Information - Surgical Treatment of Glaucoma

Glaucoma is the name given to a group of eye diseases often associated with too much pressure inside one or both eyeballs. It is a leading cause of damage to vision or blindness in people over 40 years of age but can affect anyone. If glaucoma is detected early, treatment can prevent or reduce loss of vision in most patients.

Aqueous fluid is pumped into the eye, and then drains out through a structure called the trabecular meshwork. Glaucoma occurs when the amount of aqueous fluid pumped into the eye is greater than the fluid flowing out of the eye through the trabecular meshwork. This imbalance increases eye pressure.

This increase in intraocular pressure results in damage to the delicate fibres of the optic nerve that connects the eye to the brain. The aim of treatment is to decrease fluid production or to increase fluid drainage.

Open-Angle Glaucoma

This is the most common type of glaucoma. It’s usually painless and without symptoms, slowly damaging the eye without the person being aware it’s present. In open-angle glaucoma, the aqueous fluid can’t flow through the trabecular meshwork and drain properly, causing the pressure in the eye to rise and eventually damage the optic nerve.

Angle-Closure Glaucoma

Sudden, severe pain in the eye occurs, often with immediate disturbance of vision. The patient may have nausea and vomiting while damage to the optic nerve can occur within hours. Emergency treatment is needed to prevent partial or complete loss of vision.

Normal Pressure Glaucoma

This occurs in people with average intraocular pressures who suffer damage to the optic nerve due to increased sensitivity through pressure.

 

 

Childhood Glaucoma

 Rare, this may start during infancy, childhood or adolescence and is hereditary which if not treated, may lead to blindness.

Congenital Glaucoma

A form of childhood glaucoma usually detected during a baby’s first 6 months. It’s due to a fault in the development of the trabecular meshwork and surgery is the most effective treatment.

Secondary Glaucoma

This is due to other conditions of the eye and may be caused by certain medications. Impaired vision or blindness will result if undetected and untreated.

Diagnosis

A diagnosis if glaucoma is usually based on examination of the optic disk, visual-field testing, and on the level of eye pressure. Glaucoma can cause loss of peripheral (side) vision. Early and subtle changes to sight can’t be detected by the patient and will require visual field testing. When the condition is mild, however, diagnosis may be difficult and may require repeated examinations over time.

Medical Treatment of Glaucoma

Treatment with eye drops or tablets is usually tried before surgery, unless surgery is urgent.

The medication works by:

·        Slowing the rate that fluid is pumped into the eye, or

·        Improving drainage from the eye.

Some drops are administered as a gel, which helps the drops stay longer on the surface of the eye. Tablets can also help lower the eye pressure but may have more side effects as they have to be absorbed through the body rather than placed directly where they are needed. Both eye drops and tablets can cause side effects or interact with other medicines you may be taking.

Although drug-treatment options have continued to improve, some patients will require laser or surgery to control glaucoma.

Monitoring of Glaucoma: Once treatment for glaucoma is commenced, it’s important for your optometrist to test whether it’s working or not. This shows whether your vision is remaining stable, or if damage is occurring.

Surgical Treatment of Glaucoma

Surgery may be recommended:

·        If the medication isn’t working.

·        If the glaucoma is worsening.

·        To improve the result of the medical treatment.

·        If the patient is unable to take the medication.

·        To reduce the need for medication.

The aim of surgery is to reduce the pressure inside the eye. Your optometrist will liaise with your glaucoma surgeon who will recommend the best surgical method for your particular circumstances.

The choice of method depends on:

·        The type and severity of your glaucoma.

·        Any other condition in your eyes.

·        The state of your general health.

Laser Trabeculoplasty: During this treatment, the eye doctor directs a laser beam at the trabecular meshwork. Small areas are selectively treated to improve the normal drainage of aqueous fluid. The improved drainage reduces pressure inside the eye.

Laser Iridotomy (Iridectomy): Laser iridotomy uses a laser beam to make a small hole in the iris which allows the trapped aqueous fluid to flow more freely toward the trabecular meshwork. This is the method often used in patients with angle-closure glaucoma.

