I believe many patients with fundus disease have heard of fundus lasers, which are referred to as retinal photocoagulation. Artificial light sources have been used for the treatment of retinal diseases since the 1940’s. After the introduction of the laser in 1960, it was soon used for retinal photocoagulation. Retinal photocoagulation has been used in China since the early 1970s to treat fundus diseases. Currently, multi-wavelength fundus lasers and 532 semiconductor lasers are commonly used. For the convenience of patients, laser instruments have gradually emerged with various mounting and use options that allow laser treatment to be performed while the patient is seated or lying in a flat position. Why is ophthalmic laser treatment needed at Xuanwu Hospital Ophthalmology Department of Capital Medical University, Yeannan Wang? Because the fundus is at the innermost end of the eye and is invisible to the naked eye, it can be treated with fundus laser if diseases such as retinal fissures or fundus hemorrhage occur early and do not yet require surgery. The various layers of tissues in the fundus contain different pigments and proteins, and various pigments absorb different wavelengths of light. After the light is absorbed by the pigmented tissues, the light energy is converted into heat energy, which instantly emits high heat and can coagulate, destroy or even scar the target tissues. The laser is using the thermal effect to form dense photocoagulation points on the retina. Photocoagulation can close the leakage points to reduce the incidence of retinal edema and vitreous blood accumulation. Photocoagulation can also destroy the capillary occlusion zone to reduce neovascularization. In retinopathies where neovascularization is already present, laser can subside the abnormal neovascularization and prevent its further development, preserving useful visual function and significantly reducing the rate of vision loss. Fundus lasers can treat many eye diseases such as diabetic retinopathy, retinal vein occlusion, retinal fissures, age-related macular degeneration, retinal hemangioma, choroidal hemangioma, central placoidal chorioretinopathy, and many others. Some preparatory work is required before laser treatment. The doctor will perform a thorough eye examination, including visual acuity, intraocular pressure, cornea, pupil, anterior chamber, lens, and the presence or absence of IOL implants. The patient’s vitreous body, retinal vessels, macula, optic nerve and the entire retina will also be examined through a microscope or trifocals, and if necessary, color fundus photography and fluorescein fundus angiography will be done. The type of laser used varies from eye disease to eye disease, as does the number, duration, and course of treatment, which is usually explained to the patient and family along with precautions. Before the laser is administered, the doctor will spot the patient’s eyes with dilating medication and surface anesthetic. The patient’s head is positioned on the jaw rest of the slit lamp in a seated position, and a cleaned corneal contact lens is placed on the surface of the patient’s cornea before laser treatment can begin. Some sensitive patients may feel pain in their eyes due to the heat generated by the absorption of the laser by the fundus tissues, but most of this pain is tolerable, so there is no need to be too nervous, just try to relax and cooperate with the doctor. In some patients there is often a saying that laser is not good, the more the laser is used, the more vision loss. Even among some of the medical staff, there is also such a view. It is true that in the early stages of laser treatment, patients often experience some degree of vision loss. This is a normal process after laser treatment because: first, laser is an invasive treatment process, which will inevitably bring a certain degree of damage, a certain degree of visual function loss. But this damage can be restored after a period of repair. This is a “throw away” treatment method. Secondly, the development of macular edema may be aggravated after retinal photocoagulation. Third, there are a few patients who have progressive fundus lesions, and it is difficult to fully control the progression of the disease with laser treatment alone, and the further progression of the disease exacerbates the loss of vision. It should be clear that laser treatment of the fundus can achieve the goal of controlling the disease and reducing the risk of vision loss, not improving vision! Laser treatment can greatly reduce the chance of progression, and several studies have shown that the difference between treatment and no treatment is significant. For patients who need laser treatment, a wait-and-see and hesitant attitude often leads to a delay in the optimal timing of laser treatment, leading to further progression of the condition and even blindness! In this case, although vitreoretinal surgery can still be performed, fundus laser also remains a necessary option during as well as after surgery, and compared to laser, the procedure is costly and risky, and the treatment effect will not exceed that of timely laser treatment. Laser treatment, with less trauma and faster recovery, has great superiority. This article is published with the permission of Dr. Yannan Wang.