ACTA OPHTHALMOLOG ICA 69 (1991) 750-753 Acridine orange staining in early diagnosis of mycotic keratitis Reba Kanungo, Renuka Srinivasan and R. Sambasiva Rao zyxwv Jawaharlal Institute of Postgraduate Medical Education and Research, Pondicherry,India Abstract. We have assessed the comparative sensitivities of acridine orange stainingand 10% potassium hydroxide wet mount in the examination of corneal scrapings from one hundred and sixty-one clinically suspected cases of mycotic keratitis. The sensitivity of acridine orange was found to be 76% as compared to that of potassium hy- droxide (65%). The predictive value for culture result was also seen to be higher. Although both the values were not statistically significant zyxwvutsrq (P> 0.05), acridine orange stain- ing was a rapid and simple technique with an added ad- vantage of detecting inflammatorycells in corneal scrap- ings. Key words: acridine orange - keratitis - corneal scraphgs - detection - fungal filaments. zyxwvutsr The incidence of mycotic infection in ophthalmic practice is on the increase (Jones et al. 19’72; Jones 1975; Forster & Rebell 1975). An early diagnosis is of the utmost importance in instituting appropri- ate therapy. Examination of corneal scrapings and other intraocular material with 10 to 20% potas- sium hydroxide solution provides a rapid screen- ing technique. However, this method is not with- out its drawbacks in differentiating fungal ele- ments from artefacts such as zyxwvu lint., cotton, hair and intercellular ridges of the epithelial cells (Wilson & Sexton 1968). Experience is an important asset in reading these mounts. Acridine orange has been reported as a direct and simple fluorescent stain for fungi in corneal scrapingsof suspected mycotic keratitis (Wilson & Sexton 1968; Clayton 1969). It has the distinct advantage of facilitating fungal de- zyxw 750 tection as brightly fluorescing objects against a dark background. It makes the screening of slides simple and rapid. It is important to correlate the disease with the causal agent in order to direct spe- cific therapy. Chemofluorescent dyes such as ac- ridine orange makes the detection of the fungal elements easier. We have compared the efficacy of acridine orange staining of corneal scrapings,from cases of suspected mycotic keratitis, with the 10% potassium hydroxide wet mount. Materials and Methods One hundred and sixty-one suspected cases of fun- gal corneal ulcer were analysed for the direct 10% potassium hydroxide (KOH) smear and acridine orange stain results. Two smears were made from each of the cases on two new glass slides. One of the smears was fixed in 95% cold acetone for 10 min. The slide was then immersed in 10%femc chloride to remove tissue autofluorescence (Clay- ton 1969). After washing in distilled water the slide was stained with 1:lO 000 aqueous acridine orange for 2 min according to the method of Clayton (1969).After final washing with distilled water and air drying, the slides were examined using an epi- fluorescent microscope (BG12 excitator filter, G247 barrier filter and darkground condensor). The other slide was examinedwith 10% KOH. Both the slides were examined independently of each other and the results noted. Simultaneous corneal scraping (obtained with-