In the past, due to the limitation of conditions, the surgery was performed by intracapsular extraction of cataracts, so the surgery was usually performed only after the cataract matured and could not be seen. Nowadays, due to the development of science and medical technology, we have entered the era of microsurgery and extracapsular extraction combined with IOL implantation. Therefore, nowadays, cataract surgery is not necessary until you can’t see anything, but is decided according to the patient’s life and work situation and the level of vision needs. If necessary, surgery can be considered if the vision is within 0.3~0.4. If secondary glaucoma occurs during the expansion phase (immature phase) of cataract, i.e., elevated intraocular pressure, eye swelling and pain with ipsilateral headache, or even nausea and vomiting, the patient must go to the hospital immediately for surgery without delay to avoid irreversible blindness and lifelong damage. Therefore, before cataract surgery is required, it is important to pay attention to the changes in eye disease and the symptoms that appear.