A few simple observations will clarify what you see.
If the lines are mostly vertical, the are not caused by your eyelashes (which would create a horizontal diffraction pattern).
Vertical lines might be caused by diffraction if you can close your eye almost completely - the width of the aperture has to be a few wavelengths at most to see any diffraction "lines". If this is the mechanism then you would expect to see repeating fringes for monochromatic lights (like the yellow sodium street lights), and colored fringes in the vicinity of the center of the light.
More likely, surface tension will cause the liquid on the surface of your eye to "bead" causing a cylindrical lens. This will give a strong vertical distortion perpendicular to the opening between your eye lids. Your two eyes have slightly different angles and this would give rise to two different lines in your stereoscopic view of the world.
A better description of what you see would help!