Partial pupil block

As age increases, the lens increases, further causing the lens-iris diaphragm to shift forward, the anterior chamber is shallower, and the angle of the chamber is narrower. Under normal circumstances, the lens and the iris have a contact surface, which forms a physiological pupil block. When the posterior chamber pressure increases, this contact surface opens the aqueous humor to enter the anterior chamber intermittently. When the contact surface increases, the resistance between the aqueous humor flowing from the posterior chamber through the lens to the iris will increase, resulting in pathological pupillary block, which will cause the pressure of the aqueous posterior chamber to increase, especially when the pupils are slightly diffused. When it is large (about 4 to 5 mm), there is a pupil block, and the peripheral iris is more relaxed. Therefore, the peripheral iris is pushed forward and adheres to the trabecular meshwork, so that the drainage of aqueous humor is blocked, causing intraocular pressure.