GLAUCOMA | DIAGNOSIS | TREATMENT

A condition in which there is progressive (gets worse with time, if untreated) damage of the optic nerves of the eyes. The damage of the optic nerves causes vision loss, usually the peripheral or side vision at first, but the straight ahead or central vision can eventually be damaged.

What causes glaucoma?
There was a time when the glaucoma was defined by increased eye pressure (intraocular pressure, not blood pressure), so that anything over 21 mm Hg (the unit of measure of pressure is millimeters of mercury, mm Hg) was considered abnormal. While eye pressure is still an important measure of glaucoma (for diagnosis and treatment), it is not the only factor. There are a significant number of patients affected by glaucoma, who do not have high eye pressures; some patients, in fact, have a condition called normal pressure (tension) glaucoma. Pressure may still be important in these normal-pressure glaucoma patients, but pressure-independent (non-pressure) factors may be relatively more important in this group (see below). The cut-off value of 21 mm Hg is no longer valid.

Traditionally, the pressure-dependent (high eye pressure) mechanisms by which the optic nerves are damaged in glaucoma was either mechanical or vascular. The mechanical theory states that increased eye pressure directly puts pressure on the optic nerve head to cause damage. The vascular or ischemic theory states that the increased eye pressure decreases blood flow to the optic nerves, indirectly damaging the nerves.

To explain why there are glaucoma patients with normal levels of intraocular pressure (normal-pressure glaucoma), the pressure-independent mechanisms of damage have been proposed.

While it is not exactly clear what initiates the damage in high-pressure or normal-pressure glaucoma, there are theories of what ultimately causes the death of the retinal ganglion cells (RGC) that make up the human optic nerve. Some of these point to toxic amino acids such as glutamate, interruption of chemicals that help nourish the RGC (neurotrophin starvation), defects in protective mechanisms (heat shock proteins), autoimmunity (one’s body attacking itself), and nitric oxide (NO) pathways of damage.
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What is the difference between open and narrow angle glaucoma?

Open angle glaucoma

Narrow angle glaucoma

Besides high-pressure and normal pressure glaucoma, the disease can also be classified as open or narrow angle (angle closure) glaucoma. The angle of the eye is the part of the eye located where the iris, the colored part of the eye, and the cornea, the clear dome of the eye, meet. It is in the angle that the trabecular meshwork is located; this is the sieve-like structure though which the aqueous fluid drains out of the eye. The human eye produces a watery fluid called aqueous humor, which provides nourishment to the internal parts of the eye. The fluid circulates throughout the anterior or front chamber of the eye, only to drain out of the eye through the trabecular meshwork. For patients who have open-angle glaucoma, the aqueous has easy access to the trabecular meshwork, but cannot drain out quickly enough, resulting in a build-up of fluid and therefore, pressure. For all purposes, there is resistance to fluid moving out through the trabecular meshwork. For patients who have narrow-angle glaucoma, there is very little space where the iris and cornea meet; the aqueous may have trouble getting into the angle itself, unable to drain out through the trabecular meshwork.

There are patients who have narrow angles, but no glaucoma. The angles are narrow but not enough to cause a problem with fluid drainage under most circumstances. These patients need to be followed carefully for changes in their condition. Some may go on to develop some form of narrow angle glaucoma.

There are many prescription and over-the-counter medications that may not be safe for patients who either have narrow angles or narrow angle glaucoma. Usually, these medications have labels that warn patients to ask their doctor if it’s safe to use these medications.
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GLAUCOMA DIAGNOSIS
Diagnosing glaucoma early in the disease process is extremely important. It is usually a silent disease; patients usually don’t feel anything or have a change in their vision, until the late stages when serious vision damage can occur. It is very important for high-risk patients to have a thorough exam. The ophthalmologist makes the diagnosis of glaucoma based on the following:

Intraocular or eye pressure
Appearance of the optic nerve heads (disks)
Visual field test
Gonioscopy
Corneal thickness
Other risk factors

Intraocular pressure
The eye pressure is typically measured with an applanation tonometer. The Goldmann applanation tonometer is currently the gold standard when it comes to measuring intraocular pressure. A yellow dye and anesthetic eyedrops are put into the eye. The tonometer makes light contact with the cornea to measure the intraocular pressure. No pain whatsoever is experienced with this test. The old-fashioned air puff test, the non-contact tonometer, is not as accurate as the Goldmann applanation tonometer. There was a time when an eye pressure of 21 mm Hg or less was considered normal. We now know that no single number applies to everyone. What may be acceptable in one person, may be unacceptable in another. In general, the worse the glaucoma, the lower the pressure required to decrease the risk of further damage.
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Appearance of Optic Nerve Head

