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Updated September 12, 2013.

Worldwide, trachoma is the leading cause of preventable blindness. It is caused by a chlamydia infection of the eye.

These chlamydia pictures show the blindness that is one of the potential long-term consequences of a chlamydia infection. Genital chlamydia infection will not cause blindness -- only infection of the eye itself can do so.

Blindness caused by chlamydia is rare in the U.S. because doctors routinely treat newborn infant's eyes to prevent such infections.

Ocular chlamydia infection is usually transmitted during birth, but it can also be transmitted by touching infected secretions and then touching the eye.

Gonorrhea can also cause ocular disease.