Conjunctivitis or pinkeye is a common eye infection that causes the conjunctiva, or the clear membrane that covers the white part of the eye and the inner surface of the eyelids, to inflame. The inflammation causes the tiny blood vessels in the conjunctiva to darken which makes the eyes appear to be bloodshot.
Conjunctivitis should not be confused with iritis, or the inflammation of the iris that also leads to reddening of the eye.

Causes and Risk Factors

Conjunctivitis is commonly caused by bacterial infection. However, it can also be caused by viral infection or allergies.

	Bacterial Conjunctivitis: Bacterial Conjunctivitis is caused by pyogenic, or pus producing, bacteria such as Staphylococcus (staph) or Streptococcus (strep). This infection can be contracted when the patient comes into contact with infected individuals, environmental factors or by using poor quality or expired eye makeup.
	Viral Conjunctivitis: Viral Conjunctivitis is typically associated with upper respiratory tract infection and it is spread by aerosol or by contact with a number of contagious viruses, including the viruses that cause the common cold. Susceptibility to this infection increases during winter and rainy months because of the increase in humidity.