The most scary thing about glaucoma is that it can steal your vision gradually and without you noticing.  The best defense against glaucoma is a regular eye examination.  Glaucoma most often strikes people over age 50, but it is recommended that during adult life everyone be tested at least once every year.  Some people with glaucoma do experience symptoms, but symptoms vary depending on the type of glaucoma.

• Primary open-angle glaucoma 
  By far the most common type, primary open-angle glaucoma develops gradually and painlessly.  Since there are no early warning signs, it can slowly destroy your vision without you knowing it.  The first indication may only occur after some considerable vision loss.
• Acute angle-closure glaucoma 
  This results from a sudden blockage of the drainage channels within your eye, causes a rapid build-up of pressure inside your eye accompanied by blurred vision, the appearance of colored rings around lights and sometimes extreme pain or redness in the eyes.