UVEITIS BASICS

yo͞ovēˈīdəs / u-vee-I-tis

Inflammation of the uvea; a term describing a group of inflammatory diseases that produces swelling and destroys eye tissues.

Uveitis can develop at any age, however onset typically occurs in the third or fourth decade of a patient’s life; the majority of patients are between the ages of 20 and 60. The disease can affect one or both eyes (unilateral or bilateral).

Uveitis is the third leading cause of preventable blindness in the developed world.

Foster, C. Stephen. 2005. Ocular Immunology and Uveitis Foundation,

Based on insurance claims in Prevalence of Noninfectious Uveitis in the United States, non-infectious uveitis (the most prevalent type of uveitis in developed countries) affected an estimated 298, 801 adults and 21, 879 children in the United States in 2015, with an estimated prevalence of 121 per 100,000 and 29 per 100,000, respectively.

Types of Uveitis

Uveitis can occur suddenly or insidiously. It’s characterized by duration and by location of the inflammation within the eye.

Uveitis by duration

  • Acute (sudden onset with limited duration),
  • Recurrent (episodes separated by periods of inactivity without treatment ≥ 3 months in duration) or
  • Chronic (persistent uveitis with relapse within < 3 months after discontinuing treatment).

Uveitis based on location of inflammation

Uveitis is categorized into types based on the location of the inflammation within the eye:

  • Anterior (includes Iritis, Iridocyclitis, and Anterior cyclitis): Inflammation of the iris. This is the most common type of uveitis and can be associated with rheumatologic, skin, gastrointestinal, lung and infectious diseases.
  • Intermediate (includes Pars Planitis, Posterior cyclitis, and Hyalitis): Inflammation of the uvea, often in the vitreous. It can be associated with sarcoidosis and multiple sclerosis
  • Posterior (includes Focal, multifocal, or diffuse choroiditis, Chorioretinitis, Retinochoroiditis, Retinitis, and Neuroretinitis): Inflammation of the choroid and/or retina. This category includes “Birdshot” Retinochoroidopathy, a rare form of posterior characterized by yellow-white lesions in retina and choroid, among other symptoms.
  • Panuveitis: Inflammation across all areas of the eye.

Symptoms

The signs, symptoms and characteristics of uveitis include:

  • Light sensitivity
  • Blurred vision
  • Dark, floating spots in the field of vision (floaters)
  • Bursts of light in the field of vision (flashes)
  • Decreased vision
  • Eye pain
  • Eye redness

Diagnostic Indicators

During an eye examination, the following are indicative of a diagnosis of uveitis.

  • Anterior chamber flare
  • Keratic precipitates
  • Synechiae
  • HLA-B27 Gene (Anterior)
  • Pupil size or shape (Anterior)
  • Macular edema or optic nerve swelling (Posterior)
  • Retinal lesions (Posterior)
  • Retinal vasculitis (Posterior)

See Terminology for definitions.

Standardization of Uveitis Nomenclature

In 2004, a group of uveitis specialists met in a working group known as Standardization of Uveitis Nomenclature (SUN). Their work was published in a paper, cited below, established terminology and methods for reporting clinical data so that doctors are all speaking the same language regarding the disease.

(2005). Standardization of Uveitis Nomenclature for Reporting Clinical Data. Results of the First International Workshop. American Journal of Ophthalmology, 140(3), 509-516.

The article quoted and linked below provides an overview of the findings including the tables.

The SUN Working Group established an anatomic classification of uveitis as the framework for subsequent work on diagnostic criteria for specific uveitic entities. They also addressed consistent approaches for disease onset and course of the uveitis. Standardised definitions of outcomes, including inactive, improvement and worsening of the inflammation, were also established.

Causes

There are infectious and non-infectious forms of uveitis. These categories describe how a patient developed the disease; uveitis itself is not contagious.

Infectious uveitis may be caused by bacteria, parasites, fungus, viruses and is associated with rubella, HIV; sexually transmitted diseases such as herpes, AIDS, syphilis, Chlamydia, or gonorrhea; or rare infections, such as tuberculosis, toxoplasmosis, or Lyme disease.

Non-infectious uveitis (NIU) may be be brought on by injury or trauma or may be related to an auto-immune disease or systemic inflammatory disorder. Auto-immune diseases that are associated with uveitis include: ankylosing spondylitis, inflammatory bowel disease, juvenile rheumatoid arthritis, multiple sclerosis, Ulcerative colitis, and psoriatic arthritis. Other inflammatory disorders include: Vogt Koyanagi Harada’s syndrome, sarcoidosis, Behcet’s disease, and Kawasaki’s disease.

Read Uveitis Crash Course: A primer on the prevalence and epidemiology of uveitis.

The cause of non-infectious uveitis can also be unknown (idiopathic). This is true for at least one-third of the cases of uveitis. There are various theories as to the underlying cause of idiopathic uveitis which involve the immune system.

“Inflammation in non-infectious uveitis is driven by a T-cell mediated autoimmune process and perpetuated by pro-inflammatory cytokines.”

Yeh, Steven, and Jessica G Shantha. “The Burden of Noninfectious Uveitis of the Posterior Segment: A Review.” Retina Today, Bryn Mawr Communications, 2016.

The autoimmune hypothesis was developed through laboratory studies that have stimulated adaptive immunity towards retinal targets via retinal inflammation. This inflammation would be a response to a pathogen. If in these individuals, the B and T cells lose the ability to differentiate between the pathogenic cells and the retinal cells, uncontrolled dis-regulated host immune response continues after the infection subsides. [There is also theory that the microbiome of the host may be the source of the infectious agent, which may or may not impact a host with an adequate immune system]. In individuals with posterior uveitis, it may be that the inflammation causes a breakdown of the blood-retinal barrier.

Another explanation for non-infectious uveitis is that it is auto-inflammatory, which means there is a genetic mutation in the innate (rather than adaptive) immune system. The patient has a gene (gone wrong) that causes an auto-inflammatory disease, or a gene that is associated with an auto-inflammatory disease and the interplay between genetics and the environment triggers the disease.

Source: Autoimmunity, Autoinflammation, and Infection in Uveitis

Also, check out: Inflammation and Immune Response

Complications

Many cases of uveitis are chronic and can come with various serious complications, which are often side effects of the medications used to treat the uveitis itself. Complications may include, cataracts, elevated Inter-ocular Pressure (IOP), swelling of the retina or retinal detachment. These complications can result in permanent vision loss.

This is a great overview of the eye and uveitis:
Uveitis – CRASH! Medical Review Series