Abstract
PurposeTo determine cellular features of fungal (FK), Acanthamoeba (AK), and bacterial keratitis (BK) using HRT3 in vivo confocal microscopy (IVCM).DesignProspective observational cross-sectional study.MethodsEligible participants were adults with microbiologically positive FK, AK, or BK, of size ≥ 3 mm, attending Aravind Eye Hospital from February 2012 to February 2013. Exclusion criteria were descemetocele or perforation. At presentation, IVCM imaging was performed, then corneal scrapes were obtained for culture/light microscopy. An experienced grader (masked to microbiology/clinical features) assessed IVCM images for presence/absence of normal keratocyte-like morphology, stellate interconnected cells with/without visible nuclei, dendritiform cells (DFCs), inflammatory cells in a honeycomb distribution, and organism features. Statistical significance was assessed by logistic regression, adjusted for age, sex, ulcer size, and symptom duration. Main outcome measures were presence/absence of IVCM features in FK, AK, BK.ResultsA total of 183 participants had FK, 18 AK, 17 BK. Acanthamoeba appeared as bright spots (16/18, 89%), double-walled cysts (15/18, 83%), or signet rings (3/18, 17%), and often formed clusters after topical steroid use (univariable odds ratio [OR] 9.98, 95% confidence interval [CI] 1.02-97.96, P = .048). BK was associated with bullae in anterior stroma (OR 9.99, 95% CI: 3.11-32.06, P < .001). Honeycomb distribution of anterior stromal inflammatory cells was associated with FK (univariable OR 2.74, 95% CI: 1.01-7.40, P = .047). Aspergillus ulcers were associated with stromal DFCs (OR 11.05, 95% CI: 1.49-82.13, P = .019) and Fusarium ulcers with stellate appearance of interconnected cell processes with nuclei (OR 0.24, 95% CI: 0.09-0.65, P = .005).ConclusionSpecific cellular and structural features observed using IVCM in microbial keratitis may be associated with organism.
Highlights
To determine cellular features of fungal (FK), Acanthamoeba (AK), and bacterial keratitis (BK) using HRT3 in vivo confocal microscopy (IVCM)
In fungal keratitis (FK), which formed the majority of cases in this study of large ulcers, the only IVCM feature weakly associated with this disease was the presence of an anterior stromal honeycomb distribution of inflammatory cells
This specific honeycomb pattern of inflammatory cells is similar to that observed after abrasion injury in real-time in vivo HRT3 IVCM imaging of the mouse cornea; these inflammatory cells were identified as neutrophils using immunohistochemistry in the same tissue ex vivo, and their close interaction with keratocytes was found to be mediated through action of cell adhesion molecules.[9]
Summary
To determine cellular features of fungal (FK), Acanthamoeba (AK), and bacterial keratitis (BK) using HRT3 in vivo confocal microscopy (IVCM). METHODS: Eligible participants were adults with microbiologically positive FK, AK, or BK, of size ‡ 3 mm, attending Aravind Eye Hospital from February 2012 to February 2013. IVCM imaging was performed, corneal scrapes were obtained for culture/light microscopy. An experienced grader (masked to microbiology/clinical features) assessed IVCM images for presence/absence of normal keratocyte-like morphology, stellate interconnected cells with/without visible nuclei, dendritiform cells (DFCs), inflammatory cells in a honeycomb distribution, and organism features. Honeycomb distribution of anterior stromal inflammatory cells was associated with FK (univariable OR 2.74, 95% CI: 1.01-7.40, P [ .047). Aspergillus ulcers were associated with stromal DFCs (OR 11.05, 95% CI: 1.49-82.13, P [ .019)
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