Glaucoma

Glaucoma – “The Sneak Thief of Vision”

Glaucoma can damage your vision so gradually you may not notice any loss of vision until the disease is at an advanced stage. The most common type of glaucoma, primary open-angle glaucoma, has no noticeable signs or symptoms except gradual vision loss.

Regular eye exams are the key to detecting glaucoma early enough for successful preventive treatment.

The term “glaucoma” refers to several eye diseases in which a blockage in the eye’s fluid drainage system causes fluid to back up, increasing the intraocular pressure (pressure within the eyeball). If the pressure stays too high for that eye, the optic nerve can be permanently injured. The optic nerve is like a telephone cable transmitting images from the eye to the brain. If it is damaged by pressure, blind areas develop in the visual field that can progress to partial or even total blindness.

Open-Angle Glaucoma

Open-angle glaucoma (OAG) is the most common type. It is particularly dangerous because there are no symptoms — no pain or other warning that you are losing vision — until it is too late.

OAG usually occurs after midlife and affects both eyes. Sometimes it runs in families. Glaucoma is not contagious and is not related to cancer. The high pressure in the eyes is not the same as high blood pressure.


Narrow Angle Glaucoma

The term “glaucoma” refers to several eye diseases in which a blockage in the eye’s drainage system causes fluid to back up, increasing the intraocular pressure (pressure within the eyeball). In narrow-angle glaucoma (NAG) — also called closed-angle or angle-closure glaucoma — the drainage space is cramped, so when the iris dilates (enlarging the pupil) it sometimes blocks the drainage channels, raising the pressure.

If the pressure rises suddenly, NAG is called “acute”; it is “chronic” if the attacks are milder and repetitive. Either type can cause damage to the optic nerve, the “cable” that transmits images from the eye to the brain. Permanent sight loss can occur in only a few hours (in an acute attack) or over many months or years (if the attacks are chronic).

NAG is much less common than open-angle glaucoma. It can occur in both eyes, though usually at different times and with different degrees of severity. Most patients are middle age or older.

Beta Blockers for the Treatment of Glaucoma

While there is no cure for glaucoma, it can be controlled.

Elevated intraocular pressure (IOP) may damage the optic nerve, which can lead to vision loss. Treatment for glaucoma focuses on lowering the IOP to a level that is less likely to cause further optic nerve damage. This is known as the “target pressure” or “goal pressure.”  The target pressure differs from individual to individual. Your target pressure may change during your course of treatment if the progression of glaucoma is not arrested.

If you have glaucoma, your ophthalmologist (Eye MD) may prescribe medication to lower your eye pressure. There are many more choices for topical treatment today than there were only a few years ago. Your ophthalmologist has chosen a beta blocker medication to treat your glaucoma:

How Do Beta Blockers Work?  Beta blocker (beta andrenergic antagonists) medications are reliable for lowering intraocular pressure. They work by decreasing the amount of fluid that the eye continually produces, called the aqueous humor. For many years, beta blockers were the mainstay of treatment.  Hence, we have a lot of experience with this medication for the treatment of glaucoma.

Types of Beta Blocker Medication There are two general classes of beta blockers: nonselective and selective. Nonselective beta blockers have more effects on the body’s beta receptors system-wide, and are associated with more side effects. The nonselective beta-blockers are also more effective at lowering intraocular pressure.

The nonselective beta blockers include:
• Levobunolol (Betagan)
• Timolol hemihydrate (Betimol)
• Carteolol (Ocupress)
• Metipranolol (Optipranolol)
• Timolol maleate (Timoptic) and Timolol maleate gel (Timoptic XE)

(Generic versions of Timolol are now available. Check with your ophthalmologist to make sure that a generic product is an acceptable alternative for you.)

The only available selective beta blocker medication is:
• Betaxolol (Betoptic-S)

While a selective beta blocker eyedrop has a better safety profile, especially in terms of breathing symptoms, it still must be used with caution in patients with asthma or emphysema. The eye pressure lowering effect is slightly less with selective beta blockers. There is only a minimal additive effect in terms of lowering eye pressure in patients already taking oral beta blockers and there is the risk of further additive side effects.  If you are already taking a beta blocker medication by mouth or if your primary care doctor newly prescribes a beta blocker, please notify your Eye MD.

Possible Side Effects of Beta Blockers All medications, including eyedrops, have not only benefits but may also have side effects. Some people taking beta blocker eyedrops may experience:
• Increased or worse asthma or emphysema
• Slow or irregular heartbeat and/or decreased response of heart rate to exercise
• Increased risk for heart failure
• Depression or change in sex drive (impotence)
• Headache or dizziness or weakness
• In diabetics, difficulty sensing blood sugar changes
• Eye irritation or allergy

Medication Tips For glaucoma medications to work, you must take them regularly and continuously as prescribed by your doctor.  With each new medication that your ophthalmologist prescribes, make sure you understand the following:
• The name of the medication
• How to take it
• How often to take it
• How to store it
• If you can take it with your other medications (make sure each of your doctors knows about all the different medications you take, including non-prescription medications)
• What the possible side effects may be
• What you should do if you experience side effects
• What you should do if you miss a dose

Alpha Agonists for the Treatment of Glaucoma

While there is no cure for glaucoma, it can be controlled.

Elevated intraocular pressure (IOP) may damage the optic nerve, which can lead to vision loss. Treatment for glaucoma focuses on lowering the IOP to a level that is less likely to cause further optic nerve damage. This is known as the “target pressure” or “goal pressure.” The target pressure differs from individual to individual. Your target pressure may change during your course of treatment.

If you have glaucoma, your ophthalmologist (Eye MD) may prescribe medication to lower your eye pressure. There are many more choices for topical treatment (eyedrops) today than there were only a few years ago. Your ophthalmologist has chosen an alpha agonist medication to treat your glaucoma.

How Do Alpha Agonists Work?
Alpha agonist medications are reliable for lowering the intraocular pressure. They work by decreasing the production of the fluid that the eye continually makes, called the aqueous humor.

What Are the Alpha Agonists?
There are two alpha agonist drugs:

• Brimonidine (Alphagan and Alphagan P)

Possible Side Effects of Alpha Agonists
All medications, including eyedrops, have not only benefits but may also have side effects. Some people taking alpha agonist eyedrops may experience:

• Dry mouth
• Ocular allergy with a red eye and/or red eyelids
• Headache, fatigue, irritability or sleep disorder
• Low or high blood pressure and possible slowing of heart rate (less than with beta blockers)
• Joint aches
• Upset stomach, nausea or constipation

For glaucoma medications to work, you must take them regularly and continuously as prescribed by your doctor.

Medication Tips
With each new medication that your ophthalmologist prescribes, make sure you understand the following:

• The name of the medication
• How to take it
• How often to take it
• How to store it
• If you can take it with your other medications (make sure each of your doctors knows about all the different medications you take, including non-prescription medications)
• What the possible side effects may be
• What you should do if you experience side effects
• What you should do if you miss a dose

Glaucoma: Primary Open Angle

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Glaucoma: Narrow Angle

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Glaucoma: Shunts

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