Vision Health: Conditions, Disorders & Treatments GLAUCOMA Glaucoma is a disease of the optic nerve, which transmits the images you see from the eye to the brain. The optic nerve is made up of many nerve fibers (like an electric cable with its numerous wires). Glaucoma damages nerve fibers, which can cause blind spots and vision loss. Glaucoma is related to the pressure inside the eye, known as the intraocular pressure (IOP). When the aqueous humor (a clear liquid that normally flows in and out of the eye) cannot drain properly, pressure builds up in the eye. The resulting increase in IOP can damage the optic nerve and lead to vision loss. Open-Angle Glaucoma The most common form of glaucoma is primary open-angle glaucoma, in which the aqueous fluid is blocked from flowing back out of the eye at a normal rate through a tiny drainage system. Most people who develop primary open-angle glaucoma notice no symptoms until their vision is impaired. Ocular hypertension is often a forerunner to actual open-angle glaucoma. When ocular pressure is above normal, the risk of developing glaucoma increases. Several risk factors will affect whether you will develop glaucoma, including the level of IOP (intraocular pressure), family history, and corneal thickness. If your risk is high, your eye surgeon may recommend treatment to lower your IOP to prevent future damage. Angle Closure Glaucoma In angle-closure glaucoma, the iris (the colored part of the eye) may drop over and completely close off the drainage angle, abruptly blocking the flow of aqueous fluid and leading to increased IOP or optic nerve damage. In acute angle-closure glaucoma there is a sudden increase in IOP (intraocular pressure) due to the buildup of aqueous fluid. This condition is considered an emergency because optic nerve damage and vision loss can occur within hours of the problem. Symptoms can include nausea, vomiting, seeing halos around lights, and eye pain. Even some people with normal IOP can experience vision loss from glaucoma. This condition is called normal-tension glaucoma.
In this type of glaucoma, the optic nerve is damaged even though the IOP is considered normal. Normaltension glaucoma is not well understood, but lowering IOP has been shown to slow progression of this form of glaucoma. Childhood glaucoma, which starts in infancy, childhood, or adolescence, is rare. Like primary open-angle glaucoma, there are few, if any, symptoms in the early stage. Blindness can result if it is left untreated. Like most types of glaucoma, childhood glaucoma may run in families. Your eye surgeon may tell you that you are at risk for glaucoma if you have one or more risk factors, including having an elevated IOP, a family history of glaucoma, certain optic nerve conditions, are of a particular ethnic background, or are of advanced age. Regular examinations with your eye MD are important if you are at risk for this condition. The goal of glaucoma treatment is to lower your eye pressure to prevent or slow further vision loss. Your eye surgeon will recommend treatment if the risk of vision loss is high enough to justify intervention. Treatment often consists of eyedrops but can include laser treatment or surgery to create a new drain in the eye. Glaucoma is a chronic disease that can be controlled but not cured. Ongoing monitoring (up to every three to six months, but more often annually) is needed to watch for changes. Ask your eye surgeon if you have any questions about glaucoma or your treatment. Glaucoma Testing Because it has no noticeable symptoms, glaucoma is a difficult disease to detect without regular, complete eye exams. During a glaucoma evaluation, your surgeon will perform the following tests: Tonometry Your Surgeon measures the pressure in your eyes (intraocular pressure, or IOP) using a technique called tonometry. Tonometry measures your IOP by determining how your cornea responds when an instrument (or sometimes a puff of air) presses on the surface of your eye. Eyedrops are usually used to numb the surface of your eye for this test. Gonioscopy For this test, Your Surgeon inspects your eye s drainage angle the area where fluid drains out of your eye. During gonioscopy, you sit in a chair facing the microscope used to look inside your eye. You will place your chin on a chin rest and your forehead against a support bar while looking straight ahead.
The goniolens is placed lightly on the front of your eye, and a narrow beam of light is directed into your eye while your doctor looks through the slit lamp at the drainage angle. Drops will be used to numb the eye before the test. Ophthalmoscopy With this test, your surgeon can evaluate whether or not there is any optic nerve damage by looking at the back of the eye (called the fundus). With ophthalmoscopy, your surgeon uses a powerfully magnified light that magnifies up to about 15 times. This type of ophthalmoscopy is most commonly done during a routine physical examination. Ophthalmoscopy allows a better view of the fundus, even if your natural lens is clouded by cataracts. Visual Field Test A visual field test (perimetry test), measures all areas of your eyesight, including your side, or peripheral, vision. A visual field test can help find certain patterns of vision loss and is a key way to check for glaucoma. It is very useful in finding early changes in vision caused by nerve damage from glaucoma. To take this painless test, you sit at a bowl-shaped instrument called a perimeter. While you stare at the center of the bowl, lights flash. Each time you see a flash you press a button. A computer records the location of each flash and whether you pressed the button when the light flashed in that location. At the end of the test, a printout shows if there are areas of your field of vision where you did not see the flashes of light. This test shows if you have any areas of vision loss. Loss of peripheral vision is often an early sign of glaucoma. Visual field testing is used together with the clinical exam and HRT testing to determine if you have glaucoma or if your glaucoma is worsening. Photography Sometimes photographs or other computerized images are taken of the optic nerve to inspect the nerve more closely for damage from elevated pressure in the eye. Optical Coherence Tomography (OCT) Optical coherence tomography (OCT) is a special scan used to study the anatomy of the retina and optic nerve in fine detail.
