Confocal Microscopy in Early Diagnosis of Acanthamoeba Keratitis

Abstract

PURPOSE: This study correlated confocal microscopic images obtained using the Nidek ConfoScan 2.0 System in corneas with clinical suspicion of Acanthamoeba keratitis, with diagnosis confirmed by either cytological and/or histological analysis. METHODS: Fifteen eyes of 14 patients with a clinical diagnosis of Acanthamoeba keratitis underwent confocal microscopy evaluation. RESULTS: Fifteen eyes of 14 patients (one bilateral case) showed Acanthamoeba keratitis alterations that ranged from massive infestation to cicatricial opacity in the stroma. Ten patients (71%) were females. Mean age was 26 years (range 19 to 37 yr). All patients were contact lens wearers. CONCLUSION: Confocal microscopy was a useful, noninvasive technique in the diagnosis and treatment of Acanthamoeba keratitis, especially in those cases in which corneal scraping, cytological analysis, and culture are negative. It also eliminated the necessity of tissue biopsy, considered an invasive procedure. [J Refract Surg 2004;20 (suppl): S737-S740]

Acanthamoeba keratitis and contact lens wear

“…Corneal scrapings should always be performed to confirm the diagnosis of AK and, if both smears and cultures are inconclusive, corneal biopsy may be required. In vivo confocal microscopy can also be used to confirm the presence of Acanthamoeba 41 as was done in Cases 2 and 3.…”

Incidence and morbidity of hospital‐presenting corneal infiltrative events associated with contact lens wear

“…Consideration of CIEs as a continuous spectrum of disease obviates the need to differentiate the various proposed sub-types according to aetiology, especially with respect to the less severe manifestations; however, we recognise the clinical value of attempting to identify the causative microbial agent in the case of severe disease. For example, utilising corneal scraping and culturing [8][9][10]18 and occasionally employing confocal microscopy to confirm the presence of acanthamoeba 26 will often yield results that have a crucial bearing on the management of the condition.…”

Contemporaryin vivoconfocal microscopy of the living human cornea using white light and laser scanning techniques: a major review

“…7). [61][62][63] The doubled-walled structure of cysts may also be apparent, with a visible endocyst surrounded by the ectocyst. 61 The active trophozoite form is irregular in shape and ranges between 11 and 25 µm in diameter.…”

“…60,61 Irregularly thickened, hyper-reflective stromal nerves with associated round structures have also been noted in acanthamoeba keratitis and may represent radial neuritis with trophozoite infiltration. 61,62 In a large study by Mathers et al, 84% of patients with suspected acanthamoeba keratitis, on the basis of in vivo confocal microscopy, were subsequently confirmed positive for the organism on cytology of epithelial biopsy specimens. 64 Although the definitive diagnosis of acanthamoeba keratitis still requires positive identification of the organism from corneal scrape/biopsy specimens, in vivo confocal microscopy is a useful diagnostic adjunct as results are immediately available and may be used to prompt appropriate corneal scraping or biopsy.…”