This herb tightens the mucous membranes of the eye and helps relieve inflammation. Aucubin, one of the primary constituents in this herb, demonstrates anti-inflammatory and antibacterial activity, making this herb especially useful for bacterial infections affecting the eye. This herb is helpful for acute and chronic eye problems such as redness and irritation, stinging, inflammation, infection, oversensitivity to light, and particularly blepharitis (inflammation of the eyelid) and conjunctivitis (inflammation of the conjunctiva, the transparent membrane that lines the eyeball and eyelid), commonly referred to as "pink eye". A study involving 65 patients with conjunctivitis treated with single-dose eye drops of this herb found that 81.5% had complete recovery and 17% showed a clear improvement. What is this herb?