Cup-to-disk ratio

Inferior Notch

End stage cup

Large cup

The ophthalmologist will look at the optic nerve head (disk) by dilating the eyes , and using a special magnifying lens held in front of the eye.One characteristic that is evaluated is the cup-to-disk ratio. The optic nerve head is a round and somewhat flat structure, with a center pit or cup. Imagine taking an ice cream scoop and scooping out the middle of the disk. The diameter or size of the cup, relative to the diameter or size of the disk as a whole, constitutes the cup-to-disk ratio. The average ratio is about 1/3 or 0.3. The cup-to-disk ratio is often increased in glaucoma patients. A larger cup can mean there is less nerve tissue, a sign of glaucoma. The optic disk should be imaged, either with stereo disk photos or one of the new scanning machines, or both. This allows the doctor to know what the nerve head looks like at one point in time. Any future pictures can be compared to the first one, to check for possible worsening of the disease. Some machines also allow measurement of the nerve fiber layer thickness, which can also be used to follow the disease.
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Visual field test

Normal Visual Field | Inferiorarcuate
Progressing	Progressing
Progressing

The visual field test allows the doctor to see whether there has been damage to a patient’s vision. While most people think about vision from the standpoint of the smallest line of letters they can see on an eye chart, there is also the matter of peripheral or side vision to consider. Glaucoma typically damages this peripheral vision first, which is why glaucoma patients may not even recognize a problem. It should be noted that a patient can have early glaucoma and a normal visual field test. It has been shown that a person has to lose at least 30-40% of the nerve fibers in an optic nerve, before anything shows up on the visual field test.

Visual Field Machine

Most ophthalmologists use an automated perimeter (visual field machine) which is computer based. The device looks like a big hollow ball which has been cut in half. A patient places his/her face into the open end of this bowl-shaped device. A computer generates tiny spots of light of different intensities, throughout the bowl. The patient clicks a handpiece whenever he/she sees a spot of light. In this way, the machine can map out a patient’s peripheral vision. It is a painless test but does require some degree of concentration. The newest versions of the machine can test one eye in less than 5 minutes, though the speed depends on a cooperative and responsive patient. There are newer visual field machines that use different strategies in an attempt to detect glaucoma at an earlier stage.
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Gonioscopy
Gonioscopy is the technique by which the angle of the eye is examined. The angle of the eye cannot be directly examined; mirrors are needed to visualize the angle. Gonioscopy is necessary to correctly classify and treat glaucoma, as some patients have open, and others, narrow angle glaucoma. A special contact lens is placed on the eye, after anesthetic eyedrops have been put into the eye. The exam is done in the office, and only takes a few minutes. It is a painless, diagnostic procedure. This procedure should be done from time to time, as the angle can change with age.
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Corneal thickness
The measurement of corneal thickness has arguably become a standard of care in the evaluation of potential and actual glaucoma patients. The cornea of the eye is the clear domed structure that forms the front of the eyeball. The cornea is a clear continuation of the white part of the eye (sclera) which arches over the iris or colored part of the eye. People who wear contact lenses, put their lenses on the surface of their corneas. The average human cornea has a thickness of about _ millimeter (there are about 25 millimeters in one inch). The Goldmann applanation tonometer operates under the assumption that the center of the cornea is 545 microns (a micron is 1/10th of a millimeter; 545 microns is 0.545 millimeter) thick. If a cornea has a central thickness (central corneal thickness, or CCT) more than than 545 microns, the pressure reading on the Goldmann tonometer has to adjusted downwards (cornea thicker than average means that the true pressure is lower than measured); if a cornea has a central thickness less than 545 microns, the pressure reading on the Goldmann tonometer has to be adjusted upwards (cornea thinner than average means that the true pressure is higher than measured). Even with a corneal thickness measurement, there is no universally accepted conversion table that allows one to convert the measured reading to the true reading, but the trend above holds. The corneal thickness can be measure either optically, with some form of light, or with sound.
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Ultrasound pachymeter

The ultrasound pachymeter measures corneal thickness using ultrasound, which cannot be heard by the human ear. The doctor puts an anesthetic eyedrop into the eye, and then uses a hand-held probe to lightly touch the eye. This is painless and takes just seconds. Some newer machines that measure intraocular pressure have been designed to take different corneal thicknesses into account; time will tell if these will become the new standard in measuring pressure. For now, the Goldmann tonometer is the standard.

