Analysis of the blood-aqueous barrier by measurement of aqueous flare in 31 eyes with Fuchs' heterochromic uveitis with and without secondary open angle glaucoma

Background: Fuchs' heterochromic uveitis is characterized by low-grade intr aocular inflammation and a relatively benign clinical course. It was the ai m of this study to quantitatively determine alterations of the blood-aqueou s barrier in this disease by measuring the aqueous flare. Methods: 31 affected eyes of 31 patients with the characteristic clinical p icture of Fuchs' heterochromic uveitis, 31 apparently unaffected contralate ral eyes, and 120 age and sex-matched normal control eyes were included in this retrospective study. Five of the eyes with Fuchs' heterochromic uveiti s showed signs of secondary open-angle glaucoma. Determination of aqueous f lare was performed in all eyes using the laser flare-cell meter FC-1000 (Ko wa, Japan) after pupillary dilation. Results: Aqueous flare values were moderately but significantly increased i n eyes with Fuchs' heterochromic uveitis (mean 12.1 +/- 3.6 photon counts/m s) in comparison to normal control eyes (4.1 +/- 1.3 photon counts/ms, p < 0.001). Flare values of apparently unaffected contralateral eyes (mean 3.9 +/- 1.1 photon counts/ms) did not differ from normal control eyes (p = 0.5) . In the group of eyes with Fuchs' heterochromic uveitis, aqueous flare was comparable in eyes with and without secondary open angle glaucoma (11.9 +/ - 2.5 versus 12.1 +/- 3.8 photon counts/ms, p = 0.9). Conclusion: The alteration of the blood-aqueous barrier in patients with Fu chs' heterochromic uveitis is unilateral and relatively mild, corresponding to the well-known clinical picture of the disease. Secondary open-angle gl aucoma appears not to be associated with additional increase of aqueous fla re. The unilaterality and the relatively homogeneous distribution of the de gree of increased aqueous flare Values support the clinical impression that Fuchs' heterochromic uveitis is a distinct clinical entitiy that should be differentiated from other variants of chronic anterior uveitis.