Glaucoma Procedures

 

Peripheral Iridotomy 

If your ophthalmologist (Eye M.D.) or optometrist suspects that you have “narrow” or “closed” angles, this means that the drainage channel of your eye is blocked or nearly blocked by the iris, the colored part of your eye. This places you at high risk for elevated intraocular pressure and vision loss. This is called angle-closure glaucoma. 

 

An attack of acute angle-closure glaucoma is marked by sudden onset of very high eye pressure and complete blockage of the drainage channel in the eye. Symptoms include pain, red eye, and decreased vision. Here, the laser is done as an emergency procedure. The eye pressure can also rise gradually (chronic angle closure glaucoma)--you would have no symptoms at all. Most often, peripheral iridotomies are done when your eye doctor discovers the iris to be touching or dangerously close to the eye’s drain "(known as narrow angles)."

 

To treat angle-closure glaucoma, your ophthalmologist will perform a peripheral iridotomy (PI), creating a hole in the upper part of the iris (the colored part of the eye) using a laser. This opening is typically so small that it cannot be seen with the naked eye. The opening in the iris allows fluid to flow from behind the iris through the opening, allowing the iris to fall back into a more normal position, opening the drain. 

 

This laser treatment is performed on an outpatient basis, often in the ophthalmologist’s office. The treatment will not improve your vision, but it can help prevent vision loss from angle-closure glaucoma. Side effects of the treatment are unusual and include the a temporary rise in intraocular pressure and inflammation. 

 

Selective Laser Trabeculoplasty 

Selective laser trabeculoplasty (SLT) is a laser surgical procedure used to lower intraocular pressure (IOP) of patients with open-angle glaucoma. SLT is used to treat the eye’s drainage system, known as the trabecular meshwork – the mesh-like drain that surrounds the iris. Treating this area of the eye’s natural drainage system improves the flow of fluid out of the eye, helping to lower the pressure. 

 

The laser used in SLT is very low-powered. It treats specific cells selectively, leaving untreated portions of the trabecular meshwork intact. It causes no demonstrable damage to the eye’s drain, unlike the older argon laser. For this reason, SLT, unlike other types of laser surgery, may be safely repeated. 

 

SLT is typically performed in the ophthalmologist’s (Eye M.D.’s) office or an outpatient surgery center. The procedure usually takes about five minutes. First, anesthetic drops are placed in your eye. The laser machine looks similar to the examination microscope that your ophthalmologist uses to look at your eyes at each office visit. 

 

You will experience a flash of light with each laser application. Most people are comfortable and do not experience any significant pain during the surgery, although some may feel a little pressure.

 

Most people will need to have their pressure checked soon after the laser treatment, since there is a risk of increasing IOP right after the procedure, almost always temporary. If this does occur, you may require medications to lower the pressure, which will be administered in the office. Very rarely, the pressure in the eye increases to a high level and does not come down. If this happens, you may require a surgery in the operating room to lower the pressure. 

 

Most people notice some blurring of their vision after the laser treatment. This typically clears within a few hours. The chance of your vision becoming permanently affected from this laser procedure is extremely small. 

 

Most patients can resume normal daily activities the day of laser surgery. You may need to use eye drops after the procedure to help the eye heal properly. 

 

Risks associated with SLT include:

• Increased pressure in the eye, possibly requiring medication or surgery

• Inflammation in the eye – actually, a little inflammation may help the procedure to work

• Failure to adequately lower the eye pressure

• Need for repeat laser surgery

 

It will take several weeks to determine how much SLT lowered your eye pressure. You may require additional laser, drops or glaucoma drainage surgery to lower the pressure, if it is not sufficiently lower after the first laser treatment. 

 

In some, the laser is recommended as first-line therapy in order to avoid using drops. In others, it is used to make the drops the patient takes work better. In still others, SLT is used to avoid adding drops to the current drop regimen. 

 

When your glaucoma is first diagnosed, you may be given the option of treatment with drops or laser. The advantage to laser is that, if it works, you can avoid taking drops for the rest of your life, avoiding the expense, effort and possible side effects of drops. SLT works about 75% of the time, on average. If it does not, drops will work just as well as if you never had the laser. 

