Glaucoma is a group of eye conditions that cause progressive damage to the optic nerve head, which can lead to vision problems and irreversible vision loss if it is not treated early. It is typically classified as open angle or closed angle and primary or secondary.
What is glaucoma?
Glaucoma is a group of eye conditions (typically classified as open- or closed-angle, and primary or secondary) characterized by progressive damage to the optic nerve head. Because the optic nerve transmits visual information from the eye to the brain, glaucoma can lead to vision problems if not treated early, and can eventually cause irreversible vision loss if left untreated.[1]
What are the main signs and symptoms of glaucoma?
Open-angle glaucoma is usually asymptomatic in the early stages, with visual symptoms developing subtly and gradually over time. The most common visual symptoms reported are needing more light, blurry vision, seeing glare, and difficulty seeing objects in peripheral vision.[2]
Angle-closure glaucoma can present chronically, often without symptoms. However, it can also present acutely, with a sudden increase in the pressure inside the eye causing symptoms that include blurry vision, reddening of the eye, intense eye pain, severe headache, and nausea and vomiting.[3]
How is glaucoma diagnosed?
A complete eye exam for glaucoma diagnosis typically includes five tests:[4]
- Tonometry; to measure intraocular pressure
- Pachymetry; to measure the thickness of the cornea
- Ophthalmoscopy; to examine the optic nerve for damage
- Perimetry; to assess the field of vision
- Gonioscopy; to measure the eye’s anterior chamber angle
What are some of the main medical treatments for glaucoma?
Elevated intraocular pressure (pressure inside the eye) is so far the only treatable risk factor for glaucoma. As such, current management strategies all aim to lower intraocular pressure. Depending on the situation, this is achieved with medications (applied topically to the eye or taken orally), laser treatment, surgery, or a combination of any of these.[5]
Have any supplements been studied for glaucoma?
Limited preliminary evidence suggests that a handful of supplements may have beneficial effects in glaucoma by reducing intraocular pressure, improving inner retinal function, increasing blood flow, or slowing visual field loss. These supplements include ginkgo biloba, blackcurrant anthocyanins, epigallocatechin-gallate, vitamin B3, and Erigeron breviscapus (a Chinese herb).[6][7]
How could diet affect glaucoma?
The available evidence examining the links between dietary patterns or dietary components and glaucoma risk is limited, mostly observational, and often conflicting. That said, the consumption of fruits and vegetables rich in vitamin A, carotenes, and nitrate has been linked to a reduced risk of glaucoma. Moreover, some studies have linked caffeinated tea intake with a lower risk of glaucoma. On the other hand, caffeine and caffeinated coffee transiently increase intraocular pressure (a risk factor for glaucoma onset and progression) in individuals with glaucoma, but do not seem to affect individuals without glaucoma.[8]
Are there any other treatments for glaucoma?
A small number of studies have examined the potential efficacy of non-medical glaucoma treatments, including exercise, cannabis, acupuncture, and relaxation techniques.
The effects of exercise on intraocular pressure have been mixed, and seem to depend on the type and intensity of exercise. While marijuana use has been shown to effectively reduce intraocular pressure, its effects are short-lived, requiring dosing of 8–10 times per day for a sustained therapeutic effect. Clear evidence supporting the efficacy of acupuncture and relaxation techniques is lacking.[9][10][11][12]
What causes glaucoma?
Although the exact causes of primary glaucoma have not yet been established, in most cases, the level of intraocular pressure is related to the degree of glaucomatous damage observed. Independently or in addition to intraocular pressure, other factors — including an insufficient supply of oxygen to the optic nerve head, excessive stimulation of the glutamate system, and the formation of free radicals and inflammatory cytokines — may individually or collectively contribute to the development of glaucomatous damage.[13][14]
Examine Database: Glaucoma
Research FeedRead all studies
Does gingko biloba improve vascular health in glaucoma?
In this 4-month controlled trial in 17 participants with open-angle glaucoma, supplementing with ginkgo biloba did not improve vascular health around the retina and optic nerve.
Vitamin B3 intake and glaucoma
Vitamin B6 and glaucoma risk
Nicotine and eye health
Ultraprocessed foods and glaucoma risk
Frequently asked questions
What is glaucoma?
Glaucoma is a group of eye conditions (typically classified as open- or closed-angle, and primary or secondary) characterized by progressive damage to the optic nerve head. Because the optic nerve transmits visual information from the eye to the brain, glaucoma can lead to vision problems if not treated early, and can eventually cause irreversible vision loss if left untreated.[1]
What are the different types of glaucoma?
Quick answer:
Glaucoma is classified into two main types based on the drainage system's appearance: open-angle and closed-angle glaucoma. These types can be further categorized as primary or secondary. Each type includes specific examples, such as primary open-angle glaucoma and secondary closed-angle glaucoma.
