Blepharitis is a endemic inflammatory disease caused mainly by Demodex folliculorum and Demodex Brevis, This mites are often associated with anaerobic bacteria that produces a skin inflammation, so a intervention that reduces the number of mites and bacteria would be desirable. Ivermectin a macrolid compound have demonstrated activity against scabies and lice in humans and in animals and a single application have show a good response in lice eradication.

In this study , investigators will determinate the security and effectiveness of this compound in the eradication of mites

Inclusion Criteria:

• • Patients with symptomatic Demodex blepharitis for duration of at least 3 months.

  • Age range: 18 yeras and older.
  • Both genders and all ethnic groups comparable with the local community.
  • Able to understand and willing to sign a written informed consent
  • Able and willing to cooperate with the investigational plan.
  • Able and willing to complete all mandatory follow-up visits.

Exclusion Criteria:

• • Patients who are currently engaged in another clinical trial, unwilling or unable to give consent, to accept randomization, or to return for scheduled visits.

  • Children under 18.
  • Pregnant women or expecting to be pregnant during the study.
  • Systemic immune deficient conditions such as AIDS or under systemic immunosuppressant.
  • Concomitant use of ophthalmic topical medications (excluding non-preserved tear substitutes).
  • Concomitant use of systemic antibiotics or steroids.
  • Contact lens wear
  • Active ocular infection or allergy
  • Unable to close eyes or uncontrolled blinking Previous allergic reaction to metronidazole and / or ivermectin