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

• PORN (Progressive Outer Retinal Necrosis)

What is Progressive Outer Retinal Necrosis? (Definition/Background Information)

• Progressive Outer Retinal Necrosis (PORN) is a rapidly progressing and aggressive eye condition that results in necrotizing inflammation of the retina (necrosis of outer layers of the retina). Along-with acute retinal necrosis (ARN), PORN is termed as a variant of necrotizing herpetic retinopathy (NHR)
• The retina is a layer of tissue situated at the back of the eye and 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
• Progressive Outer Retinal Necrosis is the second-most common form of infectious retinitis. PORN typically develops in immunocompromised individuals, especially in patients with advanced AIDS. It affects both the eyes in a majority of cases and the course of the disease is generally unfavorable
• In many cases, the cause of development of Progressive Outer Retinal Necrosis is associated with varicella zoster virus infections against a background of severely compromised immunity. Thus, any condition resulting in poor immune system can increase the risk for PORN
• The signs and symptoms of the condition include loss of visual acuity, blurred vision, eye floaters and eye flashes. Progressive Outer Retinal Necrosis is usually diagnosed through retinal examination along with ancillary test, aqueous humor and vitreous humor fluid sample studies, and imaging studies
• Aggressive treatment for Progressive Outer Retinal Necrosis needs to be provided, in order to prevent complications such as retinal detachment. If the condition is not treated with urgency, Progressive Outer Retinal Necrosis can lead to total blindness

Who gets Progressive Outer Retinal Necrosis? (Age and Sex Distribution)

• Progressive Outer Retinal Necrosis is a rare condition that is observed in individuals of any age group with poor immune systems
• Both males and females are affected
• PORN is observed worldwide and all racial and ethnic groups may be affected

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

The risk factors for the development of Progressive Outer Retinal Necrosis include any condition that causes severe immunodeficiency in an individual. These include:

• HIV infection or AIDS
• Chemotherapy for cancer
• Long-term corticosteroid therapy for conditions such as nephrotic syndrome, optic neuropathy, rheumatoid arthritis, and graft vs host disease after bone marrow transplant

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 Progressive Outer Retinal Necrosis? (Etiology)

Progressive Outer Retinal Necrosis is reportedly caused by a viral infection in individuals with severely immunocompromised status. The infection causes necrosis of the outer layer of the retina of the eye.

• In approximately 70% of the cases, the varicella zoster virus (VZV) is identified as the cause. In such cases, the condition is termed VZV PORN
• Herpes simplex viruses 1 and 2 (HSV 1 and HSV 2) is the next more common virus known to cause PORN

Conditions, such as HIV infection and AIDS, lead to weak immune system that opens the body to opportunistic infections. PORN may be caused a new infection of VZV, or due to the reactivation of old VZV infection.

Long-term treatment of certain conditions, such as nephrotic syndrome, optic neuropathy, rheumatoid arthritis, and graft versus host disease, using corticosteroids may also result in the development of PORN.

What are the Signs and Symptoms of Progressive Outer Retinal Necrosis?

The signs and symptoms due to Progressive Outer Retinal Necrosis may vary from one individual to another. It also depends on whether one eye or both eyes are affected; although, in a vast majority (over 70% of the cases), the condition is bilateral.

The signs and symptoms of PORN may include:

• Blurring of vision
• Redness of the eye
• Aversion to light (or photophobia) is not usually noted
• Eye pain that 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
• Loss of visual acuity is noted in most of the individuals
• Narrowing or constriction of the visual field
• Over 65% of the individuals have VZV infection of the skin
• Occlusion of the retinal blood vessels due to inflammation

One of the important features of Progressive Outer Retinal Necrosis is minimal to an absence of intraocular inflammation. This helps the healthcare provider to distinguish PORN from ARN (acute retinal necrosis).

Apart from the above, the signs and symptoms arising from the underlying condition causing severely weak immunity, such as HIV infection or AIDS, may be observed.

How is Progressive Outer Retinal Necrosis Diagnosed?

The various tests and examinations conducted to diagnose Progressive Outer 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
• 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
  • 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 retinal necrosis: A severe form of inflammatory condition involving the retina usually seen in adults
  • Behcet's disease: A disorder that presents recurrent oral ulcers, genital ulcers, and uveitis of the eye
  • CMV retinitis: Inflammation of the retina due to infection from cytomegalovirus (CMV)
  • Fungal or bacterial endophthalmitis: Severe infection involving the eye (intraocular) fluids that necessitates immediate treatment to prevent vision loss
  • Intraocular lymphoma: A form of malignancy that involves the lymphocytes in the lymph nodes and other body parts affecting the eye
  • Leukemia: A form of malignancy involving the white blood cells (blood and bone marrow)
  • Retinal vasculitis: A disorder involving blood vessels of the retina that can result in blindness
  • 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
  • Syphilitic retinitis: Inflammation of the retina due to infection from syphilis bacterium Treponema pallidum 
  • Toxocariasis: A parasitic and zoonotic infection in humans caused by roundworms belonging to the genus Toxocara
  • Toxoplasma retinochoroiditis: An inflammatory eye condition due to the pathogen Toxoplasma gondii
  • Tuberculosis (TB): A contagious bacterial infection of the lungs causing persistent coughing, fever, chills, and fatigue

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 Progressive Outer Retinal Necrosis?

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

• Retinal hemorrhages
• Epiretinal membrane
• Macular edema
• Impaired color vision
• Retinal detachment: Nearly 50% of the patients present retinal detachment
• Retinal holes and tears
• Optic nerve atrophy: A permanent visual impairment that occurs when the optic nerve is damaged
• Blindness
• Recurrence of infection
• Complications that develop from severely immunocompromised status of the individual

How is Progressive Outer Retinal Necrosis Treated?

The treatment of Progressive Outer Retinal Necrosis depends on the degree of signs and symptoms and severity of the condition. An early recognition of PORN 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 Progressive Outer Retinal Necrosis include the following:

• Antiviral medications: It may be immediately administered following a clinical diagnosis of PORN, even before lab test results are obtained. However, systemic antiviral therapy is not known to be very effective in many
• 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)
• Treatment for the underlying condition causing weak immunity

Periodic checkups and long-term medical follow-up is warranted to minimize the risk for recurrence of PORN.

How can Progressive Outer Retinal Necrosis be Prevented?

It is difficult to prevent the development of Progressive Outer Retinal Necrosis, since it occurs against a background of severely weakened immunity.

• Early diagnosis and aggressive treatment of conditions causing weak immunity such as HIV infection and AIDS may help lower one’s risk for PORN
• Regular health check-ups may help individuals with a history of PORN (to help minimize the risk for recurrence)

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

Progressive Outer Retinal Necrosis is a rapidly progressing eye disease that develops in individuals with a severely compromised immune system.

• In general, the visual prognosis of the condition is unpredictable to guarded
• The overall prognosis depends upon several factors including the severity of the underlying immunosuppressive condition and the health status of the individual; the outcomes vary from one individual to another

Additional and Relevant Useful Information for Progressive Outer Retinal Necrosis:

• Acute retinal necrosis (ARN) is a debilitating condition involving the retina, which can cause blindness, if left untreated. It is observed to develop in healthy individuals with normal immunity too
• 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:

http://www.dovemed.com/health-topics/vision-center/