The normal range is 10-21 mm Hg. In a normal person, IOP is stable within this range to maintain the normal shape of the eye and to ensure maximum optical performance of the refractive interstitium. Factors affecting IOP Although the contents of the eye include atrial fluid, lens, and vitreous humor, it is the atrial fluid that has the greatest impact on IOP. Under normal conditions, the production and excretion of atrial fluid are in dynamic balance, with equal amounts of atrial fluid produced and excreted over a given period of time. If the elimination pathway of atrial fluid is obstructed, or if the amount of atrial fluid produced increases, which leads to a buildup of atrial fluid, the IOP will increase. Conversely, if the amount of atrial fluid produced is too low, resulting in the inability to accumulate a certain amount of atrial fluid, low IOP will result. IOP, like other physiological indicators of the body such as body temperature, heart rate, and blood pressure, is fluctuating. Generally speaking, IOP is highest in the morning and lowest in the evening or late at night, with a normal fluctuation of 3-6 mm Hg. However, for some eye diseases, such as glaucoma, the fluctuation range of IOP may be greater than this. In addition, body position can also affect IOP. Some medications may also have side effects that cause IOP to rise, especially those containing steroids, and extra care needs to be taken when using them. What is the role of intraocular pressure? The role of IOP is to maintain the shape of the eye and normal physiological function, so it must be kept within a constant range, not high or low. It is like a balloon, the IOP is the gas inside, with the support of the gas, the pressure on the wall of the ball, the balloon can bulge, if the gas is less, the ball will deflate, if the gas is too much, there is the possibility of bursting at any time. Intraocular pressure is an important factor in the diagnosis of glaucoma. When the intraocular pressure exceeds the normal range, called hypertension, the presence of glaucoma is usually suspected. However, high IOP is not the same as glaucoma, nor can the presence of glaucoma be judged purely and mechanically by the level of IOP. One example is “low IOP glaucoma,” in which the IOP remains within the normal range from the time of disease to the time of blindness. The relationship between intraocular pressure and myopia First of all, high intraocular pressure will promote the rapid growth of the eye axis, and secondly, there is a fluid called atrial fluid in the eye, which is constantly produced and discharged, and the amount of production and discharge is balanced, so the intraocular pressure is maintained at a certain normal level. In highly myopic eyes, these micropores become fewer in number, smaller in size, and less open, resulting in increased resistance to atrial water flow, leading to a vicious cycle. And, most importantly, increased IOP is an irreversible and blinding eye disease. The importance of IOP measurement in children The development of vision is the most primitive of all sensory development; after birth a baby’s vision continues to develop until school age. In the subsequent course of life, the eyes play a vital role as the windows to the soul. However, in recent years, the incidence of myopia has been increasing and moving toward a younger age, and, myopia is growing too fast. High intraocular pressure is an important influencing factor for the rapid growth of myopia in adolescents. We hope that parents will not just focus on the growth of myopia and neglect the examination of intraocular pressure in the examination of vision screening for adolescents.