Open angle glaucoma

Related Terms

Acute angle closure glaucoma, ALT, aqueous humor, argon laser trabeculoplasty, caffeine, canal of Schlemm, cataract, closed-angle glaucoma, congenital glaucoma, cornea, corticosteroid, diabetes, fluoroscein, glaucoma drainage device, glaucoma filtration procedure, Goldmann applanation tonometry, gonioscopy, hypertension, hypothyroidism, ICE, intraocular pressure, IOP, irido-corneal-endothelial syndrome, iris, iritis, juvenile glaucoma, laser peripheral iridotomy, lens, medical marijuana, miotic, myopia, nearsightedness, neovascular glaucoma, neuroprotection, normal tension glaucoma, NTG, open angle glaucoma, ophthalmologist, ophthalmoscope, pacymetry, pediatric glaucoma, perimetry, PI, pigmentary glaucoma, primary glaucoma, pseudoexfoliation syndrome, retina, retinal detachment, retinal fibers, secondary glaucoma, shunt, tonometry, trabecular meshwork, trabeculectomy, transscleral cyclophotocoagulation, tumor, uveitis, vitreous humor.

Background

Glaucoma is the name given to a group of conditions caused by increased intraocular (inside the eye) pressure, or IOP, resulting either from a malformation or malfunction of the eye's drainage system. Left untreated, an elevated IOP may cause irreversible damage to the optic nerve and retinal fibers resulting in a progressive, permanent loss of vision. However, early detection and treatment can slow or even halt the progression of the disease.
Most individuals with glaucoma are not aware of problems with their vision. This is because the central vision (for reading and recognizing people) is only affected when glaucoma has advanced to a late stage. Even when central vision is still good, glaucoma may affect the vision needed for driving and other daily functions, including seeing steps or reading.
For most glaucoma sufferers, the main effect of the condition is the inconvenience of taking eye drops daily. Blindness from glaucoma is rare. If blindness does occur, it is usually because the glaucoma is already advanced when it is first diagnosed, because the eye pressure has not responded well to treatment, or because patients have not used their prescription eye drops regularly.
Healthcare professionals recommend that individuals at risk for glaucoma should get eye exams at least every two years. According to the National Eye Health Education Program (NEHEP), higher risk populations include African Americans over age 40, individuals over age 60 (especially Mexican Americans), and individuals with a family history of glaucoma. Inhaled steroids, such as beclomethasone (Beclovent?), fluticosone (Flovent?), and budesonide (Pulmicort?), may also increase the risk of developing glaucoma.
It is estimated that over three million Americans have glaucoma but only half of those know they have it. Approximately 120,000 are blind from glaucoma, accounting for 9-12% of all cases of blindness in the United States. About two percent of the population ages 40-50 years and eight percent over 70 years of age have elevated IOP.
Glaucoma is the second leading cause of blindness in the world, according to the World Health Organization (WHO). Glaucoma is the leading cause of blindness among African-Americans.
Estimates put the total number of suspected cases of glaucoma at around 65 million worldwide.
Without treatment, the loss of vision usually gets worse over the course of many months or several years. Loss of vision in glaucoma is permanent, but with early treatment, the damage to vision can be minimized. Early treatment can help protect the eyes against vision loss. Treatments usually include prescription eye drops and/or surgery. It's best to have routine eye checkups every two to four years after age 40 and every one to two years after age 65. Because African-Americans have a much higher risk of glaucoma, screening should begin every three to five years from age 20-29, and every two to four years after age 30.

Signs and symptoms

Glaucoma occurs in several types, and signs and symptoms vary depending on the type of glaucoma.
Open-angle glaucoma: Open-angle glaucoma progresses with few or no symptoms until the condition reaches an advanced stage. As increased intraocular pressure (IOP) continues to damage the optic nerve, the individual loses more and more of their peripheral vision. If glaucoma is left untreated, the individual can develop tunnel vision and eventually lose all sight. Open-angle glaucoma usually affects both eyes, although at first vision loss may occur in just one eye.
Acuteangle-closure glaucoma: Acute angle-closure glaucoma develops suddenly in response to a rapid rise in eye pressure. Permanent vision loss can occur within a day of the attack, so it requires immediate medical attention. An attack often happens in the evening or in a darkened room when the light is dim and the pupils have become relatively dilated. Pain may be severe. Signs and symptoms include blurred vision, halos around lights, reddening of the eye, severe eye pain, and nausea and vomiting.
Both open-angle and angle-closure glaucoma can be primary or secondary conditions. They are called primary when the cause is unknown and called secondary when the condition can be traced to a known cause, such as an injury or an eye disease. Signs and symptoms of secondary glaucoma vary and depend on the cause of the glaucoma.

Diagnosis

To establish a diagnosis of glaucoma, several factors must be present, including an elevated intraocular pressure (except in normal tension glaucoma), areas of vision loss, and damage to the optic nerve. In glaucoma, the optic disk shows visible signs of damage. The optic disk is the area where all of the nerve fibers come together at the back of the eye before exiting the eyeball. An optic disk that has been affected by glaucoma appears indented or excavated, as if someone scooped out part of the center of the disk. This condition is known as cupping. The normal contour and color of the disk may also be affected by the loss of nerve fibers.
Because glaucoma does not cause symptoms in most cases, those who are 40 or older should have an annual examination including a measurement of the intraocular pressure. If glaucoma is suspected, additional testing may be needed.
Tonometry: Tonometry is the measurement of intraocular pressure (IOP, or the pressure inside the eye) and can be carried out with several different instruments. In general, Goldmann applanation tonometry (with the blue light) is used in hospitals and non-contact (air puff) tonometry is used in optometric (optician and ophthamalogical) practices. Goldmann applanation tonometry involves the administration of local anesthetic drops (with a yellow dye called fluorescein) to allow the instrument to touch the front of the eye. The drops may sting, but the procedure itself is completely painless. It is generally considered to be the most accurate method of measuring the pressure. In non-contact tonometry, a puff of air is blown at the eye from the instrument. This does not require any form of anesthetic and is generally considered to be somewhat less accurate.
Ophthalmoscopy: The appearance of the optic disc can be examined by an ophthalmologist (eye doctor) using an ophthalmoscope (a special lighted instrument) or by the use of a slit lamp. An ophthalmoscope enables the doctor to look directly through the pupil to the back of the eye. This allows the examiner to assess the degree of cupping of the optic disc, check nerve fiber damage, and the health of the retina.
Perimetry: Perimetry is the technique of mapping out the blank or less sensitive areas in the field of vision, so that the presence of optic nerve damage can be assessed. The ophthalmologist or technician manipulates a small object on a wand at different locations in the visual field. The individual indicates whenever an object comes into view. By repeating this process over and over again, the individual's entire visual field can be mapped.
Pachymetry: Pacymetry uses an ultrasonic-wave instrument to gauge the thickness of each cornea. The thickness of the corneas is an important factor for accurately diagnosing glaucoma. If the individual has thick corneas, their eye pressure reading may seem high even though glaucoma is not present. Conversely, individuals with thin corneas can have low pressure readings, but have glaucoma. The eyes are anesthetized (numbed) for this test.
Other tests: To distinguish between open-angle glaucoma and angle-closure glaucoma, the ophthalmologist may use a technique called gonioscopy, in which a special lens with an angled mirror is placed on the eye to inspect the drainage angle. Another test, tonography, can measure how fast fluid drains through the trabecular meshwork.
Normal tension glaucoma: Individuals with normal tension glaucoma (NTG) do not have increased intraocular pressure (IOP). NTG is diagnosed by observing the optic nerve for signs of damage. This can be done using an ophthalmoscope and using the visual field test. This test produces a map of the patient's complete field of vision. Using this test, the doctor can check for any areas of sight loss that may be caused by damage to the optic nerve. The damage would appear as slight changes in the person's vision occurring anywhere from near the center to the edge of the field of vision. These changes are not necessarily noticeable to the patient.

