Acute retinal necrosis syndrome

Introduction to acute retinal necrosis syndrome Acute retinal necrosis syndrome (ARN) is an ocular disease caused by viral infection (mainly varicella-zoster virus and herpes simplex virus infection), typically characterized by retinal focal necrosis and retinal arteritis Main retinal vasculitis, moderate vitreous opacity, and later retinal detachment. basic knowledge The proportion of illness: 0.003% Susceptible people: no specific population Mode of infection: non-infectious Complications: retinal detachment retinopathy vitreous hemorrhage cataract optic atrophy

Causes of acute retinal necrosis syndrome

(1) Causes of the disease

It is currently believed that the disease is mainly caused by varicella-zoster virus or herpes simplex virus. As for why these viruses sometimes cause anterior uveitis and sometimes cause ARN, there is no satisfactory explanation.

(two) pathogenesis

It is generally believed that after infection with a herpes simplex virus or a latent virus, they can reach the iris and ciliary body along the parasympathetic fibers of the oculomotor nerve, causing anterior uveitis; in the central nervous system, viral replication is mainly limited In the optic nucleus of the visual nucleus and the hypothalamus, the virus may transit from the brain to the retina through retrograde axonal transport, directly causing cytopathological changes; at the same time, viral infection may also cause an immune response, which may result in an immune response. Necrosis of the retina; experiments have shown that the herpes virus infection of the retina is affected by T lymphocytes, so it is believed that T cells play a role in the occurrence of ARN, although it is not clear whether the patient's retinal vasculitis is a direct invasion of the virus or an immune response. Caused by, but the appearance of retinal vasculitis will undoubtedly increase the retinal ischemia and promote retinal necrosis, the destruction of blood-retinal barrier function causes proteins and inflammatory chemokines to enter the vitreous, trigger proliferative vitreoretinopathy, retinal necrosis Multiple retinal tears and proliferative vitreous optic network Lesions traction retinal detachment patients prone to late.

Acute retinal necrosis syndrome prevention

Improving the body's immunity can prevent the occurrence of ARN.

Acute retinal necrosis syndrome complications Complications, retinal detachment, retinopathy, vitreous cataract, optic atrophy

1. Retinal detachment: The most common complication of this disease is retinal detachment, the incidence rate is as high as 75% to 86%, often occurs in the recovery period of infection (1 month to several months after onset), manifested as rhegmatogenous retinal detachment Retinal tears are often multiple, prone to the junction of necrosis and normal retina, which is related to full-thickness retinal necrosis, vitreous fibrosis and traction, and exudative retinal detachment can also occur in the acute phase of inflammation.

2. Proliferative vitreoretinopathy: This is due to a large amount of exudate, inflammatory factors, and inflammatory chemokines entering the vitreous.

3. Retinal and / or optic disc neovascular membrane formation: This is related to retinal capillaries without perfusion, a small number of patients after retinal detachment occurs retinal neovascularization, these new blood vessels are prone to bleeding, causing vitreous hemorrhage.

4. Concurrent cataract: Concurrent cataract can occur in the later stages of the disease, and opacity in the posterior capsule of the lens is common.

5. Others: Some patients may have optic atrophy, and individual patients have eyeball atrophy.

Symptoms of acute retinal necrosis syndrome Common symptoms Eye pain keratitis Congestive sclera Outer inflammatory eye pressure Increase retinal bleeding Eye shadow

1. Symptoms: Patients usually have occult occultity, often with unilateral redness, eye pain, periorbital pain, irritation or foreign body sensation. Some patients usually complain of blurred vision, black eyes in front of the eyes, and generally no obvious visual loss in the early stage, but Significant loss of vision may occur in the later stages due to involvement of the macula and retinal detachment.

2. Signs

(1) Anterior segmental lesions: The original affected part of ARN is in the middle retina, and the anterior segment of the eye is secondary. Therefore, the anterior segment of the eye is generally mild, and mild ciliary congestion, dusty or sheep-like KP may occur. Mild to moderate anterior chamber flash, small and moderate amount of anterior chamber inflammatory cells, scattered in the iris after adhesion, occasionally causing anterior chamber empyema, this inflammation is different from other causes of anterior uveitis, it usually causes Increased intraocular pressure, therefore, the possibility of this disease should be considered for those with elevated intraocular pressure in the early stage of the disease.

Some patients with immunodeficiency may be accompanied by viral keratitis. In some patients, diffuse scleral inflammation, scleritis, or eyelid inflammation may occur.

(2) lesions in the posterior segment of the eye: changes in the posterior segment of the eye mainly include retinal necrosis, retinal vasculitis and vitreous inflammatory response.

Retinal necrosis lesions first appeared in the mid-peripheral retina, with plaque-like "thumbprint" or large yellow-white necrotic lesions. The necrotic lesions appeared dense, thickened, and advanced from the middle to the posterior pole retina. Atrophy and salt-like pigmentation, retinal vasculitis usually involves the retinal artery, the vein can also be affected, manifested as vasculitis, vascular occlusion (blood vessels become white line), this vasculitis can not only occur in the area of retinal necrosis, but also Seen in the normal appearance of the retina, may be accompanied by a bit or piece of retinal hemorrhage.

