What are the other Names for this Condition? (Also known as/Synonyms)

• ARN (Acute Retinal Necrosis)
• BARN (Bilateral Acute Retinal Necrosis)
• Bilateral Acute Retinal Necrosis (BARN)

What is Acute Retinal Necrosis? (Definition/Background Information)

• Acute Retinal Necrosis (ARN) is a debilitating eye condition involving the retina, which can cause blindness, if left untreated. Along-with progressive outer retinal necrosis (PORN), ARN is termed as a variant of necrotizing herpetic retinopathy (NHR)
• In a majority of individuals with Acute Retinal Necrosis, only one eye is involved (termed Unilateral ARN); whereas in others, both the eyes may be affected (termed Bilateral ARN)
• The retina is a layer of tissue situated at the back of the eye that helps in sensing light. When the blood supply to the retina is blocked, it will not be able to receive enough blood and oxygen leading to the loss of vision
• Acute Retinal Necrosis is usually observed to develop in healthy individuals with normal immunity, particularly in middle-aged and older adults. Even though all racial and ethnic groups are at risk, certain American Caucasians and Japanese populations with specific genetic makeup have a higher risk
• The cause of development of Acute Retinal Necrosis is not well-established, although several viral infections have been implicated. These include infections that develop from varicella zoster virus, herpes simplex virus, and cytomegalovirus
• The signs and symptoms of the condition include blurred vision, light sensitivity, floaters and flashes, and eye pain. Acute Retinal Necrosis is usually diagnosed through retinal examination along with ancillary test, aqueous humor and vitreous humor fluid sample studies, and imaging studies
• The treatment for Acute Retinal Necrosis needs to be provided in a timely manner, in order to prevent complications such as retinal detachment. If the condition is not treated with urgency, Acute Retinal Necrosis can lead to total blindness

Who gets Acute Retinal Necrosis? (Age and Sex Distribution)

• Acute Retinal Necrosis is a rare condition that affects individuals of all age groups
  • However, it is mostly seen in young and older adults
  • Individuals with a healthy immune system, usually in the 40-70 years’ age group, are commonly affected
  • The condition is rare in infants and children
• Both males and females are affected
• ARN is observed worldwide and all racial and ethnic groups may be affected

What are the Risk Factors for Acute Retinal Necrosis? (Predisposing Factors)

The risk factors for the development of Acute Retinal Necrosis include:

• Individuals with certain genetic makeup may have an increased risk for developing Acute Retinal Necrosis. Studies have shown that the following genetic markers make these populations susceptible to the condition:
  • Caucasians in USA: HLA-DQw7, HLA-Bw62, and HLA-DR4
  • Japanese: HLA-Aw33, HLA-B44, and HLA-DRw6
• Immunosuppression due to corticosteroid treatment
• Immunocompromised status due to HIV infection or AIDS

It is important to note that having a risk factor does not mean that one will get the condition. A risk factor increases one’s chances of getting a condition compared to an individual without the risk factors. Some risk factors are more important than others.

Also, not having a risk factor does not mean that an individual will not get the condition. It is always important to discuss the effect of risk factors with your healthcare provider.

What are the Causes of Acute Retinal Necrosis? (Etiology)

The exact cause of Acute Retinal Necrosis is currently unknown. The condition is commonly observed in individuals with a good/normal healthy immune system (immunocompetent individuals). However, researchers believe that it may be caused by a viral infection.

• The viruses that have been implicated include the varicella zoster virus (VZV) and herpes simplex viruses 1 and 2 (HSV 1 and HSV 2)
• In younger individuals, Acute Retinal Necrosis is associated with HSV 2 infection; whereas in older individuals its associated with VZV or HSV 1
• Some experts believe that Acute Retinal Necrosis can be also associated with cytomegalovirus (CMV) and Epstein-Barr virus (EBV)

In some individuals, a previous history of a viral infection may be noted; while in others, there may not be a history of a viral infection.

Regardless of the type of infection resulting in Acute Retinal Necrosis, there are two phases of the eye condition that have been described:

• Acute herpetic phase: In this phase, there is inflammation in the retina causing closure of small retinal blood vessels (retinal arterioles) resulting in the necrosis of retinal tissue and tissues surrounding the retina
• Late cicatricial phase: The inflammation that occurs in the acute phase over a period of time can cause formation of thin membranes over the retina and in the vitreous fluid of the eye. This can also cause a significant thinning of the retina. Due to this, it can result in retinal detachment usually within 3 months of ARN onset

The acute phase of Acute Retinal Necrosis may last for a period of 6-12 weeks without treatment.

