Cystoid macular edema

Introduction to cystoid macular edema Cystoid macular edema (CME) is a common fundus disease, but it is not an independent disease, but the performance of many fundus diseases in the macula. basic knowledge The proportion of illness: 0.002% Susceptible people: no specific population Mode of infection: non-infectious Complications: macular hole

Causes of cystoid macular edema

(1) Causes of the disease

The most common diseases that can cause cystoid edema of the macula are: retinal vein occlusion, diabetic retinopathy, retinal vasculitis, macular retinal anterior membrane, retinal telangiectasia or Coats disease, uveitis, intermediate uveitis , cataract or other internal eye surgery, macular choroidal neovascularization, retinitis pigmentosa, and rare niacinosis, youthful retinal palpebral fissure, Goldmann-Favre syndrome and idiopathic macular cystic edema ,

(two) pathogenesis

Under normal physiological conditions, the fluid and electrolyte in the eye are drained from the vitreous through the retina and choroid to the blood circulation. In this process, the drainage function of the retinal capillary endothelial cells and the retinal pigment epithelium prevents the accumulation of extracellular fluid. Under the retina and retinal nerve epithelium, plays an extremely important role, the tight connection of retinal capillary endothelial cells prevents the macromolecular substances in the blood vessels from leaking in one direction.

Once the tight structure of the retinal capillary endothelial cells is destroyed, the fluid and macromolecular substances in the blood vessels can leak outward, and the liquid accumulates in the extracellular space of the outer plexus layer of the retina, forming retinal edema if the lesion is located in the macular area. Since the Henle fibers in the outer plexiform layer of the macula are radially arranged, the liquid accumulated in this region forms a characteristic polycystic morphology, and the extracellular space in the central region of the macula is expanded by liquid accumulation due to the central region. The gap is large, and the formed capsule cavity is also large, and the surrounding is surrounded by some small capsules.

The vast majority of cystoid macular edema is caused by leakage of retinal capillaries, but a few diseases such as retinitis pigmentosa, excessive niacin intake and other diseases can not detect any abnormalities in retinal capillaries, even in fundus fluorescence. Under angiographic examination, no leakage was found, and angiography was completely normal. For this reason, it may be because the leakage of retinal capillaries is very slight, and the molecules of fluorescein are large, and the damage cannot be transmitted through this. Endothelial cells, thus invisible to fluorescein leakage; or due to certain diseases of the retina, causing some substances to be released into the extracellular space, causing changes in local osmotic pressure; or due to damage to the inner limiting membrane of the retina, Causes fluid to accumulate in the macular area.

The nature of the exudate during retinal edema depends on the extent of damage to the retinal capillary endothelial cells: if the damage to the endothelial cells is light, the leakage is mild and the fluid in the capsule is clear; if the retinal capillary endothelium is heavier, The leaking liquid contains macromolecular fat and protein, and the liquid in the capsule is inevitably turbid. At the same time, the fat and protein of these macromolecules are not easily absorbed and deposited in the retina, forming a yellow-white hard exudation and hard exudation. Arranged around the center of the exudation or radially according to the radial direction of the Henle fibers in the macular area.

Macular cystic edema prevention

The disease is related to factors such as ischemia caused by inflammatory vasculopathy. Found in DPR, RVO, uveitis (especially uveitis), hypertension, retinitis pigmentosa and so on. Various endoscopic procedures, such as cataract, glaucoma, and retinal detachment surgery, vitreous surgery, laser, and condensation can occur. The CME that occurs 6-10 weeks after cataract is called Irvine-Cass syndrome, and most of them resolve spontaneously in 6 months. CME can also occur in subretinal lesions such as CNV and vitreoretinal traction. Should find the cause and actively treat.

Macular cystic edema complications Complications

Prolonged edema can lead to the destruction of nerve fibers and photoreceptor cells. The pigment epithelial cells undergo atrophy, form cystoid degeneration of the macula, permanent damage of visual function, and macular holes can be formed due to rupture of the macula vesicles.

