Modern cataract surgery techniques are becoming more and more sophisticated, so, in general, most patients are able to improve their vision to some extent after surgery. However, there are some patients who had a very smooth surgery and their vision improved after the surgery and they could see very clearly. However, after a period of time, seeing becomes blurry again and vision decreases again, similar to how it felt before the surgery. What is this? Did the cataract come back? The most common type of cataract is posterior cataract, which occurs after cataract extraction. 1. Why does it happen? — Related to the method of surgery Modern cataract surgery does not involve removing the entire cataract. The lens is like an unpeeled orange with a capsule membrane wrapped around its surface. During the surgery, a circular opening is torn out of the anterior capsule of the lens, then the instrument is inserted into the opening of the capsule, and the core of the cataract is crushed and sucked out, leaving a capsule like a pocket, and then the IOL is placed into the capsule, so that the position of the IOL can be as close as possible to the physiological position of its own lens, and only then can it remain stable without being fixed with sutures. In other words, this capsular membrane, which was originally part of the cataract, was left inside the eye during the surgery and was not removed. There are actually some lens cells still present on the inner surface of the capsule, and these cells cannot be removed during surgery. After a period of time after the surgery, the residual cells keep proliferating and growing along the capsular bag, and finally a cloudy, light-impervious mechanized film is formed on the capsular membrane, thus is the patient’s vision is lost again. 2.What are the clinical characteristics of posterior cataract: slow, painless, vision loss When does it occur? — It is most likely to occur 1~2 years after surgery, but it may occur as early as 3 months after surgery. Who is more likely to develop it? — Patients who are relatively young, have diabetes, or suffer from iritis are most likely to develop it. The presentation is painless, with gradual blurring of vision and loss of visual acuity. There is no distortion of vision. The loss of vision occurs slowly. Some people ask, “Will we have to do the surgery again?” In fact, the treatment method is not complicated, an outpatient laser, the cloudy posterior capsule a hole, so that the light can be smoothly shine into the eye, vision can be restored. The operation is simple and does not require hospitalization. If you have vision loss soon after cataract surgery, you should check whether there is postoperative macular edema. 1. Why does it happen? — It is the response of the retinal blood vessels in the fundus to the surgery Although the surgery went well, it is, after all, a disturbance to the eye. Cataract surgery belongs to the anterior segment of the eye, but because of the moment when the eye is cut open during the surgery, the fluid inside the eye flows out and the eye pressure suddenly decreases, it also has an effect on the retinal blood vessels in the posterior segment of the eye. If the patient’s blood vessels are unhealthy, they will be more easily affected and the water inside the vessels will leak out from the canals, leading to macular edema. 2. What are the clinical characteristics of macular edema: rapid, painless, vision loss When does it occur? — It is most likely to occur within 1 month after surgery. Who is more likely to have it? — The elderly, those with diabetes, iritis, macular degeneration, these patients are most likely to have it. This is characterized by loss of vision and distortion of vision. Vision loss occurs rapidly. 3. Treatment: – Intraocular/intraocular injection The patient has macular edema, which has a great impact on vision. Some patients can recover on their own within 3 months. For patients with significant vision loss that cannot be absorbed on their own, treatment is necessary. Methods: Paraocular injection of hormonal drugs (commonly used is tretinoin) For patients with poor hormonal effect, intraocular injection of anti-VEGF drugs is given. Third, combined with other eye diseases that affect vision There are many other eye diseases that cause painless, vision loss, most of which are easily combined with such diseases in elderly patients. The common ones are: 1. diabetes caused fundus hemorrhage and edema 2. retinal vein obstruction caused macular edema 3. age-related macular degeneration 4. glaucoma Therefore, after cataract surgery, if the vision does not recover well, or if the vision becomes poor again, patients should come to the hospital in time for early diagnosis and treatment.