Newborns receive erythromycin eye ointment after birth to prevent pink eye in the first month of life, also called ophthalmia neonatorum (ON). The most common cause of ON is chlamydia, a sexually transmitted infection. A less common but more serious cause of ON and the reason for mandatory eye ointment is gonorrhea, another sexually transmitted infection, that now accounts for less than 1% of reported ON cases in the U.S. A newborn can only get ON from chlamydia or gonorrhea if the mother is infected at the time of the birth. Other bacteria account for 30%-50% of ON infections, which are not considered serious.
~ quote from Evidence on: Eye Onitment by Rebecca Dekker, PhD, RN, APRN