In vivo confocal microscopy of equine fungal keratitis.

This research investigates the usage of in vivo corneal confocal microscopy on horses with fungal keratitis, comparing the findings with clinical evaluations, histopathological examinations and microbiological assessments. The study found that this imaging technique is a quick and non-invasive method of diagnosing fungal keratitis in horses.

Methods and Participants

• The study focused on 12 horses suffering from naturally-acquired fungal keratitis, as well as equine corneas experimentally infected with clinical fungal isolates.
• The horses with natural fungal keratitis were examined using a modified Heidelberg Retina Tomograph II and Rostock Cornea Module.
• The researchers also obtained in vivo confocal microscopy images of clinical strains of the Aspergillus fumigatus, Fusarium solani, and Candida albicans fungi, both through examination of in vitro cultures and experimentally-infected ex vivo equine corneas.

Results

• The research unveiled a range of non-specific findings in horses with fungal keratitis under in vivo corneal confocal microscopy. These included leukocyte infiltrates, activated keratocytes, anterior stromal dendritic cell infiltrates, and vascularization.
• For all horses with filamentous fungal keratitis, linear, branching, hyper-reflective formations with widths between 2-6 μm and lengths between 200 to over 400 μm were observed.
• In a horse with yeast fungal keratitis, the researchers detected round to oval, hyper-reflective structures that were 2-8 μm in diameter.
• The test also revealed that the in vivo confocal microscopic characteristics of the organisms were consistent with the fungal morphologies discerned during examinations of in vitro cultures and infected ex vivo equine corneas.

Conclusions

• The findings support the usability of in vivo corneal confocal microscopy as a swift and non-invasive means of diagnosing fungal keratitis in horses.
• This imaging method holds utility for both ulcerative and non-ulcerative forms of fungal keratitis. In particular, it proves especially beneficial for confirming the presence of fungi in deep corneal stromal lesions.