Idiopathic macular anterior membrane

Introduction

Introduction to idiopathic macular anterior membrane

The idiopathic macular epiretinal membrane (IMEM) is an age-related proliferative disease characterized by secondary changes in the formation and contraction of the macular epiretinal membrane. Most patients are asymptomatic, with a few with progressively progressive visual impairment.

basic knowledge

The proportion of sickness: 0.0052%

Susceptible people: no specific population

Mode of infection: non-infectious

Complications: edema

Pathogen

Idiopathic macular epiretinal etiology

Causes:

1. The cause of the disease is unknown. The essence of the membrane is composed of cells derived from the retina and various derivatives or metabolites. According to clinical and cytological studies, the formation of the primary macular anterior membrane is mainly related to posterior vitreous detachment and retina. The cells are involved in the migration of the macular area, which can form a fibrous membrane with contractile capacity (Fig. 1). (1) Posterior vitreous detachment: Most of the primary macular epiretinal membranes (80% to 95%) occur after clinical vitrectomy, which is consistent with the rule of senile vitreous changes, so it is more common in the elderly, in the vitreous In the process of detachment, due to the traction of the vitreous on the retina, the inner limiting membrane of the retina is loosened, stimulating the stellate cells on the surface of the retina so that it can migrate to the inner surface of the retina through the damaged inner limiting membrane; On the other hand, the surface of the retina is conducive to the proliferation of the retinal surface cells and migration to the macular area due to the loss of the vitreous surface. In addition, after the vitreous detachment, the thin vitreous posterior cortex and the vitreous cells remaining on the surface of the macula promote the cells on the retina surface. Migration and retention to the macula. (2) Cell migration: The cells and extracellular components of the macular epiretinal membrane were analyzed by immunohistochemistry and electron microscopy. The main cellular component in the primary macular epiretinal membrane was Müller cells. Through the intact inner membrane, followed by pigment epithelial cells, may have the ability to cross the non-porous retina, or migrate through the peripheral fine pores to the inner surface of the retina, and other cells include fibroblasts, myofibroblasts, and nerve glue. Qualitative cells, clear cells, pericytes and macrophages, these cells may be derived from the retinal blood circulation, some belong to the cell body's own cellular components, extracellular matrix (such as fibronectine, vitronectin and thrombospondine, etc.) from the blood-retinal barrier Plasma, or synthesis by pigment epithelium that migrates to the surface of the retina. Preretinal cells are connected to each other by these substances and form fibrous membrane tissue. The contraction of myofibroblasts can cause contraction of the membrane, thereby pulling the retina and causing a series of Pathological changes and clinical symptoms.

2. According to the primary eye disease causing the anterior membrane and the cellular components constituting the anterior membrane, the secondary macular membrane can be roughly divided into two categories:

(1) caused by rhegmatogenous retinal detachment and its reduction surgery (such as electrocoagulation, condensation or photocoagulation, intraoperative or postoperative bleeding or uveal reaction, etc.), called macular pucker, which is The most common type of secondary macular epiretinal membrane in clinical practice, the incidence rate is up to 50%, often occurring several weeks to several months after surgery. The composition of this type of anterior membrane is mainly pigment epithelial cells, which are from the pigment epithelium of the retina. The risk factors for the formation of the macular anterior membrane after rhegmatogenous retinal detachment through the retinal tears are: 1 The patient is older. 2 preoperative retinal conditions are poor, such as total retinal detachment, vitreoretinal proliferative lesions (PVR) are obvious, retinal fixed folds appear. 3 There is vitreous hemorrhage before or after surgery. 4 puncture or incision of the scleral choroidal discharge, especially in multiple discharges. 5 used during surgery, especially in a wide range, excessive coagulation, condensation or photocoagulation.

(2) Retinal vascular disease, inflammation or trauma can be secondary to the macular epiretinal membrane, other eye diseases such as diabetic retinopathy, retinal vein occlusion, posterior uveitis, Bechet disease, Eales disease, vitreous hemorrhage, Von-Hippel disease, Intraocular tumors, eyeball trauma, and ocular inflammation can also be caused. Because of the different primary eye diseases, the cellular components of the anterior membrane are not the same. For example, inflammatory cells are common with inflammatory cells, accompanied by epithelial or glial cells.