Other risk factors
There are other risk factors which are considered in evaluating a patient for glaucoma. African-American ethnicity, older age, positive family history of glaucoma, systemic diseases such as diabetes and high blood pressure, and myopia or nearsightedness, are some of these risk factors.

The ophthalmologist looks at all of the above, in deciding whether someone has glaucoma. None of the tests individually are generally sufficient to make a definite diagnosis of glaucoma. Some patients will have increased intraocular pressures, suspicious appearing optic nerve heads, and abnormal visual fields; this is the typical high-pressure glaucoma. Others will have increased intraocular pressure but normal appearing optic nerve heads and visual fields; this is an example of ocular hypertension, high eye pressure without evidence of damage to the nerves. Over time, patients who have ocular hypertension may develop glaucoma damage, which is why this group needs to be followed over time. There are patients who have what would be considered normal intraocular pressures, abnormal-appearing optic nerve heads, and abnormal visual fields; these are examples of normal-tension (pressure) glaucoma. There are patients who have some abnormal finding, but not enough to cinch the diagnosis of glaucoma; these patients are termed glaucoma suspects, and like the ocular hypertensives, need to be carefully followed.

At least half of the types of glaucoma are thought to be inherited. A number of genes responsible for some glaucoma have been identified. A commercially available test, OcuGene, tests for mutations in one such gene, the TIGR/MYOC gene. A person with a particular mutation in the TIGR gene, the so-called mt.1 variant, may have as much as 20% worsening over 6-10 years, compared to 10% worsening in someone without the mutation. In other words, this test may be of help in identifying those glaucoma patients who should be followed and possibly treated more aggressively.
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GLAUCOMA TREATMENT
There are many surgical and medical options available for glaucoma treatment. Surgical treatment of glaucoma includes lasers and the more invasive surgeries done in the operating room. The type of surgical treatment used may depend on the type of glaucoma. Narrow angle glaucoma is generally initially treated with a particular laser treatment called Laser Iridotomy. Medications may also be necessary before and after laser iridotomy. Open angle glaucoma is generally treated initially with medications, though laser treatment is available as initial therapy. Below is a list of topics of interest regarding glaucoma treatment.

Eyedrops & Glaucoma Meds
Open Angle Surgical Treatment
Narrow Angle Surgical Treatment
Other Surgeries
Strategies for treating glaucoma
Things you should know about glaucoma

Eyedrops & Glaucoma Meds
Medical treatment generally consists of eyedrops which work by lowering the eye pressure. There are several different classes of glaucoma medications. They work to lower eye pressure through different mechanisms. Some decrease the production of aqueous fluid, others increase the rate at which the aqueous drains out of the eye, and still others work through both mechanisms.

Glaucoma meds

The so-called prostaglandin analogues and postamides have arguably become the first-line drugs in the treatment of glaucoma. These include Xalatan, Travatan, Lumigan, and Rescula. Currently, there are no generic equivalents. All of these eye drops are used once a day, typically at bedtime, except for Rescula, which is instilled twice a day. As with any medication, there are possible side-effects to consider when using any of these. As a class, these drugs can sometimes cause darkening of the colored part of the eye, the iris, as well as eyelashes. There have been documented cases of patients whose eyelashes grow longer and who grow more of them, and less commonly, darkening of the eyelid skin. These potential cosmetic changes should be considered especially when any of these drops are being considered for use in one eye only.

The beta blockers used to be considered first line therapy for glaucoma. These include Timoptic, Betoptic S, Betagan, Ocupress, and OptiPranolol. There are many generics for this class. These drops are generally used twice a day, and may come in different strengths or concentrations, usually 0.25 or 0.5%. Timoptic and the generic, timolol, also come in a once-a-day formulations, called Timoptic XE and timolol gel-forming solution (GFS), respectively. Possible side effects of the beta blockers include worsening of asthma and congestive heart failure, and interference with the heart rate. Diminished effect over time can occur with the beta blockers.

