The principle of why diabetes affects the eye is simple: diabetic retinopathy is mainly caused by the occlusion of the retinal blood vessels in the fundus (as in many other diabetic complications), which causes ischemia in the entire retina, but the retina is very demanding and sensitive to blood supply, so once the ischemia starts, the nerve cells in the retina will start to die because of ischemia. start to die because of ischemia. But these nerve cells do not sit still after the ischemia, but send a “cry for help” to the body by secreting something we call neovascular growth factor. This is a compensatory mechanism of the body, which can cause many new blood vessels to grow in tissues with high concentrations. However, this acquired growth of neovascularization itself has many defects: its confinement is not good, the blood inside can seep out through the blood vessels, while it grows everywhere, and this blood vessel does not have its own ability to contract to stop bleeding, so once the growth of this neovascularization, the eye is very easy to bleed. Imagine if a building’s water supply pipe is broken, but every household needs water, they start calling for help and making phone calls. At this time, the irresponsible property management in order to save money and trouble, called the black-hearted businessmen to all use poor quality water pipes to each household indiscriminately connected to the water, over time, the building will be what? This is roughly the reasoning. Here is the principle of laser treatment. Based on the above rationale, since we cannot “cure” diabetes yet, we cannot fundamentally stop the progression of this vascular occlusion. This is why once diabetic retinopathy occurs, the loss of vision is almost irreversible: because the retinal nerve cells supplied by this vessel become necrotic and cannot regenerate due to the occlusion of the vessel. So, since we can’t change such a process, we have to think of other ways. For example, if the building leaks and causes water shortage for serious users, one way is to fix the water pipes, and if they are not fixed, we can also move some, or even a large part of the residents away, so that the remaining residents may have enough water and they will not call. The laser treatment of diabetes is based on the idea that since the retinal blood supply is not good, we use the laser to “kill” some, or even most, of the retinal nerve cells, so that the remaining cells can get enough blood, so they will not continue to “call for help They will not continue to “cry for help” and secrete neovascular growth factor. This is how it works: a laser is used to necroticize the retina except for the part where we can see most clearly, to ensure that the remaining cells get enough blood vessels. In principle, this involves hitting 900-1200 light points on the retina. Since after a certain number of dots are hit (around 300-400 dots), the stimulation of the laser starts to cause pain to the patient, and also if more are hit, the retina may become edematous because it is damaged too much at one time, leading to vision loss, therefore, it is usually necessary to hit the laser 3-4 times in one eye. This method sounds very impersonal, and after half a day, it is going to kill all my retinal cells, but, at the current medical level, it is the most accurate and the treatment that can maintain the patient’s current vision level to the maximum. There are 2 main side effects regarding laser treatment: 1. It is the retinal edema we talked about earlier, mainly in the part of the eye that sees most clearly, called the macula in medical terminology. Diabetic retinopathy itself can lead to edema of the macula (without laser), and laser treatment can aggravate the macula level if there are more points, or just the patient’s own health condition is not good. But this is a treatable problem, although the treatment method and means are a bit difficult. 2, because the laser is to beat necrosis of the retina other than this part where we see things most clearly, so except for the area where the macula is located, almost all of the retina will be hit by the laser, which may cause the eye to see things in a reduced range in some patients, somewhat like looking outside through a tube, we become a tubular vision. Also, since the peripheral retina that is hit with the laser has no visual function in normal times, it is meant to see in a dark environment, so it is also possible that the patient may experience a loss of vision in dark situations, such as at night, in a dark room. These two side effects are unfortunate if they occur in someone alone. Therefore, for a patient with diabetic retinopathy, such laser treatment (term: total retinal photocoagulation, PRP) is also not considered to be given until after his disease has progressed to a certain point. However, for patients with diabetic retinopathy who would be totally blind in both eyes if left untreated, it is definitely something that can be done without great concern by throwing away the car. So they don’t necessarily happen, and even if they do, they are no worse off than if they don’t get laser. So every patient with diabetic retinopathy should go and actively cooperate with their doctor and be advised to actively cooperate with their doctor for laser treatment once the need arises.