In view of the presence of primary eye disease, the degree of visual acuity affecting the secondary macular membrane is often difficult to judge, and most of the diseased anterior membrane develops slowly, and is often in a stable state later. The posterior vitreous detachment is rare, and about 40% of the macular is present. Cystic degeneration.

Pathogenesis:

1. The role of posterior vitreous detachment in the formation of idiopathic macular anterior membrane. Posterior vitreous detachment (PVD) occurs in more than 60% of the elderly over 65 years old, from 60 to 70 years old. The rate increased from 20% to 52%. In patients with idiopathic macular epiretinal membrane, posterior vitreous detachment is the most common ocular accompanying change, with an incidence of 57% to 100%, most of which are complete posterior vitreous detachment. In patients with posterior vitreous detachment, the incidence of idiopathic macular anterior membrane is also high. It is speculated that when the vitreous appears to detach, the local retinal anatomy changes accordingly, making the retina more susceptible to damage, after the vitreous. When detached, traction is generated on the posterior pole, and the weak zone of the inner limiting membrane is pulled by this, which is prone to damage. This is the beginning of cell proliferation on the surface of the retina and the formation of the macular anterior membrane. If the vitreous body is incomplete, the detachment persists. Causes sustained vitreous macular traction, resulting in macular damage such as cystoid macular edema.

Although the posterior vitreous detachment is closely related to the idiopathic macular anterior membrane, there are still a considerable number of idiopathic macular epiretinal patients with no posterior vitreous detachment, the occurrence of idiopathic macular anterior membrane and posterior vitreous detachment. The relationship still needs to be explored.

2. Cell migration and the development of idiopathic macular anterior membrane. It is generally believed that glial cells are derived from the inner layer of the retina, migrate to the inner surface of the retina through the lesion of the inner limiting membrane, and proliferate along the surface of the retina, moving to the periphery. From an anatomical point of view, the inner limiting membrane on the surface of the optic disc and the large blood vessel is relatively weak, prone to breakage, providing a channel for the migration of glial cells. Under the electron microscope, the proliferative macular anterior membrane tissue can be directly observed with the inner limiting membrane. The rupture phase continues, confirming this theory.

Another cell component of the macular membrane - retinal pigment epithelial cells may migrate to the inner surface of the retina by:

(1) Entering the inner surface of the retina through a subclinical retinal tear or autistic retinal tear.

(2) Retinal pigment epithelial cells may be transformed from glial cells.

(3) Various physical and chemical factors in the vitreous cells can induce chemotaxis of retinal pigment epithelial cells, so that the trans-retinal migration can be completed. Under the influence of various factors in the vitreous cavity, the retinal pigment epithelial cells undergo morphological changes through cell deformation. The outer layer of the retina migrates to the inner surface of the retina, and the retinal pigment epithelial cells release chemokines and attract astrocytes.

(4) In addition, there may be resting primitive retinal pigment epithelial cells on the inner surface of the retina, which are activated by various factors, but these speculations are currently unclear.

3. Pathophysiological changes of the retina caused by the idiopathic macular anterior membrane. Electron microscopic observation confirmed that the contraction of the cellular components in the anterior membrane of the idiopathic macula leads to the retina being pulled to form a anterior membrane of various shapes, before the macula. The contraction of the membrane on the retina is mainly in the tangential direction, so the chance of causing cystoid edema of the macula is small. If the macular anterior membrane is accompanied by vitreous macular traction, it is prone to cystoid edema, even the lamellar hole. .

The fovea of the macula is pulled, deformed and displaced, and small blood vessels around the macula are pulled by the anterior membrane, oppressed, resulting in dilatation, deformation, venous return disorder, decreased capillary flow velocity, etc., which will lead to vascular leakage, bleeding spots, etc. Phenomenon, clinical manifestations of visual distortion, enlargement or reduction, visual fatigue and other symptoms.

