“…Fluorescein is a highly coloured chemical dye that has been used for many years as an aid to diagnosing abnormalities of the ocular surface and tear film (Bellarminoff, 1893; Anderson, 1949; Doughty et al. , 2005; Ward, 2008), as well as to undertake procedures such as applanation tonometry (Moses, 1960) and contact lens fitting (Schneider, 2001). In broad terms, its chemical and spectral properties might be considered as well known, since various notes and even some spectra can be found in a number of optometry and ophthalmology texts (Havener, 1978; Boothe, 1991; Goodwin, 1991; Hogan and Zimmerman, 1997; Schneider, 2001; Hopkins and Pearson, 2007; Doughty, 2009).…”