Common causes of either right or left eye pain include blepharitis, conjunctivitis and corneal abrasions or infections. Other causes of eye pain are glaucoma, optic neuritis and sinusitis, according to WebMD.
Blepharitis is a condition in which the eyelid becomes inflamed or infected, causing irritation and pain. Conjunctivitis, also referred to as pink eye, is due to allergies or infections in the conjunctiva, states WebMD. The conjunctiva is a super-thin covering on the outside eye wall and inside the eyelid. This condition causes the blood vessel in the conjunctiva to swell, which induces symptoms such as red eyes, itchiness and discharge.
Corneal abrasions are due to scratches on the cornea, which is a very sensitive part of the eye. Corneal infections are commonly associated with wearing contact lenses overnight or wearing dirty contact lenses, says WebMD.
Glaucoma rarely shows early symptoms, but over time it causes severe eye pain, nausea, headaches and vomiting and decreases the ability to see, advises WebMD. These symptoms require immediate treatment to prevent impending blindness.
Optic neuritis happens when the nerve that connects the back of the eyeball to the brain becomes inflamed. Autoimmune conditions and infections are common causes of this condition, explains WebMD. Associated symptoms are loss of vision and pain when looking from side to side.