Glossary

AUTOIMMUNE DISEASE

A healthy immune system produces substances called antibodies that help fight and destroy viruses, bacteria, and other foreign substances that invade the body. In autoimmune disorders, the immune system produces antibodies against the body’s healthy cells and tissues. These antibodies, called autoantibodies (“auto” means self), contribute to the inflammation of various parts of the body, including, sometimes, the eye, causing damage and altering the function of target organs and tissues.

In autoimmune diseases, the body harms its own healthy cells and tissues. This leads to inflammation and damage to various body tissues. In addition, some autoantibodies join with substances from the bodyÇs own cells or tissues to form molecules called immune complexes. A buildup of these immune complexes in the body also contributes to inflammation and tissue injury in people with some forms of autoimmune disorder.

Thus autoimmune disease is a disease in which the immune system destroys or attacks the patient’s own body tissue. Regardless of the form of autoimmunity, any autoimmune disease affecting the eye will require systemic (e.g., oral as opposed to local, topical, ocular) therapy; the components of the immune system reside not in the eye, but rather are systemic, and therefore, regulation of those components will require systemic therapy. Such therapy is typically designed to suppress the overly aggressive immune system, allowing the body to eventually re-regulate itself, with the result often being that after the patient has been kept on systemic medications to suppress the inappropriate immune response for a finite length of time (for example, one year), medication can then be tapered and stopped without recurrence of the autoimmune attack. Sometimes resumption of the attack does occur, in which case the patient must be re-treated.

AUTOIMMUNITY

Under normal conditions, the immune system protects the body from diseases and infections by killing harmful “foreign” substances, such as germs, that enter the body. Autoimmunity is a condition in which the immune system mistakenly attacks and harms the body’s own cells and tissues; this immune reaction is the basis of a variety of autoimmune diseases including some forms of uveitis, diabetes, rheumatoid arthritis, and systemic lupus erythematosus, among others. Uveitis on the basis of autoimmunity is the most common form of uveitis.

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BAND KERATOPATHY

Deposition of calcium in the cornea associated with degenerative corneal disease, high blood calcium levels and juvenile arthritis and chronic uveitis.

BIRDSHOT RETINOCHOROIDOPATHY (BSRC)

Birdshot retinochoroidopathy is a chronic intraocular inflammatory disease affecting mainly the posterior segment of the eye. It is distinct from other forms of posterior uveitis because of a very characteristic clinical presentation and a strong association with HLA-A29.2 antigen. Its etiology remains unknown. An autoimmune mechanism is likely to play an important pathogenic role given the demonstration of retinal autoantigen reactivity and the very strong association with the human leukocyte antigen (HLA)-A29 phenotype unique to this disease.

BSRC is an uncommon disease. In contrast to most other uveitic entities in which the onset of disease is in younger age groups, BSRC typically occurs during middle age, presenting at an average age of 50, with a range of between 35 and 70 years of age. The reason for this age shift is unclear. BSRC is found almost exclusively among whites, with a higher incidence in those of Northern European descent. An apparent gender preference is observed in some series, with women representing up to 70% of reported cases, whereas no significant predilection for sex is found in other series.

BINOCULAR VISION

Each eye looking at the same object sees a slightly different image. Binocular vision is the ability to fuse these two images into one and gives us the ability to perceive depth and judge distances.

BLEPHARITIS (INFLAMMATION OF THE EYELIDS)

Blepharitis refers to an inflammation in the oily glands of the eyelid. This usually results in swollen eyelids and excessive crusting of the eyelashes, most evident in the morning. Tenderness of the eyelids and a foreign body sensation in the eye may occur as well. Blepharitis is a chronic or long term inflammation of the eyelids and eyelashes. It affects people of all ages. Among the most common causes of blepharitis are poor eyelid hygiene; excessive oil produced by the glands in the eyelid; a bacterial infection (often staphylococcal); or an allergic reaction.

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CATARACT

Inside the eye, there is a lens which helps us to focus on what we see. The lens is made mostly of water and protein. The protein is arranged to let light pass through and focus on the retina.

Sometimes some of the protein clumps together and starts to cloud a small area of the lens.This cloudiness of the lens is called a cataract. Over time, the cataract may grow larger and cloud more of the lens as shown in the photograph below, making it more difficult to see. In the early stages, stronger lighting may lessen the vision problems caused by cataracts. At a certain point, however, surgery may be needed to improve vision.

Today, cataract surgery is safe and very effective. Although researchers are learning more about cataracts, no one knows for sure what causes them. The most common type of cataract is related to aging. More than half of all Americans age 65 and older have a cataract. Scientists think there may be several causes, including smoking and diabetes. Or, it may be that the protein in the lens just changes as it ages. There is also some evidence that cataracts are linked to certain vitamins and minerals. The National Eye Institute (NEI) is doing a study to see whether taking more of these substances prevents or delays cataracts.

CATARACT AND UVEITIS

Cataract develops in patients with uveitis because of the uveitis itself and also because of the prolonged use of steroid medications. Cataract developing in an eye with a history of chronic or recurrent uveitis has historically been called cataracta complicata.

The picture on the right is of a subcapsular cataract. A subcapsular cataract is often found in people taking steroids. Subcapsular cataract develops slowly and starts as a small opacity, usually at the back of the lens. Significant visual symptoms may not appear until the cataract is well developed. Typical symptoms are glare and blur.