KeratouveitisKeratouveitis is a term used when there is a combination of keratitis and uveitis. Uveitis is an inflammation inside the eye (as described in "What is Uveitis?"). It is necessary, then, to describe what keratitis is.
Keratitis occurs when the cornea becomes inflamed. The cornea is the clear "window", through which light enters the eye. It is always covered with a layer of tears. As it is the outer layer of the front of the eye, it needs to protect the eye from the outside world, like our skin does. However, unlike the skin which can easily return to normal after being inflamed, the cornea is affected more seriously by inflammation because it is easily scarred and can lose its clarity.
SymptomsKeratitis usually involves:- light sensitivity, pain, redness and tearing.
CauseKeratitis may be caused by various forms of injury to the cornea but the vast majority of cases are caused by infection. By far the most common infection is by the virus, Herpes simplex-1 (HSV-1), although it may be caused by bacteria or other viruses, such as Herpes zoster, the virus which causes "Shingles".
Herpes simplex-1The best way to understand this infection is to describe the common cold sore which most of us have either experienced or know about. HSV-1 affects the cornea in exactly the same way as it causes the cold sore. The HSV-1 virus is very common, with some figures showing that 90% of the population have been infected. It is spread quite easily by droplet infection and close contact. A great number of these are subclinical infections, that is, there are no clinical signs and the person infected is unaware of any problem. The first time a person is infected is called the primary infection and this commonly occurs in the first few years or life. As above, usually this primary infection causes no symptoms. Occasionally it causes fever and severe mouth ulceration or it may cause a conjunctivitis or ulceration of the eyelids.
The HSV-1 virus at the primary infection stage, travels down the nerve that supplies that area which is called the trigeminal nerve. It remains in a part of the nerve called a ganglion permanently and becomes dormant. For many people it remains dormant, but for others the virus is re-activated by certain trigger factors which include sunlight, stress or other illness. Once re-activated, the virus multiplies and travels back down the nerve to cause a herpes infection. This normally results in a cold sore as the virus travels down the branch of the trigeminal nerve that supplies the mouth and lips. More rarely the virus travels down another branch of the trigeminal nerve which supplies part of the eye and this causes a keratitis, an inflammation of the cornea.
The first time the patient is aware of a problem, then, will probably be due to a re-activation of an "old" infection perhaps many years previously. The number or times the infection recurs will vary enormously from person to person. It is obviously very important to be aware of these recurrences and to seek urgent advice from an Ophthalmologist.
Keratouveitis occurs when the keratitis causes a uveitis normally near the front of the eye (anterior uveitis). The uveitis may vary in severity and may be recurrent. The condition may vary between patients greatly.