Effects of onion juice on the normal flora of eyelids and conjunctiva in an animal model

Background: Traditional medicine/complementary alternative medicine may suggest new ideas to modern medicine in order to face new challenges however these concepts should be acknowledged based on experimental studies.

Objectives: We aimed to study the effects of onion (Allium cepa) juice on the normal flora of conjunctiva and eye lids, and to follow the histopathology changes of conjunctiva in an animal study.

Materials and methods: Twenty-four rabbits were randomly classified into three equal groups. Groups 1, 2 and 3 received fresh red onion juice, as an eye drop, into the right eye twice daily for; one week, one month, and two months, respectively. Microbiological sampling by sterile swabs was performed before and after the intervention. Cultural characteristics, including the growth rate and the kind of organisms, are reported. At the end of the study, pathological samples were collected from the inferior fornix.

Results: After the intervention, the number of positive cultures in the samples, collected from both the conjunctiva and eyelid, had decreased. Group 3 demonstrated the lowest amount of growth after the administration of the onion juice and the bacterial isolation rates from each organism had decreased. All pathological samples revealed some degree of inflammation. There was no evidence of metaplasia or dysplasia. There was no significant difference between the growth rates of organisms in the experimental groups using statistical analysis.

Conclusions: According to our experiment, onion has an inhibitory effect on the growth of normal eye flora; although the duration of onion juice instillation did not show any significant effect on the group results. Hence, this finding is an initiating point for further investigations into the antimicrobial properties of this herb to treat common eye infections, including conjunctivitis and blepharitis.