The most common eye infection is called conjunctivitis - often caused by an adenovirus. Viral conjunctivitis is contagious, because the virus can spread quickly.
Eye infections may lead to serious problems, the infection causes often include: ocular histoplasmosis syndrome, herpes simplex, chlamydia and gonorrhea, shingles, bacterial keratitis.
Histoplasmosis refers to the fungal infection - in the lungs because of inhaling spores. It usually causes no symptoms, but it will gradually damage the retina, particularly the macula, and it may eventually lead to retinal decay. Chronic herpes infection can cause acute retinal necrosis. Chlamydia and gonorrhea are sexually transmitted infections, they often cause retina or cornea damages.