The epiretinal membrane (abbreviated as ERM) is a common eye disease, which manifests itself in the formation of a thin translucent film formation on the retina in the region of the macula, which leads to impaired clarity and distortion of central vision without affecting the lateral. The proportion of occurrence of this pathology in a number of ophthalmic disorders is 7%. ERM does not lead to complete blindness.
What is a herm?
The epiretinal membrane is a thin layer of fibrous cellular material that resembles a cellophane film in appearance. Such a structure consists of fibrous tissue and forms in the area of the macula, which is located in the back of the eye. This portion of the retina is responsible for central vision.
In medicine, the epiretinal membrane has 2 synonymous designations:
- cellophane macula (so named because of the visual resemblance to a packet film);
- epimacular membrane (EMM).
These concepts can be equally considered both as a disease and as a histological structure that serves as its cause.
General characteristics of the disease
The epiretinal membrane is predominantly an age-related disease. Most often, it is diagnosed in patients aged 65 to 70 years and only in 3.7% of cases detected in people under 60.
ERM is most often formed in only one eye, but bilateral pathology also occurs. The rate of development of the disease is very slow.
The structure and formation of the ERM
The epiretinal membrane of the eye consists of fibrous scar tissue and is formed on the vitreomacular surface from retinal cells and (or) the pigment epithelium located below it.
The structure of the computer consists of 2 main components:
- cells;
- extracellular matrix.
The structure of the latter includes collagen fibers of type I, II, III, IV and VI, capable of reduction, as well as fibronectin and laminin. The ratio of components depends on the stage of development of the membrane. So, the extracellular matrix of late ERM consists mainly of collagen of the first and second types, the sixth is also present in large quantities. It is believed that the latter serves to attach the epiretinal membrane to the retina.
Collagen fibers form an inhomogeneous network of thin extracellular fibrils oriented in an arbitrary direction. Their diameter varies from 6 to 15 nm. It is collagen fibrils that provide the ability of the ERM to contract, which in turn leads to wrinkling of the surface of the retina in the macula.
The causes of the disease
By origin, ERM is either idiopathic (of unknown origin) or secondary. In the latter case, the formation of a fibrous film has the nature of a concomitant pathology and can accompany such eye diseases as:
- uveitis;
- blunt and penetrating eye injuries;
- retinal tears;
- retinal vascular disease;
- oncological formations;
- diabetic retinopathy;
- retinal detachment;
- vitreous hemorrhage.
In most cases, the epiretinal membrane is idiopathic and has no connection with other eye diseases. In this case, the reason for the formation of a film on the surface of the macula is natural (most often age-related) changes in the structure of the vitreous body, which lead to the release of cells from the retina and the pigment layer into its cavity. Settling on the macula, they begin to secrete collagen fibers, forming an ERM.
Pathogenesis
The clinical picture of ERM is associated with two factors:
- the film covers the surface of the retina, making it difficult for the light to access and distorting its rays, which reduces the sharpness and correctness of visual perception;
- contraction of collagen fibrils leads to wrinkling of the retina itself, causing distortion of central vision.
The level of symptomatic manifestations with ERM depends on the degree of development of the disease. In the early stages, the presence of the fibrous film has no clinical manifestations, since it is thin and the layer of the retina has not yet undergone deformation.
Typical symptoms of progressive ERM are:
- decreased visual acuity;
- metamorphopsia;
- visual double objects;
- blurred vision;
- image blur;
- problems reading small text.
Metamorphopsia is a distortion of the visible contours of objects. With such a defect, straight lines may appear curved or wavy. This effect is observed when the ERM strongly tightens the surface of the retina in the region of the macula. In this case, peripheral vision remains unchanged.
In some cases, a progressive epiretinal membrane can lead to serious pathological disorders in the retina (edema, exfoliation, rupture), as well as fibrotic changes.
