test and FALANT. The basic principle of treatment – correction of color sight by means of points or lenses with special filters. Etiotropny therapy of the acquired forms is directed to restoration of transparency of optical environments of an eye and elimination of pathologies of a makulyarny part of a retina.
Anomalies of color sight
Anomalies of color sight are a heterogeneous group of the diseases in ophthalmology which are followed by violation of color perception. In 1798 the English physicist J. Dalton for the first time described clinical displays of daltonism as itself had this pathology. Prevalence of a color blindness among men makes 0,8:1 000, among women – 0,05:1 000, achromatopsia – 1:35 000. The acquired insufficiency of color sight occurs among persons men's and female with an identical frequency. The people accepting in toxic doses , patients with avitaminosis And yes with degenerate and dystrophic changes of a retina enter into risk group. Congenital forms of anomalies of color sight diagnose at the age of 3-5 years.
Reasons of anomalies of color sight
Distinguish the congenital and acquired anomalies of color sight. The reason of development of achromatopsia with bacillary monochromatism – a mutation of genes of CNGA3, CNGB, GNAT2, PDE6C which is inherited on autosomno-recessive type. Violation of synthesis of the proteinaceous molecules which are responsible for information transfer from a rodopsin in a cage is the cornerstone of pathogenesis. At conformational change of a visual pigment the threshold of depolarization of a membrane of a photoreceptor decreases. It exerts negative impact on synthesis of a glutamate, thereby increasing excitability of bipolar cages which in connection with emergence of a mutation of proteins transmitters do not react to light influence and change of structure of a visual pigment. At this form of anomalies of color sight the receptors of sticks incapable of color perception display the image in various shades of gray.
Congenital daltonism develops at a mutation of genes of OPN1LW and OPN1MW which are localized on the H-chromosome therefore the disease is inherited on the H-linked mechanism. Less often the color blindness is diagnosed for newborns with dystrophy of flasks, amavrozy Lebera, a pigmentary retinit. The acquired option of this anomaly of color sight is observed at patients with traumatic damages, pathological new growths, hemorrhages or ischemia in the field of an occipital share of a brain. The passing color blindness develops at persons with sharp poisoning or chronic intoxication. The disease arises separately, however in rare instances belongs to manifestations of a makulodistrofiya, idiopathic parkinsonism, retinopathy against the background of diabetes.
The etiology of the acquired insufficiency of color sight is connected with decrease in transparency of optical environments of an eyeball. Common causes of this phenomenon – turbidity of a cornea, a cataract, existence of pretsipitat or inflammatory exudate in the forward camera of an eye, destruction of a vitreous body. Anomalies of color sight of the acquired genesis arise at the course of pathological processes in makulyarny area of an internal cover of an eyeball (an epiretinalny membrane, an age makulyarny degeneration).
Symptoms of anomalies of color sight
Achromatopsia, the acquired insufficiency of color sight and daltonism is among anomalies of color sight. The main clinical display of achromatopsia – black-and-white sight. The accompanying symptoms of this anomaly of color sight are presented nistagmy, a gipermetropiya. Hypersensibility to light leads to photophobia and a gemeralopiya. As a rule, patients have characteristic appearance with looked down down because of the expressed photophobia. Often patients use sunglasses. Sometimes this anomaly of color sight is complicated by clinic of a strabizm.
The clinical picture of daltonism is presented by lack of ability to differentiation of one and more flowers or its shades. At a protanopiya perception of red color, a tritanopiya – blue-violet, deyteranopiya – green is broken. At persons with a trikhromaziya of anomalies of color sight it is not observed. At change of brightness or a saturation of a certain part of a range this group of people is capable to perceive all colors and their shades. Patients with a dikhromaziya do not differentiate one of primary colors, replacing it with those shades of a range which are kept. In case of a monokhromaziya patients see everything around only in one chromatic shade. This option of daltonism can become complicated nistagmy, photophobia and decrease in visual acuity.
Unlike other anomalies of color sight the monocular beginning of a disease is characteristic of the acquired defects. However at poisoning or chronic intoxication there is a simultaneous damage of both eyeballs. The clinical symptomatology arises again, against the background of specific displays of the main pathology. Symptoms are decrease in visual acuity, narrowing of the visual field, emergence of "front sights" or "veil" before eyes.
