Ocular Rosacea is a systemic disease related to the faulty functioning of the immune system. This means that there will be repeated flare-ups and frequent recurrences of the 'pink eye' condition it triggers. Systemic illnesses are best treated with  systemic means such as antibiotics. Because facial rosacea (red nose and cheeks) does not correlate with manifestations of ocular rosacea, such a pink eye or blepharitis (red eye lids), it is often underdiagnosed. The fundamental approach using specifically doxycycline at only 40mg permits maintaining the treatment over long periods to prevent frequent recurrence. This could be particulary important for patients suffering  repeated bouts of blepharits / conjuntivits.  Its effectiveness at a low sub-antibiotic level has been shown in a study by Ines Pfeffer et al. (2011). Please also have a look at Insight 74700 Ocular Rosacea 1