Complications

Complications of glaucoma include decreased vision and even loss of vision.
Individuals with angle closure glaucoma may experience severe eye pain accompanied by nausea, blurred vision, rainbows or halos around lights, and a red eye.

Treatment

The treatment of glaucoma is aimed at reducing intraocular pressure (IOP) by improving aqueous humor outflow from the eye, reducing the production of aqueous humor, or both. These treatment goals are accomplished with eye drops, systemic (throughout the body) medications, laser treatment, surgery, or a combination of treatments.
If the doctor determines that the individual has elevated IOP, an excavated (a depression or pit) optic disk, and loss of visual field, the individual will likely be treated for glaucoma. If there is only slightly elevated eye pressure, an undamaged optic nerve, and no visual field loss, the individual may not need treatment. However, more frequent examinations to detect any future changes usually are necessary. If there are any signs of optic nerve damage and visual field loss, even if the eye pressure is in the normal range, the individual may need treatment to lower eye pressure further, which may help slow the progression of glaucoma.
Glaucoma cannot be cured and damage caused by the disease cannot be reversed. But with treatment, glaucoma can be controlled. Treatments can prevent or slow further damage.
Eye drops: The first line of treatment for most cases of glaucoma, except emergency situations, is medication in the form of eye drops. All anti-glaucoma drugs work to reduce intraocular pressure. Eye drops are frequently prescribed because they tend to have fewer side effects. Using eye drops as prescribed is very important. Some of the most common medications used include the following:
Adrenergic agents: Adrenergic agents reduce the amount of fluid in the eye by reducing the production of fluid and increasing the amount of fluid drainage. Allergic reactions, such as red, itchy, and watery eyes, frequently occur. Other side effects include increased heart rate and dry mouth. Examples include epinepherine (Adrenalin?) and dipivefrin (Propine?).
Alpha-adrenergic agents: Alpha agonists reduce aqueous humor production and increase the eye's fluid outflow. Side effects may include fatigue (extreme tiredness), dry mouth, a red eye, or red skin around the eye. Examples include apraclonidine (Lopidine?) and brimonidine (Alphagan?).
Beta-blockers: Beta-blockers work to lower the intraocular pressure by decreasing the rate at which fluid flows into the eye. Side effects may include a slow or irregular heartbeat, depression, impotence, and breathing problems for patients with asthma or emphysema. Examples include timolol (Timoptic?), levobunolol (Betagan?), and betatoxol (Betoptic?).
Carbonic anhydrase inhibitors: Carbonic anhydrase inhibitors reduce fluid flow into the eye. Side effects may include skin rash, red eye or irritation, nausea or upset stomach, altered taste (especially with carbonated beverages), weight loss, and fatigue (decreased energy). Examples include dorzolamide (Trusopt?) and brinzolamide (Azopt?).
Combinations of eye drops are available for patients who require more than one type of eye drop. Examples include Cosopt? (dorzolamide and timolol) and Xalacom? (latanoprost and timolol).
Miotics: Miotics, or cholinergic agents, help increase the rate of fluid drainage from the eye. Miotics constrict the pupil, helping to open blockages of aqueous humor flow. Side effects may include headache, blurred vision, and darkening of vision. Examples include pilocarpine (Pilocar?) and carbachol (Isopto Carbachol?).
Prostaglandin analogs: Prostaglandin analogs reduce pressure in the eye by increasing the outward flow of fluid from the eye. Side effects may include eye redness or irritation, a change in eye color (mostly in hazel or green eyes), increase in thickness and number of eyelashes, and joint aches or flu-like symptoms. Examples include latanoprost (Xalatan?), bimatoprost (Lumigan?), and travopros (Travatan?).
Combination medication: Timolol (a beta-blocker) and dorzolamide (a carbonic anhydrase inhibitor) are combined into one medication called Cosopt?. This product helps reduce the number of bottles needed and the number of times eye drops must be administered.
How to use eye drops: Proper application of eye drops is critical. Proper use of eye drops for glaucoma can improve the medicine's effectiveness and reduce the risk of side effects. Healthcare professionals recommend first washing the hands, then holding the bottle upside down and tilting the head back. Next, hold the bottle in one hand and place it as close as possible to the eye. With the other hand, pull down the lower eyelid, forming a pocket. Next, place the prescribed number of drops into the lower eyelid pocket. If more than one eye drop is being used, be sure to wait at least five minutes before applying the second eye drop. When instilling drops, it is important not to let the container touch the eye to prevent contamination leading to possible infection.
Close the eye or press the lower lid lightly with the finger for at least one minute. These steps keep the drops in the eye and help prevent the drops from draining into the tear duct, which can increase the risk of side effects due to systemic (throughout the body) absorption.
Oral medications: If eye drops alone do not bring the intraocular pressure (IOP) down to the desired level, oral medications may also be prescribed, including the carbonic anhydrase inhibitors acetazolamide (Diamox?). Taking these medications with meals may reduce side effects of nausea and vomiting. When the individual begins treatment with carbonic anydrase inhibitors, they may experience a frequent need to urinate and a tingling sensation in the fingers and toes. After several days, these symptoms usually disappear. Other possible side effects of carbonic anhydrase inhibitors include rashes, depression, fatigue, kidney stones, lethargy, stomach upset, a metallic taste in carbonated beverages, impotence, potassium loss, and weight loss. A doctor may tell the patient to eat bananas to help minimize the potassium loss that these medications can cause.
Laser peripheral iridotomy (PI): A laser peripheral iridotomy (PI) is performed almost exclusively in individuals with narrow angles, narrow angle glaucoma, or acute angle closure glaucoma. Laser peripheral iridotomy involves creating a tiny opening in the peripheral iris, allowing aqueous fluid to flow from behind the iris directly to the anterior chamber of the eye, causing a decrease in intraocular pressure (IOP). This typically results in resolution of the forwardly bowed iris and thereby an opening up of the angle of the eye. The PI procedure is usually completed in the office or as a brief outpatient procedure. Prior to the procedure, the pupil is often constricted with a miotic such as pilocarpine (Pilocar?). The procedure itself is completed with the patient seated at the laser, and requires no sedation. Usually, a lens is placed on the eye after topical anesthetic drops are applied to better control the laser beam. The entire procedure only takes a few minutes. The lens is then removed from the eye, and vision will quickly return to normal. After the procedure, the eye surgeon may recommend anti-inflammatory eye drop medications, including flurbiprofen sodium (Ocufen?), for a few days. A post-op visit will be scheduled.
Argon laser trabeculoplasty (ALT): Argon laser trabeculoplasty (ALT) is a procedure that has been proven to be efficient for different types of glaucoma. ALT seems to work best in patients with primary open angle glaucoma, pseudoexfoliation (exfoliation) syndrome, and pigmentary dispersion syndrome (pigmentary dispersion glaucoma). ALT is often recommended when medical therapy alone is insufficient in controlling pressure and the progression of glaucoma. However, it has recently been advocated by some as primary therapy in the treatment of glaucoma, especially for those individuals who have contraindications to glaucoma medications or, for any reason, are unable to use eye drops. In the ALT procedure, the eye surgeon directs a laser beam into the trabecular meshwork, which is the primary aqueous (fluid) drainage region of the eye. The trabecular meshwork is located in the angle of the eye, approximately where the cornea meets the iris. In most cases, 180 degrees of the trabecular meshwork is treated with laser spots, which typically require about 40-80 laser applications. The effect of the procedure is increased drainage of aqueous fluid out of the eye, thereby lowering the intraocular pressure. The ALT procedure can be completed as an out-patient procedure. The procedure is completed with the patient seated at the laser, with topical (eye drop) anesthesia, and a lens applied to the surface of the eye to allow delivery of laser applications into the trabecular meshwork. This procedure is typically painless or results in only minor discomfort. After the procedure, the patient is typically treated with anti-inflammatory eye drops for a few days, perhaps in association with their usual glaucoma medications. Vision is minimally, if at all, affected, even on the day of the procedure. There is generally no discomfort after the procedure. Most patients are scheduled for a return visit within a week to re-evaluate. In most cases, the pressure-lowering effect with an ALT will last three to five years. If the initial treatment is effective, a second ALT, in which the opposite half of the trabecular meshwork is treated, may be appropriate. The risks with an ALT procedure are rare, and when they do occur, are even more rarely serious. In general, the risks include post-operative inflammation, pressure spikes, and worsening of glaucoma. The latter complication is likely to be due to the underlying disease, and not the ALT procedure itself.