Most ERMs are thin, soft, and have virtually no effect on vision. Such structures are most often found not on the basis of patient complaints, but during a random examination. The clinical symptoms of ERM are manifested only in the case of wrinkling of the surface of the retina due to contraction of the collagen membrane fibrils, which is relatively rare.
Stages of the disease
The epiretinal membrane of the eye has 3 stages:
- the appearance of structural disorders of the retina with a diameter of not more than 400 microns;
- an increase in the diameter of pathological changes (more than 400 microns);
- the formation of Weiss rings.
The first stage does not have a pathological effect on photoreceptors and therefore does not have symptomatic manifestations.
The disease is characterized by a rather slow development, in which 2 stages are distinguished:
- a-period - corresponds to the appearance of a small yellow spot in the central fossa located on the inner side of the fundus;
- in-period - corresponds to the formation of a flat circular contour in the central fossa.
Most often, the pathological process occurs in only one eye. In the case of bilateral pathology, the disease develops asymmetrically.
Diagnostics
The primary detection of ERM usually occurs during a routine examination of the fundus, during which the ophthalmologist sees this formation in the form of a shiny wrinkled film covering the macula. In the early stages of the disease, such a structure may not be visible.
Examination of the fundus may not be effective in the presence of clouding of the transparent media of the eye (sclera, lens). In this case, if there is suspicion of an ERM, an ultrasound of the eye is prescribed.
To assess the degree of development of the epiretinal membrane and the structural disturbances caused by it, deeper studies are prescribed, which include:
- optical coherence tomography (OCT) ;
- fluorescence angiography - allows you to assess the degree of edema of the macula.
Hardware and visual diagnostics of the ERM is usually combined with a visual examination, which includes conventional visometry (detection of acuity) and the Amsler lattice (determining the degree of metamorphopsy).
Treatment
The only way to treat the epiretinal membrane of the eye is through surgery, which involves removing the resulting fibrous film from the surface of the vitreous. The scientific name for this procedure is vitrectomy.
In order to remove the epiretinal membrane, it is first necessary to access the surface of the retina. Therefore, at the first stage of the operation on the sclera, the eyes make incisions and remove the vitreous gel, replacing it with saline. Then, with the help of special tools, the epiretinal membrane is separated from the retina. The operation is performed under local anesthesia. Holes made in the sclera are sutured.
In some cases, to prevent relapse, along with the removal of the ERM, membrane retinal peeling is performed. However, the effectiveness of this procedure in reducing the risk of re-formation of cellophane macula is still controversial.
According to professional reviews of the epiretinal membrane of the eye, the appropriateness of vitrectomy should be determined by the surgeon based on an anamnesis and a thorough examination. However, the patient's wishes are also taken into account in this matter. So, if the presence of an ERM does not imply serious complications, and vision problems are not critical for the patient, then the latter himself determines the need for treatment.
The success of an operation is determined by three main factors:
- the duration of the existence of the computer;
- stage of the disease;
- the origin of the membrane (treatment of an idiopathic disease is more successful than secondary ERM).
The treatment of the epiretinal membrane of the eye with medical methods has no effect, since the drugs cannot change the mechanical disturbances caused by the fibrous film. Glasses and contact lenses are also useless in this case.
Previously used drugs for the treatment of the epiretinal membrane are not currently used due to their high toxicity to the eyes.
Complications after surgery
In most cases, vitrectomy has no complications, and nevertheless, surgery is prescribed only in case of noticeable visual impairment. Otherwise, the ERM is simply monitored by observing the patient with an ophthalmologist.
Possible complications of vitrectomy include:
- retinal detachment (1 out of 100 cases);
- cataract progression - clouding of the lens in the eye;
- endophthalmitis (1 out of 1000 cases) - postoperative infection, can lead to blindness;
- increased intraocular pressure.
The risks of surgery can also include bleeding, visual impairment, scarring, the appearance of a dilapidated eyelid and complications associated with anesthesia. In 10 percent of cases after vitrectomy, the epiretinal membrane forms again.