Symptoms of cystoid macular edema Common symptoms Macular cystic edema Visual impairment Fundus changes Retinal edema Uveitis Bleeding or flaming

The early lesions can be basically normal under the ophthalmoscope, and the foveal reflection of the macula is diffuse or disappeared. During the course of the disease, the retinal edema area has different degrees of reflective enhancement or satin-like reflex, the retina thickens, and the late macular edema has a honeycomb or saclike appearance. The thickness of the wall retina is uneven, and the separation of the honeycomb interior and the shadow of the blood vessels can be seen. Some of the small capsules can be very thin and even form a slit.

Clinically, it is difficult to make a diagnosis of macular cystic edema by using ophthalmoscope alone. The ophthalmoscope should be combined with a three-sided mirror or a slit lamp plus a front mirror-90D mirror. The narrow area of the slit lamp is used to check the macular area, and the macular area can be seen. Retinal thickening and vascular shadows, with posterior glare, sometimes visible in the macular area, honeycomb-like appearance, retinal cystic gap, fundus fluorescein angiography is an essential means to diagnose cystoid macular edema, is the diagnosis of cystoid The most commonly used method for edema is also the current gold standard for the diagnosis of cystoid edema. In recent years, optical coherence tomography (OCT) has been used to clearly show the appearance of cystic edema in the posterior pole retinal macular area. One of the best ways of cystic edema.

Irvine-Gass syndrome: Clinically, some patients with cataract surgery have cystoid edema, especially Irvine-Gass syndrome. This syndrome occurs mostly after 4 to 12 weeks after cataract surgery. There were no complications during the operation period. In patients with successful intracapsular cataract extraction, 50% to 70% of patients with fundus fluorescein angiography had retinal capillary leakage around the macula. Therefore, some people think that this leakage is likely to be A normal physiological response after surgery, most of the patients with successful surgery, most of the symptoms are mild or no symptoms, more than 90% of the fundus microscopic examination can not find fundus changes, only the fundus fluorescein angiography found cystoid edema However, when the cystoid macular edema is severe, there may be obvious visual impairment. Only 5% to 15% of fundus fluorescein angiography shows visual impairment in patients with leakage. In recent years, with the improvement of surgical instruments, the improvement of skills Intracapsular cataract extraction without intraocular lens implantation, the clinically significant cystoid macular edema is about 2%; the same surgery if implanted anterior chamber artificial The incidence rate increased to 9.9%. The incidence of extracapsular cataract extraction and posterior chamber intraocular lens implantation was about 1.3%, while that of phacoemulsification combined with posterior chamber intraocular lens implantation was 0.5%. The symptoms of cystoid macular edema are not obvious, the visual impairment is mild, the patient is tolerable, and usually resolves spontaneously 3 months after surgery.

Idiopathic cystoid macular edema: extremely rare, the diagnosis must be very cautious, first of all must be asked in detail about the patient's history of eye surgery, laser and eye trauma; then carefully examine the anterior segment of the eye, including KP, Anterior chamber floating cells, Tyndall phenomenon, to exclude very slight anterior uveitis; then fully dilated pupils, use a slit lamp to carefully check the vitreous cells for inflammatory cells, and then use indirect ophthalmoscopy, three-sided mirror to examine the ciliary The flat part of the body and the peripheral part of the fundus to exclude the middle part of uveitis; and the use of fundus fluorescein angiography to exclude retinal vein occlusion, retinal vasculitis, diabetic retinopathy, retinitis pigmentosa, etc., all of which can cause macular cystic edema After the eye disease, it can diagnose idiopathic macular cystic edema.

Examination of cystoid edema of the macula

The necessary exclusionary laboratory tests can be performed for reasons caused by cystoid macular edema.

