A film on the use of the zebrafish model system to study Retinitis pigmentosa, a group of eye diseases in which there is damage to the retina of the eye. Issues involved: How does the eye work? ; What is Retinitis pigmentosa? ; Why use zebrafish? ; What can be achieved? Among a range of eye diseases, Retinitis Pigmentosa (RP) is a serious disease that affects the central function of the eye, the light response. It is shown how zebra fish is used as a model system to discover more about human conditions and diseases.