OCT testing requires dilation of the pupils but does not require a needle in the arm and does not involve touching the eye. A healthy retina is only ¼ of a millimeter thick, but it contains multiple layers of specialized cells. One layer converts light into nerve signals, another processes the nerve impulses, while another transmits these processed impulses to the brain where they are interpreted. OCT testing is like having an optical biopsy of the retina and optic nerve; it provides excellent visualization of these structures, and aids greatly in the diagnosis and treatment of glaucoma. Not every patient needs an OCT test. In Ontario, OCT testing is now covered by OHIP. Each of these evaluation tools is an important way to monitor your vision to help ensure that glaucoma does not rob you of your sight. Some of these tests will not be necessary for everyone. Your surgeon will discuss which tests are best for you. Some tests may need to be repeated on a regular basis to monitor any changes in your vision caused by glaucoma. Glaucoma Treatment While there is no cure for glaucoma, it can be controlled with proper management. Elevated intraocular pressure (IOP) can damage the optic nerve, which may 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. The target pressure differs from individual to individual. Your target pressure may change during your course of treatment. If you have glaucoma, your surgeon may prescribe a medication to lower your eye pressure. For glaucoma medications to work, you must take them regularly and 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 all of your doctors know about all the different medications you take, including nonprescription medications); what the possible side effects may be; what you should do if you experience side effects; and what you should do if you miss a dose.
There are several different medications available for the treatment of glaucoma including: 1) beta-blockers 2) prostaglandin analogues 3) alpha-agonists 4) carbonic anhydrase inhibitors 5) combined agents Beta-Blockers in the Treatment of Glaucoma How do beta blockers work? Beta-blocker (beta adrenergic antagonist) 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. Thus, we have a lot of experience with this medication for the treatment of glaucoma. Types of beta-blocker medications 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 IOP. The nonselective beta blockers include: levobunolol (Betagan, AKBeta) timolol (Timoptic) timolol gel (Timoptic XE) Generic versions of timolol and timolol gel are now available. Consult with your ophthalmologist to be sure that a generic product is an acceptable alternative for you. The only available selective beta-blocker medication is betaxolol (Betoptic, Betoptic S) Betaxolol is the generic form of Betoptic While a selective beta-blocker eyedrop has a better safety profile, especially in terms of respiratory 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 ophthalmologist. Possible side effects of beta blockers
All medications, including eyedrops, can have side effects. Some people taking beta-blocker eyedrops may experience: wheezing or difficulty breathing; slow or irregular heart beat or decreased response of heart rate to exercise; increased risk for heart failure; depression; impotence; headache, dizziness or weakness; in diabetics, difficulty sensing blood glucose changes; and eye irritation or allergy. Prostaglandin Analogs & Prostamides in the Treatment of Glaucoma How do prostaglandin analogs or prostamides work? Prostaglandin analogs and prostamides lower IOP by increasing the outflow of the aqueous humor, the fluid made continuously by the eye. All of these medications are taken once a day, except for Rescula, which is taken twice per day. What are the prostaglandin analog and prostamide medications? latanoprost (Xalatan) bimatoprost (Lumigan) travoprost (Travatan) Possible side effects of prostaglandin analogs or prostamides All medications, including eyedrops, can have side effects. Some people taking these eyedrops may experience: redness of the eye darkening of the iris (the colored part of the eye); this color change occurs slowly and may not be noticeable for months or even years; increased growth, thickness, and pigmentation of the eyelashes; eye irritation or itching; blurred vision; darkening of the eyelid skin; muscle aches (rare); and headaches (rare). Patients with a history of uveitis (inflammation in the eye), ocular herpes infection, or swelling in the retina (called cystoid macular edema) should use this medication with caution. If you have a history of any of these conditions, please discuss it with your doctor. Alpha-Agonists in the Treatment of 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 three alpha agonist drugs: apraclonidine (Iopidine); brimonidine (Alphagan, Alphagan P); and dipivefrin (Propine). A generic version of Alphagan called brimonidine is available. Possible side effects of alpha-agonists All medications, including eyedrops, can have side effects. Some people taking alpha-agonist eyedrops may experience: dry mouth; ocular allergy with a red eye or red eyelids (30% of patients); tiredness or fatigue; low or high blood pressure and possible slowing of heart rate (less than with beta blockers); blurred vision; sensitivity of the eyes to bright light; and headache. Carbonic Anhydrase Inhibitors (CAIs) in the Treatment of Glaucoma How do CAIs work? CAI medications are very reliable at lowering the intraocular pressure. They work by decreasing the production of the fluid that the eye continually makes, called the aqueous humor. What are CAI medications? Topical drugs: dorzolamide (Trusopt); and brinzolamide (Azopt). Oral medications: acetazolamide (Diamox, AK-Zol); acetazolamide sustained-release (Diamox Sequels); and methazolamide (Neptazane, GlaucTabs). Generic versions of the eyedrop formulations are not yet available. Possible side effects of CAIs All medications, including eyedrops, can have side effects. Some people taking topical carbonic anhydrase medications (eyedrops) experience: blurred vision bitter taste in the mouth dry eyes eye irritation or allergy with a red eye or red eyelids headache or dizziness upset stomach. The oral (pill) form of these medications has more side effects, including:
