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Glaucoma

Glaucoma is a serious eye disorder that can cause blindness if left untreated. It is a disease that often runs in families, and can steal sight discretely with the individual hardly noticing vision loss until late stages. Glaucoma screenings for individuals over age 55 are recommended, and are generally covered by most insurance companies, including MediCare. Treatment is often successful with the use of drops; however other options are now available including the use of laser treatment.

Glaucoma: The Effects of High Pressure Within the Eye

Glaucoma is a disease of the eye that can silently steal one's sight with no suspicion of the problem until often at a point in time that is too late to reverse. The problem is related to elevated pressure within the eye to the point where it damages the delicate nerve fibers in the optic nerve. The elevated level of pressure that can cause damage will vary in any individual. The amount of damage depends on not only how high the pressure actually is, but also on how sensitive to damage one's optic nerve is. A mild elevation in intra-ocular pressure in one individual may cause no damage to the optic nerve, whereas the same mild elevation in a second individual whose optic nerve is more sensitive to damage, may indeed lead to visual loss.

Causes of Glaucoma

• Eye injuries
• Serious eye infections
• Congenital - i.e. present at birth
• Related to medical diseases, e.g. diabetes
• Medications - particularly cortisone related medications either oral or in drop form
• familial
• Blood vessel occlusions in the eye
• Structural abnormality from birth (Narrow Angle Glaucoma) leading to sudden onset of glaucoma later in life
• Gradual constriction of internal fluid drainage channels for no known reason (Chronic Open Angle Glaucoma) - the most common scenario of glaucoma

Above:Fluid flow in eye is generated in the ciliary body, behind the iris - and percolates anteriorly through the pupil and is drained internally by the trabecular meshwork. Glaucoma arises when either the outflow in the trabecular meshwork is clogged, or too much fluid is produced by the

ciliary body.

Physiology of Glaucoma

In any eye, there is a normal pressure that exists to promote the health of the eye. Picture a sink that has a water faucet that is turned on as well as a drain that is emptying the sink. Fluid can accumulate in this sink by either the faucet being turned on to a stronger level, or the drain becoming more and more clogged. In the human eye, research has taught us that the predominant factor in increased intra-ocular pressure is a gradual clogging of the drain, known as the trabecular meshwork.

If the pressure is high enough for a long enough period of time, the delicate nerve fibers in the optic nerve will be damaged.

Diagnosis of Glaucoma

Once damaged, visual fibers will not regenerate. For this reason, the key to treating glaucoma is in early diagnosis so that measures can be taken to reduce the pressure before damage is done. It is important to understand that not only should the actual pressure be routinely checked in individuals of any age, but in addition, examination of the optic nerve is an important part of the evaluation. (Insert photo of normal optic nerve head vs glaucoma optic nerve head)If there is any suspicion of glaucoma, then a visual field examination (computerized testing of peripheral vision) should also be performed. (Insert photo of normal visual field vs glaucoma visual field). One of the newer technologies available today at Walman Eye Center is the availability of "Retinal Tomography". This technology utilizes a low energy level that bounces off the retina and optic nerve and the interference patterns are captured by a specialized camera that analyzes the cupping pattern of the optic nerve and the retinal nerve fiber layer and is capable of diagnosing and monitoring glaucoma at a much earlier stage than previous technologies.

Treatment Options in Glaucoma

Treatment of glaucoma generally depends on an analysis of the underlying problem. If the glaucoma is related to one of the several mitigating factors listed above, then treatment of the glaucoma problem itself as well as treatment of the underlying factor is critical. Assuming that underlying factors have been treated, management of the pressure problem, hopefully before significant damage is done, can be categorized as follows:

Topical Medications (Drops)

The oldest method of reducing the intra-ocular pressures involved the use of eye drops. There is a large variety of medications that are available for treatment of the glaucoma problem. They work either by decreasing the flow of fluid (turning down the faucet) or stretching open the trabecular meshwork (opening up the drainage channels). In the last 2 or 3 years, significant improvement in effectiveness of medications have been seen. Most medications, however, have the potential for side effects in some (not all) individuals. The appropriate medication or combination of medication use needs to be carefully evaluated with your Ophthalmologist in view of the patient's overall medical status.

Systemic Medications (Tablets)

There are a small number of tablets that also work at decreasing the intra-ocular pressure, primarily by decreasing the outflow mechanisms. Examples are Diamox , and Neptazine. These medications in general have limited long term usefulness because of side effects; but they do have some important uses for short term usage.

Laser

Argon Laser

The argon laser (green light) has been used for many years in the treatment of chronic open angle glaucoma. In this procedure, a sophisticated lens ins gently placesd in front of the eye, and the laser beam is focused into the area of the trabecular meshwork (the outflow channel). Multiple applications of laser light are spread around the trabecular meshwork with the intent of stretching open these outflow channels ("trabeculoplasty") and thus decreasing the intra-ocular pressure. The procedure is generally not associated with any significant discomfort and the patient is able to return to normal activities immediately.

For most people, the argon laser trabeculoplasty (ALT) is used when an inadequate response from medications is detected, or if the medications cause too many side effects. In some individuals, the decision is made to start treatment with the Argon Laser even before medications are tried. Each individual is different, and the appropriate method of treatment for any individual can only be determined through appropriate evaluations through one's Ophthalmologist.

The argon laser treatment is generally a good treatment that often (not always) decreases one's dependence on drops. There is, however, some feeling that the effects of the laser treatment wear off in approximately 7 to 10 years and may have to be repeated. If, however, it can keep the intra-ocular pressure down in an individual with glaucoma, it can go a long way in preventing visual loss.

Laser Iridotomy

In narrow angle glaucoma, because of a structural defect in eye development, the passageway leading to the trabecular meshwork is too narrow and can suddenly be blocked off in adult life. A decade ago, the only treatment for this type of sudden onset of painful glaucoma was a surgical procedure which involved cutting an artificial opening internally in the iris. With the improvements in laser technology, however, a surgical procedure in this scenario can be avoided. The laser is used to efficiently and for the most part , painlessly, fashion an opening in the iris to open the blocked passageway. The opening is usually done with the Argon laser, but occasionally, the 'YAG' laser is also utilized when more power is needed in challenging situations.

Diode Laser Cyclophotocoagulation ('CPC')

In some individuals, particularly with severe, longstanding glaucoma problems, the increased power of the 'Diode' laser is used. With this instrument, multiple laser applications are applied on the white of the eye in the area overlying the 'ciliary body' (structure of the eye that produces the internal fluid - i.e. the 'faucet'). The laser partially damages these cells that produce the fluid, thus turning down the faucet.

EndoCyclo Photocoagulation ('ECP')

This next generation laser treatment is a technology that is utilized in conjunction with cataract surgery, or on its own. A microscopic fibre-optic camera is utilized to visualize the ciliary body (the fluid producing tissue within the eye) and a laser is utilized through the same fibre-optic probe to coagulate the surface cells of the ciliary body. {Insert ECP photos}

Surgery for Glaucoma

In individuals who do not respond adequately to either medications or laser treatments, and pressures are still too high, the only alternative is surgery; a procedure known as a "Trabeculectomy". In this procedure, an artificial opening is surgically made to allow fluid to flow and bypass the clogged natural outflow channels. Current techniques have increased the success rate of the procedure, but as with any surgery, there are some risks.

Fortunately, technology has improved significantly for both the medication and laser treatment alternatives in glaucoma, so that only a very few individuals need ever progress to the point of needing surgery. The key to a lot of these successes however, lie in prevention; specifically, the earlier that glaucoma can be diagnosed, the more effective the treatment through either medications or laser.