Glaucoma filtration procedure (trabeculectomy): When glaucoma continues to progress despite the use of medication regimens and possible laser treatments, a glaucoma filtration procedure (trabeculectomy) may be recommended. However, in some cases, a glaucoma filtration procedure may be recommended before other methods of treatment are attempted. This decision is based on the type of glaucoma, the degree that it has advanced, the general health of the patient, and the patient's ability to comply with treatment regimens. In a smaller proportion of patients, the glaucoma filtration procedure is combined with a cataract operation. The procedure is completed in the operating room, usually under local anesthesia. Some ophthalmologists will complete the procedure under topical (eye drop) anesthesia. On the day of surgery, the individual should expect to have several eye drop medications applied multiple times to the eye for approximately one hour prior to the procedure. Finally, the eye drop anesthetic or local anesthetic is applied just prior to the procedure. Once in the operating room, the eye will be "prepped" for surgery with sterilizing solutions. Usually, a semi-opaque sterile drape will be applied over the operative field, using a small instrument to hold the lids apart for the procedure. The eye should be entirely comfortable during the operation. The surgeon may recommend a mild sedative during the procedure, such as midazolam (Versed?), and this is usually determined on a case-by-case basis.
The goal of the glaucoma filtration procedure is to create a new passageway by which aqueous fluid inside the eye can escape, thereby lowering the IOP. The escape route, however, is not directly to the external surface of the eye, as this would obviously allow access for bacteria inside the eye and thus, potential infection. The filter, therefore, allows the drainage of fluid from inside the anterior chamber of the eye to a "pocket" created between the conjunctiva, which is the outermost covering of the eye, and the sclera, which is the underlying white anatomical structure of the eye. The fluid is eventually absorbed by blood vessels. In many cases, medication to control scarring, and thus to help prevent closure of the filtration site, is applied to the eye during the operation or just afterwards. These medications, including mitomycin C (Mutamycin?) and 5-fluorouracil (5-FU or Adrucil?), will be used in some cases and not others, depending on both surgeon and patient variables.
In most cases, a patch and shield will be placed over the eye on the day of surgery. This is usually removed later that day or the day after surgery and eye drop medications are begun. The surgeon will usually want to evaluate the eye on the day of surgery or on the first post-operative day. At that time, depending on pressure in the eye, the surgeon might elect to cut sutures on the flap of the filter to modulate the filtration process. This is often done with a laser while in the office. Antibiotic and anti-inflammatory eye drop medications are continued after surgery for up to six weeks or more. In some cases, the surgeon will apply additional medicines (such as 5-FU) to further prevent scarring and failure of the filter. The exact regimen will vary from one surgeon to another as well as surgical outcome variables. Cutting of sutures may be completed up to several weeks after surgery, again depending on the degree of filtration noted at each office visit. The number of visits to the doctor after surgery may vary widely depending on circumstances. In general, follow-up visits after filtration procedures are quite frequent, as often as every day or two shortly after surgery, with office visits decreasing in frequency as healing progresses. Eye drop medications for glaucoma are used after surgery for the first four to 10 weeks. After the filter site of the eye has entirely healed, the need for glaucoma medications will depend largely on the IOP as well as the peripheral vision (based on a visual field test). In most cases, dependence on glaucoma medication is reduced, and in some cases, glaucoma medications are no longer required. The eye surgeon will determine whether medicines are appropriate or not based on the final outcome with surgery.
The primary risks of trabeculectomy include, but are not limited to, infection, bleeding, swelling in the retina, choroidal detachment (development of fluid under the retina), retinal detachment, droopy eyelid, double vision, loss of vision, and even loss of the eye. The likelihood of these risks is quite low.
Glaucoma drainage device (tube shunt): Glaucoma drainage devices, also known as tube shunts, are implanted devices that are designed to maintain an artificial drainage pathway for patients with glaucoma. This procedure is often chosen for patients at high risk of failure with a traditional glaucoma filter procedure (trabeculectomy). Such patients might include those with neovascular glaucoma, glaucoma associated with uveitis (inflammation of the uvea), prior history of failure with a filter procedure, and any patient with glaucoma less than 30 years of age. All of these patients are at significant risk for failure of a routine glaucoma filter procedure due to greater inflammation and fibrosis (scarring), which might close off the drainage canal.
Prior to surgery, the ophthalmologist may have the individual take eye drop medications, including antibiotics and anti-inflammatory eye drops, to prepare the eye for surgery. These may be begun on the day of surgery, or even up to three days prior to surgery. Just prior to surgery, local anesthesia will typically be given to numb the eye for surgery. In young children, the procedure must be performed under general anesthesia. The eye will be prepped in the operating room and sterile drapes placed to maintain a sterile field. An operating microscope will be moved into place. The surgeon will place a small instrument to hold the lids apart during the surgery. A small incision is made in the conjunctiva, usually towards the top of the eye. However, the surgery may be performed in other areas of the eye. The surgeon will then make a tiny incision in the sclera of the eye and will fashion an opening for the drainage implant device. The drainage tube will be placed such that the opening of the tiny tube is inside the anterior chamber of the eye where it is bathed in aqueous fluid. The tube is sutured in place with the drainage device attached to the sclera of the eye. Most surgeons will place an absorbable suture around the tube at the time of surgery to prevent filtration through the device until a fibrous capsule has formed. As such, the device is not expected to function until about three to eight weeks following the procedure. This technique is thought to prevent over-filtration. Once the tube shunt is securely sutured into the desired position, the conjunctiva over the device is closed with tiny sutures, which are considerably finer than human hair.
The individual will be prescribed antibiotic eye drops, anti-inflammatory eye drops, and probably glaucoma eye drops following the procedure. The individual may expect to use these additional medicines for up to two to three months after surgery to help prevent infection and control inflammation. The individual will likely be able to return to most activities within a day or two after surgery. The eye may feel scratchy or have a foreign body sensation. This should usually resolve in the first one to two weeks. The efficacy of the tube shunt implantation usually will not be known until at least eight to 12 weeks after surgery or more. At that time, a new baseline level of pressure within the eye will usually be established. The risks of this procedure include, but are not limited to, over-filtration (pressure too low in the eye), under-filtration (pressure remains too high in the eye), infection, bleeding, swelling of the retina, choroidal detachment (fluid under the retina), droopy eyelid, double vision, loss of vision, and even loss of the eye.
Transscleral cyclophotocoagulation: Transscleral cyclophotocoagulation is a procedure for glaucoma that is performed on an outpatient basis. In this procedure, the ciliary body of the eye, which creates aqueous fluid, is treated with laser to decrease production of aqueous. This in turn reduces pressure inside the eye. The cyclophotocoagulation procedure is usually performed with local anesthesia. About 20-40 laser delivery applications are completed. After the procedure, the patient is usually started on both dilating and anti-inflammatory eye drop medications and perhaps oral anti-inflammatory medications as well. Cyclophotocoagulation is most often employed when other means of glaucoma treatment have failed to properly control high pressures. Many patients will require more than a single treatment. The procedure appears to have significant success and relatively low risk.
Neuroprotection: Investigational trials are underway for an experimental procedure called neuroprotection. Neuroprotection, or nerve protection, can be used to protect against nerve cell death in the eyes, thereby reducing IOP. Several approaches to neuroprotection in glaucoma are being evaluated, including use of betaxolol (Betoptic?) and brimonidine (Alphagan?).
Medical marijuana: Although studies in the early 1970s showed that marijuana, when smoked, lowers intraocular pressure (IOP) in people with normal pressure and those with glaucoma, medical marijuana for glaucoma remains controversial. Nine states have laws that allow for the legal use of medical marijuana for glaucoma and acquired immunodeficiency syndrome (AIDS). However, most medical professionals, including the American Academy of Ophthalmology and the American Medical Association (AMA), say that marijuana's side effects (increased heart rate, impaired immune response, addictiveness, poor pregnancy outcomes, emphysema-like lung changes, higher cancer risk, and legal issues) do not justify its use in lowering IOP.