What are the Signs and Symptoms of Acute Retinal Necrosis?

The signs and symptoms due to Acute Retinal Necrosis may vary from one individual to another. It also depends on whether one eye or both eyes are affected. The signs and symptoms may include:

• Blurring of vision
• Redness of the eye
• Aversion to light (or photophobia)
• Eye pain that may involve one eye or both eyes; eye pain is generally uncommon
• Eye floaters: The individuals experience illusions that some small objects such as spots, hairs, or strings are moving in the eye
• Flashes in the eye: Sudden appearance of ‘flashing’ bright lights
• Poor vision clarity (visual acuity) - it is reportedly seen in nearly 50% of the individuals with ARN after about 6 months

Acute Retinal Necrosis usually affects one eye (observed in about two-thirds of the individuals), while both eyes may be affected in nearly one-third of the individuals.

How is Acute Retinal Necrosis Diagnosed?

The various tests and examinations conducted to diagnose Acute Retinal Necrosis may include:

• Complete physical examination and comprehensive medical history
• Thorough eye examination by experts in eye disorders such as ophthalmologists and retinal specialists
• A variety of tests can be performed on aqueous humor and/or vitreous humor fluid samples that include:
  • Polymerase chain reaction (PCR) studies for viral infections
  • Viral cultures
  • Immunofluorescence studies, direct or indirect, to detect the presence of viruses
  • Blood tests to detect antibodies against viruses
  • Viral antibody titer in aqueous humor and vitreous humor fluid samples
• Testing for syphilis and HIV infection
• Specific tests related to the retina such as:
  • A  thorough inspection of the retina after dilating the pupil in both eyes
  • Slit lamp examination: This test uses an instrument that gives a 3-dimensional picture of different parts of the eye
  • Ultrawide field imagint (Optos) can be used to study peripheral involvement of the retina
  • Fundus fluorescein angiogram: In this technique, the eye blood vessels are examined using a fluorescein dye. It can help detect the degree of occlusion of the retinal blood vessels
  • Optical coherence tomography (OCT) of eye: It is a radiological imaging technique to visualize the eye structure. It can help determine the amount of edema within the macula of the eye and in also detecting epiretinal membrane, if present
  • Visual field examination: An eye examination that concentrates on checking the abnormality in the central and peripheral vision, which may have been caused by various other medical conditions
  • Visual acuity: Eye test that is performed to check the clearness of vision
• A differential diagnosis may be undertaken to eliminate the following conditions:
  • Acute multifocal hemorrhagic retinal vasculitis (AMHRV): It is an uncommon eye disorder of unknown cause with severe involvement of the retina
  • Bacterial/fungal retinitis: Inflammation of the retina from infectious causes
  • Bacterial/fungal endophthalmitis: Severe infection involving the eye (intraocular) fluids that necessitates immediate treatment to prevent vision loss
  • Behcet disease: A disorder that presents recurrent oral ulcers, genital ulcers, and uveitis of the eye. The ocular presentations of ARN and Behcet disease may be indistinguishable from each other
  • Central or branch retinal artery occlusion: A condition wherein a blockage occurs in the arteries that carry blood to the retina
  • CMV retinitis: Inflammation of the retina due to infection from cytomegalovirus (CMV)
  • Collagen-vascular disease: A group of autoimmune disorders that affect the connective tissues that includes systemic lupus erythematosus, scleroderma, rheumatoid arthritis, etc.
  • Commotio retinae: Also known as Berlin's edema, it occurs from trauma to the eye
  • Large cell lymphoma or intraocular lymphoma: A form of malignancy that involves the lymphocytes in the lymph nodes and other body parts
  • Ocular ischemic syndrome: A rare condition that results from a narrowing or blockage of the carotid arteries leading to loss of vision and orbital pain
  • Progressive outer retinal necrosis (PORN): A progressive eye condition that leads to inflammation and necrosis of the retina, particularly in immunocompromised individuals
  • Retinoblastoma: A malignant tumor of the retina, especially affecting young children
  • Sarcoidosis: A systemic disease that affects several parts of the body, leading to the growth of small lumps of inflammatory cells. It most commonly affects the lungs, skin, eyes, and lymph nodes
  • Sympathetic ophthalmia: An extremely rare eye condition that takes place following a history of injury or surgery to the eye
  • Syphilis: A common bacterial disease that is generally transmitted through sexual contact
  • Toxoplasma chorioretinitis: Chorioretinitis develops from exposure to the pathogen Toxoplasma gondii
  • Vogt-Koyanagi-Harada syndrome: A disease causing chronic inflammation of melanocytes affecting several body parts including the nervous system, skin, and eyes