Fundus fluorescein angiography

In the early stage of angiography, because the liquid in the cystic edema area obscures the background fluorescence of the choroid, the edema is in a dark area. During the venous phase, the retinal capillaries in the macular area are dilated, and the capillaries begin to have fluorescein leakage from the vessel wall. Then the blood vessels become blurred, and the fluorescein leakage gradually increases, forming a strong fluorescence in the macular area. In the late stage of angiography, after 15 to 30 minutes, the macular area can be seen as a typical cystic-like strong fluorescence, forming a petal-like appearance ( Figure 2), if the edema is not very serious, fundus fluorescein angiography can only see a slight strong fluorescence in the macular retina.

2. Optical coherence tomography (OCT)

It is an optical imaging technology with high resolution to the microstructure of the tissue fault. Due to the difference in structure and density of the tissue, the absorption and reflection of light are different. Different colors can be used to represent different tissue structures. Simulating color fundus tomographic images, the depth of the tomographic scan is related to the wavelength of the laser used, the wavelength is long, the penetration is strong, the tomographic scan is deep, and the tomographic accuracy of optical coherence tomography is 8-10 m. Therefore, optical coherence tomography The examination showed the same appearance as the histopathological histology of the living body. The image of OCT in the cystoid macular edema clearly showed the cystic space of the retinal neuroepithelial layer in the macular area. OCT is very sensitive to the detection of cystoid macular edema, and It has a very typical characteristic, even if the fundus fluorescein angiography is not clearly expressed in some cases, OCT can also have a positive finding.

The normal macular center sag disappears, showing that the fovea is flattened or even bulged, the neuroepithelial layer is thicker than normal, and the light-reflecting intensity of the ganglion cell layer, the inner and outer plexiform layers, and the photoreceptor cell layer is generally reduced, with several capsules in between. In the dark area, the sac is in the sac, showing a uniform dark cavity. Different sizes and depths of the cyst can be observed in different scanning directions, mainly in the outer plexiform layer, but also in other layers, dense Distributed in and around the fovea of the macula.

Usually in the early stage of cystoid macular edema, OCT is characterized by multiple small vesicles. As the disease progresses, the small vesicles can gradually fuse into one or several large vesicles. At this time, the fovea is highly raised and vesicles. The surface is only covered by the inner limiting membrane (Fig. 4). If the cystoid edema of the macula continues to increase, once the large vesicle ruptures, the retinal tissue in it is missing, which may form a macular hole.

Diagnosis and differentiation of cystoid edema of macular

According to symptoms, fundus manifestations, and fluoroscopy and OCT, it is not difficult to confirm the diagnosis.

Differential diagnosis

1. Central serous chorioretinopathy (referred to as "middle pulp")

More common in young men, the macular part of the serous discoid retinal detachment and / or serous retinal pigment epithelial (RPE) detachment, self-limiting and recurrence tendency, fluorescein imaging with RPE leakage points and / or Serous RPE detachment; CME fluorescein imaging is the accumulation of petal-like fluorescent dyes in the macular area, so CME and "medium pulp" are easy to identify.

2. Intraocular tumor

Regardless of benign or malignant masses, especially choroidal hemangioma often associated with macular degeneration of the retina and/or cystoid macular edema, there are subretinal choroidal masses in addition to CME in the fundus, which is the first to encounter CME clinically. Should look for the cause of CME, use binocular indirect ophthalmoscope to examine the fundus in detail, can avoid misdiagnosis and treatment errors.

3. Central retinal artery occlusion

This is an emergency case. There is a sudden loss of vision. The yellow spot on the fundus has cherry red spots, and the retina of the posterior pole is milky white. This is the swelling of the cells themselves and intracellular fluid. Fluorescence angiography can show that the central retinal artery is blocked or insufficient. Fluorescence angiography is completely different from CME in that the arteries are not filled or delayed, or the circulation time is prolonged. The two are easy to identify.

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