The alpha-2 agonists include Iopidine 0.5%, Alphagan P, and brimonidine. Alphagan P is an altered version of Alphagan, which is no longer available as a branded drug. There is, however, a generic version of Alphagan (not Alphagan P) called brimonidine 0.20%. Iopidine, Alphagan P, and brimonidine are used three times a day. Alphagan P and brimonidine can also be used twice a day, but their effectiveness may not adequately cover a full 24 hr. cycle. The alpha agonists can cause dryness of the mouth and drowsiness. There is a significant risk of allergy, as high as 12% with the generic brimonidine. Alphagan P is less likely to cause dry mouth, drowsiness, and allergy, when compared to brimonidine. Iopidine is not generally used for long-term glaucoma therapy because of side-effects. The sympathomimetics include Propine and its generic, dipivefrin. It is used twice a day.

The miotics include pilocarpine, which comes in 0.5, 1.0, 4.0, and 6%, and Pilopine HS Gel, which is an ointment-like medication that is instilled into an eye at bedtime only. A very strong miotic called phospholine iodide is used rarely. These medications cause the pupil of the eye to become smaller, which is why they are called miotics. Possible side-effects include decreased vision, because less light can enter an eye with a smaller pupil (especially in patients with cataracts), brow ache in younger patients (heaviness or headache above the eye), changes in an eye’s prescription (change in glasses prescription), and some evidence that they may increase the risk of retinal tears and detachment. The stronger ones may contribute to cataract formation.

The topical (eyedrop) carbonic anhydrase inhibitors include Azopt and Trusopt which are used three times a day, and sometimes twice a day if they are used with a beta-blocker. These medications can cause a metallic taste in the mouth; they are also sulfa based medications, so they may be contraindicated in patients who have sulfa allergies. There are no generics for Azopt and Trusopt. There are orally taken carbonic anhydrase inhibitors, Diamox (acetazolamide) and Neptazane (methazolamide) which were used as medications of last resort before the eyedrop versions became available; these orally-taken medications had more systemic side effects because of their non-local route of administration. Possible side-effects include tingling in fingers and toes, loss of energy and appetite, and abdominal discomfort. They are contraindicated in those who have a history of kidney stones.

There is a developing class of fixed combination drops, drops that contain more than one drug in one bottle. The benefits of fixed combination drops include convenience and higher likelihood that patients will use their medications consistently (it’s easier to use one drop that contains two drugs, than using two different eyedrops). They may also be easier on the pocketbook, as there is only one co-pay for those have a prescription benefit. One available fixed combination glaucoma medication is Cosopt. Cosopt contains both Timoptic, a beta blocker, and Trusopt, a topical carbonic anhydrase inhibitor. Cosopt is now available as a generic. Another fixed combination drop named Combigan, contains brimonidine 0.2% and timolol 0.5%.
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Open Angle Surgical Treatment

The standard laser treatment for the open-angle variety of glaucoma is called argon Laser Trabeculoplasty or ALT . At least 40% of the angle of the eye needs to be open, for this treatment to be considered. This procedure is done in the office-setting, user an argon laser. Lasers focus light of a single wavelength in a powerful fashion. ALT is performed after anesthetic eyedrops are put into the eye, which makes the laser treatment essentially painless. A special contact lens is placed onto the eye, and the laser is used to make tiny burns on the trabecular meshwork in the angle of the eye. Usually, 50 tiny burns are placed over 180 degrees of the angle. The procedure is considered safe, but there are possible risks including a postoperative increase in intraocular pressure (IOP spike). Such a spike in a patient with advanced glaucoma could cause further damage to vision. Hence, a patient who is treated with ALT usually has his or her pressure rechecked a short time after the treatment. Medications can be used to treat any IOP spike. If successful, the pressure lowering effect can last several years, and can be repeated if necessary. Another type of laser which produces light similar to that of the argon laser is called 532 nm diode laser. For all purposes, it produces the same pressure-lowering effect as the argon laser.

A newer laser procedure called selective Laser Trabeculoplasty or SLT is now available. There is no evidence that SLT is a better procedure than ALT. SLT appears to cause more inflammation than ALT; it may be of use in patients who do not respond to ALT.

