Many different infections can cause Parinaud's syndrome, including bacteria, viruses, fungi and parasites.

The most common causes are tularemia (rabbit fever) and cat-scratch fever. Tularemia can infect the eye either by direct inoculation of the bacteria into the eye (by a finger or other object) or via aerosolization of the bacteria into the air, which then land on the eye. Other infectious diseases can spread both by these mechanisms and also through the bloodstream to the eye.

The eye is often red, irritated and painful, with an increased amount of tears, similar to conjunctivitis. There may be a swelling of the lymph glands nearby, often in front of the ear. A fever and generalized illness may be present.

An examination shows a red, tender, inflamed eye with possible ulcers in the cornea (surface). Tender lymph nodes may be present, in front of the ear. These lymph nodes can fester, depending on the cause of the infection. A fever and other signs of generalized illness may also be found.

The white blood cell count may be high or low, depending on the cause of the infection. For many of the infections that cause Parinaud's syndrome, blood tests to check antibody levels are the main methods used to make a diagnosis. Sometimes, culture of the eye, lymph node, or blood or biopsy of the lymph node can be helpful.

Depending on the cause of the infection, antibiotics may be helpful. Surgery may be necessary to clean away the infected tissues.

The outlook depends on the cause of the underlying infection. In general, if the diagnosis is made early and prompt treatment is begun, the outcome of Parinaud's syndrome can be very good.

• It is possible for the infection to spread into nearby tissues or into the bloodstream.
• Eye complications resulting in blindness can occur.

You should call your health care provider if you develop a red, irritated, painful eye.

Frequent hand washing can reduce the likelihood of acquiring Parinaud's syndrome. Specifically, tularemia can be avoided by not having contact with wild rabbits, squirrels, or ticks.

Cat scratch disease is usually a self-limited, acute illness associated with enlarged lymph nodes, fatigue, headache, and decreased appetite. It is more likely to be transmitted by kittens than by older cats.