Effect of shear stress on attachment of corneal endothelial cells in association with corneal endothelial cell loss after laser iridotomy.

PURPOSE: Laser iridotomy often causes bullous keratopathy; however, the mechanism is unclear. We investigated whether changes in aqueous humor hydrodynamics after laser iridotomy have any role in corneal endothelial cell loss.

MATERIALS AND

METHODS

Porcine corneal endothelial cells were plated onto glass slides. Following 1 or 3 hours for adhesion, the endothelial cells were exposed to shear stresses (0.1-10 dyne/cm) for 15 minutes, and the number of detached cells was counted. In addition, the pressure and shear stress on corneal endothelial layer were calculated in a virtual model of laser iridotomy.

RESULTS

The number of detached corneal endothelial cells increased with shear stresses in a dose-dependent manner. Significant increase of rate of detached corneal endothelial cells was observed at >0.3 dyne/cm after 1-hour attachment and at 1 dyne/cm after 3-hour attachment. The maximum pressure on corneal endothelial layer was 0.007 mm Hg, which is negligible compared with intraocular pressure. However, the maximum shear stress on the corneal endothelial layer could be> dyne/cm in some conditions of laser iridotomy.

CONCLUSIONS

The resistance of corneal endothelial cell loss to shear stress is time dependent. Shear stress could be a cause of corneal endothelial cell loss in some conditions of laser iridotomy.