Bright Sight

Oliver Backhouse, Consultant Eye Surgeon


Toxoplasmosis is a type of infection which is found all over the world. Many people have antibodies against Toxoplasmosis meaning that they have been exposed to it at some point in the past but only a very few have symptoms such as blurred vision and floaters. It is mainly caught from raw / undercooked meat (especially pork and lamb), contaminated water and soil that has been in contact with cat faeces. One can feel ‘flu like’ but most patients who have eye problems with Toxoplasmosis will have got it as a child or even when developing in the womb. This means the usual complaint with the eyes is that of floaters and reduced vision without the ‘flu’.

Eye Toxoplasmosis is a clinical diagnosis. There is a blood test to detect antibodies to Toxoplasma but if it is positive it just means that your eye inflammation may be due to it – remember a large percentage of the population have already been exposed to Toxoplasma and have no symptoms and therefore they will be positive for the antibody test. Conversely if the test is negative it means that it is unlikely to be the cause of the eye problem.

The inflammation inside the eye will resolve on its own but floaters can persist for many months. Medication is advised if the inflammation is close to an important part of the eye such as the optic nerve (the cable that take the message from the eye to the brain), the macula (part of the retina that sees fine detail) or the blood vessels of the retina. If the floaters are very bad then this also can be an indication to treat. There are numerous suggested treatment regimes – this reflects the fact that none are able to ‘get rid’ of the infection but they are able to speed up recovery and have some protection against damage to the vision. The recommended combination is that of an antibiotic and steroid. It is the steroid that offers the best protection as it softens the inflammation which is potentially damaging to the eye. Recurrences of the inflammation are common and one can expect 5-7 recurrences in ones lifetime approximately.

You don’t need to say goodbye to your cat. If you are pregnant or have a week immune system your vet would be able to advise you about reducing the risk of toxoplasmosis from cats. Daily changing of cat litters is advised followed by good hand washing with soap. It is not helpful to have your cat tested for Toxoplasma as cat infection and spreading of it by their faeces is usually only for a few weeks of their lives.

You will require regular review in the Uveitis clinic over a period of a few months. Any drops used that make the pupil large will further blur the vision.