Acute retinal necrosis overview
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Acute retinal necrosis is an inflammatory eye condition usually caused by reactivation of latent viruses, including Herpes simplex virus 1 & 2, Varicella-zoster virus, cytomegalovirus, and Epstein-Barr virus. Symptoms include eye pain, vision loss, floaters, flashes, excessive sensitivity to light, flu symptoms, and redness of the affected eye. The pathogenesis of acute retinal necrosis is characterized by retinal inflammation due to ocular viral infection. Particles from Herpes simplex virus 1 (HSV-1), Herpes simplex virus 2 (HSV-2), and Varicella zoster virus (VZV) infiltrate the retina through various locations of epithelial penetration, including the skin, conjunctiva, cornea, and nasal cavity. Acute retinal necrosis may be classified both by staging—acute or late—or by severity: mild or fulminant. The natural progression of ARN depends on whether the case is mild or fulminant. Mild cases of ARN present with white-yellow necrotic lesions that do not coalesce or lead to retinal detachment; the disease is self-limited. Fulminant cases of ARN will lead to progressive necrosis of retinal tissue, leading to pigmentation scarring, vitreous debris, and retinal detachment. Without treatment, ARN will usually progress to bilateral acute retinal necrosis (BARN) within weeks to a few months. With treatment, the prognosis for ARN is good if the therapy is administered early and sustained until symptoms resolve. The mainstays of medical therapy for acute retinal necrosis are regimens of empiric and pathogen-directed antimicrobial therapy. The primary risk factors for acute retinal necrosis include immunocompromised status and immunosuppression from disease and prolonged corticosteroid use.
Acute retinal necrosis was first discovered in 1971 by Urayama A, Yamada N, Sasaki T. Acute retinal necrosis was first officially classified as bilateral acute retinal necrosis in 1978 by N.J. Young and A.C. Bird, applied to 4 cases of bilateral necrotizing retinitis that progressed to retinal detachment and phthisis despite corticosteroid and antibiotic therapy. In the 1980s, emergence of pathological and electron findings from analysis of vitrectomy and enucleation specimens led to the identification of members of the herpes virus family as the cause of acute retinal necrosis. The official diagnostic criteria for acute retinal necrosis was proposed by the American Uveitis Society in 1994.
- The pathogenesis of acute retinal necrosis is characterized by retinal inflammation due to ocular viral infection. Particles from Herpes simplex virus 1 (HSV-1), Herpes simplex virus 2 (HSV-2), and Varicella zoster virus (VZV) infiltrate the retina through various locations of epithelial penetration, including the skin, conjunctiva, cornea, and nasal cavity. Acute retinal necrosis develops from HSV-1, HSV-2, and VZV due to the viruses' ability to transmit and replicate in the central nervous system (CNS), as well as their ability to transport anterograde through the optic nerve, establish latency, reactivate, and cause retinal inflammation.
- For Caucasian populations, possessing the HLA-DQw7, HLA-Bw62, and HLA-DR4 antigens is correlated to a genetic predisposition to ARN. For Japanese populations, possessing the HLA-Aw33, HLA-B44, and HLA-DRw6 antigens is correlated to a genetic predisposition to ARN.
- Acute retinal necrosis is associated with the following ocular conditions: progressive outer retinal necrosis, uveitis, cytomegalovirus retinitis, toxoplasmic chorioretinitis, and endophthalmitis.
Epidemiology and Demographics
- The incidence of acute retinal necrosis (ARN) is approximately 6.3 per 100,000 individuals.
- ARN developed from Herpes simplex virus 1 and Varicella-zoster virus is most common among patients older than 50 years, while the incidence of HSV-2 caused ARN is highest in children and young adults between age 9 and 22 years.
- There is no racial or gender predisposition to acute retinal necrosis.
The primary risk factors for acute retinal necrosis include immunocompromised status and immunosuppression from disease and prolonged corticosteroid use. Genetic predisposition for certain Caucasian and Japanese populations heightens the possibility of developing ARN.
Natural History, Complications and Prognosis
- Symptoms of acute retinal necrosis (ARN) develop rapidly upon onset of pathogenic infection.
- The natural progression of ARN depends on whether the case is mild or fulminant.
- Without treatment, ARN will usually progress to bilateral acute retinal necrosis (BARN) within weeks to a few months. Complications resulting from acute retinal necrosis occur due to retinal tissue damage and subsequent infection from the causative pathogen.
- Without treatment, the prognosis for acute retinal necrosis (ARN) varies.
- With treatment, the prognosis for ARN is good if the therapy is started early and sustained until symptoms resolve.
History and Symptoms
Patient history of prior or concurrent diseases, particularly those associated with acute retinal necrosis pathogens or sources of immunocompromised status, should be considered in the diagnosis of ARN.
- eye pain
- vision loss
- excessive sensitivity to light
- flu-like symptoms
- redness of the affected eye
Physical examination of patients with acute retinal necrosis may reveal erythema and hyperaemia of the retina, white-yellow necrotic lesions, purulent exudate, opaque vitreous, and other indications of inflammation in the eye.
Laboratory findings consistent with a diagnosis of acute retinal necrosis are those used to determine the presence of the viral pathogen, including PCR test results, viral cultures, immunoflourescence results, and detection of antibodies indicative of sources of ARN via the Goldmann-Witmer coefficient.
Chest X Ray
CT imaging may reveal indicators of inflammation and infection by the causative pathogen for acute retinal necrosis, including hypoattenuation along the optic tract—indicative of Varicella-zoster virus (VZV) infection—and hyperattenuation along the optic tract, retina, sclerae, and lateral geniculate body.
Echocardiography or Ultrasound
Other Imaging Findings
Other Diagnostic Studies
Surgery is not the first-line treatment option for patients with acute retinal necrosis; it is indicated primarily when there is a substantial risk of complications, including retinal detachment and tissue atrophy.
Preventing the onset of acute retinal necrosis is dependent upon preventing the causative infection from Herpes simplex virus (HSV), Varicella-zoster virus (VZV), Cytomegalovirus (CMV), and Epstein-Barr virus (EBV).
While recurrence of acute retinal necrosis is not completely preventable at present, the administration of topical and intravitreal antiviral therapy targeted to the specific cause of the disease can reduce the chance of recurrence.