In Vivo Confocal Microscopy of Keratic Precipitates

Abstract

To evaluate the heterogeneity of keratic precipitates (KP) in varying subtypes of uveitis by in vivo confocal microscopy (IVCM). 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. 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 mum. 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. 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.