Prevention

Idiopathic macular anterior membrane prevention

There is currently no relevant content description, and lifestyle and eating are very important. Lifestyle and diet are very important. Retinal detachment should increase the intake of crude fiber food, eat more fresh vegetables, fruits and appropriate amount of pig liver, sheep liver avoid smoking, ban drinking, eat less or not eat irritating food, such as pepper.

Complication

Idiopathic macular anterior membrane complications Complications edema

Macular anterior membrane thickening can cause retinal deformation, edema, small bleeding spots, cotton wool spots and local serous retinal detachment.

Symptom

Idiopathic macular anterior membrane symptoms Common symptoms Visual distortion of the fundus changes visually small lens opacity double vision

1. Common symptoms of idiopathic macular anterior membrane are visual acuity, visual acuity, visual distortion and monocular diplopia. Early disease can be asymptomatic. Visual acuity can occur when the macular anterior membrane affects the fovea. , usually mild or moderate, rarely less than 0.1, when the macular edema folds, can cause significant vision loss or visual distortion, Amsler checklist can detect visual deformation, when the vitreous occurs After complete detachment, the macular anterior membrane and the retina are separated, the symptoms can be relieved by themselves, and vision is restored, but this situation is relatively rare.

Reasons for the impact of the function include the following:

1 turbid macular anterior membrane obstructs the fovea;

2 The retina of the macula is deformed by traction;

3 macular edema;

4 due to traction of the macular anterior membrane leads to local retinal ischemia, the severity of the symptoms is related to the type of macular anterior membrane. If the macular anterior membrane is relatively thin, 95% of the eyes can maintain visual acuity of 0.1 or more, usually around 0.4.

2. The ocular changes of the idiopathic macular anterior membrane are mainly in the fundus macular area. Most cases are accompanied by complete or incomplete detachment of the vitreous. In addition, the idiopathic macular anterior membrane often occurs in the elderly, often There are varying degrees of lens opacity or lens core hardening.

In the early stage of the disease, the macular anterior membrane is a transparent membrane tissue attached to the surface of the retina. It appears as a silky shape in the posterior pole. The retinal light is reflected or drifting. The lower part of the retina is slightly edematous and thick, sometimes used. The oblique light obliquely shows the projection of large blood vessels on the surface of the retina on the retinal pigment epithelial layer. At this time, the fovea of the macula is generally not invaded, and does not affect vision.

When the macular anterior membrane tissue is thickened and contracted, the retina can be pulled to form wrinkles on the surface. These wrinkles have different shapes and can be expressed as slender linear stripes, which are radially dispersed by one or more centers; It is characterized by irregularly arranged broadband strips. The thickened macular anterior membrane gradually changes from early translucent to opaque or grayish white. It crawls on the retina surface in groups or strips. Sometimes these bands are seen leaving the retina and suspended. In the posterior space of the vitreous, or in the form of a bridge attached to the surface of the retina in the distance.

After the retina is pulled, the small blood vessels of the radial disc of the optic disc are deformed, distorted, and even the vascular arch is concentrically contracted, and the area of the macular avascular area is reduced. In the advanced stage, the retinal large vein can become dark, dilated or deformed, and sometimes the macular retina Also visible fine cotton wool spots, bleeding spots or microaneurysms, if the macular anterior membrane is centered, its traction will lead to the displacement of the macular area, if the thickened macular anterior membrane is incomplete, can form pseudo-macular hole (pseudohole), The defect is dark red in appearance.

Most macular anterior membranes are confined to the optic disc and vascular arch, and in very few cases they can extend beyond the vascular arch and even reach the equator.

Examine

Examination of idiopathic macular anterior membrane

No special laboratory tests.

1. FFA examination FFA can clearly show the shape of the capillary ring of the macular area, the deformation of the small blood vessels, the distortion phenomenon, and the abnormal strong fluorescence from the lesion area, fluorescent shielding or spot-like, irregular fluorescent leakage.