Vitreous inflammatory response is an important feature of this disease, which can occur in almost all patients, usually characterized by moderate inflammatory response, vitreous opacity, inflammatory cell infiltration, late vitreous liquefaction, proliferative changes and traction retinal detachment.

In addition to the above changes, some patients may have optic neuritis, optic disc edema, macular edema, afferent pupillary defects and other changes.

Examination of acute retinal necrosis syndrome

The diagnosis of ARN is mainly based on typical clinical manifestations, laboratory and auxiliary examinations. In general, serious eye examinations are performed on patients, especially with indirect ophthalmoscopy or three-sided examination. The diagnosis is not difficult, but it is clinically suspicious. Patients should perform some necessary laboratory tests:

1. Detection of aqueous humor and vitreous antibodies: Immunofluorescence can be used to detect specific antibodies. If specific anti-herpes virus antibodies are found in the eye, it is helpful for diagnosis. Serum-specific antibody detection also helps in diagnosis. However, it should be noted that many ARN patients have negative serum antibody or immune complex test results. Therefore, the diagnosis of ARN cannot be excluded based only on negative results.

2. Histopathological examination: It is an invasive examination. The clinical variation of this disease is large. It is feasible for some suspected patients to have diagnostic vitrectomy and/or retinal biopsy. The obtained specimens can be used for virus culture, histology and immune tissue. Chemical examination, PCR detection, in situ hybridization, etc., specimen culture results are positive, histological examination found that virus inclusion bodies and electron microscopy observed viral particles, which is important for diagnosis, but if the culture results are negative and no virus inclusions are found, it cannot Excluding the diagnosis of ARN, it has been shown that a large number of virus specimens are observed under electron microscope, and negative results may still occur in culture.

3. Other laboratory tests: Although these tests cannot directly confirm the diagnosis of ARN, they are very useful for excluding certain systemic diseases, guiding clinical medication, monitoring the side effects of drugs, etc., for those who use acyclovir, Blood cell count, creatine, blood urea nitrogen and liver function tests should be performed before and during treatment, and regular follow-up observation during treatment; chest X-ray examination and tuberculin skin should be performed in patients who are scheduled to undergo glucocorticoid therapy Test to exclude tuberculosis from active tuberculosis or other organs; in immunosuppressive patients, some infections (such as syphilis) can appear similar to the clinical manifestations of ARN, so patients should be tested for HIV antibodies and syphilis to determine or Excluding these diseases, in addition, the detection and examination of serum angiotensin-converting enzyme, Toxoplasma antibody, etc. should be selectively performed according to the specific conditions of the patient.

1. Fluorescein fundus angiography: Fluorescein fundus angiography is very useful for determining the cause of visual loss in the center of the patient, the extent of infection, etc. The angiographic changes that may occur in ARN are as follows:

1 retinal movement, segmental dilatation of the vein, dye leakage and staining of the vessel wall;

2 retinal dye leakage, showing patchy strong fluorescence;

3 bleeding masks fluorescence;

4 focal choroidal filling defects can be seen in the arterial phase, and this change is related to local choroidal inflammatory cell aggregation and damage of retinal pigment epithelium;

5 obstruction of the central retinal artery or its branches;

6 In the venous phase, there is no or only less retinal perfusion in the active retinitis area, and both arterial and venous fluorescence show a sudden cut-off appearance. This fluorescence cutoff is helpful for the diagnosis of ARN, but also It should be noted that this change can also be seen in the cytomegalovirus (CMV) retinitis and intravitreal injection of aminoglycosides to the retina toxicity;

7 can see optic disc staining during the circulation period, especially in patients with optic neuritis;

8 cystoid edema of the macula;

9 In the stage of disease recovery, window-like defects may occur due to changes in the retinal pigment epithelium.

2. Indocyanine green angiography examination of acute retinal necrosis syndrome can also cause choroidal changes, indocyanine green angiography can find the following lesions:

1 choroidal vasodilation;

2 strong flaky fluorescence caused by increased choroidal vascular permeability;

3 weak fluorescent dark spots.

3. Other examinations: Ultrasound is a very useful auxiliary examination method for determining the presence or absence of retinal detachment when vitreitis significantly affects the visibility of the fundus. It is also helpful for finding optic nerve sheath enlargement caused by optic neuritis.

Active inflammatory phase electroretinogram (ERG) examination can find that a, b wave is reduced, with or without oscillation potential reduction, changes in the retinal current map are directly related to the extent of the affected tissue, the severity of the involvement, severe outbreaks Early detection of the type ARN can be seen as flash ERG extinguished.

CT scans revealed an enlarged optic nerve sheath of the affected eye or even the unaffected eye; MRI found that the patient had a visual beam, a change in the chiasm and lateral geniculate body, suggesting that the infection may have been transmitted through the glial axon.

