Adaptive optics (AO) -- invented more than 50 years ago -- has transformed optical and infrared ground-based astronomy. All the world's major telescopes are now equipped with adaptive optics, and the next generation of extremely large telescopes of 30–42 m diameter will rely on AO to produce the desired image quality. While the most exotic AO systems are installed on large telescopes, adaptive optics has also found application in many other fields, and at this symposium, we highlight two of these: microscopy and ophthalmology. Modern microscopy has developed enormously since the time of physicist Ernest Abbe over a century ago. Although many new techniques are designed to overcome his "diffraction limit" for resolution, they are still hampered by specimen-induced features. This is where adaptive optics can play a role, to ensure that the highest resolution is always achieved. The eye is a very imperfect optical instrument, with imaging performance very far from the diffraction limit. Using adaptive optics, scientists can correct for the optical aberrations of the eye, and therefore take sharper pictures of the retina, for early detection of disease, and provide subjects with improved or changed vision. One application in the latter case is for simulating the outcome of cataract surgery using one of the many new designs for intraocular lenses. In this symposium, speakers explore these aspects of adaptive optics, both individually and in relation to each other.