RDH8 and Stargardt disease: (Photo)toxicity of retinaldehyde and its degradation products is of particular relevance to blinding diseases caused by delayed clearance of all-trans-retinaldehyde, such as Stargardt’s disease caused by dysfunction of enzymes responsible for all-trans-retinaldehyde removal: ATP-binding cassette transporter A4 (ABCA4) or retinol dehydrogenase 8 (RDH8) [25,26,27].