Evaluation of infectious crystalline keratitis with confocal microscopy in a case series

We sought to determine whether there are unique findings in infections crystalline keratitis (ICK) examined by confocal microscopy and if confocal microscopy is predictive for bacteriology in ICK. A retrospective review of consecutive patients with a presumed diagnosis of ICK by slit-lamp examination was performed. These patients were then examined with confocal microscope and cultured. Sixteen patients were identified by biomicroscopy. Average age was 71 years; 12 of 16 patients were women; 10 of 16 had prior penetrating keratoplasty; and 12 of 16 were taking topical steroids. Confocal microscopy revealed a variable appearance to the crystals in the corneal stroma. Eight of 16 patients had distinct needle-like deposits at varying depths in the stroma, and eight had amorphous deposits grouped at different levels of the stroma. The results of confocal microscopic examination resembled the reported histopathology with clusters of deposits, but its current resolution does not allow identification of bacterial morphology. There was no correlation of morphology with culture results. Organisms were recovered in 12 of 16 patients by culture. In 10 of 16 patients, the infection was successfully treated with topical antibiotics, usually cefazolin. Crystal morphology of ICK can be observed by confocal microscopy. No pathognomonic, single pattern for this disease is seen with the confocal microscope. The latter may be an aid in determining the clinical response to treatment.