Uveitis
What is Uveitis?
Uveitis is an inflammation that occurs in the middle layer of the eye. It can also lead to inflammation in the adjacent areas, like the retina and fluid in the back of the eye (called vitreous).
To understand what Uveitis is, we must first know how a normal eye works. The eye is like a camera. The lens allows light to pass through it and then focuses that light on a film at the back of the camera to form a clear picture.
The eye works in a similar manner. In a normal eye the lens is clear and allows the light to pass through it. The light is focused on a thin film called the retina, which is located in the back of the eye. The different parts of the eye collect this light and send a message to the brain, thus forming the image that we see.
What causes Uveitis?
While the basic cause for Uveitis remains undetermined in most cases, it may be a manifestation of systemic diseases. It can also occur as a result of an auto-immune reaction to ocular antigens or be due to a local infection caused by virus, bacteria, fungus or a parasite.
Doctors often order laboratory tests, X-rays and consultations with specialists to determine the cause of Uveitis. However, even after detailed tests, they may still not understand its cause.
Types of Uveitis
Uveitis can be of four types, depending upon the location of the inflammation.
Anterior Uveitis: This kind of Uveitis affects the front or anterior portion of the eye. The common symptoms are redness, watering, decreased vision, pain in the eye, and photophobia or intense discomfort while looking at light. In low-grade inflammation, the eye may appear normal but still have signs of damage.
Intermediate Uveitis: In this type of Uveitis, the uveal tract (middle part of the middle layer) is affected. The patient usually sees black spots in front of the eye. There may be loss of vision due to fluid accumulation in the central area of the retina.
Posterior Uveitis: This type affects the back or the posterior portion of the eye. The eye may appear normal or there may be little inflammation in the front. The inflammation may affect the retina, choroid (posterior or back part of the middle layer) or both. The inflammation may be localised at several places, or even widely spread. Patients usually complain of poor vision, or absence of central vision or peripheral vision.
Panuveitis: Panuveitis affects the entire uveal tract (middle layer from the front and back). It often causes a distinct blurring of the vision with varying degrees of pain and redness. This is also associated with inflammation in the vitreous cavity at the back of the eye.
