The space between the atrium behind the cornea and the iris is called the anterior chamber, the central part is about 2.5 to 3 mm deep, and its surrounding part is called the anterior chamber angle. Behind the iris, the annular gap between the ciliary body and the equatorial part of the lens is called the posterior chamber. The clear fluid that fills the anterior and posterior chamber is called atrial fluid. The atrial fluid is produced by the epithelial cells of the ciliary process, and the total amount is about 0.15-0.3 ml. The main component is water, containing a small amount of chloride, protein, vitamin C, urea and inorganic salts, etc. The atrial fluid is weakly alkaline and has a slightly higher specific gravity than water. Atrial water is produced and discharged through the following channels: atrial water is produced by the epithelium of the ciliary process → posterior chamber → pupil → anterior chamber → anterior chamber angle → trabecular meshwork → scleral venous sinus (Schlemm’s canal) → via the collecting duct and atrial vein → finally entering the anterior ciliary vein on the surface of the sclera and returning to the systemic blood circulation. A small amount of atrial fluid is absorbed at the saphenous fossa on the iris surface, in addition to a small amount of atrial fluid absorbed via the suprachoroidal space. The main functions of atrial aqueous are: 1. to supply nutrients and oxygen to intraocular tissues, especially the cornea and lens, and to discharge their metabolic products. 2. to maintain intraocular pressure. 2, maintain intraocular pressure. The production and discharge of atrial fluid and intraocular pressure are closely related, and the two are in balance when normal. When a certain factor makes the balance out of balance, it can lead to an increase or decrease in intraocular pressure, causing damage to eye tissue and visual function. 3, is one of the refractive interstitial, with refractive action, refractive index of 1.3336.