increased need to urinate; tingling sensation in fingers and toes; rarely, severe allergic reactions or blood disorders can occur; change in taste (especially with carbonated beverages); and unusual tiredness or weakness. WARNING These medications are sulfonamides. If you are allergic to sulfa antibiotics, the same types of adverse reactions can occur with carbonic anhydrase inhibitors. Also, rare adverse drug interactions have occurred in patients taking high doses of aspirin and carbonic anhydrase inhibitors. Combined Agents in the Treatment of Glaucoma Several eyedrops are available that combine the actions of two drugs from different categories. The reasoning behind the use of combined agents is that it is easier for patients to put just one drop in their eyes instead of two; it may also be healthier for the eye as less preservative is being applied. What are the combined medications? Combigan (Combines a beta-blocker and an alpha-agonist) Cosopt (Combines a beta-blocker and a CAI) DuoTrav (Combines a prostaglandin analog and a beta-blocker) Xalacom (Combines a prostaglandin analog and a beta-blocker) For glaucoma medications to work, you must take them regularly and continuously as prescribed by your doctor. Selective Laser Trabeculoplasty (SLT) in the Treatment of Glaucoma What is selective laser trabeculoplasty? Selective laser trabeculoplasty is a common laser procedure used to treat glaucoma. Glaucoma is an eye disease in which the optic nerve is damaged, usually by high pressure inside the eye. Eye pressure can become too high if you have a problem with the drainage of fluid from your eye. Damage to the optic nerve can cause a loss of vision. In this procedure, your surgeon uses a laser to create microscopic bursts of energy in the drainage pathways (the trabecular meshwork) in your eye. The burns open the drainage holes in the meshwork and allows fluid to drain better through them. The procedure can lower the pressure in your eye and help prevent more damage to the optic nerve and loss of vision. Your Surgeon may recommend this procedure after you have tried treating high pressure in your eye with eye drops or pills. These medicines may not be reducing your eye pressure enough, or they may be causing side effects.
As the laser is very selective in its application of energy, sometimes Your Surgeon may even recommend it before starting glaucoma drops. What happens during the procedure? This procedure is performed in your surgeon s office. Your surgeon uses eye drops to numb your eye and other drops are used to make the pupil small. A special contact lens is put on your eye to help direct the laser's high-energy beam of light at the trabecular meshwork in your eye. The laser makes about 50 evenly spaced burns over 180 degrees of the eye. You will see a few brief flashes of light and feel little, if any, discomfort. The procedure usually takes less than 10 minutes. You will be able to go home soon after it is done. Your surgeon will ask you to return to the office two hours after your laser treatment to check the eye pressure. You will also have a further appointment in approximately two weeks to have the other 180 degrees lasered. What happens after the procedure? Your vision will probably be blurred for a few hours, but then it should clear. You will not need to wear an eye patch. Your surgeon will ask you to use Voltaren eye drops four times a day for five days. If your vision does not clear within a day or if you feel any pain or discomfort, call your surgeon. If it is the evening or the weekend and you are having problems, you should go to emergency to be assessed. This procedure is usually successful. Several days or weeks after the procedure, the flow of fluid from your eye should improve. Improved flow usually reduces the pressure inside the eye. It can take 2 to 4 weeks, and sometimes longer, to learn the results. Most people do still need to take glaucoma drops after the procedure. The effects of this treatment may not last. In 50% of people it stops working in about 5 years. It can be repeated at that point. What are the risks? Although there are some risks with the laser treatment such as inflammation, bleeding inside the eye, and raised pressure in the eye, the risks are fewer risks than with other types of surgery. Problems may occur that could threaten your vision, but they are rare. If you have any questions about the risks of selective laser trabeculoplasty, ask your surgeon. Laser Peripheral Iridotomy in the Treatment of Glaucoma What is laser peripheral iridotomy? Laser peripheral iridotomy is a surgical procedure in which a laser is used to create an opening in the iris (the coloured part of the eye) so that fluid can leave the angle of the eye more easily.
