AIM: To analyze the effectiveness and safety of different concentrations of tea tree essential oil in the treatment of Demodex blepharitis.

METHODS: The clinical data of 120 patients(240 eyes)with blepharitis caused by Demodex infection in our hospital from June 2017 to June 2019 were retrospectively analyzed. According to the use of tea tree essential oil concentrations of 10%, 15%, 20% and 25%, patients were divided into 4 groups(group A, group B, group C, group D), each group with 30 people. All patients were given meibomian gland massage, eyelid margin cleaning, and then scrubbed with different concentrations of tea tree oil to clean the eyelid margin. The number of demodex mites, clinical symptom score, clinical sign score, tear film break-up time(BUT), corneal fluorescein staining(FL)and SchirmerⅠtest(SⅠt)were compared before and 2, 4wk after treatment.

RESULTS: The number of Demodex mites, clinical symptom score, clinical sign score, BUT, FL and SⅠt were not statistically significant in the four groups before treatment(P>0.05). After treatment, the number of Dmodex mites, clinical symptom score, and clinical sign score in each group were lower than those before treatment, and the number of Demodex mites, clinical symptom score, and clinical sign score after 4wk of treatment in each group were lower than those after 2wk of treatment(all P<0.008). After 2 and 4wk of treatment, the number, clinical symptom score and clinical signs score of Demodex mites in group A were the highest, while those in group D were the lowest(all P<0.008). After treatment, the BUT of each group was higher than before treatment, and reached the peak in the 4wk. After 2 and 4wk of treatment, BUT among groups was highest in group D and lowest in group A(all P<0.008). After treatment, FL and S I t of each group were lower than before treatment, and reached the lowest value in the 4wk. After 2 and 4wk of treatment, FL among the groups was the lowest in group D and the highest in group A(all P<0.008).

CONCLUSION: Compared with 10% tea tree essential oil, 15% tea tree essential oil can effectively repel mites, relieve clinical symptoms and eye signs in patients with Demodex blepharitis, and is safer than 20% and 25% tea tree essential oils. As the preferred concentration of tea tree essential oil against Demodex blepharitis.