1 The nerve travelling from the back of the eyeball into the brain can become inflamed. Multiple sclerosis or other autoimmune conditions or infections are often to blame. Symptoms include eye pain and loss of vision.  Sinusitis can create pressure behind the eyes, causing eye pain on one or both sides.
http://www.webmd.boots.com/eye-health/guide/eye-pain-causes
1 Pink Eye: This is the most common eye problem, and it can be caused by allergies, a bacterial or viral infection, or a chemical burn. Pain is usually mild and the eye appears pink or red..  Stye or hordeolum: An infection of the eyelid glands can cause eye pain along the eyelid.
http://www.eyehealthweb.com/eye-pain/
The increased pressure, called intraocular pressure, can damage the optic nerve, which transmits images to the brain. If damage to the optic nerve from high eye pressure continues, glaucoma will cause permanent loss of vision. Without treatment, glaucoma can cause total permanent blindness within a few years.
http://www.webmd.com/eye-health/glaucoma-eyes
Because most people with glaucoma have no early symptoms or pain from this increased pressure, it is important to see your eye doctor regularly so that glaucoma can be diagnosed and treated before long-term visual loss occurs.
http://www.webmd.com/eye-health/glaucoma-eyes
1 A stye is often painful and most often caused by infection.  Foreign bodies. Sometimes there really is something in the eye -- a bit of dirt, plant debris, or a fragment of a contact lens. Foreign bodies are usually just irritating, and tears or a water rinse clears them out.
http://www.webmd.boots.com/eye-health/guide/eye-pain-causes
1 Blepharitis occurs when there is inflammation or infection of the eyelid. A sensation of grit in the eyes, and sometimes pain, result.  A stye -- also known as a hordeolum -- is an infection or inflammation of the eyelid margin that can come from the hair follicles of eyelashes or from oil glands.
http://www.webmd.boots.com/eye-health/guide/eye-pain-causes
1 A sensation of grit in the eyes, and sometimes pain, result.  A stye -- also known as a hordeolum -- is an infection or inflammation of the eyelid margin that can come from the hair follicles of eyelashes or from oil glands. A stye is often painful and most often caused by infection.
http://www.webmd.boots.com/eye-health/guide/eye-pain-causes
Eye pain: Causes, symptoms, diagnosis and treatment. There are many causes of eye pain, from infections to accidents. In many cases, eye pain will get better on its own, but in others, medical attention is needed to treat the eye and prevent lasting damage to a person's eyesight.
http://www.webmd.boots.com/eye-health/guide/eye-pain-causes
Glaucoma is a condition that causes damage to your eye's optic nerve and gets worse over time. It's often associated with a buildup of pressure inside the eye. Glaucoma tends to be inherited and may not show up until later in life.
http://www.webmd.com/eye-health/glaucoma-eyes
Less common causes of glaucoma include a blunt or chemical injury to the eye, severe eye infection, blockage of blood vessels in the eye, inflammatory conditions of the eye, and occasionally eye surgery to correct another condition.
http://www.webmd.com/eye-health/glaucoma-eyes
causes of eye pain
Pink Eye causes eye pain. Pink eye is a cause of eye pain.