It is performed for patients with narrow angles, or angles that look like they might be prone to closure. Narrow angles may predispose one to an episode of angle closure glaucoma, in which raised pressure in the eye can rapidly threaten vision and even cause blindness. What happens during the procedure? This procedure is performed in the out-patient department of your hospital or your doctor's office. Your surgeon uses eye drops to numb your eye and to make the pupil small. A special contact lens is put on your eye to help direct the laser's high-energy beam of light at the iris in your eye. The laser makes one or two holes in the iris. You will see a few brief flashes of light and feel little, if any, discomfort. The procedure usually takes less than 5 minutes. You will be able to go home soon after it is done. What are the risks? Although there are some risks with the laser treatment such as inflammation, bleeding inside the eye, and raised pressure in the eye, the risks are fewer risks than with other types of surgery. Problems may occur that could threaten your vision, but they are rare. If you have any questions about the risks of this laser treatment, ask your surgeon. What happens after the procedure? You will receive a prescription for a steroid drop from your surgeon after your surgery is completed. Take your usual glaucoma drops as well as the steroid drops four times a day for 5 days to the operated eye(s). Your surgeon will want to check you that afternoon to make sure that the laser iridotomies are still open and working properly. You will have an appointment at 12:45 pm the same day of your surgery to check the eye pressure. Your vision will probably be blurred for a short period, but then it should clear in an hour or two. You will not need to wear an eye patch. If your vision does not clear within a day or if you feel any pain or discomfort, call your surgeon. If it is the evening or the weekend and you are having problems, you should go to emergency to be assessed. Fortunately, this procedure is almost always successful. Glaucoma Surgery If you have glaucoma and medications and laser surgeries do not lower your eye pressure adequately, your eye surgeon may recommend you be evaluated by a glaucoma specialist to evaluate your suitability for a procedure called a trabeculectomy.
In this procedure, a tiny drainage hole is made in the sclera (the white part of the eye). The new drainage hole allows fluid to flow out of the eye into a filtering area called a bleb. The bleb is mostly hidden under the eyelid. When successful, the procedure will lower your intraocular pressure (IOP), minimizing the risk of vision loss from glaucoma. The surgery is performed in an operating room on an outpatient basis. Some of the risks and complications from trabeculectomy surgery include the following: failure to control intraocular pressure, with the need for another operation; infection; bleeding in the eye; swelling in the eye; irritation or discomfort in the eye; eye pressure that is too low; cataract (in cases where cataract has not already been removed); and decreased or lost vision. Using Antimetabolite Medicines with Glaucoma Surgery Certain medications, called antimetabolites, were originally developed to help treat some kinds of cancer. These same medications have also been found to be helpful when used with some types of glaucoma surgery. These medicines may be applied to the eye during or after the surgery to reduce the growth of scar tissue, a common cause of failure in glaucoma surgery. Mitomycin-C and 5-fluorouracil (5-FU) are the most commonly used antimetabolites for glaucoma surgery. When these antimetabolites are used with other medications that reduce inflammation, the success rate of surgery is greatly improved, especially for patients who are at high risk for excessive scarring. Your glaucoma specialist may consider using antimetabolite medicines with your glaucoma surgery if: you are having surgery on an eye that has been operated on before; you have inflammation in your eye (called uveitis); you have glaucoma due to new blood vessel formation within the eye; you are having glaucoma and cataract surgery at the same time; you are relatively young; you have more deeply pigmented skin; or your eyes are at risk for postoperative scarring. In addition to the usual complications of glaucoma surgery, other risks associated with using antimetabolites include: eye pressure that is too low; leaking incisions; slower healing of the cornea; blurred vision;
fluid in or behind the retina; thinning of the eye tissues; and infection. If your glaucoma specialist has decided to use antimetabolite medications, he or she will explain why they are recommended for you. While some people may experience side effects from medications or surgery, the risks associated with these side effects should be balanced against the greater risk of leaving glaucoma untreated and losing your vision. Information about eye conditions, disorders and treatments is presented courtesy of the Eye Physicians & Surgeons of Ontario.