Cyclophotocoagulation: Cyclophotogoagulation uses a laser beam to destroy parts of the eye so that less aqueous fluid is produced.

 Incisional Surgery to Treat Glaucoma

The most common incisional surgery to treat glaucoma is called a filtering procedure. In a filtering procedure called a trabeculectomy, the glaucoma specialist creates a channel through the wall of the eyeball (the sclera) near the trabecular meshwork, letting the aqueous slowly drain out of the eye. If one or two trabeculectomies haven’t worked, the doctor may need to insert a small tube or valve inside the eye to ensure drainage.

Cyclocryosurgery: A metal probe, cooled by liquid nitrogen, is touched to the outside of the eye at level, which produces aqueous fluid. The extreme cold reduces or destroys the ability of part of the eye to produce fluid.

Recovery after Surgery

The recovery period after glaucoma surgery is usually short, although you may need to wear an eye patch for a few days. Your eye doctor will prescribe eye drops to be used for a few weeks after surgery.

Don’t rub your treated eye.

Sometimes, anti-scarring injections to the surface layer of the eye may be needed. After laser trabeculoplasty or laser iridotomy, vision usually returns quickly to normal, although there may be some slight blurring for a short time.

Recovery time after trabeculectomy varies, and the eye could take up to 6 weeks to settle completely. Blurred vision is common after cyclophotocogulation and may persist for several hours. Discuss with your doctor when you can expect your vision to return to its usual level.

Until advised otherwise by your eye doctor:

·        Avoid strenuous activity.

·        Avoid getting your face wet when showering or having your hair done.

·        Don’t swim.

·        Don’t bend down.

You’ll be advised when you can resume normal activities.

 The Risks of Surgery

Prior to surgery, the commonest and most significant complications that might arise with surgery are normally discussed with the patient.

Surgery on the eyes can cause a range of emotional responses, as it involves one of the body’s most important senses.

Beforehand, find out as much as you can about the surgery, and if you have any concerns, ask your eye care consultant.

Possible Side Effects of Glaucoma Surgery

·        Excessive lowering of intraocular pressure can cause blurred vision for a variable amount of time.

·        Increase in intraocular pressure.

·        Temporary inflammation inside the eye (iritis) – the optometrist will prescribe a medicine to treat it.

·        An increased risk of developing a cataract in the treated eye.

·        Gradual closure of the new passageway with scar tissue.

·        Wound infection isn’t common but if it occurs, treatment with antibiotics may be necessary.

·        Laser iridotomy may cause small spots of bleeding, but these usually settle quickly.

·        Bleeding, discomfort or pain in the treated eye.

·        Impaired vision in the treated eye, which usually recovers but may be permanent.

·        Rarely, permanent loss of vision in the treated eye.

·        The need for further surgery and/or medication.

Blebitis and Endophthalmitis: The filtering drain or “bleb” made on outside of the eye during incisional surgery may be very thin walled. It’s possible for bacteria to get into a thin-walled bleb and start an infection called blebitis which can lead to endophthalmitis, a more serious infection inside the eye that can cause loss of vision. Treatment with antibiotics is required to minimise the risk of infection, avoid swimming, use fresh eye drops, and wash your hands before instilling eye drops.

Long-Term Follow Up

Laser trabeculoplasty reduces the pressure in the eye in 3 out of 4 patients and can be repeated a second time if the pressure rises again. However, repeat treatments are usually not as successful.

With incisional surgery, the new passage that has been created is usually efficient at draining away the excess aqueous fluid, but the underlying problem still exists. That is, natural drainage passes in the eyes is still not able to function adequately. If the new passage closes with scar tissue over the years, glaucoma can progress.

Laser or incisional surgery isn’t a cure for glaucoma. It’s possible that your glaucoma eye drops may not be needed in the short term or even long term after surgery, but regular eye examination remains crucial following this treatment.