Diagnostics of anomalies of color sight
Diagnostics of anomalies of color sight is based on anamnestichesky yielded, results of external examination, an elektroretinografiya, vizometriya, perimetry, genetic screening, inspection by means of an anomaloskop, Rabkin's tables, Ishikhar's test and FALANT test. At external examination of the patient with achromatopsia it is possible to find . Inspection with Rabkin's tables allows to diagnose violation of color perception. Lack of peaks of flasks or their expressed decrease is defined on elektroretinografiya. During a vizometriya at this anomaly of color sight decrease in visual functions is noted. The genetic sekvenirovaniye is directed to identification of a mutation and establishment like inheritance.
For diagnostics of a form of daltonism Ishikhar's test and Rabkin's tables is used. Techniques are based on formation of certain figures, pictures or figures from various flowers. At violation of perception of one of shades it is impossible to define what is represented in the test or on the table. In modern ophthalmology by method of an anomaloskopiya it is possible to survey all characteristics of functioning of receptors (extent of violation of perception of color, color adaptation, influence of physical factors and medicines on visual functions). FALANT test allows to diagnose more precisely violations of color perception since colors and shades are formed at merge of a scattered luminescence of a beacon by means of the special filter. At this anomaly of color sight the genetic research is also conducted. The acquired form of a disease is the indication for carrying out additional methods of a research – an oftalmoskopiya, biomicroscopy, a tonometriya and perimetry.
For diagnostics of the acquired insufficiency of color sight also use polychromatic tables and a method of a spectral anomaloskopiya. However at this pathology it is necessary to establish a disease etiology. The biomicroscopy with a slot-hole lamp is applied to a research of transparency of optical environments of an eye. Pathological processes in makulyarny area can be revealed by means of an oftalmoskopiya, the optical coherent tomography (OCT) and ultrasonography (ultrasonography of an eye) in the V-mode.
Treatment of anomalies of color sight
Tactics of treatment of anomalies of color sight depends on a disease form. Etiotropny therapy of achromatopsia is not developed. Symptomatic treatment is directed to correction of visual acuity by means of points or contact lenses. In places with bright lighting it is recommended to wear sunglasses. The complex of medical actions includes reception of the polyvitaminic complexes containing vitamins A and E, vazodilatator. At the present stage of development of ophthalmology restoration of color perception is possible only experimentally in animal experiments.
Etiotropny therapy is also not developed for such anomaly of color sight as daltonism regardless of that, there is a disease because of a gene mutation, against the background of Leber's amavroz or congenital dystrophy of flasks. For correction of color perception it is possible to use tinted filters for points or special contact lenses. Tactics of treatment of the acquired form of a disease comes down to elimination of etiologichesky factors (surgery at damage of structures of a brain, a cataract fakoemulsifikation).
At diagnostics of the acquired insufficiency of color sight it is necessary to establish the reason of its development. If violation of transparency of optical environments of an eyeball is caused by inflammatory process of bacterial genesis, it is recommended to appoint antibacterial and hormonal means for local introduction. At a virus origin it is necessary to use antiviral ointments. Often at makulyarny localization of pathological process the surgery directed to removal of an epiretinalny membrane is shown. At a dry form of an age degeneration special methods of treatment are absent. The damp form of this anomaly of color sight is the indication to laser coagulation of neogenic vessels of an internal cover of an eyeball.
Forecast and prevention of anomalies of color sight
Prevention of development of anomalies of color sight is not developed. All patients with daltonism, achromatopsia and the acquired insufficiency of color sight have to stay on the registry at the ophthalmologist. It is recommended to undergo 2 times a year inspection with additional carrying out an oftalmoskopiya, vizometriya and perimetry. It is necessary to accept the polyvitaminic complexes containing vitamins A and E, to carry out correction of a food allowance with obligatory inclusion of products, vitamin-rich and minerals. The forecast for life and working capacity at anomalies of color sight favorable. At the same time at patients decrease in visual acuity is often observed, it is impossible to restore normal color perception.