13th February 2025

Classification of glaucoma

Primary glaucoma is classified by the cause of the outflow obstruction:

• Open-angle glaucoma: the anterior chamber angle remains open, but outflow is impaired nonetheless, perhaps secondary to structural changes in the trabecular meshwork (Figure 8).
• Closed-angle glaucoma: the peripheral iris is pushed against the trabecular meshwork, blocking outflow. In acute cases, this is often secondary to pupillary block, where the iris comes into contact with the lens, causing a buildup of aqueous humour, which in turn causes the iris to bow outwards, closing the anterior chamber angle (Figure 9).

Secondary glaucoma has various causes including drugs, trauma and inflammation.