Integrative therapies

Good scientific evidence:
Coleus: Multiple, small, randomized controlled trials and a case series suggest that a compound found in coleus (Coleus forskohlii), called forskolin, improves glaucoma. Forskolin has reduced intraocular pressure (IOP) in low-quality laboratory studies and studies in humans. Studies use an intraocular (into the eye) suspension of forskolin, not available as a dietary supplement in the United States. Studies are needed with standardized extracts of coleus to establish safety and efficacy of coleus supplements in glaucoma.
Caution is advised when taking coleus supplements, as numerous adverse effects are possible. Coleus supplements may decrease blood pressure and should not be taken along with hypotensive (blood pressure lowering) medications or those with hypotension (low blood pressure). Forskolin may stimulate thyroid hormone production, so coleus should not be used in individuals taking medications for thyroid conditions or individuals with thyroid disorders. Coleus should not be used if pregnant or breastfeeding, unless otherwise directed by a doctor.
Unclear or conflicting scientific evidence:
Alpha-lipoic acid: There are some human studies of alpha-lipoic acid (ALA) as a treatment for glaucoma, but there is not enough scientific evidence to make a recommendation at this time.
Avoid if allergic to ALA. Use cautiously with diabetes and thyroid diseases. Avoid with thiamine deficiency or alcoholism. Avoid if pregnant or breastfeeding.
Berberine: Preliminary study indicates that berberine does not appear to reduce intraocular pressure in patients with glaucoma. The safety and effectiveness of berberine for this indication remains unclear. Additional study is needed in this area.
Avoid if allergic or hypersensitive to berberine, to plants that contain berberine such as Hydrastis canadensis (goldenseal), Coptis chinensis (coptis or goldenthread), Berberis aquifolium (Oregon grape), Berberis vulgaris (barberry), and Berberis aristata (tree turmeric), or to members of the Berberidaceae family. Avoid in newborns due to a potential for increase in free bilirubin, jaundice, and development of kernicterus. Use cautiously with cardiovascular disease, gastrointestinal disorders, hematologic disorders, leucopenia, kidney disease, liver disease, respiratory disorders, cancer, hypertyraminemia, diabetes, or hypotension. Use cautiously in children due to lack of safety information. Use cautiously in individuals with high exposure to sunlight or artificial light. Use cautiously for longer than eight weeks due to theoretical changes in bacterial gut flora. Use cautiously if taking anticoagulants, antihypertensives, sedatives, anti-inflammatories, medications metabolized by CYP P450 3A4 including cyclosporin, or any prescription medications. Avoid if pregnant or breastfeeding.
Beta-carotene: Beta-carotene is a member of the carotenoids, which are highly pigmented (red, orange, yellow), fat-soluble compounds naturally present in many fruits, grains, oils, and vegetables (green plants, carrots, sweet potatoes, squash, spinach, apricots, and green peppers). Study results of beta-carotene supplementation for cataract prevention are conflicting. Further well-designed clinical trials are needed before a conclusion can be drawn.
Supplemental beta-carotene may increase the risk of lung cancer, prostate cancer, intracerebral hemorrhage, and cardiovascular and total mortality in people who smoke cigarettes or have a history of high-level exposure to asbestos. Beta-carotene from foods does not seem to have this effect. In those who smoke, beta-carotene may increase cardiovascular death, including heart attack. Avoid if sensitive to beta-carotene, vitamin A, or any other ingredients in beta-carotene products.
Bilberry: Bilberry (Vaccinium myrtillus) is a close relative of the blueberry. Bilberry extract or products containing bilberry may reduce the risk for developing glaucoma or may help prevent cataracts from worsening. At this time, there is limited scientific information in this area.
Bilberry may increase bleeding in sensitive individuals, such as those taking blood thinning medications including warfarin (Coumadin?) and aspirin. Avoid if allergic to plants in the Ericaceae family or to anthocyanosides (a component of bilberry). Avoid with a history of low blood pressure, heart disease, bleeding, diabetes, blood clots, or stroke. Avoid if pregnant or breastfeeding. Stop use before surgeries/dental or diagnostic procedures involving blood tests.
Danshen: Danshen, or salvia (Salvia miltiorrhiza), has been proposed as a possible therapy for glaucoma, but further studies are needed in humans before a clear conclusion can be drawn. A human clinical trial found danshen (with and without other Chinese herbs) improved vision in individuals with glaucoma. Danshen should not be used in place of more proven therapies and patients with glaucoma should be evaluated by a qualified eye care specialist.
Avoid if allergic or hypersensitive to danshen. Use cautiously with altered immune states, arrhythmia, compromised liver function, or a history of glaucoma, stroke, or ulcers. Stop use two weeks before surgery/dental/diagnostic procedures with bleeding risk, and do not use immediately after these procedures. Use cautiously if driving or operating heavy machinery. Avoid if taking blood thinners (anticoagulants), digoxin, or hypotensives including ACE inhibitors such as captopril, or Sophora subprostrata root or herba serissae. Avoid with bleeding disorders, low blood pressure, and following cerebal ischemia. Avoid if pregnant or breastfeeding.
Ginkgo: Ginkgo (Ginkgo biloba) has been used in several clinical studies for the treatment of glaucoma. Ginkgo seems to improve retinal blood flow in the eye, decreasing damage to the retina.
Ginkgo may cause an increase in bleeding in sensitive individuals, including those taking blood-thinning drugs, such as warfarin (Coumadin?), or those with bleeding disorders. Avoid if allergic or hypersensitive to members of the Ginkgoaceaefamily. If allergic to mango rind, sumac, poison ivy or oak or cashews, then allergy to ginkgo is possible. Ginkgo should be stopped two weeks before surgical procedures. Ginkgo seeds are dangerous and should be avoided. Skin irritation and itching may also occur due to ginkgo allergies. Avoid supplemental doses if pregnant or breastfeeding.
