Tests and Diagnosis
The simplest and most common test for glaucoma is an intraocular pressure reading, though increased IOP does not necessarily mean glaucoma is the cause, and no one test alone can be used to establish a diagnosis of glaucoma. To get an IOP reading, a doctor or technician typically touches the front of the eye with a small instrument called a tonometer. Many doctors will also do a dilated eye exam. The purpose of dilating the pupil is to look directly at the inside back of the eye to check for retinal and optic nerve damage. The doctor will probably take pictures and measurements to establish a baseline for comparing to future eye exams. A patient with glaucoma is also likely to have a visual field test to measure losses in peripheral vision and a visual acuity test to check for visual sharpness (acuity). The doctor may also use a technique called gonioscopy to study the angle of the drainage system and tonography to study the rate of fluid drainage.
Additional testing to establish a diagnosis of glaucoma often includes pachymetry (measures central cornea thickness), visual field testing, gonioscopy and possibly NFL scanning technology.
Acute closed angle glaucoma is a medical emergency that must be treated immediately. However, the more common type of glaucoma - open angle glaucoma - can be an insidious disease with no symptoms, even as serious damage is being done to your retina and optic disk. The best approach to glaucoma is regular eye check-ups to make sure IOP is not rising, and if it is, to take aggressive measures to lower IOP.
A combination of natural therapies and conventional treatments can be used. The goal for both conventional and natural therapies is to lower IOP as much as possible and slow or halt the progression of symptoms.
Medications for glaucoma work by decreasing production and/or increasing drainage of aqueous fluid. Most glaucoma medications are topical - that is, in the form of eye drops. Categories of glaucoma medications are alpha agonists, beta blockers, carbonic anhydrase inhibitors, and prostaglandin analogs. A doctor may recommend a combination of glaucoma medications.
Alpha agonists decrease fluid production and increase drainage. Two such drugs are apraclonidine HCl (Iopidine®) and brimonidine tartrate (Alphagan®). Dryness of mucous membranes is among the side effects caused by alpha antagonists.
Beta blockers decrease production of aqueous fluid. They include timolol maleate (Istalol®; Timoptic XE®), betaxolol (Betoptic®), levobunolol HCl (Betagan®), metipranolol (OptiPranolol®), and timolol hemihydrate (Betimol®). Side effects of beta blockers include lowering of blood pressure and decreased heart rate.
Carbonic anhydrase inhibitors work by decreasing aqueous fluid production. They include brinzolamide (Azopt™), dorzolamide HCl (Trusopt®), and acetazolamide (Diamox®; Sequels®). These are available in pill and eye drop form. Systemic carbonic anhydrase inhibitor therapy may cause kidney dysfunction.
Cholinergic medications lower IOP by constricting the pupil. This increases the volume of the eye's anterior chamber and improves access of aqueous fluid to the trabecular meshwork drainage system. Cholinergic medications are sometimes prescribed in combination with other glaucoma medications to help balance fluid production and drainage. Several cholinergic medications are pilocarpine HCl (Isopto® Carpine; Pilopine HS®) and carbachol (Isopto®Carbachol). Constriction of the pupil can cause poor night vision.
Some medications contain several active ingredients. One called Combigan™ is a beta blocker and alpha agonist. It combines brimonidine tartrate and timolol maleate. Another, Cosopt®, is a beta blocker and carbonic anhydrase inhibitor. It combines dorzolmide HCl and timolol maleate. Both decrease production of aqueous fluid. An advantage is that patients get the benefit of both types of compounds in a single eye drop. A downside is the risk of side effects unique to each medicine.
Prostaglandin analogs increase aqueous fluid drainage. Due to their ability to efficiently reduce IOP, prostaglandin analogs are becoming widely employed in clinical settings. Available medications are travaprost (Travatan®), bimatoprost (Lumigan®), and latanoprost (Xalatan®). Side effects of these compounds are a change in eye color and lengthening of eyelashes; the skin surrounding the eye may darken as well.
Most eye doctors in the United States start glaucoma treatment by prescribing a regimen of medicinal eye drops. As glaucoma progresses, patients are instructed to use higher doses or a combination of different types of eye drops. Surgery may be recommended for patients whose IOP is not responsive to medicines, whose glaucoma continues to worsen, or who experience uncomfortable side effects from glaucoma medications.
Laser surgery and filtering surgery are two common forms of surgery for POAG. Most are performed in a medical office or outpatient facility. The eye is temporarily numbed to keep the patient comfortable.
Laser surgery uses a high-energy laser beam to open obstructed trabecular drainage channels and to allow aqueous fluid to flow more freely from the anterior chamber of the eye. Many people who have this surgery, called laser trabeculoplasty, continue with glaucoma medication, although usually at a lower dose. Types of laser surgery for open angle glaucoma include argon laser trabeculoplasty (ALT) and selective laser trabeculoplasty (SLT). SLT is a newer and more selective procedure that targets individual cells of the trabecular meshwork.
