LED lighting products are subject to European safety standards regarding eye safety and classified into 4 risk groups. Lighting products falling into the top two groups can be harmful if stared at directly and must be clearly labelled with the warnings.
We are not aware that the use of LED lighting products in home aquariums has caused any problems but would nonetheless advise aquarists to be aware of the risks, only use LEDs for the purpose for which they are intended, and avoid staring directly at the light source for any length of time. Reducing a light’s brightness when close to it will also help reduce any risks and aquarists could consider setting light intensity at a level suited to their fishes requirements (not just as bright as possible).
We also recommend that aquarists ensure that they are purchasing any electrical products, including LEDs, from a reputable brand that meets recognised EU and UK safety standards and to read and follow the manufacturer’s advice and warnings.