Boron is often used in very small quantities in eye wash and eye drop
solutions to preserve the solution and control pH and assist in retaining
moisture.  In contact lens solutions, boric acid helps in lubricating the
lens to be more comfortable to wear.  For eye wash solutions, boric acid
assists in providing relief from eye irritation.  Borax Decahydrate is often
used with saline solutions to buffer the pH and help cleanse the eye.