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 .
Classic ocular signs of allergic inflammation are lid swelling, diffuse conjunctival redness, and mild swelling, which often combine to give a pink rather than red color, and a velvety thickening and redness of the tarsal conjunctiva with the presence of fine excrescences called papillae, which may vary from tiny pinprick size to giant papillae which are >1 mm in diameter and give a cobblestone appearance under the lid. Macroscopic noticeable swelling of the conjunctiva, called ‘chemosis’, is sometimes seen. Other signs, such as dermatitis of the lid skin, inflammation of the lid margin (blepharitis), conjunctival scarring, and involvement of the cornea occur only in certain of the most severe disorders. When the limbus becomes inflamed might presents a pale-pink coloration in an annular pattern or with characteristic white dots called Trantas Dot´s