Abstract
Purpose::
To study the role of mucins on post-lens tear stability, we determined whether hypoxic condition alter the expression of mucins on corneal epithelial cells.
Methods::
All procedures including human subjects were conducted in accordance with the tenets of the principles of the Declaration of Helsinki, and this study was approved by the Institutional Review Board of Ehime University. Human corneal epithelial cells (HCECs) were obtained from normal volunteers (12eyes) and soft contact lens (SCL) wearers (13eyes) by impression cytology after obtaining informed consent. Immortalized HCECs (SV40-HCECs) were cultured under normal (20 %) or hypoxic (2 %) conditions. Real time PCR was used to determine the mRNA expression of MUC1, 4 & 16. The corneal surface of pre- and post (5, 15, 30, 45 and 60 min) SCL was analyzed by Tear Stability analysis system (TSAS) and the tear stability was evaluated by Break-up index (BUI).
Results::
The relative mRNA expressions of MUC1, 4, & 16 in the corneal epithelial cells from SCL wearers were reduced by 0.85, 0.3 and 0.2 fold respectively. MUC1, 4, & 16 expressions in SV40-HCECs under hypoxic conditions were also reduced by 0.6, 0.25 and 0.25 fold respectively. Post-lens tear stability was evaluated by TSAS and BUI was reduced by 70 % at 5 min, and was recovered to normal level at 45 min after removal of SCL.
Conclusions::
Hypoxia under SCL wear may induce the down-regulated expression of mucins in corneal epithelial cells and the hypoxic conditions may be responsible for unstable post-lens tear film.
Keywords: hypoxia • contact lens • cornea: epithelium