Several different types of glaucoma are the leading cause of blindness in the US1, and yet many cases of glaucoma begin without symptoms. Half of the 3 million-plus Americans who have glaucoma have been diagnosed.2 Glaucoma can affect anyone, but it is especially prevalent in persons over age 60. Everyone should have regular eye exams throughout their lives to screen for glaucoma, especially a dilated eye exam. Glaucoma tends to run in families, but anyone can get it.
How Glaucoma Is Diagnosed
Most people are familiar with the puff of air or the glaucoma device that looks like a metal light pen that is a standard part of any eye exam. The test measures intraocular pressure (IOP). Elevated eye pressure is a sign of glaucoma, but normal pressure does not necessarily mean that the patient doesn’t have glaucoma. Normal pressure is in the range of 10 to 21 millimeters of mercury (mm Hg). Anything higher than 21 mm Hg is called “ocular hypertension” (OHT): elevated eye pressure.
Glaucoma is now considered to be a group of diseases that cause optic nerve damage. Diagnosis of glaucoma does not totally rely on the intraocular pressure measurements. In fact, up to 40% of patients with the most common type of glaucoma called “open angle” do not have elevated eye pressure (often referred to as “Normal Tension Glaucoma”). Further examination is required to diagnose this type of glaucoma.
The intraocular pressure test catches many cases of glaucoma. It also helps identify the “glaucoma suspect.”3 These are people who have elevated intraocular pressure but are symptomless. For example, they have not experienced changes in the optic nerve and/or less peripheral vision versus prior visits to the optometrist. Risk factors for glaucoma include:
- having hypertension, heart disease, diabetes, obesity, or hyperthyroidism
- being extremely farsighted or nearsighted
- being a heavy computer user
- having a family member who has been diagnosed with glaucoma
Regular Testing Important
Anyone who might be a glaucoma suspect should be tested for glaucoma regularly and may consider trying nutritional support to help either prevent the onset of glaucoma or at least help nourish the optic nerve to help reduce the risk of damage and loss of vision.
African-Americans have a higher prevalence of the most common primary open angle glaucoma versus Caucasians. African-Americans tend to develop glaucoma younger and the condition deteriorates faster, with a higher chance of resulting in blindness.
If a typical glaucoma patient has symptoms, they may include loss of peripheral vision and eventually, tunnel vision (vision in the center of the visual field). Damage takes place before symptoms are noticed. A rarer type of glaucoma called narrow- or acute-angle glaucoma may have symptoms including headache, eye redness, halos and/or nausea, and need to be managed carefully by your eye doctor.
Types of Glaucoma: Causes
With most types of glaucoma, the optic nerve is damaged. Sometimes it is the result of increased pressure of the clear fluid that is inside the eye between the lens and cornea (Aqueous Humor). This clear liquid provides oxygen and nutrients to the front of the eye. Aqueous humour is generated constantly, circulates, and then drains out through tiny holes behind the lower eyelid.
However, in patients with open-angle glaucoma, the drainage area called the “trabecular meshwork” gets compromised which prevents the fluid from draining completely. Pressure builds up in the front of the eye causing swelling, resulting in more pressure on the optic nerve and possibly reduced delivery of essential nutrients to the optic nerve. The first part of vision to fail is peripheral vision (the vision on the sides).
In modern times, glaucoma is considered to be a collection of diseases that cause optic nerve damage. High intraocular pressure is no longer required for a glaucoma diagnosis.
Narrow- or acute-angle glaucoma is also known as angle-closure glaucoma. It is quite serious and requires immediate treatment. Symptoms may include the eye becoming red suddenly, headache, visual halos, and even nausea. Angle-closure glaucoma means the aqueous fluid cannot drain because of a narrow angle between the cornea and iris. Anyone with these symptoms should go to the emergency room.
Low-tension glaucoma is a result of poor circulation. Insufficient blood is reaching the optic nerve, which damages it. This is a side effect of a primary condition, such as heart conditions or brain tumors or even simply poor circulation for example, or may be from toxic substances. Related topics: Optic Neuritis | Optic Nerve Atrophy
Secondary glaucoma results from health conditions including eye inflammation, eye injuries or drug side effects.
Congenital glaucoma begins shortly after being born, and affects 1 in 10,000 babies.
Without treatment, most glaucoma patients will gradually lose vision and may go completely blind. Peripheral vision goes first. The patient develops tunnel vision, which is difficult to notice until the disease has progressed significantly. This is why regular optometric visits are crucial to maintaining eye health.
The typical treatment for different types of glaucoma are customized depending on the type of glaucoma, and how far along the disease has progressed.
Open-angle glaucoma, the most common, is usually treated using eye drops or oral medicine. Surgery or laser treatment may be offered if oral medications or eye drops are not effective in keeping eye pressure low.
Other Approaches to Glaucoma Support and Prevention
A common-sense approach to preventing and supporting glaucoma includes proper exercise, nutrition and supplementation:
- Glaucoma patients who participate in a brisk 40-minute walk five days a week can reduce their IOP by approximately 2.5 mm, if they continue this walking regimen over three months.4 This result is similar to the effect of beta-blocking glaucoma medications.
- Get your thyroid functioning checked and, if necessary, treated. Hypothyroidism is associated with glaucoma.
- Eat a healthy diet that includes plenty of fresh fruits and vegetables, whole grains and lean proteins. Cut out junk food. Learn more about nutrition.
- Antioxidants help protect the body from free-radical damage. Many nutrients help support the health of the optic nerve. These include taurine, magnesium, Vitamin C, gingko biloba, bilberry, omega-3 fatty acids and Vitamin B12.
- Don’t stare at computer screens all day, especially if you are myopic5 (take regular breaks to do eye exercises). More about glaucoma and computer use.
- Drugs that may increase your risk of developing glaucoma include any that dilate the pupil, NSAIDs, steroids, oral and topical hydrocortisone, antidepressants, stimulants and much more. See a list of drugs that can increase glaucoma risk.
- Learn more about protecting your optic nerve.
- http://www.glaucoma.org/glaucoma/glaucoma-facts-and-stats.php Glaucoma Research Foundation ↩
- The Eye Diseases Prevalence Research Group, Archives of Ophthalmology, 2004; Prevent Blindness America ↩
- http://www.emedicinehealth.com/adult_glaucoma_suspect/article_em.htm ↩
- Passo, M.S. et. al., Regular exercise lowers intraocular pressure in glaucoma patients. Investigative Ophthalmology 35. In ARVO Abstracts, March 15, 1994. ↩
- Possible association between heavy computer users & glaucomatous visual field abnormalities: a cross sectional study in Japanese workers, Journal of Epidemiology and Community Health 2004;58:1021-1027 Copyright, 2004 BMJ Publishing Group Ltd
Masayuki Tatemichi, Tadashi Nakano, Katsutoshi Tanaka, Takeshi Hayashi, Takeshi Nawa, Toshiaki Miyamoto, Hisanori Hiro and Minoru Sugita ↩