Ocular Rosacea Biome Study

Even though SDD is widely used for the treatment of rosacea, very little confirmatory data exists, to indicate if this dose alters any other systemic mucosa flora or increases antibiotic resistance rates. The classification of 40mg as "sub-microbial" has never been evaluated in patients diagnosed with ocular rosacea. Additionally, confirmation of a "sub-microbial" dose has not been investigated with more sophisticated genomics and resistance tools such as metagenomic deep sequencing (MDS). The goal of this proposal is to use MDS to determine whether SDD given to patients with ocular rosacea can be truly considered sub-microbial, or if a 40mg dose of doxycycline can in fact alter the microbiome of the conjunctiva and gut and increase resistance rates when prescribed for 8 weeks. The investigators plan to evaluate the effect of SDD on resistance and microbiome alteration through a randomized controlled masked trial. This is a randomized, controlled, masked trial comparing sub-microbial dose doxycycline, treatment dose Doxycycline, and placebo in the treatment of ocular rosacea. Participants will be recruited from the F.I. Proctor Foundation and the Ophthalmology clinics at the UCSF Wayne and Gladys Valley Center for Vision and consented for participation in an IRB-approved study protocol. Participants with a diagnosis of ocular rosacea (n=50) will be prospectively enrolled and randomized to one of three arms in a 2:2:1 fashion: Arm A will receive submicrobial dose doxycycline (40mg) administered as 20mg twice day for 8 weeks Arm B will receive 200mg of oral doxycycline administered as 100mg twice a day for 8 weeks Arm C will receive a placebo twice a day for 8 weeks