Kinetin: Kinetin is a chemical analogue of cytokinins, a class of plant hormones that promotes cell division. Kinetin is found in both plants and animals. The use of kinetin may reduce adverse effects associated with cataract surgery. More research is needed in this area.
Avoid if allergic or hypersensitive to kinetin. Use cautiously with coagulation or hematologic (blood) disorders or taking anticoagulants or antiplatelets (blood thinners). Avoid if pregnant or breastfeeding.
Kudzu: In China, the main herb-derived eye drops for glaucoma are pueraria flavonoids (compounds found in kudzu). The addition of puerarin to conventional drugs for glaucoma has yielded favorable results. Additional research is needed to confirm these results.
Use caution with anticoagulants/anti-platelet and blood pressure lowering agents, hormones, antiarrhythmics, benzodiazepines, bisphosphonates, diabetes medications, drugs that are metabolized by the liver's cytochrome P450 enzymes, mecamylamine, neurologic agents, and methotrexate. Well designed studies on the long-term effects of kudzu are currently unavailable. Avoid if allergic or hypersensitive to Pueraria lobata or members of the Fabaceae/Leguminosae family. Avoid if pregnant or breastfeeding.
Lutein: Lutein and zeaxanthin are found in high levels in foods such as green vegetables, egg yolk, kiwi fruit, grapes, orange juice, zucchini, squash, and corn. For some commercially available supplements, lutein is extracted from marigold petals. Human study has not found a benefit of lutein supplementation on visual performance in people with cataracts. More research is required to make a conclusion.
Avoid if allergic or hypersensitive to lutein or zeaxanthin. Use cautiously if at risk for cardiovascular disease or cancer. Avoid if pregnant or breastfeeding.
Melatonin: Melatonin is a neurohormone (brain hormone) produced by the pineal gland from the amino acid tryptophan. Melatonin synthesis also occurs in the retina of most animals as well as in humans. The synthesis and release of melatonin are stimulated by darkness and suppressed by light, suggesting the involvement of melatonin in circadian rhythm and regulation of diverse body functions. Levels of melatonin in the blood are highest prior to bedtime. It has been theorized that due to effects on photoreceptor renewal in the eye, high doses of melatonin may increase intraocular pressure and the risk of glaucoma, age-related maculopathy and myopia, or retinal damage. However, there is preliminary clinical evidence that melatonin supplementation may actually decrease intraocular pressure in the eye and it has been suggested as a possible therapy for glaucoma. Additional study is necessary in this area. Patients with glaucoma taking melatonin should be monitored by a healthcare professional.
Based on available studies and clinical use, melatonin is generally regarded as safe in recommended doses for short-term use. However, case reports raise concerns about risks of blood clotting abnormalities (particularly in patients taking warfarin), increased risk of seizure, and disorientation with overdose. Melatonin supplementation should be avoided in women who are pregnant or attempting to become pregnant, based on possible hormonal effects, including alterations of pituitary-ovarian function and potential inhibition of ovulation or uterine contractions. High levels of melatonin during pregnancy may increase the risk of developmental disorders.
Riboflavin (vitamin B2): Riboflavin is a water-soluble vitamin that is involved in vital metabolic processes in the body, and is necessary for normal cell function, growth, and energy production. Small amounts of riboflavin are present in most animal and plant tissues. It has been suggested that low riboflavin levels may be a risk factor for developing cataracts, or that riboflavin supplementation may be beneficial for prevention of cataracts. Additional evidence is needed before a clear conclusion can be drawn.
Avoid if allergic or hypersensitive to riboflavin. Since the amount of riboflavin a human can absorb is limited, riboflavin is generally considered safe. Riboflavin is generally regarded as safe during pregnancy and breastfeeding. The U.S. Recommended Daily Allowance (RDA) for riboflavin in pregnant women is higher than for non-pregnant women, and is 1.4 milligrams daily (1.6 milligrams for breastfeeding women).
Thiamin: Thiamin, also known as thiamine and vitamin B1, is a water-soluble B-complex vitamin. Preliminary evidence suggests that high dietary thiamin intake may be associated with a decreased risk of cataracts. Further evidence is necessary before a firm conclusion can be reached concerning the use of thiamin for cataract prevention.
Thiamin is generally considered safe and relatively nontoxic. Avoid if allergic or hypersensitive to thiamin. Rare hypersensitivity/allergic reactions have occurred with thiamin supplementation. Skin irritation, burning, or itching may rarely occur at injection sites. Large doses may cause drowsiness or muscle relaxation. Thiamin appears safe if pregnant or breastfeeding. Use cautiously if pregnant or breastfeeding.
Thymus extract: Well-designed clinical trials are required before thymus extract can be recommended in the treatment of glaucoma.
Avoid if allergic or hypersensitive to thymus extracts. Use bovine thymus extract supplements cautiously due to potential for exposure to the virus that causes "mad cow disease." Avoid use with an organ transplant or other forms of allografts or xenografts. Avoid if receiving immunosuppressive therapy, with thymic tumors, myasthenia gravis (neuromuscular disorder), untreated hypothyroidism, or if taking hormonal therapy. Avoid if pregnant or breastfeeding; thymic extract increases human sperm motility and progression.
Vitamin A: Vitamin A is a fat-soluble vitamin derived from preformed retinoids and provitamin carotenoids. Retinoids such as retinal and retinoic acid are found in animal sources such as liver, kidney, eggs, and dairy produce. Carotenoids like beta-carotene (which has the highest vitamin A activity) are found in plants such as dark or yellow vegetables and carrots. Vitamin A has been suggested to prevent cataract formation. Carotenoids such as beta-carotene, lutein, and zeaxanthin may decrease the risk of severe cataracts. There is currently insufficient evidence to form a clear conclusion at this time regarding the use of vitamin A for cataract prevention.