Diagnosis and diagnosis of acute retinal necrosis syndrome

Diagnostic points

The U.S. Uveitis Society Research and Education Committee has developed the following diagnostic criteria:

1 One or more necrotic lesions appear in the peripheral retina, the boundary of the lesion is clear, and the damage in the macular area is rare, but if it exists simultaneously with the peripheral retina, the diagnosis of ARN cannot be ruled out;

2 If the antiviral drug is not used, the lesion progresses rapidly;

3 The disease progresses in a ring;

4 occlusive retinal vasculopathy with arterial involvement;

5 Vitreous and anterior chamber significant inflammatory reaction, optic nerve involvement, scleritis and eye pain are helpful for diagnosis, but not necessary for diagnosis. The diagnosis of ARN does not depend on the scope of necrosis. As long as the above criteria are met, diagnosis can be made. .

Differential diagnosis

Because ARN can cause anterior uveitis, significant vitreous inflammation and retinal inflammation, it should be differentiated from many types of uveitis or other diseases, including progressive outer retinal necrosis syndrome, syphilitic retinitis, Large cell lymphoma, Behcet's disease, acute multifocal hemorrhagic retinal vasculitis, bacterial endophthalmitis, fungal endophthalmitis, sarcoma-like uveitis.

1. Progressive outer retinal necrosis syndrome: Progressive outer retinal necrosis syndrome is an independent necrotizing retinitis that occurs after infection with herpesvirus in immunocompromised patients. It is characterized by the rapid progression of necrotizing retinitis. Unlike ARN, it rarely occurs or does not have retinal vasculitis, and vitreous inflammation occurs less frequently, and the posterior pole is involved in the early stages of the disease.

2. Cytomegalovirus (CMV) retinitis: CMV retinitis occurs in immunosuppressed or systemic CMV-infected neonates. The course of disease is long and progresses slowly. The early stage of the disease often involves the posterior retina. The lesions are not dense. Yellow-white necrotic foci, but a granule-like appearance of inflammatory changes, usually lesions along the arcuate blood vessels, and often involve the optic nerve, but the vitreous inflammatory response is often light, involving the peripheral part of CMV retinitis often shows before and after In necrotic areas with narrow directions, necrosis is often adjacent to the site of pigmentation and at the posterior part. CMV-induced retinal necrosis has a unique "broken cheese"-like appearance, often accompanied by retinal and subretinal exudation. However, the incidence of retinal detachment is not as high as the incidence of ARN, and according to these characteristics, it can be distinguished from ARN.

3. Toxoplasma retinal choroiditis: In immunosuppressors, Toxoplasma gondii can cause extensive retinal necrosis and severe vitreitis, and intraocular fluid and serum-specific antibody tests can help to confirm the diagnosis. For immunosuppressors, In the case of diagnostic treatment or no treatment, serum-specific antibodies and clinical changes are dynamically observed to determine the diagnosis.

4. syphilitic retinitis and retinal vasculitis: syphilis can cause retinal arteritis, flaky retinal opacity and vitreitis, it can cause extensive fulminant retinal damage in HIV-infected patients, Tremella and Borrelia serological examination Help with diagnosis.

5. Intraocular lymphoma: Intraocular lymphoma (formerly known as reticular cell sarcoma) can cause changes similar to ARN, with a long course of disease, atypical signs of acute inflammation, but easy to cause subretinal lesions, accompanied by retinal pigment epithelium Dissociation, generally no large retinal necrosis, vitreous biopsy helps to confirm the diagnosis.

6. Behcet's disease uveitis: Behcet's disease can cause retinitis and significant retinal vasculitis, often accompanied by obvious anterior segment inflammation, high incidence of anterior chamber empyema, and recurrence, this uveal retinitis has Repeated attacks, frequent recurrence characteristics, patients often accompanied by clear systemic manifestations, such as recurrent oral ulcers, pleomorphic skin lesions, genital ulcers, arthritis, central nervous system involvement, etc., according to these characteristics is generally not difficult to ARN phase identification.

7. Exogenous bacterial endophthalmitis: Exogenous bacterial endophthalmitis often has a history of ocular trauma or a history of intraocular surgery, rapid progression of inflammation, accompanied by significant anterior segment inflammation and vitreous inflammation, and cell smear examination Bacterial culture with intraocular fluids is helpful for diagnosis.

8. Sarcoma-like uveitis: sarcoma-like uveitis often manifests as a granulomatous inflammation with relatively slow progression, many nodular changes in the iris, and fundus changes mainly around the retinal vein, around the vessel wall A typical "candle tear spot" occurs, no retinal necrosis occurs, chest X-ray examination and serum angiotensin converting enzyme level determination are helpful for diagnosis and differential diagnosis.

9. Intermediate uveitis: Although ARN can cause obvious vitreous inflammatory reaction, it does not cause snow-like lesions in the flat part of the ciliary body and the base of the vitreous. In addition, the typical retinal necrosis of ARN is not seen in the middle grape. Membrane inflammation, based on these characteristics, is easy to distinguish between the two.

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