The eye consists of three different layers of tissue. The outermost layer is the sclera, which maintains the shape and structure of the eye and protects it from foreign matter. The middle layer of the eye is the uvea, which contains many of the eye’s blood vessels. And the innermost layer is the retina. The eye’s interior is largely made up of the aqueous and vitreous humor or fluids which help to provide nourishment to certain parts of the eye, such as the lens.

Uveitis is really a broad term for a variety of problems involving inflammation of any of the parts that make up the middle layer of the eye known as the uvea. The uvea is composed of the following parts:

• The iris, which is the colored circle at the front of the eye. It defines our eye color, controls the amount of light that enters the eye by adjusting the size of the pupil so that it constricts in response to light and dilates when it is dark.

• The ciliary body, which is the part that makes the fluid called aqueous humor and is also the part that changes the shape of the lens so that the eye can focus.

• The choroid, which is the layer made up of many blood vessels and the connective tissue between the white of the eye and the retina (at the back of the eye). It provides nourishment to the retina and its nerve cells.

Inflammation of the tissue in the uvea can significantly affect a person’s vision quality. It can even lead to permanent loss of sight if not properly treated.

Uveitis is estimated to have a worldwide incidence of 17-52 per 100,000 persons per year, varying depending on nationality and country of residence. Of these, an estimated 10-14% of patients contract severe uveitis to such a degree that it results in vision loss.

Uveitis patients can develop a variety of signs and symptoms depending on which part or parts of the eye are inflamed. For example, those with uveitis often experience eye redness, eye pain, light sensitivity and decreased vision. If the patient has vitreous inflammation, they may experience an increase in eye floaters (spots), although without change in their visual clarity. Retinal inflammation may cause a complete loss of vision, or visual field loss or defects. These various symptoms can occur suddenly or gradually.

Nowadays, we are able to distinguish between the many different categories or types of uveitis. The most common causes of uveitis in Thailand and most other Asian countries include infections, an attack from the body’s own immune system (autoimmunity), vasculitis, and cancer, among others. In the past, we were only able to make specific diagnoses and pinpoint the exact cause in 40-50% of cases, but due to greater knowledge and a better understanding of the disease, along with the far more advanced medical technologies currently available, we are now able to identify the cause of up to 80% of cases.

If a person begins to experience symptoms that they suspect may be uveitis, or if they are a part of any of the at-risk groups for uveitis, including patients with autoimmune diseases such as lupus or SLE, ankylosing spondylitis, or scleroderma, and patients with immunodeficiency, they should consult a uveitis specialist for proper diagnosis and treatment. The ophthalmologist will gather a thorough health history and conduct a detailed eye and health exam. Additionally, if necessary, the patient may be referred for further examinations and laboratory testing in order to provide further diagnosis and treatment.

By Dr. Chaisiri Jumroendararasame, Ophthalmologist specializing in Uveitis, Eye Center, Bumrungrad International Hospital

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