Neovaskulyarization of a cornea
Neovaskulyarization of a cornea is a disease at which blood vessels of a limb sprout in Strom of a cornea. Clinically pathology is shown by decrease in visual acuity up to a blindness, visualization of vessels in the form of "red branches" on a cornea surface, violation of binocular sight. The eye biomicroscopy, a vizometriya, a keratometriya, ultrasonography of an eye is applied to diagnosis. Surgical tactics comes down to carrying out a keratoplasty, keratoprotezirovaniye, laser coagulation or photodynamic therapy. Conservative treatment is based on instillations of glucocorticosteroids in a conjunctiva cavity, their subconjunctival and parabulbarny introduction.
Neovaskulyarization of a cornea
Neoangiogenesis of a cornea – widespread pathology in practical ophthalmology. According to statistical data, about 40 million patients around the world need change of a cornea in connection with development of complications of this disease. It is proved that normal only 0,01% of endoteliotsit are at a division stage. This indicator increases in a condition of a chronic hypoxia in tens of times. At 14,5% of patients permanent decrease in visual functions is observed. The risk of development of a blindness makes about 20-25%. The disease with an identical frequency occurs among persons men's and female. Geographical features of distribution are not noted.
Cornea neovaskulyarization reasons
Allocate a set of the factors leading to this disease. All of them have the uniform mechanism of development as the strengthened angiogenesis is a compensatory reaction of fabrics to deficiency of oxygen. Main reasons for a neovaskulyarization:
- Traumatic damages. Owing to injuries (wounds, burns of eyes) or surgical interventions in areas of a cornea, an orbital conjunctiva and limb cicatricial defects which lead to a deep neovaskulyarization are formed.
- Chronic keratit. The long course of inflammatory processes (keratit, keratokonjyunktivit) becomes the reason of a hypoxia of covers of an eye and provokes neoangiogenesis.
- Degenerate and dystrophic changes. Multiple ulcer defects and recurrent erosion stimulate vascular proliferation because of a thickening of a cornea and insufficient intake of oxygen in deep layers.
- Long carrying contact lenses. The disease develops because of a mechanical barrier on the way of intake of oxygen. At high risk or the first symptoms of pathology to the patient recommend to use lenses with high oxygen permeability and to alternate them to glasses wearing.
Normal the cornea - it is the eyeball cover deprived of blood vessels. Its blood supply and to a traffic is provided by the vascular network located in the field of a limb. A starting factor of development of a disease – a regional hypoxia at which the insufficient amount of oxygen comes to a cornea. It leads to the strengthened nitrogen oxide secretion that is shown by expansion and increase in permeability of vessels on border skler and a cornea. Proteolytic degradation of a basal membrane and activation of a plazminogen promote proliferation of endotelialny cages. The strengthened formation of endoteliotsit, mobilization of peritsit and cells of smooth muscles are the cornerstone of a cornea neovaskulyarization.
From the clinical point of view ophthalmologists allocate the following forms of a neovaskulyarization of a cornea:
- Superficial. Vessels from area of a limb in not changed look pass to a cornea.
- Deep. Vessels, going from peripheral departments to central, grow into thickness of a cornea. Average and deep layers of a stroma are surprised. Skleralny and episkleralny vessels have an appearance in parallel of the going threads.
- Mixed. Process of a neovaskulyarization affects all thickness of a cover.
Cornea neovaskulyarization symptoms
The strengthened angiogenesis leads to growth of vessels on the surface of a cornea that involves decrease in its transparency. At initial stages of a disease visual acuity decreases slightly. If process of a neovaskulyarization reaches the central area, the patient completely loses sight. Narrowing of visual fields is followed by violation of spatial perception. Emergence of fotopsiya and metamorfopsiya is possible. Patients from a neovaskulyarizatsiy cornea shows complaints to emergence of dark stains or "veil" before eyes, note increased fatigue when performing visual work.
At unilateral process binocular sight is broken. Adaptation to monocular sight at defeat of an optical part is complicated at patients of mature age. Because of the constant discomfort caused by hindrances before eyes there is a headache. Many patients use color lenses to reduce expressiveness of visual changes, it aggravates clinical symptomatology even more. The long course of a disease leads to change of radius of curvature of a cornea, its thickening that becomes the reason of increase in an index of refraction and distortion of sight.
The most widespread complication of a neovaskulyarization of a cornea – total vascular turbidity. Besides change of normal color of eyes, the cataract leads to a blindness. Patients with this pathology enter into risk group of development of inflammatory and infectious diseases (keratokonjyunktivit, keratit). The pathological neovaskulyarization often is complicated by hemorrhage in the forward camera of an eye. Seldom intensive angiogenesis acts as the reason of a gemoftalm. At late stages the polimegatizm at which irreversible change of the sizes of endoteliotsit is observed develops.
For the purpose of diagnosis perform external examination and a complex of ophthalmologic researches. Visually germination of vessels in the form of "red threads" is defined. Ophthalmologic inspection provides:
- To Vizometry. Visual acuity measurement – a basic method of diagnostics. Depending on extent of growth of vessels visual acuity varies from insignificant decrease in visual functions to their full loss.
- Eye biomicroscopy. The technique allows to study degree of transparency of optical environments of an eye, to reveal signs of inflammatory and dystrophic changes. At a superficial form blood current in neogenic vessels is defined.
- To Keratometry. The research gives the chance to study structure of a cornea, to define as far as the radius of its curvature changed.
- Ultrasonography of an eye. The purpose of performing ultrasonography in the V-mode – to reveal the secondary changes connected with progressing of a neovaskulyarization.
Treatment of a neovaskulyarization of a cornea
At early stages elimination of an etiologichesky factor excludes progressing of a disease or reduces expressiveness of clinical manifestations. Neogenic arteriola zapustevat and take a form of hardly noticeable "vessels ghosts". Conservative therapy comes down to instillations of glucocorticosteroids in a conjunctival cavity or to parabulbarny and subconjunctival introduction. Surgical treatment is applied at far come forms and includes:
- Through keratoplasty. The technique is used when growing vessels into a cornea on the limited site. After removal of the changed site of a cornea on its place hem donor material.
- Keratoprotezirovaniye. It is a choice method in treatment of patients with a deep form of a neovaskulyarization or with the complicated course of pathology because of emergence of a total vascular cataract. Keratoprotez establish only 3 months later after implantation of a basic plate.
- Laser coagulation of neovessels. Stage-by-stage coagulation of endotelialny channels and capillaries from the central part to the periphery is carried out. The technique is more effective at superficial option of a disease. In the late postoperative period the rekanalization of vessels is possible.
- Photodynamic therapy. The method is based on svetoindutsirovanny chemotherapy. The photosensitizer selectively collects in fabrics with the increased proliferative activity.
Forecast and prevention
The forecast for life at a cornea neovaskulyarization favorable, the forecast concerning visual functions depends on extent of germination of vessels. In the majority a case timely treatment provides a complete recovery of visual acuity. Specific preventive measures are not developed. Nonspecific prevention includes observance of safety measures in conditions of production, monitoring duration of carrying contact lenses within a day. The patient who carries lenses needs to address for consultation the expert at least once a year and to choose lenses with high coefficient of a transmission of oxygen.