The Value of Calcofluor White in the Diagnosis of Mycotic and Acanthamoeba Infections of the Eye and Ocular Adnexa

Abstract

In search of an easy and quick method for the diagnosis of fungal and Acanthamoeba infections of the eye, the authors have used calcofluor white (CFW), a fluorescent brightener with marked affinity for chitin and cellulose which are present in the cell walls of fungi and cysts of Acanthamoeba. Paraffinembedded tissues containing mycotic organisms were stained with CFW and examined under a fluorescent microscope. Several fungi such as Candida sp, Aspergillus sp, Phycomycetes, Fusarium solani, Histoplasma capsulatum, Cryptococcus neoformans, Rhinosporidium seeberi, and others were studied. Trephine corneal biopsy specimens (2 mm) and methanol-fixed corneal scrapings containing Acanthamoeba sp were also examined. The walls of fungi and Acanthamoeba cysts stained bright greenish white in contrast to the reddishorange background of the supporting tissues. The results demonstrate that the CFW method is a highly reliable and rapid technique for identification of mycotic organisms as well as cysts of Acanthamoeba. This method may also be applied in surgical pathology when performing frozen sections, as well as cytologic examination of corneal smears, vitrectomy specimens, and others.