What causes constant twitching of the lower eyelid under the left eye?

The twitching of the lower left eyelid, known as eyelid twitching or myokymia, is usually caused by involuntary contractions of the eyelid muscles. This condition is typically temporary and may be associated with fatigue, stress, lack of sleep, or excessive caffeine intake. In most cases, eyelid twitching does not require specific treatment and can be relieved through the following measures: 1. Ensure adequate rest and sleep. 2. Practice relaxation techniques and reduce stress. 3. Maintain good eye lubrication by using artificial tears. 4. Limit caffeine intake. 5. Perform gentle eye massages. Note that if the eyelid twitching persists for a prolonged period (more than a few weeks), occurs frequently, or is accompanied by symptoms such as vision loss, eye pain, or eyelid swelling, you should seek medical attention promptly.