In the early stage of idiopathic macular anterior membrane, there is only cellophane or silk-like reflection in the fundus, and there is no change caused by retinal traction. At this time, there is no obvious abnormal change in fluorescence angiography, and sometimes the fluorescence of RPE damage can be found. .

With the development of the disease, the retina of the macula is pulled and a series of pathophysiological changes appear. The main manifestations of fluorescein angiography are:

(1) The small blood vessels in the macular area are pulled by the macular anterior membrane, twisted or straightened, and the macular arch ring becomes smaller, deformed or displaced. According to the degree of blood vessel being pulled, Maguire et al will have an idiopathic macular The fundus fluorescein angiography was classified into 4 grades. The affected vessels were divided into 1 quadrant, 2 quadrants, 3 quadrants and 4 quadrants. The retinal vessels were rarely abnormal.

(2) In the progressive development of the idiopathic macular anterior membrane, the vascular barrier is damaged due to the pulling of the membrane, dye leakage occurs, and sometimes membrane staining is observed.

(3) There is a star or petal-like leakage in the cystoid edema of the macula. Because the macular area is pulled, the cystoid edema of the macula is more atypical and has irregular fluorescence accumulation.

(4) If the macular anterior membrane is thicker, it can show different degrees of fluorescence obscuration. In rare cases, the local superficial retina is accompanied by tiny hemorrhagic plaques, which also appear as fluorescent obscuration.

2.O CT examination Optical coherence tomography is a new non-contact, non-invasive tomography technique developed in the 1990s. It is measured by light reflection. Its axial resolution is up to 10m, which can show the back of the eye. The microscopic morphology is similar to the histopathological observation. The OCT examination is very intuitive for the observation of the idiopathic macular anterior membrane. The exact rate is more than 90%. It can diagnose the opaque transparent macular anterior membrane and provide the macular front. The characteristics of the retinal section of the membrane and its deep part, analysis of the location, shape, thickness and relationship of the macular anterior membrane to the vitreous of the retina to determine the presence or absence of cystoid edema, full-thickness, lamellar or pseudo-macular hole, and presence The macular area is shallowly detached.

OCT examination can confirm the diagnosis of the macular anterior membrane, especially in the early clinical manifestations. OCT can show the macular anterior membrane when the fundus examination only shows hyalinization. In the OCT examination, the main manifestations are:

(1) A medium-high-enhanced and widened light band connected to the inner layer of the macula, sometimes the anterior membrane and the inner surface of the retina are widely adhered and it is difficult to distinguish the boundary, and sometimes it may be agglomerated to the vitreous cavity.

(2) thickening of the retina, if accompanied by macular edema, it can be seen that the fovea sag becomes shallow or disappears.

(3) If the macular anterior membrane is surrounded by the fovea, a concentric contraction occurs, and the fovea has a steep or narrow shape, forming a pseudo-macular hole.

(4) If the neuroepithelial layer is partially missing, a lamellar macular hole is formed. The thickness of the macular anterior membrane can be quantitatively measured by OCT examination. Wilkins et al. measure the 169 eyes macular anterior membrane with an average thickness of (61±28) m. .

3. Visual field examination As a psychophysical examination method, the early changes of macular diseases can be accurately reflected by measuring the macular threshold. With the automatic perimetry, the corresponding regional photosensitivity can be performed according to the extent of macular lesions. Sensitivity analysis showed that there was no visual field abnormality in the early idiopathic macular anterior membrane, and most of the late visual field changes were different degrees of light sensitivity reduction (Fig. 5). Using the sensitivity of light sensitivity and light threshold, it can be used for idiopathic macular The course of disease progression and surgical outcome were evaluated for visual function.

