In vitro and in vivo killing of ocular Demodex by tea tree oil
- Y-Y Gao1,2,
- M A Di Pascuale1,
- W Li1,
- A Baradaran-Rafii1,
- A Elizondo1,
- C-L Kuo1,
- V K Raju1,
- S C G Tseng1
- 1Ocular Surface Center and Ocular Surface Research and Education Foundation, Miami, FL, USA
- 2Department of Ophthalmology, the Second Affiliated Hospital, Fujian Medical University, Quanzhou, Fujian, China 362000
- Correspondence to: Scheffer C G Tseng MD, PhD, Ocular Surface Center, 7000 SW 97 Avenue, Suite 213, Miami, FL 33173, USA;
- Accepted 6 June 2005
Aims: To compare the in vitro killing effect of different agents on Demodex and to report the in vivo killing effect of tea tree oil (TTO) on ocular Demodex.
Methods: Survival time of Demodex was measured under the microscope. Sampling and counting of Demodex was performed by a modified method.
Results:Demodex folliculorum survived for more than 150 minutes in 10% povidone-iodine, 75% alcohol, 50% baby shampoo, and 4% pilocarpine. However, the survival time was significantly shortened to within 15 minutes in 100% alcohol, 100% TTO, 100% caraway oil, or 100% dill weed oil. TTO’s in vitro killing effect was dose dependent. Lid scrub with 50% TTO, but not with 50% baby shampoo, can further stimulate Demodex to move out to the skin. The Demodex count did not reach zero in any of the seven patients receiving daily lid scrub with baby shampoo for 40–350 days. In contrast, the Demodex count dropped to zero in seven of nine patients receiving TTO scrub in 4 weeks without recurrence.
Conclusions:Demodex is resistant to a wide range of antiseptic solutions. Weekly lid scrub with 50% TTO and daily lid scrub with tea tree shampoo is effective in eradicating ocular Demodex.
Proprietary interest: none
Supported in part by an unrestricted grant from Ocular Surface Research and Education Foundation, Miami, FL, USA.