Characterized by redness and often pain and a feeling that the patient has sand in his eye; also by hypersensitivity to light and weeping. The commonest inflammation of the eye is the largely harmless conjunctivitis, usually caused by viral or bacterial infection, sometimes by allergic reaction. Iritis is a less common condition, usually caused by reaction to infection elsewhere in the body or by a rheumatic disorder, sometimes by bacterial infection. Inflammation of the vascular membrane is caused in the same way as iritis. Damage to the cornea by a sharp object can result in inflammation of the cornea, as can bacterial inflammation, which can also break through to the interior of the eyeball. Corneal infection can also be viral. If the cornea or conjunctiva are penetrated in an eye injury, the whole eye can become inflamed and may even be lost.