Glaucoma is known to be the second leading cause of blindness worldwide after cataracts, and the first irreversible blindness. According to World Health Organization (WHO) estimates, there will be 80 million glaucoma patients worldwide by 2020. Primary open-angle glaucoma (POAG) is the main type (58,500,000). In recent years, the proportion of primary open-angle glaucoma diagnosed in China has also been increasing year by year. At the same time, a large number of patients with suspected glaucoma are increasingly being taken seriously by ophthalmologists. Glaucoma has great specificity compared to other ophthalmic diseases. The diagnosis of glaucoma, especially early glaucoma, is often uncertain. This cannot be attributed simply to the standard of the doctor, although the experience of the doctor does play a decisive role. The deeper reason is that glaucoma as a disorder is highly individual and, simply put, no two glaucoma patients are exactly the same. Even in the United States, which has invested the most in glaucoma research, the diagnosis of glaucoma is not completely correct. Therefore, the international approach to primary glaucoma has generally adopted a graded diagnosis based on diagnostic certainty, i.e., definite, highly probable, and suspicious. This diagnostic concept is scientifically sound, because according to the different levels of risk, doctors can tailor their treatment strategies accordingly. For example, for definitive glaucoma, not only should IOP-lowering treatment be given, but also the target IOP for treatment should be set together with the patient; for highly suspected glaucoma, IOP-lowering treatment needs to be started, but the control of IOP can be loosened; and for suspicious glaucoma, long-term follow-up observation is the main focus. Unfortunately, this philosophy is not easily accepted by the general public or even by many doctors in China. Our national situation is more inclined to give patients a definite yes or no answer in the short term. Changing the above-mentioned concept is actually beneficial for both glaucoma patients and physicians. We often see patients in glaucoma clinics who have run through major hospitals to seek a definitive answer because of a physical examination or because some doctors suspect open-angle glaucoma, and the answers they get are still inconsistent. This creates a lot of confusion for patients and forces many doctors to start using glaucoma treatment out of protection for themselves and their patients. We know that treatment for glaucoma is usually lifelong, meaning that once treatment is started, it often means that anti-glaucoma medications need to be ordered every day for the rest of your life. On the other hand, those who have experienced glaucoma medication have experienced the discomfort and heavy medical burden associated with glaucoma medication use to a greater or lesser extent. In short, the use of glaucoma medications can create a long-term psychological, physical, and financial burden for the suspect patient. Therefore, it is necessary to carefully diagnose patients with suspected glaucoma. For the physician, establishing a scientific concept of diagnosis not only provides a truer picture of the nature of the condition, but also provides the opportunity for targeted treatment. So are we able to conclusively determine if it is primary open-angle glaucoma? The answer is yes. The question is what it will take to get that answer. Glaucoma is a progressively worsening eye disease that eventually leads to atrophy of the optic nerve and loss of visual function. Therefore, it is only a matter of time before glaucoma is finally identified by simply performing follow-up observations without any intervention. However, no one wants to determine if they have glaucoma at the expense of their visual function. This creates a situation of choice – do we determine glaucoma simply by regular observation or do we risk misdiagnosis and begin diagnosis and treatment? This is a scientific question as well as a human one. The wisest approach is: if a diagnosis can be made straightforwardly, there is no need to wait for observation before drawing conclusions, but observation is needed to know whether the outcome is stable; if there is a high degree of suspicion, attempted treatment and observation is needed; and if it is suspicious at low risk, regular observation is needed. We also set the interval of observation follow-up according to the risk of glaucoma. If there is no change in the disease through several years of observation, we can remove the glaucoma cap for the suspected patient. Even for definite glaucoma, if the disease is stable over time, we can even begin to reduce the intensity of treatment to improve quality of life. At this point, we have a better understanding of the significance of a graded diagnosis of glaucoma and follow-up observations. In recent years, glaucoma experts from many countries, led by Professor Weinreb of UCSD (past president of the World Glaucoma Society), have begun to advocate longitudinal diagnostic criteria for glaucoma. In other words, for patients with suspected glaucoma who cannot be given a one-time diagnosis, time is used as a yardstick for definitive diagnosis through a strict follow-up strategy and reasonable follow-up methods. Dr. Gangwei Cheng’s Glaucoma Longitudinal Population Study Group in Los Angeles, USA has confirmed the rationality and feasibility of this diagnostic system in a population study. Glaucoma experts in China have also recognized the value of this diagnostic system and have started to establish longitudinal diagnostic criteria for primary open-angle glaucoma in Chinese people. It is hoped that in the near future, the diagnostic problems that have plagued numerous glaucoma patients and doctors will be better solved.