Another laser treatment called laser cyclophotocoagulation works differently from ALT and SLT. Instead of increasing drainage, it reduces fluid production. It does so by destroying part of the ciliary body of the eye where aqueous fluid is formed.
For patients in whom laser surgery is not ideal, there is also filtering surgery. Here the eye surgeon manually makes a small opening in the white of the eye (sclera) and removes a small part of the trabecular meshwork and nearby structures. This procedure, called a trabeculectomy, gives the aqueous fluid an additional outflow route. The surgeon covers the scleral opening with a natural membrane to protect the inner eye and to capture the fluid against the sclera, where it is absorbed.
An alternative to natural drainage through the opening in a trabeculectomy is drainage through a surgically implanted valve. The valve allows aqueous fluid to bypass the trabecular meshwork altogether. Aqueous fluid drains through a small tube from the anterior chamber onto the outside surface of the eye. A drainage valve is sometimes used when a trabeculectomy fails. It can also be used for treating juvenile glaucoma or glaucoma that is caused by trauma or severe eye inflammation.
Some patients may be better candidates for one or the other type of treatment (trebeculectomy or ALT/SLT). For example, ALT is generally preferred for patients older than 50. Further, a major study, called the Advanced Glaucoma Intervention Study (AGIS), supported by the National Eye Institute of the National Institutes of Health, showed a difference in treatment outcomes based on race. Caucasians had better outcomes than African Americans when medical therapy was followed initially by trabeculectomy, for unknown reasons (AGIS  2001). Research comparing outcomes in Latinos and Caucasians showed no differences (Nguyen 2011).
Emergency glaucoma surgery for acute angle-closure glaucoma takes a different approach. A surgeon might create holes in the iris rather than the sclera. This treatment, performed using laser or conventional surgical techniques, rapidly decreases IOP by opening up the angle formed by the iris and drainage channels. Fortunately, the risk that a patient will develop angle-closure glaucoma is predictable based on the results of routine eye exams. Therefore, regular checkups can help avoid an acute angle closure crisis altogether because, upon detection of ocular anatomy favoring development of angle-closure glaucoma, a clinician can employ preventive procedures.
Nutrients for Glaucoma
The key with glaucoma is to detect increased IOP as soon as possible and immediately act to counter it, before stronger prescription drugs or invasive surgery become necessary. Researchers have recently discovered a pair of nutrients that target underlying mechanisms of glaucoma.
If clinical signs like increased IOP have already developed, but there are still no noticeable symptoms, it is even more important to act quickly to prevent disease progression. In this case, natural therapies, when combined with standard glaucoma medicines, may act synergistically to lower IOP; natural ingredients may also counteract the underlying damage caused by glaucoma.
French maritime pine bark and bilberry
Human studies have shown a powerful effect of French maritime pine bark and bilberry extract on the underlying symptoms of glaucoma. These two nutrients are rich in proanthocyanidins, powerful antioxidants known for their ability to neutralize harmful free radicals. Proanthocyanidins have also been shown to support cardiovascular health (Nishioka 2007).
In a 2010 study combining treatment with French maritime pine bark and bilberry with the traditional glaucoma drug Latanoprost - a prostaglandin analog that increases aqueous fluid drainage - researchers found a clear benefit of the combination treatment (Steigerwalt 2010).
Pine bark and bilberry may act on a molecular level to decrease the production of aqueous humor, improve blood vessels structure and function, and decrease the resistance to fluid drainage.
Latanoprost causes smooth muscle cells, such as those in blood vessels and the eyes, to relax or contract. However, in part due to risk of side effects associated with its use, latanoprost eye drops may not be ideal for people with elevated IOP without symptoms. By contrast, the natural intervention of French maritime pine bark and bilberry is not associated with the side effects of latanoprost, which include ocular cysts, swelling, and inflammation (ALM 2008).
In this encouraging study, researchers studied 79 patients who had elevated IOP but no signs of glaucoma. Patients were randomized to receive either (1) an oral nutrient compound containing standardized French maritime pine bark extract and a phenolic bilberry (Vaccinium myrtillus) extract, (2) standard medical therapy with latanoprost eye drops alone, or (3) the nutrient compound and latanoprost drops, for 24 weeks.
IOP improved in patients in all treatment groups. The most rapid drop in pressure (28%) was seen in the latanoprost-only group, beginning four weeks after treatment began. In group 1, significant improvement began at 6 weeks. IOP reduction was 24% at week 16 and was maintained throughout the study. The most exciting results, however, were in the group receiving latanoprost in combination with pine bark and bilberry, those receiving the combination therapy. Patients in this group showed a 28% reduction in pressure at 4 weeks. Their reduction soared to 40% at 24 weeks. These results show the natural intervention amplifying the effect of the conventional intervention.
Pine bark and bilberry are among the newest nutrients used to fight glaucoma, but research has long supported the use of antioxidants to counter the oxidative damage caused by glaucoma. Dietary antioxidants have been shown to protect retinal ganglion cells against damage. Antioxidants include glutathione, lutein, zeaxanthin, zinc, vitamin A, vitamin C, vitamin E, beta-carotene, bioflavonoids, EGCG from green tea, and curcumin, among others.