Many clinical conditions may have similar signs and symptoms. Your healthcare provider may perform additional tests to rule out other clinical conditions to arrive at a definitive diagnosis.

What are the possible Complications of Acute Retinal Necrosis?

The following complications could potentially occur in individuals with Acute Retinal Necrosis:

• Retinal hemorrhage
• Epiretinal membrane
• Macular edema
• Impaired color vision
• Retinal detachment: Nearly half to three-fourths of patients with Acute Retinal Necrosis may develop retinal detachment, if the condition is left untreated. This may occur within 3 months after onset of signs and symptoms of ARN
• Retinal holes and tears
• Optic nerve atrophy: A permanent visual impairment that occurs when the optic nerve is damaged
• Blindness
• Recurrence of infection

How is Acute Retinal Necrosis Treated?

The treatment of Acute Retinal Necrosis depends on the degree of signs and symptoms and severity of the condition. An early recognition of ARN and aggressive treatment is very important, often to prevent the involvement of the other unaffected eye (fellow eye). A consultation with an expert in eye (ophthalmologist), who specializes in retinal disorders, is frequently recommended.

The treatment modalities for Acute Retinal Necrosis include the following:

• Antiviral medications: It may be immediately administered following a clinical diagnosis of ARN, even before lab test results are obtained
• Anti-inflammatory medications such as aspirin and steroids
• Antithrombotic therapy through the use of antiplatelet agents (such as aspirin)
• Use of local and systemic corticosteroids
• Laser photocoagulation treatment for retinal detachment
• Retinal surgery to repair extensive retinal detachments: Vitrectomy (with or without scleral buckle) can be helpful in certain types of retinal detachments (such as traction-rhegmatogenous retinal detachment)

Periodic checkups (usually every 3 months) and long-term medical follow-up is warranted to minimize the risk for recurrence of ARN.

How can Acute Retinal Necrosis be Prevented?

It is difficult to prevent the development of Acute Retinal Necrosis, since the cause is not definitely known.

• However, aggressive treatment using antiviral therapy during the acute phase will help not only in decreasing the severity of signs and symptoms, but also significantly reduce the incidence of potential complications, such as retinal detachment and blindness.
• It is also important to note that providing aggressive treating during the acute phase of Acute Retinal Necrosis with single eye involvement can also help prevent the development of the condition in the unaffected eye
• Regular health check-ups may help individuals with a history of the condition (to help minimize the risk for recurrence)

What is the Prognosis of Acute Retinal Necrosis? (Outcomes/Resolutions)

Acute Retinal Necrosis is a destructive eye disease and its prognosis varies from one individual to another. It depends on the severity of the signs and symptoms and the rapidity of disease progression.

• Individuals, who have been diagnosed early and provided adequate treatment, have better prognoses than individuals with delayed diagnosis and/or treatment
• With aggressive treatment, the condition can be treated and the development of significant complications. In such individuals, the prognosis can be excellent
• In some individuals, complications can develop despite aggressive therapy; in such cases, and in individuals who remain untreated, the prognosis is guarded
• Also, aggressively treating retinal detachment that occurs due to ARN can also help reduce significant long-term complications such as blindness. According to some reports, nearly 50% of the individuals go blind due to ARN

Additional and Relevant Useful Information for Acute Retinal Necrosis:

• Acute Retinal Necrosis is described as a recently-discovered eye condition; it was first reported among Japanese populations in the year 1971
• Progressive outer retinal necrosis (PORN) is a rapidly progressive and aggressive eye condition that results in necrotizing inflammation of the retina of the eye
• Retinal detachment is an eye disorder, wherein the retina gets separated from the underlying layer of blood vessels, which supplies oxygen and other nutrients to it

Please visit our Eye & Vision Health Center for more physician-approved health information:

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