Some elderly people have very obvious cataracts and their physicians recommend cataract surgery. The old man just didn’t want to do it. When asked why, the old man said that one of his partners had a cataract surgery six months ago, but recently it had “recurred” and his vision had decreased again, and the doctor said it was a “posterior cataract”. The doctor said it was a “posterior cataract”. He thought that since it would come back, he didn’t want to have the surgery. Why did his vision decline again six months after cataract surgery? What is posterior cataract? Because the capsular bag of the lens is largely preserved during surgery. The epithelial cells of the lens under the remaining anterior capsule continue to grow and migrate posteriorly. Originally, the posterior capsule was clear with no cells; with the growth of many cells, it becomes cloudy or even wrinkled, which causes a loss of vision that we call posterior cataract. In general, 100% of pediatric patients and over 30% of adult patients will develop posterior cataracts within 6 months to 2 years after cataract surgery, resulting in vision loss. Posterior cataracts require YAG laser treatment and generally do not require further surgery. What is YAG laser treatment for posterior cataracts and is it dangerous? Usually what we call laser treatment for cataract is to use YAG laser to make a hole out of the posterior capsule membrane, there is no more blockage on the pathway of light, and the vision is not affected. If the mechanized membrane is too hard for the YAG laser to cut through, the posterior capsule can only be surgically cut out. The advantages of YAG laser treatment for posterior cataracts are: safe and reliable, easy to operate, painless for the patient, no hospitalization, low cost, and vision restoration ” immediately”. In conclusion, not every post-cataract patient will have posterior cataract. Moreover, even if posterior cataract has occurred after surgery, it can be treated by YAG laser without either incision or hospitalization. Therefore, there is no need to worry too much about posterior cataracts to prescribe cataract surgery.