Avoid if allergic or hypersensitive to vitamin A. Vitamin A toxicity can occur if taken at high dosages. Use cautiously with liver disease or alcoholism. Smokers who consume alcohol and beta-carotene may be at an increased risk for lung cancer or heart disease. Vitamin A appears safe in pregnant women if taken at recommended doses; however, vitamin A excess, as well as deficiency, has been associated with birth defects. Excessive doses of vitamin A have been associated with central nervous system malformations. Use cautiously if breastfeeding because the benefits or dangers to nursing infants are not clearly established.
Vitamin E: Vitamin E is a fat-soluble vitamin with antioxidant properties. There is conflicting evidence regarding the use of vitamin E to prevent cataracts. Although some studies across populations have suggested some effects for cataract prevention (which may take up to 10 years to yield benefits), other studies in humans report a lack of benefits when Vitamin E is used either alone or in combination with other antioxidants. Additional research is necessary before a clear conclusion can be reached.
Avoid if allergic or hypersensitive to vitamin E. Avoid with retinitis pigmentosa (loss of peripheral vision). Use cautiously with bleeding disorders or if taking blood thinners. Avoid above the recommended daily level in pregnant women and breastfeeding women.
Fair negative scientific evidence:
Vitamin C (ascorbic acid): Although early population research suggested reduction in cataract formation among individuals taking vitamin C for at least 10 years, subsequent research found no reduction in the seven-year risk of age-related cataracts with the use of daily vitamin C. Additional research may be needed to confirm the effects of Vitamin C for prevention or progression of cataracts.
Vitamin C is generally considered safe in the amounts found in foods. Vitamin C supplements are also generally considered safe in most individuals if taken in recommended doses. Avoid high doses of vitamin C with glucose 6-phosphate dehydrogenase deficiency, kidney disorders or stones, cirrhosis (inflammation of the liver), gout, or paroxysmal nocturnal hemoglobinuria (bleeding disorder). Vitamin C intake from food is generally considered safe if pregnant or breastfeeding. It is not clear if vitamin C supplements in doses higher than dietary reference intake recommendations are safe for pregnant or breastfeeding women. Vitamin C is naturally found in breast milk.
Historical or theoretical uses lacking sufficient evidence:
Acupuncture: The practice of acupuncture originated in China 5,000 years ago. Today, it is widely used throughout the world and is one of the main pillars of Chinese medicine. It involves the insertion of needles in various point of the body to help move the "chi" or energy. Research suggests that acupuncture may decrease intraocular pressure (IOP), increase visual acuity, and improve subjective symptoms. Although the results of this study should be interpreted cautiously, acupuncture may be used to supplement conventional therapy for glaucoma or cataracts. Additional research is needed in this area.
Needles must be sterile in order to avoid disease transmission. Avoid with valvular heart disease, medical conditions of unknown origins, or infections. Acupuncture should not be applied to the chest in patients with lung diseases or on any area that may rely on muscle tone to provide stability. Avoid use in patients with needle phobias. Use cautiously with bleeding disorders, neurological disorders, seizure disorders, or diabetes. Use cautiously in elderly or medically compromised patients. Use cautiously in patients who will drive or operate heavy machinery after acupuncture. Use cautiously if taking anticoagulants.
L-arginine: L-arginine, or arginine, is considered a semi-essential amino acid, because although it is normally synthesized in sufficient amounts by the body, supplementation is sometimes required. Arginine is a precursor of nitric oxide, which causes vasodilation (blood vessel relaxation). Laboratory evidence suggests that arginine may be useful in the treatment of medical conditions that are improved by vasodilation, including glaucoma.
Avoid with allergy to arginine, or a history of stroke, or liver or kidney disease. Avoid if pregnant or breastfeeding. Use caution if taking blood-thinning drugs (like warfarin or Coumadin?) and blood pressure drugs or herbs or supplements with similar effects. Blood potassium levels should be monitored. L-arginine may worsen symptoms of sickle cell disease. Caution is advised in patients taking prescription drugs to control sugar levels.
Omega-3 fatty acids: Omega-3 fatty acids are essential fatty acids found in cold water fish (including salmon, herring, and tuna) and other marine life (such as krill and algae). Omega-3 fatty acids can also be found in certain plants and nuts, including purslane (Portulaca oleracea) and walnuts. Several clinical trials have reported that the increased consumption of omega-3 fatty acids as fish or fish oils have been effective in decreasing intraocular pressure (IOP) in glaucoma patients. More human trials are needed.
Omega-3 fatty acid supplements (including fish oils) may cause an increase in bleeding in sensitive individuals, including those taking blood-thinning drugs such as warfarin (Coumadin?) or those with bleeding disorders. Avoid if allergic or hypersensitive to fish, omega-3 fatty acid products that come from fish, nuts, linolenic acid or omega-3 fatty acid products that come from nuts. Use cautiously before surgery. The Environmental Protection Agency (EPA) recommends that intake be limited in pregnant/nursing women to a single 6-ounce meal per week, and in young children to less than 2 ounces per week. For farm-raised, imported, or marine fish, the U.S. Food and Drug Administration recommends that pregnant/nursing women and young children avoid eating types with higher levels of methylmercury and less than 12 ounces per week of other fish types. Women who might become pregnant are advised to eat 7 ounces or less per week of fish with higher levels of methylmercury or up to 14 ounces per week of fish types with about 0.5 parts per million (such as marlin, orange roughy, red snapper, or fresh tuna).

