Ocular Rosacea microBiome Study (ORBS)-sub-microbial versus antibiotic dosing of doxycycline versus placebo in treatment of symptomatic ocular rosacea: study protocol for a parallel-arm randomized clinical trial

Background: Ocular rosacea is common and is often managed with long-term antibiotic treatment. Doxycycline is the most commonly selected antibiotic for the treatment of rosacea. As there is no established standard of care treatment dose for rosacea, prescribed doses of doxycycline vary widely. The FDA classifies 40 mg daily dose of doxycycline for ocular rosacea as sub-microbial in comparison to an antibiotic dose of 200 mg daily. However, this sub-microbial dose has never been evaluated in patients with ocular rosacea, and even the sub-microbial dose has potential to alter systemic mucosa flora. Here, we present a randomized controlled trial using RNA sequencing to fully characterize the impact of sub-microbial antibiotic dosing of doxycycline on antimicrobial resistance and bacterial composition of the ocular and gut flora. Methods: In a triple-masked parallel randomized control trial, patients with ocular rosacea will be randomized to three arms: a 40-mg dose of doxycycline, a 200-mg antibiotic dose of doxycycline, or placebo. Collected rectal and lower eyelid samples will be compared for frequency of antimicrobial resistance genetic determinants and microbiome diversity. A subjective ocular surface disease index survey and objective tear breakup time measurement will be determined. Discussion: These results will enhance our understanding of the overall systemic impact of long-term systemic sub-microbial antibiotic dosing for the treatment of chronic recurrent ocular inflammatory diseases.

Automated summary

This article presents a randomized controlled trial to evaluate the impact of sub-microbial antibiotic dosing of doxycycline on the ocular and gut flora. The results of this study will enhance our understanding of the overall systemic effects of long-term sub-microbial antibiotic treatment for chronic recurrent ocular inflammatory diseases.