Tears in the eyes when you laugh can be caused by physiological phenomena or by diseases such as blocked tear ducts.
When you laugh, the pressure in the nasal cavity increases, which can cause the tears to flow back into the eyes, thus forming the manifestation of tears. However, when you are not laughing, the tear ducts are open and there is no tearing, which is a physiological phenomenon and does not require treatment.
Lacrimal duct obstruction is usually caused by trauma, inflammation, and other causes of scarring in the lacrimal duct, and when you laugh, the muscles around the lacrimal sac contract, which squeezes the tear fluid that has accumulated in the lacrimal sac, thus causing tears to flow. These patients may also have tearing when they do not laugh.
If the patient has the manifestation of tearing when laughing, he should go to the ophthalmology department of the hospital in time to find out the specific cause, and then under the guidance of the doctor for treatment.