Prevention

Eye examination: Primary open-angle glaucoma gives few warning signs or symptoms until permanent damage has already occurred. That is why regular eye exams are the key to detecting glaucoma early enough for successful treatment. It is best to have routine eye checkups every two to four years after age 40 and every one to two years after age 65. Because African-Americans have a much higher risk of glaucoma, screening should begin every three to five years from age 20-29 and every two to four years after age 30.
Diet: Eating a healthy diet full of fruits and vegetables helps to ensure that enough vitamins and minerals are consumed for use by the body and eyes. Some nutrients that are especially important to eye health include vitamin A, vitamin C, vitamin E, and zinc. Drinking fluids in small amounts over the course of a day can help individuals with increased intraocular pressure (IOP). Drinking a quart or more of any liquid within a short time may increase eye pressure. Limiting caffeine to low or moderate levels may be helpful.
Exercise: Individuals with open-angle glaucoma who exercise regularly, at least three times a week, may be able to moderately reduce their eye pressure. However, angle-closure glaucoma is not affected by exercise and people with pigmentary glaucoma, a form of secondary glaucoma, may experience increased eye pressure after exercise. Also, yoga and other exercises that use the head in lowered positions may increase the pressure in the eyes. Healthcare professionals recommend talking to a doctor about an appropriate exercise program.
Stress reduction: Stress may trigger an attack of acute angle-closure glaucoma. Relaxation techniques may be helpful in dealing with stress.
Eye protection: Eye trauma can result in increased IOP. Wearing safety glasses or goggles when sports are played, when using tools or machinery, or when working with chemicals is important.

Author information

This information has been edited and peer-reviewed by contributors to the Natural Standard Research Collaboration (www.naturalstandard.com).

Bibliography

American Academy of Family Physicians. .
American Academy of Ophthalmology. .
American Health Assistance Foundation. .
Glaucoma Research Foundation. .
International Glaucoma Foundation. .
Kurusu M, Watanabe K, Nakazawa T, et al. Acupuncture for patients with glaucoma. Explore (NY). 2005;1(5):372-6. .
Natural Standard: The Authority on Integrative Medicine. .
National Eye Institute. .
Nguyen CT, Bui BV, Sinclair AJ, et al. Dietary omega 3 fatty acids decrease intraocular pressure with age by increasing aqueous outflow. Invest Ophthalmol Vis Sci. 2007;48(2):756-62. .
Ren H, Magulike N, Ghebremeskel K, et al. Primary open-angle glaucoma patients have reduced levels of blood docosahexaenoic and eicosapentaenoic acids. Prostaglandins Leukot Essent Fatty Acids. 2006;74(3):157-63. .
Rhee DJ, Katz LJ, Spaeth GL, et al. Complementary and alternative medicine for glaucoma. Surv Ophthalmol. 2001;46(1):43-55. .
The Glaucoma Foundation. .

Causes

The eye is made from soft, but strong tissues. However, like a camera, the eye needs to maintain its shape so that it can focus light accurately. This is achieved by using secretions which keep the eye firm and expanded, similar to a balloon. These fluids include the vitreous humor (or vitreous body), a thick, gel-like fluid that fills most of the spaces in the eyes, and the aqueous humor, a clear fluid that fills the anterior chamber (the space between the cornea and iris). The aqueous humor carries oxygen, sugars, vitamins, minerals, and other essential nutrients for the eye.
The production of the aqueous humor is a constant process, and its removal is just as important. The aqueous humor filters through a spongy meshwork called the trabecular meshwork, and then drains out of the anterior chamber through a complex drainage system that leads through structures (vessels) called the canal of Schlemm, then exits out of the eye. The balance between production and drainage of the aqueous humor determines the intraocular pressure or IOP (the fluid pressure in the eye). Most individual's IOPs fall between 10 and 21 millimeters of mercury (mmHg). However, some individual's eyes can tolerate higher pressures than others.
Most, but not all, forms of glaucoma are characterized by high intraocular pressure. In most types of glaucoma, fluid cannot flow effectively through the trabecular meshwork and this causes an increase in intraocular pressure causing damage to the optic nerve and leading to vision loss.
The optic nerve is the part of the eye that carries visual information to the brain. It is made up of over one million nerve cells and while each cell is several inches long, they are extremely thin (about one twenty-thousandth of an inch in diameter). When the IOP in the eye increases, the nerve cells become compressed, causing them to become damaged and, eventually, die. The death of these cells results in permanent vision loss.
Blurry vision and "seeing stars" are warning signs of increased intraocular pressure, which can result from overproduction of aqueous humor or damage to the drainage system, among other causes. This is glaucoma, and uncorrected, it can damage the eye, causing injury to the retina or optic nerve and eventual blindness.
The CYP1b1 gene provides instructions for making the CYP1b1 protein. Although the functions of the CYP1b1 protein are still being investigated, researchers suggest that it may help control the secretion of fluid inside the eyes. When the CYP1b1 gene is mutated, the body produces too much of this protein, causing pressure to build up in the eyes.
The MYOC gene provides instructions for making the protein myocilin. This protein is found in parts of the eye that help regulate intraocular pressure. If the MYOC gene is mutated, the body may produce dysfunctional myocilin. Although researchers are still learning about the function of myocillin, it has been suggested the defective protein may build up in the eyes. As a result, fluid may not be able to flow through the eyes, causing intraocular pressure to increase.

