Glaucoma Drainage Implant


Glaucoma drainage implant is a medical device that divert fluid from the front part of the eye (anterior chamber) to the external posterior whitish portion (subconjunctival space) of the eye. Theoretically, an implant can avoid healing scar tissue and is especially useful in patients who have already undergone trabeculectomy or conjunctival manipulation.



The purpose of glaucoma drainage device is to divert fluid from the anterior chamber to the external reservoir created by the surgery and hence can relieve the high pressure caused by the accumulated fluid inside the eye.



With Ahmed implant (Figure 1), a conjunctival flap is created in the upper outer quadrant of the eye, usually between two eye muscles. The body of the implant is positioned 8-10 mm behind the white-black interface of the eye. The tube of the implant is inserted about 1-3 mm posterior to the white-black interface into the anterior chamber of the eye. The drainage tube is covered with a piece of preserved donor sclera (Figure 2). The conjunctival flap is then closed and sutured.

The procedure of implanting an Express shunt (Figure 3) is very similar to trabeculectomy described above except that instead of a hole being punched at the white-black interface, a stainless steel spur like device 3 mm long is inserted into the anterior chamber under a whitish sclera like flap (Figure 4).



  • Early complications of glaucoma drainage implants are:

Bleeding inside the eye (hyphema, suprachoroidal hemorrhage)

A too low eye pressure (hypotony)

A too high eye pressure (blockage of the tube)

Infection (endophthalimitis)


  • Late complications of glaucoma drainage implants are:

A too low eye pressure (hypotony, hypotonic maculopathy)

A too high eye pressure and excessive capsule fibrosis

Tube exposure and conjunctival erosion

Corneal decompensation and edema

Infection (endophthalmitis)


Estimated Cost

Prices are subject to change without prior notice, need to pay in accordance with the actual medical expenses.

The Ahmed valve implant (downloaded from Ophthalmology Management)

The implant is usually put on the upper-outer quadrant of the eye. (downloaded from the New World Medical)

The Express shunt (downloaded from Lakewood, Long Beach CA of glaucoma)

The Express shunt is inserted into the anterior chamber under a whitish sclera like flap. (downloaded from M.D./Alert)