In Vivo Confocal Microscopy Cellular Features of Host and Organism in Bacterial, Fungal, and A canthamoeba Keratitis

• Published in: American journal of ophthalmology Vol. 190; pp. 24 - 33
• Main Authors: Chidambaram, Jaya D., Prajna, Namperumalsamy V., Palepu, Srikanthi, Lanjewar, Shruti, Shah, Manisha, Elakkiya, Shanmugam, Macleod, David, Lalitha, Prajna, Burton, Matthew J.
• Format: Journal Article
• Language: English
• Published: Chicago Elsevier Limited 01-06-2018
• Subjects: Consent; Cysts; Microscopy; Morphology; Ophthalmology; Organisms; Ulcers; India
• ISSN: 0002-9394; 1879-1891
• DOI: 10.1016/j.ajo.2018.03.010

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.