For several decades, basic research on acquired and inherited retinal degeneration was substantially based on a variety of animal models, most of them originating from spontaneous mutations, others induced by damaging external agents. In the past few years, however, progress in genetic engineering has led to a rapidly growing number of transgenic animals, mostly mice, carrying constructs that lead to disruption or overexpression of candidate genes for retinal degenerations. On the one hand, these new models constitute a powerful and adaptable tool to investigate the role of specific gene mutations and the resulting cellular defects that finally lead to photoreceptor cell death. On the other hand, they extend the spectrum of animal models suitable for the newly arisen field of retinal somatic gene therapy.

To assist researchers and clinicians interested in the field, this article attempts to provide a structured overview on recently developed transgenic animal models as well as on models based on spontaneous mutations and induced degenerations. In this review the authors focus on animal models for photoreceptor degeneration since the rapidly growing field of models for ganglion cell death merits its own review and would be beyond the scope of this article. Even with this restriction, the abundance of information generated especially in the past few years makes the attempt of a complete overview almost illusory. Therefore, we apologise for omissions or shortfalls extant in this review. Furthermore, we want to point out that some of the model systems described have already been used extensively. We will therefore occasionally not cite original publications but rather reviews dealing with the specific model system.

Finally, we did not incorporate strategies using viral vectors and/or pharmacological substances. The specific deletion or overexpression of genes susceptible for the modulation of photoreceptor apoptosis, however, was included. The authors are aware that these …