WEISS' RING FROM A POSTERIOR VITREOUS DETACHMENT

The arrow points to a Weiss' Ring, which is an opacity associated with the optic nerve.  It indicates a posterior vitreous detachment, where the clear vitreous membrane pulls off the retina.  This occurs in most people at some point in their lives.  The Weiss' Ring is where the membrane was up against the optic nerve head before it detached.

TOPICAL AZITHROMYCIN FOR OCULAR ROSACEA

From Ocular Immunology and Inflammation, Volume 21, Number 5, October 2013 , pp. 371-377(7)

Topical azithromycin may represent an additional treatment for ocular rosacea, with a shorter duration of treatment and absence of gastrointestinal side effects as compared to systemic doxycycline.