The lids influence on corneal shape.

Background: The lids are in contact to the corneal surface in normal viewing. Refractive surgery, however, is performed with a speculum in place and thus the lids are not in contact with the cornea.

Purpose: To investigate central corneal shape with and without the lids touching the corneal surface.

Methods: The technique consists of exporting the point cloud of the topography scanner into computer software that recreates the corneal surface. The technique of surface modeling was used to form central corneal elevation height difference maps of four normal eyes with and without lid contact to the corneal surface.

Results: Surface modeling demonstrated the trend that the lids influence the corneal shape.

Conclusion: The lids distort corneal shape.