Laboratory studies show that antioxidant treatment helps mitigate risk factors for glaucoma (Zhou 1998). Research into epigallocatechin-gallate (EGCG), a powerful antioxidant found in green tea, for example, shows a potential impact on the physiology of retinal cells in patients with glaucoma (Falsini 2009). The researchers used electrical measurements of retinal activity to show the effect.
Most scientists agree that more research is needed to understand the role of antioxidants in preventing or treating glaucoma and to determine effects of different doses and combinations of antioxidants in food and food supplements. Vitamin C and bioflavonoids in combination, for example, are thought to preserve the structure and function of blood vessels, which may improve blood flow to the retina and optic nerve to prevent glaucoma or slow decline in vision.
Vitamin C is also used in the formation of collagen, which gives strength and structure to tissues in the body. In the eye, collagen helps maintain the integrity of blood vessels and the trabecular meshwork. A recent study found that vitamin C serum levels were significantly lower in normal-tension glaucoma patients than in healthy controls (Yuki 2010).
Vitamin A is necessary for the formation of rhodopsin, a pigmented compound in specialized retinal cells the retina which allow the eye to see in low light. The eyes are strong indicators of vitamin A deficiency, becoming dry, itchy, or inflamed, and experiencing night blindness when levels are insufficient (Zanon-Moreno 2011). Most anyone taking a multivitamin supplement will not be deficient in vitamin A.
Vitamin A can be obtained through food (green leafy vegetables, liver, kidney, egg yolks, butter, fortified dairy products, cold-liver oil, and orange-colored foods, for example) or supplemental beta-carotene. Beta carotene is a pro-vitamin of vitamin A. It is converted, as needed, into vitamin A in the liver or during intestinal absorption.
Gingko biloba extract has been studied as a neuroprotector of retinal ganglion cells in glaucoma due to its ability to open (dilate) blood vessels and its antioxidant effect. Along with oxidative stress and high IOP, blood vessel inadequacy has also been proposed as a contributor to glaucoma, especially in normal tension glaucoma.
Gingko biloba has been shown to increase blood volume and velocity of blood flow in the eyes of healthy people (Park 2011). In patients with normal tension glaucoma, studies show that it improves visual field loss (Park 2004; Kim 2004). These encouraging findings will hopefully lead to more research.
Coleus forskohlii is one of 200 varieties of the plant Coleus (Solenostemnon) found around the world. The therapeutic ingredient in Coleus forskohlii is found in its root, which was used originally in a paste form for treating a variety of disorders including cardiovascular conditions because of its vasodilating effect. In vitro studies show its significant antioxidant properties (Khatun 2011). In clinical studies involving both animals and humans, a special preparation of Coleus forskohlii, applied directly to the eye, was shown to reduce IOP by increasing intraocular circulation and decreasing aqueous humor inflow into the posterior cavity (Caprioli 1984; Hartman 1988). Benefits were observed about an hour after application and remained significant for at least 5 hours.
Coleus forskohlii has also been used in the treatment of hypothyroidism as well, a condition in which the thyroid gland underperforms. Interestingly, hypothyroidism is a proven risk factor for glaucoma (Cross 2008).
The value of minerals
Magnesium has long been recognized as nature's calcium balancer. Previous studies have demonstrated that calcium channel-blocking drugs offer benefits for some glaucoma patients. Armed with this revelation, researchers at the University Eye Clinic in Basel, Switzerland, evaluated the effect of supplemental magnesium on glaucoma patients. Magnesium (121.5 mg twice daily) was administered to 10 glaucoma patients for 1 month. At the conclusion of the study, results substantiated that magnesium supplementation improved the peripheral circulation, with an accompanying beneficial effect on the visual field in patients with glaucoma (Gaspar 1995).
Magnesium also has the ability to suppress the sympathetic nervous system. This is a reputation that earned magnesium credit in cardiology (Altura 1990), acting as an anti-adrenergic, meaning that it can block the “fight-or-flight” reaction, which causes the pupil to dilate and put added pressure on the drainage angle in the anterior chamber of the eye.
The trace mineral chromium has won credit beyond stabilization of blood glucose levels by improving focusing of the eye and lowering IOP (Head 2001). Selenium has also been associated with glaucoma (Bruhn 2009) and zinc with other vision disorders including age-related macular degeneration (National Eye Institute 2011).
Small amounts of the pineal hormone melatonin are synthesized in the retina of humans and most other animals. Melatonin is a powerful antioxidant that may help reduce oxidative damage in the eye. In studies of animals with induced glaucoma, researchers found that placing melatonin in the anterior chamber of the eye reversed the negative effect of ocular hypertension on retinal function and diminished the impact of ocular hypertension on retinal ganglion cells. These results indicate that melatonin could be a valuable resource for treating glaucoma (Belforte 2010).
Rutin, a bioflavonoid from the citrus family, has demonstrated the ability to lower IOP when used in conjunction with standard drugs. Moreover, experiments have revealed that orally ingested rutin is capable of reaching the eyes (Pescosolido 2010).