Flush your eyes with water or saline solution
Just as your tear is supposed to flush the sand out, it might not be able to provide enough lubrication to get the particles out. It would help to lie down, look up, and use an eyewash or saline solution to flush your eye. If there is no saline solution, you can use clean, running water.
Lift your upper eyelid over your lower eyelid
To do this, you should ensure that your hands are clean. The American Academy of Ophthalmology [2] notes that lifting your upper eyelids over your lower eyelids allows your eyelashes to act as natural brushes to sweep the sand out of your eye.