Drainage implant surgery is a procedure which involves inserting a tiny device in the eye to treat glaucoma, a disease caused by the dysfunction of the eye’s drainage canal, which increases the internal pressure or intraocular pressure (IOP). Prolonged IOP damages the optic nerve leading to decreased vision and blindness, if left untreated.

The ophthalmologist can recommend a drainage implant when other forms of glaucoma treatment like medication and laser therapy, produce unsatisfactory results. It may also be used in the treatment of some forms of glaucoma caused by eye injuries.

The first device was the Molteno glaucoma implant tested in 1969. Other implants have since been developed, and there are two basic types, namely Ahmed or Krupin (valved) and Molteno, Baerveldt (non-valved) designs.

It’s essential to note that while drainage implants may help prevent further glaucoma damage, no treatment can reverse the damage already done to the optic nerve.

Also Known As

  • Glaucoma drainage implant surgery
  • Glaucoma drainage devices surgery
  • Aqueous shunt surgery
  • Tube shunt surgery


Preparation & Expectation Before Surgery

The surgeon and the patient will discuss the surgery during the consultation before the procedure. S/he will take a complete medical and surgical history, including medication the patient is using such as eye drops, aspirin or blood thinners, etc. S/he will also conduct a comprehensive eye examination to assess the affected eye and evaluate any pre-existing eye disorders that can lead to complications during or after the operation.

The surgeon will respond to any concerns and questions the patient may have and provide instructions about medication. The patient may be required not to drink or eat anything for a given period before the surgery. They should also be accompanied by someone or make arrangements to be taken home because of the effects of the anesthesia used during the operation.

Types, Purpose & Procedure

The glaucoma drainage implants work to lower the IOP by improving the outflow of the aqueous humor, the inner eye fluid, from the eye. The device consists of a plate and a tube. The tube is lodged into the eye to enable the humor to flow out. The plate is put under the eye skin to make a small pool known as a bleb, where the fluid drains and is reabsorbed. Thus, the humor can drain out of the eye through the implant and bypass the natural drainage system.

The procedure is usually done in a hospital or outpatient surgery center and takes about an hour. The patient is given medicine to relax and anesthesia to numb the eye area. The surgeon will make a cut in the skin of the eye, i.e., in the conjunctiva. S/he will place the drainage implant plate under it and insert the tube into the eye over the colored part, the iris.

The surgeon will sew a piece of donor tissue over the tube to protect it against friction and also prevent infection. S/he will then sew the cut in the conjunctiva over the drainage device. S/he will confirm that the bleb is working well and may patch up the eye and shield it to protect the implant.

Risks, Side Effects & Complications

Some of the risks of glaucoma drainage implants include:

  • Low IOP
  • Bleeding
  • Cataract
  • Swelling
  • Loss of vision
  • Corneal injury
  • Infection in the eye

After the operation, the patient may experience:

  • Soreness
  • Discomfort
  • Blurry vision
  • Foreign body sensation in the eye

The most common complication of glaucoma drainage implants is the scarring of the bleb, which prevents the humor from draining into it. It may call for additional surgery or the removal of the implant. Other complications may include:

  • Double vision
  • Clogging of the tube
  • Scarring in or on the eyeball
  • Interference with the external eye muscles affecting side to side movement

The patient should see the ophthalmologist urgently if they experience:

  • Pain or redness
  • Decreased vision
  • Abnormal tearing


After Care, Recovery & Results

The patient will need to keepS the eye patch and shield on overnight. The surgeon will prescribe medication to prevent infection, scarring, and to relieve any pain. In most cases, patients will need to continue taking their glaucoma medications after drainage implant surgery.

The surgeon will see the patient the day after the operation and remove the eye patch and shield. Aftercare instructions and a follow-up schedule will be provided, and the patient must follow the guidelines and keep the appointments.

During the recovery period, the patient must wear a shield at night to protect the bleb until the doctor discontinues it. The patient will also have to prevent water from getting into the eye and avoid activities such as bending, heavy lifting, sports, yoga, high-impact exercise, etc. The surgeon will advise the patient when to resume regular activities.

The procedure is successful in most cases, but about ten percent of the patients may need a second tube implant for a satisfactory outcome.