Epiretinal membrane (abbreviated as ERM) is a common eye disease that manifests itself in the formation of a thin translucent film formation on the retina in the macula region, which leads to impaired clarity and distortion of central vision without affecting side vision. The proportion of occurrence of this pathology in a number of ophthalmic disorders is 7%. ERM does not lead to total blindness.
What is ERM
The epiretinal membrane is a thin layer of fibrous cellular material that looks like cellophane film. Such a structure consists of fibrous tissue and is formed in the zone of the yellow spot, which is located in the back of the eye. This part 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 the packetfilm);
- epimacular membrane (EMM).
These concepts can equally be considered both as a disease and as a histological structure that serves as its cause.
General characteristics of the disease
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 is detected in people younger than 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.
Structure and formation of 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 under it.
The ERM structure consists of 2 main components:
- cells;
- extracellular matrix.
The latter contains type I, II, III, IV and VI collagen fibers capable of contracting, as well as fibronectin and laminin. The ratio of components depends on the stage of membrane development. 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 assumed 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 the collagen fibrilsprovide the ability of the ERM to contract, which in turn leads to wrinkling of the surface of the retina in the macula.
Causes of disease
By origin, ERM is idiopathic (of unknown origin) or secondary. In the latter case, the formation of a fibrous film has the character of a concomitant pathology and may accompany such eye diseases as:
- uveitis;
- blunt and penetrating eye injuries;
- retinal tears;
- retinal vascular disease;
- oncological education;
- diabetic retinopathy;
- retinal detachment;
- Vitreous hemorrhage.
In most cases, the epiretinal membrane is idiopathic and has no connection with other eye diseases. The reason for the formation of a film on the surface of the macula in this case are 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 due to two factors:
- film covers the surface of the retina, obstructing the access of light and distorting its rays, which reduces the sharpness and correctness of visual perception;
- shrinkage of collagen fibrils causes wrinkling of the retina itself, causing distortion of central vision.
The level of symptomatic manifestations in ERM dependson the degree of development of the disease. In the early stages, the presence of a fibrous membrane is not clinically evident because it is thin and the retinal layer has not yet undergone deformation.
Typical symptoms of progressive ERM are:
- decrease in central vision acuity;
- metamorphopsia;
- visual doubling of objects;
- blurred vision;
- image blur;
- trouble 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 ERM strongly tightens the surface of the retina in the macula region. At the same time, peripheral vision remains unchanged.
In some cases, a progressive epiretinal membrane can lead to serious pathological disorders in the retina (edema, detachment, rupture), as well as fibrotic changes.
Most ERMs are thin, soft and have little to no effect on vision. Such structures are most often detected not on the basis of patient complaints, but during a random examination. The clinical symptomatology of ERM is manifested only in the case of wrinkling of the retinal surface due to the contraction of the collagen fibrils of the membrane, which occurs relatively rarely.
Stages of disease
The epiretinal membrane of the eye has 3 stages:
- appearance of structural retinal disorders with a diameter of no more than 400 microns;
- increase in the diameter of pathological changes (more400 microns);
- formation of Weiss rings.
The first stage has no pathological effect on photoreceptors and therefore has no 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 inside of the fundus;
- in-period - corresponds to the formation of a flat circular contour on the fovea.
Most often, the pathological process occurs in only one eye. In the case of bilateral pathology, the disease develops asymmetrically.
Diagnosis
The initial 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, this 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 ERM is suspected, an ultrasound of the eye is prescribed.
To assess the degree of development of the epiretinal membrane and the structural disorders caused by it, deeper studies are prescribed, which include:
- optical coherence tomography (OCT);
- fluorescein angiography - allows you to assess the degree of macular edema.
Hardware and visualERM diagnosis is usually combined with an eye test, which includes conventional visometry (detection of acuity) and Amsler lattice (determination of the degree of metamorphopsia).
Treatment
The only way to treat the epiretinal membrane of the eye is a surgical intervention, which involves the removal of the resulting fibrous film from the surface of the vitreous body. The scientific name for this procedure is vitrectomy.
In order to remove the epiretinal membrane, it is first necessary to gain access to the surface of the retina. Therefore, at the first stage of the operation, incisions are made on the sclera of the eye and the vitreous gel is removed, replacing it with saline. Then, using 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, in order to exclude recurrence, along with the removal of ERM, membrane peeling of the retina is performed. However, the effectiveness of this procedure in reducing the risk of cellophane macula recurrence is still debatable.
According to professional opinions about the epiretinal membrane of the eye, the vitrectomy should be determined by the surgeon based on the history and careful examination. However, the wishes of the patient are also taken into account in this matter. So, if the presence of ERM does not imply serious complications, and vision problems are not critical for the patient, then the latter himself determinesneed for treatment.
The success of the operation is determined by three main factors:
- duration of ERM;
- disease stage;
- membrane origin (treatment of idiopathic disease is more successful than secondary ERM).
Treatment of the epiretinal membrane of the eye with medical methods has no effect, since drugs cannot change the mechanical disturbances caused by the fibrous film. Glasses and contact lenses are also useless in this case.
Previously used drugs to treat 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 yet surgery is indicated only in case of noticeable visual impairment. Otherwise, the ERM is simply controlled through observation of the patient by an ophthalmologist.
Possible complications of vitrectomy include:
- retinal detachment (1 in 100 cases);
- progression of cataract - clouding of the lens in the eye;
- endophthalmitis (1 in 1000 cases) - postoperative infection, can lead to blindness;
- increased intraocular pressure.
Surgery risks also include bleeding, blurred vision, scarring, droopy eyelids, and anesthesia-related complications. In 10 percent of cases, after vitrectomy, the epiretinal membrane forms again.
