In vivo confocal microscopy of keratic precipitates

Objective: To evaluate the heterogeneity of keratic precipitates (KP) in varying subtypes of uveitis by in vivo confocal microscopy (IVCM). Methods: The KP were viewed with a scanning confocal microscope in patients (n = 33) who sought care at a tertiary referral uveitis service for immune-mediated and infectious forms of uveitis, including HLA-B27-associated uveitis, sarcoidosis, Vogt-Koyanagi-Harada syndrome, juvenile chronic arthritis, Fuchs heterochromic iridocyclitis, cytomegalovirus retinitis, herpes zoster ophthalmicus, ocular toxoplasmosis, and idiopathic uveitis. Images were captured and digitalized in real time. Results: Forty-two eyes of 33 patients were examined in this study. Patient age ranged from 22 to 84 years, with a mean age of 49.4 years. Seventeen (52%) of the patients were women, and 16 patients (48%) were men. The KP ranged in diameter from 10 to 350 μm. We observed the following absolute and speculative outcomes: KP are markedly heterogeneous and variable as documented by IVCM; KP in individual patients are consistent throughout the cornea; the morphologic features of KP change across time; infectious vs noninfectious causes of uveitis seem to be readily distinguishable by using IVCM; and KP may have consistency for specific disease states and therefore may have diagnostic importance. Conclusions: To our knowledge, this is the first time that IVCM has been used to describe the architecture and heterogeneity of KP in uveitis. Such observations reveal a heterogeneity that could not be appreciated by conventional slitlamp microscopy and may have diagnostic relevance.