ADAPTIVE OPTICS

Adaptive optics (AO) is a technology for correcting wavefront distortions that reduce the resolution of an image. It was originally developed for ground-based astronomical telescopes “to remove the twinkle from the stars.” When added to the ophthalmoscope, it can acquire in vivo images of cellular structures in the human eye with an optical lateral resolution of 2 µπι or less. Images with this resolution were previously only obtainable on histological specimens. Early attempts at AO imaging in the 1980s and 1990s at the University of Heidelberg using a scanning light ophthalmoscope (SLO), invented in 1980, showed that a deformable mirror could change the shape of its surface to compensate for optical distortions of the eye and enhance the resolution of retinal imaging devices. Imaging quality was subsequently improved when researchers incorporated a Shack-Hartmann wavefront sensor with a deformable mirror in the optical path of an SLO. This advance enabled compensation for higher-order wavefront aberrations, in addition to lower-order aberrations such as defocus and astigmatism.