Muscle twitching under the eyes may be caused by conjunctivitis, eye fatigue, facial muscle spasm and other reasons. 1. Conjunctivitis: mostly caused by infection of the conjunctival tissue inflammation, inflammatory factors stimulate the muscles around the eyes, it will lead to muscle twitching under the eyes. 2. Eye fatigue: working for a long time or looking at a computer screen will make the ciliary muscle of one’s eye spasmodically contract non-stop, thus causing paroxysmal involuntary twitching of the orbicularis oculi muscle. 3. Facial muscle spasm: muscle twitching under the eyes is an early sign of facial paralysis. An incomplete myelin sheath on the facial nerve is likely to cause a short circuit between the nerve and the nerve, leading to facial muscle spasms. Muscle twitching under the eyes can also be caused by muscle tension in the neck, shoulders, and back, and if it persists unrelieved, it is advisable to visit a hospital promptly.