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Glaucoma surgery

trabeculotomy during glaucoma surgery

Your eye doctor may recommend glaucoma surgery if eye drops and oral medications don’t reduce your eye pressure well enough to prevent optic nerve damage. In these cases, surgery can potentially save your eyesight.

Compared to older methods of glaucoma surgery, modern procedures continue to improve with significantly lower risks of complications.

SEE RELATED: Glaucoma: Signs and symptoms

When is glaucoma surgery needed?

Most cases of glaucoma can be controlled with one or more drugs, but in some cases surgery may be either preferred or more effective.

Many people with glaucoma fail to use their eye drop medications as directed, which results in poor control of their eye pressure and greater risk of vision loss. Sometimes, surgery can eliminate the need for glaucoma eye drops. But this is not always the case.

Types of glaucoma surgery

There are many types of glaucoma surgery, with new surgical treatments being developed and perfected all the time. An ophthalmologist will assess your individual condition and help you decide which option is best for you.

Minimally invasive glaucoma surgery (MIGS)

Doctors will consider minimally invasive glaucoma surgery (MIGS) before a more invasive procedure whenever possible.

These microsurgery procedures tend to cause fewer side effects and complications than standard glaucoma surgeries, such as trabeculoplasty. (In some cases, however, more invasive glaucoma surgeries are need to have an adequate effect despite the higher risk of complications.)

MIGS procedures require only very small incisions and typically involve the use of tiny (even microscopic-size) implants to increase the outflow of fluid (aqueous humor) from the eye.


Glaucoma surgery creates a new opening for fluid drainage. Graphic (enhanced) courtesy of National Eye Institute, National Institutes of Health.

The trabecular meshwork is responsible for most of the resistance to the normal outflow of aqueous fluid. If this meshwork becomes clogged, pressure in the eye can increase to dangerous levels. The trabecular meshwork is located in the drainage angle of the eye, which is located in the anterior chamber of the eye where the cornea and iris meet.

Minimally invasive glaucoma surgery procedures reduce eye pressure by creating new passages through or around the trabecular meshwork with tiny shunt or stent devices to allow the aqueous humor to drain more easily from the eye.

Types of MIGS procedures include:

  • Microtrabeculectomy (miniaturized version of a standard trabeculectomy)

  • Internal trabecular bypass procedures (by implanting tiny stent or shunt devises within the trabecular meshwork)

  • Certain laser procedures

In a microtrabeculectomy, microscopic-sized tubes are inserted into the drainage angle to drain aqueous fluid from inside the anterior chamber of the eye to underneath the thin outer membrane of the eye (conjunctiva) that covers the white of the eye (sclera). two new devices seem to make the trabeculectomy operation safer. Examples of devices used in this procedure are the Xen Gel Stent and PRESERFLO MicroShunt.

A laser glaucoma surgery called selective laser trabeculoplasty (SLT) is now considered a first-line surgical treatment for open-angle glaucoma and may reduce the number of eye drops a person needs to use every day to treat glaucoma.

During an SLT procedure, an ophthalmologist uses a laser to create tiny holes can allow eye fluid to drain better and lower eye pressure.

SLT often can per performed in the ophthalmologist's office. According to the Glaucoma Research Foundation, this laser glaucoma surgery can lower eye pressure by 20 to 30 percent and is successful in about 80% of patients.

Though the reduction in eye pressure from SLT may not be permanent, the procedure can often be safely repeated, if needed.


A trabeculectomy is a more significant glaucoma surgery than a microtrabeculectomy, SLT or other MIGS procedures, and is used when a more significant reduction of intraocular pressure (IOP) is needed to control glaucoma.

In this procedure, a piece of the trabecular meshwork is removed to increase the outflow of aqueous fluid from the eye.

Near the exterior junction of the cornea and sclera, the surgeon cuts and folds back a portion of the conjunctiva that covers the sclera and makes a flap in the sclera. This flap is folded back, and a small piece of the trabecular meshwork and iris are removed to make a hole into the anterior chamber of the eye. The scleral flap is then put back and sewn in place with tiny nylon sutures to essentially create an adjustable drainage valve. The conjunctiva is sewn back in place to cover the area and absorb aqueous fluid coming out of the trabeculectomy valve.

A small bubble (called a bleb) appears just below the surface of the conjunctiva, where this surgically produced valve is made. By adjusting the sutures of a trabeculectomy, the surgeon can control how quickly aqueous drains from the eye and achieve the target IOP to control glaucoma.

The trabeculectomy is performed on the upper portion of the eye (under the upper eyelid), so this bleb and incisions of a trabeculectomy are not visible to you or others.

Iridotomy and iridectomy

For a less common form of glaucoma called narrow-angle glaucoma, a surgeon may use a laser to create a small hole in the peripheral iris to allow aqueous to drain through it. This is called an iridotomy or peripheral laser iridotomy. Alternatively, an iridectomy involves cutting out a piece of the iris to create a larger drainage hole.

These glaucoma surgery procedures are used to decrease the risk of narrow-angle glaucoma developing into acute angle-closure glaucoma, which is a painful condition that causes IOP to increase very rapidly. Acute angle-closure glaucoma is a medical emergency that requires treatment within hours to prevent vision loss.

SEE RELATED: What is the best treatment for glaucoma?

Glaucoma surgery side effects and complications

Like any surgery, any glaucoma surgery carries a certain level of risk. Procedures have become safer with every new advance, but complications still are possible.

The risk of side effects and complications depends on which type of surgery you undergo. They can include:

  • Eye redness or pain

  • Irritation of the cornea (front of the eye)

  • Continued high eye pressure

  • Low eye pressure

  • Infection

  • Higher risk of cataracts after surgery

  • In rare cases, varying levels of vision loss

See your eye doctor

Only an ophthalmologist — an eye doctor who can treat eye diseases and perform surgery — can determine if glaucoma surgery is your best option.

If your regular eye doctor feels glaucoma surgery is needed, he or she will refer you to an ophthalmologist who specializes in glaucoma surgery for a consultation. Following glaucoma surgery, you can return to your regular eye doctor to monitor your eye pressure and other clinical signs of your glaucoma.

SEE MORE: Glaucoma: Research and resources

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