4. Visual electrophysiological examination The visual electrophysiological examination often used to determine macular function includes clear electroretinogram, scotopic red light and bright red electroretinogram, scintillation photoelectroencephalogram, local macular electroretinogram (local macular) Electroretinogram, multifocal electroretinogram (mfERG), visual evoked potential, etc., multi-focal electroretinogram has objective, accurate, localized, quantitative characteristics, which can more accurately, sensitively and quickly determine the posterior pole The visual function of the retina in the range of 23°, the idiopathic macular anterior membrane has little effect on the electrical activity of the retina. The early visual electrophysiological examination generally has no obvious abnormalities. The advanced local macular electroretinogram and multifocal electroretinogram may be different. The degree of amplitude reduction is thought to be related to the traction of the macular membrane to the retinal tissue, the change of the orientation of the cone cells and the decrease of the refractive interstitial transparency. These two examinations serve as objective and comparative evaluation of visual function. Sensitive indicators are important for analyzing disease progression and surgical outcomes.

5. The composition of the cell fibrotic preretinal membrane is mainly composed of cellular components and collagen fibers produced by these cells.

(1) Cellular components: All studies to date have confirmed that the cellular components of the anterior membrane are multi-sourced, the simple retinal membrane, glial cells are the most important cellular components, and the composite preretinal membrane The cellular components are much more complicated, including glial cells, pigment epithelial cells and fibroblast-like cells, as well as vitreous cells, inflammatory cells and macrophages, etc., to identify cells in the proliferating membrane, even using electron microscopy. It is also very difficult, so it sometimes needs to be identified by immunohistochemistry. The main cell morphological features are briefly described as follows:

1 glial cells: It is not only the main component of the simple anterior membrane, but also one of the most common cellular components in the complex anterior membrane. The glial cells include two kinds, namely Müller cells and stellate glial cells. Both types of cells are large in size. Müller cells have an angular nucleus with dense nuclear chromatin, polar, cytoplasmic processes, microvilli and basement membrane, and abundant cytoplasmic intermediate filaments (10 nm) in the cytoplasm. There may be microfilaments, in addition to the smooth endoplasmic reticulum, glycogen, free ribosomes, mitochondria and Golgi apparatus, stellate glial cells have elliptical nucleus, long cytoplasmic processes, around the blood vessels The base membrane is visible, and the main organelles and abundant intermediate filaments are also visible in the cytoplasm, but the smooth endoplasmic reticulum is less than the Müller cells.

2 Pigment epithelial cells: It is one of the main cellular components in the composite preretinal membrane, especially for rhegmatogenous retinal detachment, which is considered to be the most important cellular component.

(2) Interstitial: The interstitial membrane of the fibrillar preretinal membrane mainly contains a large number of collagen fibers with a diameter of 20 to 25 nm, which is about 1 times thicker than normal vitreous collagen fibers (Fig. 8), so it is considered to be The collagen fibers are produced by the cells in the anterior membrane, and the retinal pigment epithelial cells, glial cells and fibroblasts can also synthesize collagen fibers. In addition, there are some proteins in the intercellular substance, the most important of which is fibronectin. Immunohistochemical staining has been shown to be abundant in the anterior membrane. It plays an important role in promoting cell migration, cell recognition, contact, spread and aggregation. Fibronectin can be produced by cells in the anterior membrane of the retina. It can also be directly infiltrated into the anterior membrane tissue by plasma due to destruction of the blood-retinal barrier.

6. Neovascularization In the vascular fibrotic epiretinal membrane, in addition to a variety of cellular components and collagen fibers as well as the cellulosic retinal anterior membrane, there are many new blood vessels (Fig. 9), in the cellular composition. Glial cells are the most common. In addition, there are many spindle-shaped cells. It has a homogeneous nucleus, abundant cytoplasm, positive eosin staining, and new blood vessel distribution in the anterior membrane. From the optic disc or other parts of the retina, the retinal inner membrane and the posterior vitreous membrane of the new blood vessel can be seen to have a breach. The neovascularization is often dilated, the wall of the tube is thick, and the surrounding vitreous body is often concentrated. Often there is adhesion to the retina, the retina near the adhesion may have detachment and atrophic changes, there are more fibronectin in the interstitial cell, the retinal tissue itself also has pathological changes of the primary retinal disease, such as: diabetes Retinopathy, venous obstruction, etc.

Diagnosis

Diagnosis and diagnosis of idiopathic macular membrane

Diagnosis can be confirmed based on fundus changes and fundus angiography.

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