SENSITIVITY OF LASER FLARE PHOTOMETRY TO MONITOR INFLAMMATION IN UVEITIS OF THE POSTERIOR SEGMENT

Purpose: Laser flare photometry is a new quantitative method for evalu ating aqueous flare, making flare the only inflammatory parameter that can be evaluated precisely and objectively. The validity of the metho d already has been demonstrated in anterior segment inflammation. The aim of this study is to assess the validity and limitations of the met hod to quantify and monitor inflammation in uveitis with predominant i nvolvement of the posterior segment. Methods: Five well-defined condit ions with uveitis predominant in the posterior segment were analyzed i n this study: Behcet uveitis, pars planitis, posterior sarcoidosis, po sterior pole toxoplasmosis, and birdshot chorioretinopathy. (1) Mean i nitial (pretreatment) flare was determined; (2) in the patients needin g systemic steroid therapy, introduction of therapy was correlated wit h evoluting laser flare photometry; and (3) in patients with quiescent disease, the predictive value of a defined subclinical photometry-det ected flare rise for disease recrudescence was analyzed. Results: Init ial pretreatment flare was 331.8 +/- 47.7 photon counts per millisecon d (ph/msecond) (mean +/- standard error of the mean) for Behcet uveiti s, 15.6 +/- 1.3 ph/msecond for pars planitis, 26.9 +/- 4.6 ph/msecond for posterior sarcoidosis, 7.5 +/- 1.0 ph/msecond for posterior pole t oxoplasmosis, 5.8 +/- 0.7 ph/msecond for birdshot chorioretinopathy, a nd 4.7 +/- 0.1 ph/msecond for a group of 88 control eyes. A significan t flare reduction after start of steroid therapy was seen in Behcet uv eitis (78% reduction), sarcoidosis (44.8%), and pars planitis (51%), b ut not in toxoplasmosis or in birdshot. A small flare rise had a predi ctive value for disease recrudescence in 27/35 patients (predictive va lue, 0.77; sensitivity rate, 100%). The level of associated blood-aque ous barrier disruption for reliable follow-up of posterior uveitis was empirically determined to be 13 to 15 ph/msecond. Conclusion: Laser f lare photometry was found to be very sensitive to monitor inflammation in uveitis of the posterior segment as long as a sufficient level of associated blood-aqueous barrier disruption (flare) was present.