结膜炎，俗称红眼症，是最常见的眼部传染病之一。

结膜炎的病因比较复杂，一般分为感染性和非感染性两大类，主要表现为轻度的结膜充血及少量的粘液性分泌物，感染性的常见病原体包括葡萄球菌、卡他球菌、大肠杆菌、肠道病毒等等，非感染性的因素有粉尘或化学烟雾刺激、眼部长期应用有刺激性的药物、强光、屈光不正、烟酒过度、睡眠不足等引起。

Conjunctivitis, also known as pink eye, is inflammation of the outermost layer of the white part of the eye and the inner surface of the eyelid. It makes the eye appear pink or reddish. There may also be pain, burning, scratchiness, or itchiness. The affected eye may have increased tears or be "stuck shut" in the morning. Swelling of the white part of the eye may also occur. Itching of the eye is more common in cases due to allergies. Conjunctivitis can affect one or both eyes.