Evaluation of albumin concentration in rabbit anterior chamber with laser flare-cell meter

To find an appropriate way of using Kowa's laser flare-cell meter in evaluating the anterior chamber albumin concentration, we characterized the relationship among the flare intensity determined with the flare-cell meter in terms of photon count/ms (flare value), flare value converted to albumin concentration, and anterior chamber albumin concentration in drug-treated rabbit eyes. Flare measurement was done in rabbits that received intravenous administration of fluorescein isothiocyanate-labeled albumin and instillation of prostaglandin E1, pilocarpine, or tropicamide. Flare value, anterior chamber fluorescence, plasma fluorescence, and plasma albumin concentration were determined. Anterior chamber albumin concentration was calculated from the plasma albumin concentration and the corrected aqueous/plasma fluorescence ratio. The correlation between the flare value converted to albumin concentration (Albequiv) and the anterior chamber albumin concentration (Albac) had two phases: 1) Linear correlation was found when the flare value was below 100 photon count/ms: Albac = 0.53 Albequiv - 0.006, r = 0.98; 2) When the flare value was above 100 photon count/ms, the correlation was lower and had a different slope. In this condition, the Albac was correlated better with the flare value itself: Albac = 0.0042 [flare value] + 0.17, r = 0.88. The results suggested that anterior chamber albumin concentration is evaluated quantitatively from the converted flare value when the flare value is below 100 photon count/ms and from the flare value itself when the flare value is above that level.