In general, most patients who are diagnosed with open angle glaucoma are initially treated with glaucoma drops. If the medications don’t work or the patient cannot tolerate the medications, laser can be used. Having laser as the initial treatment is an option. The Glaucoma Laser Trial showed that initial ALT was better at lowering pressure than initial medical treatment (eyedrops). Getting a laser trabeculoplasty doesn’t necessarily eliminate the need to be on some eye medications.
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Narrow Angle Surgical Treatment

Prior Laser Iridotomy

Post Laser Iridotomy

The standard treatment of narrow-angle glaucoma is Laser Iridotomy , whereby a laser is used to make a tiny hole in the iris, the colored part of the eye. Either an argon laser (the same one that is used for ALT in treating patients with open angle glaucoma) or a YAG laser (and sometimes both) is used. Anesthetic eyedrops are put into the eye, and a special contact lens is placed onto the eye. A very tiny hole (not visible to the naked eye) is made in the iris. In general, there is little discomfort with the procedure,and few complications. As with some other laser procedures, there can be a temporary increase in the intraocular pressure, which should be monitored. Narrow-angle glaucoma patients who have a laser iridotomy may still need to be put on glaucoma drops, like patients with open-angle glaucoma, to control their intraocular pressure.
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Other Surgeries
The most invasive treatment of glaucoma involves having surgery in the operating room. This is sometimes necessary for both open and narrow angle varieties of glaucoma. The most practiced type of surgery is trabeculectomy. This involves creating a small hole or fistula in the wall of the eye, through which the aqueous fluid inside the eye can more easily drain out. This is usually done with local anesthesia, with sedation provided as necessary, so it is painless. If there is also a significant cataract, combined cataract and trabeculectomy surgery can be performed. Both trabeculectomy and the combined surgery can be done with or without the use of special chemicals (the antifibrotic agents, 5-fluorouracil and mitomycin C) which can help to decrease the scar formation that makes the glaucoma portion of the operations less likely to succeed. The lowest possible pressures are obtained with surgery, as compared to medicines and lasers, but there are more risks with this type of surgery. Surgery does not necessarily eliminate the need to be on glaucoma drops. In other words, even if surgery is successful, eyedrops may still be needed to keep the intraocular pressure at a safe level.

There are patients for whom traditional glaucoma surgery has a higher risk of failure, such as those who have had previous trabeculectomy or types of glaucoma resistant to that type of surgery. These patients may benefit from the use of the antifibrotic agents with the trabeculectomy. For high-risk patients, an alternative may be drainage implant or seton surgery. In this type of surgery, a tiny tube is placed in the eye so that the aqueous fluid drains out this tube in a controlled fashion.

A new type of invasive surgery called viscocanalostomy has recently emerged. It may also be called non-penetrating. It remains to be seen whether it is as effective as trabeculectomy.
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Strategies for treating glaucoma
At present, lowering of eye pressure is the core principle of glaucoma treatment. This even applies to patients with normal-pressure glaucoma. Remember, like high blood pressure, glaucoma can be treated but not cured. Glaucoma patients and patients at risk for glaucoma need to be followed on a long-term basis.

If a patient has ocular hypertension (higher than normal eye pressure but no evidence of glaucoma damage by visual fields or appearance of the optic nerve heads), lowering the eye pressure can prevent or delay the development of true glaucoma. If a patient has glaucoma, lowering eye pressure slows the rate at which glaucoma gets worse (progresses). The more advanced the glaucoma, the lower the pressure, the better. Once your doctor has recommended treatment, a specific target eye pressure or eye pressure range should be set (e.g. high teens, mid teens, or low teens). Most eye doctors consider a decrease in eye pressure of 25-35% a desirable target. The question of what to do first arises. Argon laser trabeculoplasty (ALT) as the initial treatment (before medications) is an option, but be aware that in one study, 75% of patients who have ALT as the first treatment, still need to be put on eyedrops. ALT as the initial therapy is reasonable if a patient cannot afford medications or compliance (not able to consistently use medication) is an issue. Quality-of-life arguments can be made in favor of initial laser treatment. If medical therapy is used, most doctors will generally start you on one of the prostaglandin analogues or prostamides, as they are very effective and convenient because of the once-a-day dosing. Travatan may be more effective in African-Americans than non-African-Americans. Alternatively, the beta blockers are sometimes used as first-line medications so long as a patient doesn’t have congestive heart failure, asthma, chronic obstructive pulmonary disease(COPD), or a heart rhythm problem (these contraindications are not absolute; your primary care medical doctor can help your eye care doctor in ruling out the use of these medications). They are convenient because of the availability of once-a-day formulations (Timoptic XE or Timolol GFS). The beta blockers are better at lowering eye pressure during waking hours than at sleep. There is evidence that preventing significant changes or fluctations in eye pressure is as important as the amount of pressure lowering. Therefore, beta blockers may not be as effective at controlling glaucoma for some patients. The prostaglandin analogues and prostamides tend to be better at consistently lowering pressure throughout the day and night.

