PURPOSE: The aim of this study was to determine differences in particle size between three prednisolone acetate suspensions: Pred Forte, EconoPred Plus, and generic prednisolone acetate 1%. SETTING: This study employed the setting of a laboratory evaluation. METHODS: Qualitative assessment of sedimentation rate as a function of particle size was the method employed for this study. Samples of the three products were taken from the top of the suspensions at 0 and 6 h and then at 12-h intervals from 12 to 72 h. At 72 h, a sample was pulled from the bottom of each suspension. RESULTS: Particle size in aliquots removed from the top of the suspensions steadily decreased over time. In the Pred Forte sample, results for 72 h (bottom) were consistent with T = 0 h results. In the generic and EconoPred Plus lots, the T = 72 h (bottom) results exceeded the T = 0 h results, suggesting a tendency for these particles to agglomerate more readily. CONCLUSIONS: The prednisolone particles in Pred Forte were smaller and more uniform at all time points, allowing them to stay in suspension longer. This may result in greater homogeneity between doses and increased ocular bioavailability.