There are more serious conditions that can present with a red eye such as infectious keratitis, angle-closure glaucoma, or iritis. These conditions require the urgent attention of an ophthalmologist. Signs of such conditions include decreased vision, significantly increased sensitivity to light, inability to keep eye open, a pupil that does not respond to light, or a severe headache with nausea.  Fluctuating blurring is common, due to tearing and mucoid discharge. Mild photophobia is common. However, if any of these symptoms are prominent, it is important to consider other diseases such as glaucoma , uveitis , keratitis and even meningitis or carotico-cavernous fistula .