Clouding of vision accompanied by seeing coloured haloes around lights caused by corneal oedema resulting from contact lens wear, more frequently the hard lens type (PMMA). The cause has been shown to be due to a circular diffraction pattern formed by the basal epithelial cells and the extracellular spaces. Syn. Fick's phenomenon. See central corneal clouding.
Millodot: Dictionary of Optometry and Visual Science, 7th edition. © 2009 Butterworth-Heinemann