Uveitis

Uveitis is classified anatomically into anterior, intermediate, posterior, and panuveitic forms—based on the part of the eye primarily affected.[2] Prior to the twentieth century, uveitis was typically referred to in English as "ophthalmia."[3]

• Anterior uveitis includes iridocyclitis and iritis. Iritis is the inflammation of the anterior chamber and iris. Iridocyclitis is inflammation of the iris and ciliary body with inflammation predominantly confined to the ciliary body. Between 66% and 90% of uveitis cases are anterior in location (iritis).[4] This condition can occur as a single episode and subside with proper treatment or may take on a recurrent or chronic nature.
• Intermediate uveitis, also known as pars planitis, consists of vitritis—which is inflammation of cells in the vitreous cavity, sometimes with snowbanking, or deposition of inflammatory material on the pars plana. There are also "snowballs," which are inflammatory cells in the vitreous.
• Posterior uveitis or chorioretinitis is the inflammation of the retina and choroid.
• Panuveitis is the inflammation of all layers of the uvea.

Uveitis is usually an isolated illness, but can be associated with many other medical conditions.[1] In anterior uveitis, no associated condition or syndrome is found in approximately one-half of cases. However, anterior uveitis is often one of the syndromes associated with HLA-B27. Presence of this type of HLA allele has a relative risk of evolving this disease by approximately 15%.[5]

The most common form of uveitis is acute anterior uveitis (AAU). It is most commonly associated with HLA-B27, which has important features: HLA-B27 AAU can be associated with ocular inflammation alone or in association with systemic disease. HLA-B27 AAU has characteristic clinical features including male preponderance, unilateral alternating acute onset, a non-granulomatous appearance, and frequent recurrences, whereas HLA-B27 negative AAU has an equivalent male to female onset, bilateral chronic course, and more frequent granulomatous appearance.[6] Rheumatoid arthritis is not uncommon in Asian countries as a significant association of uveitis.[7]

Infectious causes

Uveitis may be an immune response to fight an infection caused by an organism in the eye. They are less common than non-infectious causes, and require antimicrobial/ viral/ parasitic treatment in addition to inflammatory control. Infectious causes in order of global burden include:

Subretinal abscess in tubercular posterior uveitis

• tuberculosis
• brucellosis
• herpesviruses (herpes zoster ophthalmicus - shingles of the eye)
• leptospirosis
• presumed ocular histoplasmosis syndrome
• syphilis
• toxocariasis
• toxoplasmic chorioretinitis
• Lyme disease
• Zika fever[10]

Ciliary flush

Keratic precipitates

Hypopyon in anterior uveitis, seen as yellowish exudation in lower part of anterior chamber of eye

Vascularised posterior synechia

The disease course, anatomy, and laterality can vary widely and are important to consider in diagnosis and treatment. Cases may be acute (sudden onset with < 3 month duration) and monophonic, acute and recurrent, or chronic.[13] The signs and symptoms of uveitis may include the following:[1]

Uveitis is assessed as part of a dilated eye exam.[1] Diagnosis includes dilated fundus examination to rule out posterior uveitis, which presents with white spots across the retina along with retinitis and vasculitis.[1]

Laboratory testing is usually used to diagnose specific underlying diseases, including rheumatologic tests (e.g. antinuclear antibody, rheumatoid factor) and serology for infectious diseases (Syphilis, Toxoplasmosis, Tuberculosis).

Major histocompatibility antigen testing may be performed to investigate genetic susceptibility to uveitis. The most common antigens include HLA-B27, HLA-A29 (in birdshot chorioretinopathy) and HLA-B51 (in Behçet disease).

Radiology X-ray may be used to show coexisting arthritis and chest X-ray may be helpful in sarcoidosis.

Uveitis is typically treated with glucocorticoid steroids, either as topical eye drops (prednisolone acetate) or as oral therapy.[27] Prior to the administration of corticosteroids, corneal ulcers must be ruled out. This is typically done using a fluorescence dye test.[28] In addition to corticosteroids, topical cycloplegics, such as atropine or homatropine, may be used. Successful treatment of active uveitis increases T-regulatory cells in the eye, which likely contributes to disease regression.[29] In severe cases an injection of posterior subtenon triamcinolone acetate may also be given to reduce the swelling of the eye. [30]

Intravitrial injection of steroid has proven to be a newer useful way to control inflammation for longer without the need for daily eyedrops. Dexamethasone and fluocinolone acetonide are two more commonly used options for noninfectious uveitis.[31]

Non-biologic, steroid sparing therapies for noninfectious uveitis in adults are now more available. These include the disease-modifying antirheumatic drugs (DMARDs) methotrexate, mycophenolate, cyclosporine, azathioprine, and tacrolimus.[32] In comparing various studies, methotrexate is more efficacious than mycophenolate in inflammatory control for most forms of panuveitis. Methotrexate also had little to no differences in safety outcomes compared to mycophenolate.[32]

Antimetabolite medications, such as methotrexate are often used for recalcitrant or more aggressive cases of uveitis. Experimental treatments with Infliximab or other anti-TNF infusions may prove helpful.

The anti-diabetic drug metformin is reported to inhibit the process that causes the inflammation in uveitis.[33]

In the case of herpetic uveitis, anti-viral medications, such as valaciclovir or aciclovir, may be administered to treat the causative viral infection.[34]

Uveitis affects approximately 1 in 4500 people and is most common between the ages 20 to 60 with men and women affected equally. In western countries, anterior uveitis accounts for between 50% and 90% of uveitis cases. In Asian countries the proportion is between 28% and 50%.[35] Uveitis is estimated to be responsible for approximately 10%-20% of the blindness in the United States.[36]

For non-infectious uveitis, women are more likely (57%) to be affected than men, possibly due to their higher prevalence of related autoimmune diseases.[37] Vitamin D deficiency and smoking are risk factors for non-infectious uveitis.[37]

The prognosis is generally good for those who receive prompt diagnosis and treatment, but serious complication including cataracts, uveitic glaucoma, band keratopathy, macular edema and permanent vision loss may result if left untreated. The type of uveitis, as well as its severity, duration, and responsiveness to treatment or any associated illnesses, all factor into the outlook.[1]

• List of systemic diseases with ocular manifestations
• Intermediate uveitis
• Uveitis–Glaucoma–Hyphema syndrome

• Bodaghi, Bahram; LeHoang, Phuc (2017) [2009]. Uvéite (in French) (2nd ed.). Issy-les-Molineux, France: Elsevier Health Sciences. ISBN 978-2-294-74755-7.