 

While some people may experience side effects from medications or surgery, the risks associated with these side effects should be balanced against the greater risk of leaving glaucoma untreated and losing your vision. 

 

Seton Surgery for Treating Glaucoma 

The purpose of glaucoma drainage surgery is to help control the pressure in your eye and preserve your vision. If the intraocular pressure (IOP) remains too high, your optic nerve becomes damaged, leading to vision loss and eventual blindness. 

 

In cases of severe open-angle glaucoma or chronic (long-term) glaucoma, if your eye is at the high risk for scarring and your IOP needs to be lowered to preserve your vision, your ophthalmologist (Eye M.D.) may recommend placing a tiny drainage tube in your eye called a seton. 

 

The drainage tube creates a new channel for fluid to flow from the eye to a filtering area, called a bleb. A tiny plate placed on the eye helps the bleb form and remain open. The tube is covered with a patch and is typically not seen or felt. This procedure is performed in the operating room on an outpatient basis. 

 

When successful, seton surgery will decrease the pressure in your eye, minimizing the risk of vision loss from glaucoma. 

 

Some complications of seton surgery may include:

• Failure to control eye pressure with the need for repeat surgery

• Eye pressure that is too low

• Irritation or discomfort

• Double vision

• Infection

• Bleeding

• Cataract

• Erosion of the tube, requiring repeat surgery

 

While some people may experience side effects from glaucoma medications or surgery, the risks associated with these side effects should be balanced against the greater risk of leaving glaucoma untreated and losing your vision. 

  

Trabeculectomy 

If you have glaucoma and medications and laser surgeries do not lower your eye pressure adequately, your ophthalmologist (Eye M.D.) may recommend a procedure called a trabeculectomy. 

 

In this procedure, a tiny drain is made in the sclera (the white part of the eye). The new drainage hole allows fluid to flow out of the eye into a filtering area called a bleb. The bleb is usually hidden under the eyelid; it looks like a raised bubble on the sclera. When successful, the procedure will lower your intraocular pressure (IOP), minimizing the risk of vision loss from glaucoma. The surgery is performed in an operating room on an outpatient basis. 

 

One advantage trabeculectomy has compared to other glaucoma surgeries is that it can be fine-tuned after the surgery. That is because the drainage hole is created under a flap of tissue, whose tension can be adjusted later on, either by cutting stitches with a laser or removing stitches in the office. 

 

Some of the risks and complications from trabeculectomy surgery include the following:

• Failure to control intraocular pressure, with the need for another operation

• Infection

• Bleeding in the eye

• Irritation or discomfort in the eye

• Eye pressure that is too low

• Cataract (in cases where cataract has not already been removed)

• Decreased or lost vision

 

Visual Field Testing 

Because it has no noticeable symptoms, glaucoma is a difficult disease to detect without regular, complete eye exams. 

 

One particular test, called a visual field test (or, “perimetry test”), measures the sensitivity to light at many points in your vision. A typical field test for glaucoma measures the central 60 degrees. A visual field test can help find certain patterns of vision loss and is a key way to check for glaucoma or worsening of glaucoma.  

 

To take this painless test, you sit at a bowl-shaped instrument called a perimeter. While you stare at the center of the bowl, lights flash. Each time you see a flash you press a button. A computer records whether you pressed the button when the light flashed in that location. At the end of the test, a printout shows the sensitivity to light at multiple points in your field of vision. This test shows if you have any areas of vision decrease or loss. Loss of visual field is often an early sign of vision loss from glaucoma. Regular perimetry tests are an important technique for learning how, if at all, your vision is changing over time. It can also be used to see if treatment for glaucoma is working to prevent further vision loss. 

 

During the test it is important to hold still and concentrate on the target on which the technician asks you to focus. If you need a break or are uncomfortable, please tell the technician. This will help ensure accurate results. It is important to realize that, with most visual field tests, you are not supposed to see every light, each time it is presented. The machine deliberately shows you lights it is pretty sure you cannot see.