Generally, after an eyedrop is started, the doctor will recheck the eye pressure one month later, as it takes some time for the drug to achieve its maximum effect. If the initial glaucoma eyedrop doesn’t lower the eye pressure significantly, it is discontinued. If the eyedrop does lower the eye pressure significantly, but doesn’t achieve the target pressure, another drop can be added to the first. The alpha agonists are good second-line medications, or if one of the prostaglandin analogues or prostamides was used initially, a beta blocker or Cosopt (the fixed combination drop) can be added. The topical carbonic anhydrase inhibitors and sympathomimetics are generally not used as first or second-line medications. The miotics and oral carbonic anhydrase inhibitors are medications of last resort. Sometimes, an eye doctor will do a “one-eyed” trial, in which medication is started in only one eye, to see if there is an effect, before it is used in both eyes (if the eye pressure in both eyes are usually similar, a lower pressure in the eye being treated means the medication is working).

The above are just guidelines. Patients may have certain eye findings that prevent the use of some of the medications and the order of treatment may be different. Quality of life issues may influence if and how medications are used. For patients who are at an age such that they are unlikely to suffer significant visual loss during their lifetime, aggressive treatment may be unnecessary. The results of some glaucoma studies may help guide your eye doctor in treatment strategies. For African-American patients who are already on maximally-tolerated medical therapy (all the eye medications that are effective and tolerated), argon laser trabeculoplasty may more effective than trabeculectomy as the next step in treatment.
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Things you should know about glaucoma
The eye pressure reading can change or fluctuate during the course of the day and night. The pressure during sleeping hours is generally higher than those while awake for normal individuals; the reverse is true for glaucoma patients---pressure during sleep is usually lower, but it is still higher than sleeping pressures for non-glaucoma patients. Typically, it is difficult to get pressure readings after work hours and impossible during sleeping hours. Your doctor should try to get pressure readings at different times of the day; reliance on pressure readings always obtained at the same time of day may be misleading. Pressure changes are greater in glaucoma patients than in non-glaucoma patients.

It is important that you not hold your breath when your eye pressure is being measured. Doing so may artificially increase the intraocular pressure. Wearing a tight shirt collar may have the same effect. The design of the machine (slit lamp) to which the glaucoma measuring device (Goldmann applanation tonometer) is attached, is such that women may have to compress their chests against the machine for the doctor to obtain good pressure readings. This can also artificially increase the eye pressure. Proper positioning may lessen this possibility.

The medical use of marijuana has been the subject of much interest. While marijuana does lower intraocular pressure, the effect is short-lived, usually about 3 hours. As a practical point, a person would have to smoke repeatedly during the course of the day and night, to get consistently low pressures, so much so, that he or she would be “high” most of the time. The currently available glaucoma drops are sufficient to make this alternative treatment unnecessary.

Exercise has been shown to decrease eye pressure. In one study, mild to moderate exercise decreased eye pressure by 10-20%. The pressure lowering effect lasts for a short time after exercise is completed, but with regular exercise, there can be a longer-term beneficial effect. In general, exercise is rarely enough to control eye pressure in glaucoma patients, mostly because patients fail to exercise regularly. Exercise guidelines can be found on-line at www.healthierus.gov. Thirty minutes of exercise, 3-4 times a week is a worthy goal.

