Does hypoxia alone increase the bacterial adherence to exfoliated corneal epithelial cells in man?

Purpose: Previous rabbit studies of contact lens wear have shown an inverse relationship between lens oxygen transraissibility, bacterial binding, tear LDH, and surface desquamation independent of lens type (rigid, hydrogel, hybrid) This study preliminarily evaluates the role of hypoxic injury to the corneal epithelium in influencing contact lens induced bacterial binding to surface epithelial cells Methods: Four nonCTL wearers were recruited. Eyes were successively exposed to three gas mixtures (air, 100%N₂, 95%N₂-5%CO₂) through tightly fitted goggles for six hours at two week intervals. Bacterial binding was determined by measuring Pseudomonus Aeruginosa (PA) adherence to corneal cells. Exfolii ted epithelial cells were collected using a modified corneal irrigation chamber. Ctlls were incubated with PA (1×10⁷CFU/ml) for 30 minutes. The number of adherent ba:teria to the cells was counted using fluorescent microscopy- Hypoxic injury was assessed by tear LDH activity and changes in surface cell size, epithelial and stromal thickness by in vivo confpcal microscopy. Results: n=4 Bac./cell cells shed cell size epi. thickness stromal thickness LDH Air 6.6±2.1 21.5±8.6 827±156 53.1±5.2 525±37 63±39 N₂ 8.6±4.2 13.5±8.2 772±-144 54.2±3.8 565±45(A8%)* 52±12 N₂/CO₂ 6.5±2.0 12.7±5.2 724±42 53.0±5.1 549±37(A5%)* 54±53 Hypoxia induced significant corneal stromal sweeling (p<0 .05*), but did not enhance PA adherence to exfoliated epithelial cells. Hypercapnia significantly reduced hypoxic stromal swelling (p<0.05). Conclusion;: These preliminary results indicates that shortterm hypoxia alone or combined with hypercapnia docs not increase bacterial adherence. It suggests that there are otl er interactive factors, in addition to hypoxia, associated with contact lens wear in prc moting bacterial binding.