Uveitis is a general term describing a group of inflammatory diseases that produces swelling and destroys eye tissues. These diseases can slightly reduce vision or lead to severe vision loss.
The term “uveitis” is used because the diseases often affect a part of the eye called the uvea. Nevertheless, uveitis is not limited to the uvea. These diseases also affect the lens, retina, optic nerve, and vitreous, producing reduced vision or blindness.
The uvea is the middle layer of the eye which contains much of the eye’s blood vessels. This is one way that inflammatory cells can enter the eye. Located between the sclera, the eye’s white outer coat, and the inner layer of the eye, called the retina, the uvea consists of the iris, ciliary body, and choroid
Intraocular inflammation (uveitis) is classified as acute or chronic and as nongranulomatous or granulomatous, according to the clinical signs, and by its involvement of the anterior, intermediate, posterior, or all (panuveitis) segments of the eye. The common types are acute nongranulomatous anterior, granulomatous anterior, and posterior.
Anterior uveitis occurs in the front of the eye. It is the most common form of uveitis, predominantly occurring in young and middle-aged people. Many cases occur in healthy people and may only affect one eye but some are associated with rheumatologic, skin, gastrointestinal, lung and infectious diseases.
Posterior uveitis is the least common form of uveitis. It primarily occurs in the back of the eye, often involving both the retina and the choroid. It is often called choroditis or chorioretinitis. There are many infectious and non-infectious causes to posterior uveitis.
Panuveitis is a term used when all three major parts of the eye are affected by inflammation. Behcet’s disease is one of the most well-known forms of pan-uveitis and it greatly damages the retina.
In most cases the pathogenesis of uveitis is primarily immunologic, but infection may be the cause, particularly in immunodeficiency states. The systemic disorders associated with acute nongranulomatous anterior uveitis are the HLA-B27-related conditions (ankylosing spondylitis, reactive arthritis, psoriasis, ulcerative colitis, and Crohn disease).
Chronic nongranulomatous anterior uveitis occurs in juvenile idiopathic arthritis. Behçet syndrome produces both anterior uveitis, with recurrent hypopyon but little discomfort, and posterior uveitis, characteristically with branch retinal vein occlusions.
Both herpes simplex and herpes zoster infections may cause nongranulomatous anterior uveitis as well as retinitis (acute retinal necrosis).
Diseases producing granulomatous anterior uveitis also tend to be causes of posterior uveitis. These include sarcoidosis, toxoplasmosis, tuberculosis, syphilis, VogtKoyanagi-Harada disease (bilateral uveitis associated alopecia, poliosis [depigmented eyelashes, eyebrows, or hair], vitiligo, and hearing loss), and sympathetic ophthalmia that occurs after penetrating ocular trauma.
In toxoplasmosis, there may be evidence of previous episodes of retinochoroiditis. Syphilis characteristically produces a “salt and pepper” fundus but may present with a wide variety of clinical manifestations. The other principal pathogens responsible for ocular inflammation in HIV infection are cytomegalovirus (CMV), herpes simplex and herpes zoster viruses, mycobacteria, Cryptococcus, Toxoplasma, and Candida.
Retinal vasculitis and intermediate uveitis predominantly manifest as posterior uveitis with central or peripheral retinal abnormalities in retinal vasculitis and far peripheral retinal abnormalities (pars planitis) in intermediate uveitis. Retinal vasculitis can be caused by a wide variety of infectious agents and noninfectious systemic with conditions but also may be idiopathic. Intermediate uveitis is often idiopathic but can be due to multiple sclerosis or sarcoidosis.
The signs, symptoms and characteristics of uveitis may include:
- Eye redness
- Eye pain
- Light sensitivity
- Blurred vision
- Dark, floating spots in your field of vision (floaters)
- Decreased vision
Diagnosis of uveitis includes a thorough examination and the recording of the patient’s complete medical history. Laboratory tests may be done to rule out an infection or an autoimmune disorder.
A central nervous system evaluation will often be performed on patients with a subgroup of intermediate uveitis, called pars planitis, to determine whether they have multiple sclerosis which is often associated with pars planitis.
The eye exams used include:
- An Eye Chart or Visual Acuity Test. This test measures whether a patient’s vision has decreased.
- A Funduscopic Exam. The pupil is widened (dilated) with eye drops and then a light is shown through with an instrument called an ophthalmoscope to noninvasively inspect the back, inside part of the eye.
- Ocular Pressure. An instrument, such a tonometer or a tonopen, measures the pressure inside the eye. Drops that numb the eye may be used for this test.
- A Slit Lamp Exam. A slit lamp noninvasively inspects much of the eye. It can inspect the front and back parts of the eye and some lamps may be equipped with a tonometer to measure eye pressure. A dye called fluorescein, which makes blood vessels easier to see, may be added to the eye during the examination. The dye only temporarily stains the eye.
Anterior uveitis usually responds to topical corticosteroids. Occasionally periocular corticosteroid injections or even systemic corticosteroids are required. Dilation of the pupil is important to relieve discomfort and prevent permanent posterior synechiae.
Posterior uveitis more commonly requires systemic, periocular, or intravitreal corticosteroid therapy and occasionally systemic immunosuppression with agents such as azathioprine, cyclosporine, mycophenolate, methotrexate, tacrolimus, or sirolimus, of which some can be administered by intraocular injection. The use of biologic therapies is increasing. Pupillary dilation is not usually necessary.
If an infectious cause is identified, specific antimicrobial therapy is often needed. In general, the prognosis for anterior uveitis, particularly the nongranulomatous type, is better than for posterior uveitis.
Left untreated, uveitis can cause complications, including:
- Retinal swelling (macular edema)
- Retina scarring
- Optic nerve damage
- Retinal detachment
- Permanent vision loss