Principles of microscopy for ophthalmologists

This short review begins with the theories of Airy, Rayleigh and Abbe onmicroscope resolution. Next, the principal developments in microscopy in the lasthalf‐century are examined for relevance to ophthalmology: confocal microscopy,photoactivation light microscopy (PALM), stochastic optical reconstructionmicroscopy (STORM), stimulated emission depletion (STED), structured illumination(SI), 2‐photon and multiphoton excitation microscopy with a focused beam. Except forconfocal, these are difficult to apply to the eye in vivo, as are the interferencemethods available in microscopes. However, interferometry in the form of coherencetomography is now a major ophthalmic method which has diverged from microscopy.Multiphoton excitation microscopy with an unfocussed beam is a new, low‐damagemicroscope method so‐far not exploited in ophthalmoscopy. The Mesolens, which throwsoff the historic limitations in microscopy set by the human eye, is described as apossible future aid to ophthalmology of the anterior eye.