calceinA chelating agent which fluoresces brightly in the presence of bound Ca2+. The acetomethoxy derivative of calcein is used as a temporary label to test cell viability: once the calcein acetomethoxy complex enters healthy cells, intracellular esterases remove the acetomethoxy group, which fluoresces bright green—apparently in protest—something that dead cells, which lack esterases, cannot do.
Segen's Medical Dictionary. © 2012 Farlex, Inc. All rights reserved.
A staining agent similar to fluorescein but with a much higher molecular weight (710) and which is less readily absorbed by soft contact lens material. It is used in the fitting of soft or hybrid lenses (e.g. a piggyback lens). It stains a pale yellow-brown. However, it is not recommended for use with high water contact lenses (above 65%).
Millodot: Dictionary of Optometry and Visual Science, 7th edition. © 2009 Butterworth-Heinemann