COMBINED SURGERY

Combined surgery for those patients having both cataract & glaucoma

A number of factors affect the decision of whether to surgically remove cataracts in the patient with glaucoma.

A cataract is a natural clouding of the lens in the eye. Since the lens is responsible for focusing objects clearly, if the lens is cloudy seeing clearly becomes difficult. Usually the cataract does not interfere with vision initially, and cataracts are not considered an urgent problem.

A Natural Process

Again, cataracts are a natural process and, thus far, an unavoidable part of aging. As we age the chances of having a cataract increases. For example, it is estimated that in the U.S. less than 4% of men and 10% of women between the ages of 55 and 64 years have visually significant cataracts. Between the ages of 65 and 74 years, 14% of men and 24% of women experience cataracts. The incidence is even higher in those over 75 years old. Because age is a risk factor for glaucoma as well, many patients with glaucoma also have cataracts.

Although all of us will eventually develop cataracts, the good news is that the treatment for cataracts is very successful with the latest surgical techniques. When treatment for a cataract is warranted, it is surgically removed and an artificial lens is put in its place.

Glaucoma, however, damages the optic nerve, the critical structure that transmits the visual signal from the eye to the brain. Unfortunately, in contrast to cataracts, we are not yet able to repair or replace the optic nerve. This important difference affects the management of these two diseases when they co-exist in the same eye.

Tailored Treatment

We tailor the specific treatment plan for the individual eye to maximize the benefits and minimize the risk to the eye. It balances many factors that affect the decision as to when and how aggressively the glaucoma and cataract should be treated, including whether the two diseases should be treated at the same time or separately.

There are a number of options available to glaucoma patients with cataracts, and each situation must be assessed individually. If the cataract does not interfere with the glaucoma patient's activities significantly then treating the glaucoma and monitoring cataract progression—but not removing the cataract immediately—may be an appropriate plan.

Often, the glaucoma can be managed with laser treatment and anti-glaucoma medications. When this is possible, it allows us to monitor the eye while the cataract worsens.

For patients with mild glaucoma that is stable we might consider surgically removing the cataract and treating the glaucoma with pressure-lowering medications or laser treatments. Cataract surgery alone on an eye with glaucoma will sometimes lower the pressure in the eye.

For patients with more serious glaucoma and the need for cataract surgery, a combination cataract removal and glaucoma filtering procedure can be considered. For patients using multiple anti-glaucoma medications, a combination procedure such as this would be appropriate.

Combination procedures, however, are not for everyone. The decision to perform a combination procedure depends on the number of anti-glaucoma medications used, how mature the cataract is, and the state of the glaucoma.

Elevated pressure in the eye (intraocular pressure)

The principal cause of glaucoma is high pressure in the eye which damages the optic nerve and nerve fibres. This pressure comes from a build-up of a naturally produced watery fluid (aqueous fluid) in the front part of the eye that provides nutrition to the tissues inside the eye. Pressure increases when there is an imbalance between the production and drainage of the fluid.

Structure and blood supply of the optic nerve

In some patients the eye pressure is within the normal range but they still develop glaucoma due to a sensitivity of the nerve structure or its blood supply.

Family history of glaucoma

Having an immediate relative (a parent, child or sibling) with the disease significantly increases the risk. Anyone with a family history should have regular checks from the age of 40.

How is glaucoma diagnosed?

There are a number of tests that can be performed to determine whether someone has glaucoma.

Tonometry

Tonometry measures the inner pressure of the eye providing an IOP (intraocular pressure) reading. Anaesthetic eye drops are used to numb the eye and then the doctor or technician uses a special device (tonometer) to measure the eye's pressure. IOP can vary from day to day and also during the day. Sometimes it is advisable to check the pressure every couple of hours from early morning until early evening to see if there are large fluctuations in a process called phasing.

Gonioscopy

Gonioscopy is a painless eye test using a contact lens that checks to see if the drainage angle of the eye is normal.

Ophthalmoscopy

Careful 3-dimensional viewing of your optic nerve reveals features which may be abnormal. These are repeated each visit looking for signs of progressive worsening.

Pachymetry

This is a simple, quick and painless test to measure the thickness of the cornea. It is important to assess this as it can have a bearing on the accuracy of eye pressure measurements.

Perimetry (visual field testing)

Computerised measurements of a patients peripheral vision are helpful to diagnose and to monitor glaucoma. During this test, the patient is asked to look straight ahead and indicate when they see a light appear in their peripheral vision. This test helps to draw a "map" of a patient's vision and any related gaps.

Nerve fibre layer measurements

The thickness of the nerve fibre layer can be measured using a non-invasive imaging technique known as Optical Coherence Tomography (OCT). Like visual field testing, this can help in diagnosing glaucoma and also monitor its progression.

Optic nerve imaging

Obtaining baseline readings of the optic nerve, and repeating the tests regularly, is important as the doctor can then see if there are any changes over time. Photos and laser scanners are used to provide this information.

How Do I Manage Glaucoma?

The aim of treatment is to reduce the pressure (IOP) inside the eye, which will reduce stress on the optic nerve and slow down or stop any further nerve damage. If the pressure is brought down to a satisfactory level, then the risk of visual field loss in reduced.

Medical treatment

Eye drops are usually the first treatment for glaucoma. There are various eye drops that can be used and an eye specialist can recommend the one that is the most appropriate. It may be necessary to try several eye drops to find the one drop, or combination, that is best for you.

Laser for primary open angle glaucoma

A form of laser surgery called Argon Laser Trabeculoplasty (ALT) is a safe and straightforward treatment for primary open angle glaucoma. It is effective in about 70% of people but eye drops are usually required as well, to keep the pressure at a safe level.

Laser for narrow or closed angle glaucoma

Another form of laser surgery called YAG Peripheral Iridotomy (PI) surgery creates an opening through the iris which allows the eye fluid to bypass the normal drainage pathway. This can reverse closed angle glaucoma and prevent its development in those who have narrow drainage systems and are at risk of acute loss of vision.

Surgery

Surgery can be used to control pressure inside the eye but is generally used only when eye drops have proven unsatisfactory.

Ongoing management

Once glaucoma is diagnosed, ongoing management and treatment is required throughout life. Like a lot of other conditions, such as blood pressure and diabetes, treatment is about controlling the disease but not curing it. If treatment is discontinued, then the glaucoma will progress again. Fluctuations in eye pressure are damaging, so it is very important to ensure that eye drops are taken regularly as missed doses can be harmful.