Cells of P. aeruginosa SG81 adhere in patches to Lotrafilcon B after 72 h incubation. Transmitted light micrograph: deposits and adherent bacterial cells on the contact lens are visible as grey dots and shadows. DAPI staining of the biofilm (blue) shows all adherent bacterial cells (viable and dead). CTC staining of the biofilm (red) shows the metabolic activity of the viable bacterial cells. Superimposition of the transmitted light micrograph and the fluorescence micrographs (merge) shows the correlation of the CTC and DAPI stained regions. The three-dimensional representation gives an illustration of the spatial structure and the thickness of the biofilm matrix (~12 μm). Bar = 20 μm.