What is Retinitis Pigmentosa?

(Some of this material provided by Retina Australia)

Retinitis pigmentosa as seen here is actually a group of disorders characterised by progressive loss of night vision, side vision and sometimes central or reading vision due to degeneration of rod photoreceptors in the retina. The name retinitis pigmentosa (Retinitis Pigmentosa) comes from the presence of black pigment in the retina. Retinitis Pigmentosa is perhaps better termed "rod-cone dystrophy" to reflect the fact that not only rod cells are affected, but also cone cells may be affected.

Symptoms of Retinitis Pigmentosa

Symptoms of Retinitis Pigmentosa are frequently experienced in childhood and the most common early symptom is of difficulty seeing in the dark or adapting to a suddenly darkened environment. This may precede other symptoms and signs by years and a diagnosis may not be made for quite some time. Later on, side vision is gradually loss and in extreme forms may leave the individual with "tunnel vision".

The photo on the right is normal whereas the left one gives an idea of the limitation experienced by someone with tunnel vision. Finding one's way around becomes very difficult if not impossible. Legal blindness may result.

The rate of progression and degree of visual loss are highly variable. Some broad predictions can be loosely made on the basis of age of onset, type of inheritance and the experience of other affected family members.

Retinitis Pigmentosa is usually an inherited condition. It can be passed through families as autosomal recessive, autosomal dominant or x-linked. Not uncommonly it is difficult to accurately determine which type of inheritance applies, particularly if only one person is known to have the condition.

Diagnosis of Retinitis Pigmentosa

Diagnosis is made by an eye doctor based on symptoms, finding signs within the eye, in association with abnormal visual field test results, and often confirmed with electrophysiology (ERG). Retinitis Pigmentosa may be associated with other problems within the eye and elsewhere in the body. Your eye doctor should check for cataracts, glaucoma, refractive problems, macular oedema, as well as excluding other conditions which can appear similar to Retinitis Pigmentosa.

Treatment of Retnitis Pigmentosa

The most important initial step is establishing an accurate diagnosis. Preferably consult an eye doctor who has plenty of experience in this area and have confirmatory testing done. Genetic counselling is important in establishing your family tree and deciding which type of inheritance is involved. This will have an impact on other family members and on decisions about future children.

Correction of any refractive problems (poor focus) of the eyes with glasses is critical to optimise the vision that is present. Exclude glaucoma or treat it if present. Glaucoma and Retinitis Pigmentosa can co-exist! Treat cataracts if they are visually significant. Many people with Retinitis Pigmentosa have mild cataracts which mostly do not compromise vision. Some however do require surgery and this decision can only be made by consultation with an eye doctor.

Occasionally some people with macular oedema in Retinitis Pigmentosa experience relief with the use of a drug called Diamox. Unfortunately, only a very small minority of people will fit into this category. Treatment of Retinitis Pigmentosa itself with vitamin A has been much publicised and to date there is little evidence that it has any effect on the disease. Also, vitamin A in large doses has potential severe side effects.

For many people with Retinitis Pigmentosa, low vision aids will be needed. This may involve instruction in navigational techniques to cope with tunnel vision, or may involve the use of magnification devices for reading etc. Advice on this area can be obtained from some eye doctors who specialise in this area and also from the Royal Blind Society.

Peer support from other affected people is often the most useful intervention. The support group "Retina Australia" is well resourced for this task.

Gene therapy is not yet available for this condition. Neither retinal transplantation nor eyeball transplantation are available as interventions. Implantation of light sensitive microchips may prove to be of some benefit but a large amount of research must be done before any development could begin.