Risk factors

Increased intraocular pressure: If the internal pressure in the eye (intraocular pressure or IOP) is higher than normal (10-20 millimeters of mercury or mmHg), an individual is at an increased risk of developing glaucoma, though not everyone with elevated intraocular pressure develops the disease; this makes it difficult to predict who will get glaucoma.
Age: Age is a large risk factor in the development of glaucoma. Individuals older than 60 are at increased risk of developing glaucoma. For African American's, however, the increase in risk becomes apparent earlier, after age 40.
Ethnicity: African Americans are five times more likely to get glaucoma than are Caucasians and they are four times more likely to suffer permanent blindness as a result. Mexican-Americans also face an increased risk, especially those over 60 years of age. Asian-Americans are at higher risk of angle-closure glaucoma and Japanese-Americans are more prone to low-tension glaucoma. The reasons for these differences are not clear.
Family history: If an individual has a family member such as a parent or sibling (brother or sister) that has glaucoma, they have a much greater risk of developing the condition.
Medical conditions: Diabetes increases the risk of developing glaucoma. Diabetes can damage blood vessels in the eye, causing a greater risk in developing an increased IOP. A history of hypertension (high blood pressure), heart disease, or hypothyroidism (low thyroid hormone levels) also can increase the risk of developing glaucoma. Routine use of coffee, a stimulant that can raise blood pressure, has recently been found to be associated with a slight increase in IOP.
Trauma: Severe trauma (or physical injury), including being hit in the eye, can result in increased IOP. Injury can also dislocate the lens, closing the drainage angle. Other risk factors include retinal detachment, eye tumors, and eye inflammations such as chronic uveitis (inflammation of the uvea) and iritis (inflammation of the iris). Certain types of eye surgery also may trigger secondary glaucoma, including cataract surgery.
Nearsightedness: Being nearsighted, which generally means that objects in the distance look fuzzy without glasses or contacts, increases the risk of developing glaucoma.
Prolonged corticosteroid use: Using corticosteroids, including prednisone (Deltasone?) or methyprednisolone (Medrol?), for prolonged periods of time appears to put an individual at risk of getting secondary glaucoma. Inhaled steroids, such as beclomethasone (Beclovent?), fluticosone (Flovent?), and budesonide (Pulmicort?), may also increase the risk of developing glaucoma.
Eye abnormalities: Structural abnormalities of the eye can lead to secondary glaucoma. For example, pigmentary glaucoma is a form of secondary glaucoma caused by pigment granules being released from the back of the iris. These granules can block the trabecular meshwork, decreasing draining of aqueous humor.
Specific risk factors: Specific risk factors exist for different types of glaucoma. Strong risk factors for open-angle glaucoma include an increase IOP, a family history of glaucoma, being age 40 and older for African Americans, being age 60 and older for the general population (especially Mexican Americans), a thin cornea, and abnormal optic nerve anatomy. Potential risk factors for developing open-angle glaucoma include a high degree of myopia (very severe nearsightedness), diabetes, eye surgery (including cataract surgery) or injury, hypertension (high blood pressure), and use of prescription steroids. Specific risk factors for closed-angle glaucoma include age, family history, poor short-distance vision (far-sighted), eye injury or eye surgery, and Asian or Eskimo descent. Risk factors for normal tension glaucoma include family history (any type of glaucoma), Japanese ancestry, and cardiovascular disease (including high cholesterol and atherosclerosis or hardening of the arteries). In North America, normal tension glaucoma is more prevalent in women than in men.

Types of glaucoma

Glaucoma can broadly be divided into two main groups including open angle and closed angle glaucoma. Within these groups are primary and secondary conditions with chronic and acute types; each is described as to its type, symptoms, cause, detection, risk factors, and treatment.
Open angle glaucoma: Open angle (also called chronic open angle or primary open angle) is the most common type of glaucoma and usually causes no symptoms at first. With this type, even though the anterior structures of the eye appear normal, aqueous fluid builds within the anterior chamber, causing the intraocular pressure (IOP) to become elevated. Left untreated, this may result in permanent damage of the optic nerve and retina. Prescription eye drops are generally prescribed to lower the eye pressure. In some cases, surgery is performed if the IOP cannot be adequately controlled with medical therapy. Open angle glaucoma accounts for 19% of all blindness among African-Americans compared to six percent in Caucasians. Other high-risk groups include individuals over 60, family members of those already diagnosed, diabetics, and people who are severely nearsighted.
Acute angle closure glaucoma: Acute angle closure glaucoma, or closed-angle glaucoma, occurs because of an abnormality of the trabecular network and the canal of Schlemm in the eye that keeps aqueous humor fluid from draining. In most of these cases, the space between the iris and cornea is narrower than normal, putting pressure on the canal of Schlemm and leaving a smaller channel for the aqueous humor to drain. If the flow of aqueous becomes completely blocked, the IOP rises sharply, causing a sudden angle closure attack. Only about 10% of the population with glaucoma has acute angle closure glaucoma.
While patients with open angle glaucoma do not typically have symptoms, those with angle closure glaucoma may experience severe eye pain accompanied by nausea, blurred vision, seeing rainbows or halos around lights, and a red eye. This problem is an emergency and should be treated by an ophthalmologist immediately. If left untreated, severe and permanent loss of vision can occur in a matter of days.
Chronic closed-angle glaucoma: Closed angle glaucoma progresses more slowly and can produce damage without symptoms, similar to open-angle glaucoma.
Normal tension glaucoma: Normal tension glaucoma (NTG), also known as low tension or normal pressure glaucoma, is a form of glaucoma in which damage occurs to the optic nerve without eye pressure exceeding the normal range of 10-20 millimeters of mercury (mmHg). The causes of NTG are still unknown. For some reason, the optic nerve is susceptible to damage from even the normal amount of eye pressure. Researchers continue to examine why some optic nerves are damaged by these relatively low eye pressure levels. Lowering eye pressure at least 30% through medicines slows the disease in some people.
Neovascular glaucoma: A severe form of glaucoma, called neovascular glaucoma, is linked to diabetes and results from abnormal blood vessel growth that blocks the fluid drainage channels of the eye, resulting in increased eye pressure. Low blood supply to the eye as a result of diabetes, insufficient flow of blood to the head due to blocked arteries in the neck, or blockage of blood vessels in the back of the eye can cause the abnormal blood vessel growth. Blockage of aqueous humor draining may occur, causing a rise in IOP.
Secondary glaucomas: Secondary glaucomas can develop as complications of other medical conditions, such as inflammation, trauma, previous surgery, diabetes, or a tumor. These types of glaucomas are sometimes associated with eye surgery or advanced cataracts, eye injuries, certain eye tumors, uveitis (eye inflammation), and certain medications (including topical steroid creams, cocaine, chlorpromazine or Thorazine?, and phenelzine or Nardil?). Secondary glaucomas include pigmentary glaucoma, pseudoexfoliation syndrome, and irido-corneal-endothelial syndrome (ICE). Pigmentary glaucoma is a rare form of the disease where pigment granules from the iris flake off into the aqueous humor (eye fluid) and then clog the eye drainage system (trabecular meshwork and canal of Schlemm). Pseudoexfoliation syndrome occurs when outer layers of the lens flake off and block normal flow of the aqueous humor. Irido-corneal-endothelial syndrome (ICE) consists of a number of features, including the loss of cells from the cornea, which break off and block the drainage channels in the eye, resulting in increased eye pressure. There also may be scarring that connects the iris to the cornea.
Pediatric glaucomas: The pediatric glaucomas consist of congenital glaucoma (present at birth), infantile glaucoma (appears during the first three years), juvenile glaucoma (age three through the teenage or young adult years), and all the secondary glaucomas occurring in the pediatric age group. Congenital glaucoma is present at birth and most cases are diagnosed during the first year of life. Sometimes symptoms are not recognized until later in infancy or early childhood. The range of treatment is very different from that for adult glaucoma. It is very important to catch pediatric glaucoma early in order to prevent blindness.