Glaucoma is typically divided into two major types according to the appearance of the drainage system within the eye: open-angle glaucoma (i.e., the angle where the iris meets the cornea is as wide and open as it should be) and angle-closure (also called closed-angle or narrow-angle) glaucoma (i.e., the angle where the iris meets the cornea is narrower than it should be). Within each type, the condition can be primary (i.e., with no identifiable cause) or secondary (i.e., caused by an existing condition).[15] This means that different types of glaucoma can fall under one of the following four categories:[16]
- Primary open-angle glaucoma. Examples include primary open-angle high-tension glaucoma, primary open-angle normal-tension glaucoma, and juvenile glaucoma.
- Secondary open-angle glaucoma. Examples include pseudoexfoliative glaucoma, pigmentary glaucoma, and uveitic glaucoma.
- Primary angle-closure glaucoma. Examples include acute primary angle-closure glaucoma and chronic primary angle-closure glaucoma.
- Secondary angle-closure glaucoma. Examples include neovascular glaucoma and miotic-induced malignant glaucoma.
What are the main signs and symptoms of glaucoma?
Open-angle glaucoma typically has no early symptoms, and visual issues like needing more light and blurry vision develop gradually. In contrast, closed-angle glaucoma can be asymptomatic or occur within a short period of time, with symptoms such as intense eye pain, blurry vision, and nausea due to a sudden increase in eye pressure.
Open-angle glaucoma is usually asymptomatic in the early stages, with visual symptoms developing subtly and gradually over time. The most common visual symptoms reported are needing more light, blurry vision, seeing glare, and difficulty seeing objects in peripheral vision.[2]
Angle-closure glaucoma can present chronically, often without symptoms. However, it can also present acutely, with a sudden increase in the pressure inside the eye causing symptoms that include blurry vision, reddening of the eye, intense eye pain, severe headache, and nausea and vomiting.[3]
How is glaucoma diagnosed?
Glaucoma is diagnosed through a complete eye exam that includes 5 tests: tonometry for intraocular pressure, pachymetry for corneal thickness, ophthalmoscopy for optic nerve examination, perimetry for visual field assessment, and gonioscopy for measuring the anterior chamber angle. These tests help determine the presence and severity of glaucoma.
A complete eye exam for glaucoma diagnosis typically includes five tests:[4]
- Tonometry; to measure intraocular pressure
- Pachymetry; to measure the thickness of the cornea
- Ophthalmoscopy; to examine the optic nerve for damage
- Perimetry; to assess the field of vision
- Gonioscopy; to measure the eye’s anterior chamber angle
What are some of the main medical treatments for glaucoma?
The main medical treatments for glaucoma focus on lowering elevated intraocular pressure, which is the only treatable risk factor for the condition. This can be achieved through medications, laser treatment, surgery, or a combination of these approaches.
Elevated intraocular pressure (pressure inside the eye) is so far the only treatable risk factor for glaucoma. As such, current management strategies all aim to lower intraocular pressure. Depending on the situation, this is achieved with medications (applied topically to the eye or taken orally), laser treatment, surgery, or a combination of any of these.[5]
Can vision that is lost due to glaucoma be restored?
Quick answer:
Vision that is lost due to glaucoma cannot be restored because there is no treatment available to reverse the existing damage. However, early detection through routine eye exams is essential to prevent further vision loss.
In a word, no. While the available treatments can help prevent further glaucomatous damage, there is currently no treatment that can reverse any of the vision loss that has already occurred. This means that routine eye exams and glaucoma screening are crucial, as early detection of glaucoma will enable appropriate monitoring and treatment, thereby minimizing the risk of irreversible vision loss.
Have any supplements been studied for glaucoma?
Limited preliminary evidence indicates that certain supplements — such as Ginkgo biloba, blackcurrant anthocyanins, epigallocatechin-gallate, vitamin B3, and Erigeron breviscapus — may have beneficial effects on glaucoma by reducing intraocular pressure and improving retinal function.
Limited preliminary evidence suggests that a handful of supplements may have beneficial effects in glaucoma by reducing intraocular pressure, improving inner retinal function, increasing blood flow, or slowing visual field loss. These supplements include ginkgo biloba, blackcurrant anthocyanins, epigallocatechin-gallate, vitamin B3, and Erigeron breviscapus (a Chinese herb).[6][7]
How could diet affect glaucoma?
Dietary patterns and components have a limited and often conflicting relationship with glaucoma risk, but eating fruits and vegetables that are high in vitamin A, carotenes, and nitrate may reduce risk. Additionally, although caffeinated tea may be associated with lower glaucoma risk, caffeine in coffee can temporarily raise intraocular pressure in people with glaucoma.
The available evidence examining the links between dietary patterns or dietary components and glaucoma risk is limited, mostly observational, and often conflicting. That said, the consumption of fruits and vegetables rich in vitamin A, carotenes, and nitrate has been linked to a reduced risk of glaucoma. Moreover, some studies have linked caffeinated tea intake with a lower risk of glaucoma. On the other hand, caffeine and caffeinated coffee transiently increase intraocular pressure (a risk factor for glaucoma onset and progression) in individuals with glaucoma, but do not seem to affect individuals without glaucoma.[8]
Are there any other treatments for glaucoma?
