ABSTRACT
Physiological Optics, as confirmed by its central manifestation, Helmholtz’s three-volume handbook, was understood at the time to be synonymous with the current Vision Science. But nomenclature has to go along with the explosive expansion of scientific knowledge. Hence the more optical components are now subsumed under Visual Optics, and even here further subdivision is needed. Optical imagery in the living eye is continually conditioned on factors arising from being embedded in motor apparatuses, specifically those controlling the pupil aperture and the ciliary muscle. Hence a division into structural visual optics, relating to the image-forming properties of the static normal eye, and functional visual optics, which would fold in accommodative and aperture size factors, seems indicated. Though it is not recognized as a distinct discipline, one can identify a branch of research as histological optics. Insofar as it transmits light unimpeded, eye tissue, such as the cornea and the crystalline lens, needs to have unusual biological structure. This became more evident and constituted a challenge around the middle of the century when electron microscopy began to reveal the subcellular makeup of corneal and lenticular layers.
