A number of medications are currently in use to treat glaucoma here in Atlanta. Your doctor may prescribe a combination of medications or change your prescription over time to reduce side effects or provide a more effective treatment. Typically medications are intended to reduce elevated intraocular pressure and prevent damage to the optic nerve.
Eye drops used in managing glaucoma decrease eye pressure by helping the eye’s fluid to drain better and/or decreasing the amount of fluid made by the eye. Drugs to treat glaucoma are classified by their active ingredient. These include: prostaglandin analogs, beta blockers, alpha agonists, and carbonic anhydrase inhibitors. Combination drugs are available for patients who require more than one type of medication.
Prostaglandin analogs work by increasing the outflow of intraocular fluid from the eye. They have few systemic side effects but are associated with changes to the eye itself, including change in iris color and growth of eyelashes. Depending on the individual, one brand of this type of medication may be more effective and produce fewer side effects. Prostaglandin analogs are taken as eye drops. They are effective at reducing intraocular pressure in people who have open-angle glaucoma.
In initial studies, between 5% and 15% of people who used this medication reported a gradual change in eye color, due to an increased amount of brown pigment in the iris of the treated eye. The change in eye color occurs slowly and may not be noticeable for several months to years. Other side effects can include stinging, blurred vision, eye redness, itching, and burning. These medications are relatively new to the market, and long term follow up of people who use them is not yet available.
Alpha agonists work to both decrease production of fluid and increase drainage. Alphagan P has a purite preservative that breaks down into natural tear components and may be more effective for people who have allergic reactions to preservatives in other eye drops. Alphagan is available in a generic form.
Side effects can include burning or stinging upon instillation of the eye drop, fatigue, headache, drowsiness, dry mouth and dry nose.
Beta blockers work by decreasing production of intraocular fluid. They are available in generic form and, therefore, are relatively inexpensive. Systemic side effects can be minimized by closing the eyes following application, which prevents the drug from entering the tear drainage duct and systemic circulation.
Side effects can include low blood pressure, reduced pulse rate, and fatigue. Beta blockers can also cause a shortness of breath in people who have a history of asthma or other respiratory disorders. Additionally, beta blockers can change cardiac activity by decreasing the amount of blood the heart pumps out, which may reduce the pulse rate and/or slow down the heart’s response rate during exercise. Rare side effects include reduced libido and depression.
These medications reduce eye pressure by increasing the drainage of intraocular fluid through the ulabecular meshwork. Cholinergics can be used alone or combined with other glaucoma medications. A combination of medications can help control how much fluid is produced in the eye and increase the amount of fluid that drains out of the eye.
Many people who use these medications complain of dim vision, especially at night or in darkened areas such as movie theaters. This is due to constriction of the pupil. Miotics increase drainage of intraocular fluid by making the pupil size smaller, thereby increasing the flow of intraocular fluid from the eye.
Combined medications can offer an alternative for patients who need more than one type of medication. In addition to the convenience of using one eyedrop bottle instead of two, there may also be a financial advantage, depending on your insurance plan. CombiganTM is a combination of beta blocker and alpha agonist. Cosopt® is a combination of beta blocker and carbonic anhydrase inhibitor.
Side effects of CombiganTM include the symptoms of beta blockers and alpha agonists. Side effects of Cosopt® include burning and/or stinging of the eyes and changes in sense of taste. Since these medications are new to the market, long term follow up of people using these medications is not yet available.
Carbonic anhydrase inhibitors (CAIs) reduce eye pressure by decreasing the production of intraocular fluid. These are available as eye drops and as pills.
Side effects of the pill form of these medications can include tingling or loss of strength of the hands and feet, upset stomach, mental fuzziness, memory problems, depression, kidney stones, and frequent urination. Since the eye drop form of this medication is relatively new, long-term studies are yet to be completed. Side effects of the eye drop include stinging, burning and other eye discomfort.
About two-thirds of all prescriptions filled are generic forms of brand-name drugs. Generic drugs work well for most patients, but there are differences compared to the brand name products.
Although there are strict government regulations for generics, glaucoma patients who change to a generic medication may notice differences in how the drops feel and how they work. It’s important to work together with your eye doctor to ensure that the generic medication is effective for you. When switching from a branded medication to a generic, or from one generic to another, there can be issues with the way the drug is absorbed into the body.
In general, the clinical effectiveness of generic medications is assumed to be similar to the branded product. Generics are required to contain the same active ingredient as the brand-name drug and to be identical in strength, dosage form (pill, tablet, capsule, eye drop, etc.), and the way the active ingredient is absorbed by the body. While inactive ingredients can and do often vary, they have been time and laboratory tested, and for most generic drugs, they are the same.