Some nonmedical treatments for glaucoma — such as exercise, cannabis, acupuncture, and relaxation techniques — have been studied, but their effectiveness varies. Although cannabis can reduce intraocular pressure, its effects are temporary, and there is insufficient evidence to support acupuncture and relaxation techniques.
A small number of studies have examined the potential efficacy of non-medical glaucoma treatments, including exercise, cannabis, acupuncture, and relaxation techniques.
The effects of exercise on intraocular pressure have been mixed, and seem to depend on the type and intensity of exercise. While marijuana use has been shown to effectively reduce intraocular pressure, its effects are short-lived, requiring dosing of 8–10 times per day for a sustained therapeutic effect. Clear evidence supporting the efficacy of acupuncture and relaxation techniques is lacking.[9][10][11][12]
What causes glaucoma?
The exact causes of primary glaucoma are not fully understood, but it is often associated with intraocular pressure levels and may also involve factors such as insufficient oxygen supply to the optic nerve, excessive glutamate stimulation, and the presence of free radicals and inflammatory cytokines. These factors can contribute individually or collectively to damage from glaucoma.
Although the exact causes of primary glaucoma have not yet been established, in most cases, the level of intraocular pressure is related to the degree of glaucomatous damage observed. Independently or in addition to intraocular pressure, other factors — including an insufficient supply of oxygen to the optic nerve head, excessive stimulation of the glutamate system, and the formation of free radicals and inflammatory cytokines — may individually or collectively contribute to the development of glaucomatous damage.[13][14]
What are the risk factors for glaucoma?
Quick answer:
Key risk factors for glaucoma include elevated intraocular pressure (typically greater than 21 mmHg), older age, a family history of the condition, and being of Asian, African American, or Inuit descent.
Some of the most important risk factors for glaucoma are:[17]
- Elevated intraocular pressure (typically >21 mmHg)
- Older age
- A family history of glaucoma
- Asian, African American, or Inuit descent
What causes an increase in intraocular pressure?
Quick answer:
An increase in intraocular pressure is caused by reduced outflow of aqueous humor due to either stiffening of the trabecular meshwork in open-angle glaucoma or narrowing of the anterior drainage angle in closed-angle glaucoma. This build-up of aqueous humor occurs when the production rate exceeds the drainage rate.
Both the anterior (between the cornea and the iris) and posterior (between the iris and the lens) parts of the eye are filled with a water-like fluid called the aqueous humor. As new aqueous humor is constantly being produced, this rate of production has to be balanced by an equal drainage rate. The two pathways through which aqueous humor drains are the trabecular meshwork and the uveoscleral drainage.[18]
In open-angle glaucoma, there is reduced outflow of aqueous humor through the trabecular meshwork because of the stiffening of the inner wall region. In angle-closure glaucoma, the iris narrows the anterior drainage angle, causing the outflow of aqueous humor to be reduced from both the trabecular meshwork and the uveoscleral drainage.[5] The reduced outflow of aqueous humor in open-angle or angle-closure glaucoma causes the build-up of aqueous humor inside the eye, leading to an increase in intraocular pressure.
Can I have elevated intraocular pressure without glaucoma or glaucoma without elevated intraocular pressure?
Quick answer:
Yes, it is possible to have elevated intraocular pressure without developing glaucoma, and conversely, glaucoma can occur without elevated intraocular pressure, as observed in normal-tension glaucoma. This indicates that individual tolerance to intraocular pressure varies and that glaucoma's development is influenced by multiple factors beyond just intraocular pressure.
Yes and yes. While elevated intraocular pressure is an important risk factor for the development and progression of glaucoma, not all people with elevated intraocular pressure will develop glaucoma. Moreover, many people will develop glaucoma even in the absence of elevated intraocular pressure in what is termed “normal-tension glaucoma”.[19] The implication from the above is that the amount of tolerated intraocular pressure may vary between individuals,[20] and that the pathophysiology of glaucoma is likely multifactorial; that is, factors other than intraocular pressure are involved in the development and progression of the condition.
References
Examine Database References
- Heart Rate - Merritt JC, Crawford WJ, Alexander PC, Anduze AL, Gelbart SSEffect of marihuana on intraocular and blood pressure in glaucomaOphthalmology.(1980 Mar)
- Intraocular Pressure - Terai N, Gedenk A, Spoerl E, Pillunat LE, Stodtmeister RThe short-term effect of flavonoid-rich dark chocolate on retinal vessel diameter in glaucoma patients and age-matched controlsActa Ophthalmol.(2014 Aug)
- Intraocular Pressure - Parisi V, Coppola G, Centofanti M, Oddone F, Angrisani AM, Ziccardi L, Ricci B, Quaranta L, Manni GEvidence of the neuroprotective role of citicoline in glaucoma patientsProg Brain Res.(2008)
- Ocular Blood Flow - Park JW, Kwon HJ, Chung WS, Kim CY, Seong GJShort-term effects of Ginkgo biloba extract on peripapillary retinal blood flow in normal tension glaucomaKorean J Ophthalmol.(2011 Oct)