When your doctor looks at your optic nerve heads (disks), dilation is typically recommended. Eyedrops that make the pupil larger are put into your eyes. While the disks can sometimes be seen without dilation, that is not always the case, and if photos or other imaging studies need to be done, a widely dilated pupil may be necessary to get good images. Dilated evaluations are generally necessary once a year. When your doctor evaluates your disks and the cup-to-disk ratios, it is important to note the general size of the disks. Please note that when I say the size of the disk, I am not referring to the cup-to-disk ratio. If a person has a larger than average disk, a larger cup may not indicate glaucoma. If, on the other hand, a person has a smaller than average disk, a small or even average cup-to-disk ratio may not rule out glaucoma. Another way of looking at this, is as follows: the amount of actual nerve tissue is represented by the part of the nerve head bounded by the outside edge of the disk, and the outside edge of the cup. Think of a donut as being the disk. The outside edge of the donut is the edge of the disk. The hole represents the cup or pit in the middle of the disk or nerve head. The good stuff is the donut itself. Using this analogy, if you have a large disk (or donut), even if you have a large cup (or hole), there is plenty of good nerve tissue (or donut to chew on). If you have a very small disk (or donut), even if the cup (or hole) is very small, there is very little nerve tissue (or donut to chew on). Having less than the normal amount of nerve tissue may be an indication of possible glaucoma.

When you get a visual field test, it is very important that it be done properly. While current machines are automated, that does not mean that you should do the test without supervision. A technician should be in the room with you at all times, to monitor your test taking. The usefullnes of the test is, in large part, dependent on having someone guide you through the test. Typically, a demonstration is given to a patient unfamiliar with this test, before the real test is administered. The technician can pause or stop the test at any time, to give you time to rest or regroup. Visual fields are usually done once a year, but it may be necessary to repeat testing if the visual fields have gotten worse, compared to previous ones. It is necessary to confirm such changes because there can be a great deal of variability from test to test that doesn’t indicate true worsening of glaucoma. The visual field is partly subjective in that the results depend on you quickly pushing a button when you see a light. If you have difficulty doing the test because you’re not feeling well or tired, the results may be abnormal. The visual field machines are “smart” because they can check to see if you are paying attention. The doctor can read these off the printed visual fields.

When using glaucoma eyedrops, a patient can use the technique of punctal occlusion to minimize absorption of medication into the bloodstream and more widespread or systemic side-effects. In this technique, after drops are instilled into the eyes, a patient places the pads of his or her index fingers against the bone at the sides of the bridge of the nose, just inside the inner corner of the eyes. When gentle pressure is placed in these locations, the tear drainage system (there is a drainage tube that leads from the corner of the eyelids to the nose; this is primarily how eyedrops can be absorbed into the bloodstream) is occluded. Keeping the eyes closed at the same time as punctal occlusion is being performed, will further reduce systemic side-effects. When using more than one glaucoma medication, it is important to wait at least 5 and ideally 10 minutes between eyedrops. In other words, if you use two different eyedrop medications, wait at least 5-10 minutes after putting in the first glaucoma drop, before putting in the second glaucoma medication.

Using eyedrops is difficult for many patients, especially those with arthritis or tremors. Some of the glaucoma drop manufacturers have designed special delivery systems that can help patients use these bottles. There are also more generic devices that can be adapted to different bottles, to make it easier to use eyedrop bottles. Ask your eye doctor about these delivery systems. Learning to instill eyedrops properly can minimize wastage and reduce the cost of medications.

Glaucoma medications can be very expensive, particularly if you do not have prescription coverage. It is important to shop different pharmacies, as the price of glaucoma drops can vary significantly. Instead of assuming your customary pharmacy has the lowest prices, it pays to visit or call other pharmacies for prices. Make sure you specify the medication, the strength, and the bottle size, when getting quotes.

Visiting Canada to get medications is an option. Unfortunately, many of the glaucoma medications are branded, and not available as generics, which are cheaper. The question of whether generics (if available) are as safe and effective as the branded medications is always asked. Brand drugs approved by the FDA require rigorous clinical testing. It is an expensive and time-consuming process. This is one of the reasons cited by drug manufacturers when they justify the high prices of their medications. Generics generally contain the same active and inactive ingredients as the brand names, but not always. Generic drugs do not require extensive testing, and when they are approved by the FDA, a waiver of in vivo bioequivalence is issued by the FDA. What that means is that the manufacturer of the generic drug does not have to prove the generic is as effective as the brand drug. Any equivalence in effectiveness is presumed, not proven with scientific studies. Whenever possible, therefore, getting the brand drug is preferable. To make sure that a pharmacy will not substitute a generic for a brand drug, ask your doctor to write “DAW” on the prescription; DAW means “dispense as written”.


Generic versus Brand Drugs

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