The Paul glaucoma implant (PGI) will be used as an active comparator group to compare its effectiveness and safety with the Ahmed glaucoma valve in the treatment of childhood glaucoma. The PGI works by diverting excess fluid from the eye to a plate placed under the conjunctiva, which allows the fluid to drain away from the eye and be absorbed. This helps to lower the pressure inside the eye, which is important for preventing vision loss and other complications associated with glaucoma.

The PGI has a smaller internal and external tube diameter than the Ahmed glaucoma valve, which reduces the contact area between the tube and the corneal endothelium. This theoretically reduces the rate of endothelial cell loss, which can be a complication of GDDs. Additionally, the extraocular portion of the PGI is smaller, which may reduce the long-term risk of tube erosion and exposure.

The smaller lumen may theoretically reduce the risk of postoperative hypotony as well.

The Ahmed glaucoma valve (AGV) arm of the study is the active comparator group and is intended to be directly compared to the Paul glaucoma implant (PGI) in treating childhood glaucoma. The AGV is a type of glaucoma drainage device that is designed to lower intraocular pressure in patients with refractory glaucoma. It is made of a rigid plastic material and consists of a small drainage tube that is inserted into the eye and a valve mechanism that helps regulate the flow of aqueous humor from the eye to the external drainage tube.

The AGV is implanted during a surgical procedure, and its design allows it to be placed in a variety of locations in the eye. The valve mechanism helps to regulate the flow of aqueous humor, and the device is designed to be long-lasting with a low risk of complications. The AGV is a well-established treatment option for patients with refractory glaucoma and has been used for many years in clinical practice.

Both the Paul glaucoma implant (PGI) and Ahmed glaucoma valve (AGV) are types of glaucoma drainage devices (GDDs) used to lower intraocular pressure in patients with refractory glaucoma. Devices will be implanted during a surgical procedure and work by diverting excess fluid from the eye to an external drainage tube, allowing the fluid to drain away from the eye and be absorbed into the surrounding tissue. This will help to lower the pressure inside the eye, which is important for preventing vision loss and other complications associated with glaucoma.

More than 20% change from baseline without development of vision threatening complications

Assessment of changes in number of medications for IOP reduction after procedure (i.e., did patients have a reduction or gain in use of medications to reduce their IOP after the procedure?)