Ahmed Glaucoma Valve
The Ahmed glaucoma valve is a tube or shunt that is placed into the anterior chamber of the eye (fluid space between the cornea and iris) that drains the aqueous humor from the eye. The fluid is drained into the end plate or reservoir located back away from the cornea under the conjunctiva. The fluid slowly drains from the end plate into the space between the sclera and the conjunctiva. The fluid is then absorbed by the tissues around the eye. This lowers the eye pressure which is needed to control the glaucoma.
Indication for Use of the Ahmed Glaucoma Valve
In years past, the Ahmed glaucoma valve shunt device was used in people who have had a failure of the more traditional glaucoma surgery procedure called trabeculectomy. Certain eye diseases or ocular tissue status such as previous eye surgery that has scarred the conjunctiva, neovascular glaucoma, and glaucoma do not do well with traditional trabeculectomy also were an indication for the Ahmed glaucoma shunt. The Ahmed glaucoma valve is now gaining more acceptance as a primary surgical treatment for glaucoma that has not responded well to eye medications and laser treatment (selective laser trabeculoplasty).
Success Rate for the Ahmed Glaucoma Valve
Typical success rate for lowering the intraocular pressure 1 year after the surgery is in the neighborhood of 12 to 16 mmHg from pre op levels with an average eye pressure of 14 to 16 mmHg. These patients are on approximately half the number of glaucoma medications after the surgery than pre op. The overall success rate is approximately 75% to 85%.
Complications Associated with the Ahmed Glaucoma Valve
Shallow anterior chamber
Hyphema (bleeding inside the eye)
Choroidal effusion or edema
Diploplia or double vision
Cystoid macular edema (swelling in the macula portion of the retina)
Corneal touch by the tube
The Ahmed glaucoma valve or shunt has a very successful record of treating glaucoma that has not been well controlled with glaucoma medication, selective laser treatment, or traditional trabeculectomy. The Ahmed glaucoma valve is being used more commonly as a primary surgical procedure.