More than 3 million Americans and 60 million people worldwide have glaucoma. Glaucoma diagnoses are predicted to rise in the United States, reaching 4.2 million by 2030, which is a 58 percent increase from today. January is a time to spread the word and form an understanding of the disease known as the “silent thief of sight.”
What Is Glaucoma?
Glaucoma is a group of eye conditions that affects the optic nerve, causing blindness. The damage to the eye often is caused by an abnormally high pressure in the eye. Glaucoma can develop at any age, but it is one of the leading causes of blindness in people over the age of 60.
Glaucoma comes on gradually and a change of vision is not often noticed until it is at an advanced stage. Therefore, people are encouraged to get regular eye exams to help predict oncoming glaucoma.
Types of Glaucoma
There are several types of glaucoma.
In the most common type, open-angle glaucoma (also called primary or chronic glaucoma), the drainage angle where the iris and cornea meet remains open, but the trabecular meshwork is partially blocked. Open-angle glaucoma: 
- Is caused by the slow clogging of the drainage canals
- Has a wide, open angle between the iris and cornea
- Develops slowly and is chronic
- Has symptoms that are not easily noticed
Angle-closure glaucoma (also called closed-angle glaucoma, acute glaucoma, or narrow-angle glaucoma), the second most common form, occurs when the iris bulges forward to narrow or block the drainage angle formed by the cornea and iris. Angle-closure glaucoma:
- Is caused by blocked drainage canals, causing a sudden rise in eye pressure
- Has a closed or narrow angle between the iris and cornea
- Develops quickly
- Needs immediate medical attention
Normal-tension glaucoma (also called low-tension or normal-pressure glaucoma): 
- The optic nerve is damaged even though eye pressure is normal
- Is common in people with a family history of the disease
- Affects people of Japanese ancestry more than others
- Affects people with a history of systemic heart disease, such as irregular heartbeat
Congenital glaucoma occurs in babies with an incorrect or incomplete development of the eye’s drainage canals in the womb, and:
- Is rare
- May be inherited
- Causes unusually large eyes, excessive tearing, cloudy eyes, and light sensitivity
Other types of glaucoma include secondary glaucoma and pigmentary glaucoma. For a full list of all the variations, visit the Glaucoma Research Foundation website.
Symptoms of Glaucoma
Signs and symptoms vary but are determined by the type and stage of the condition.
Symptoms of open-angle glaucoma are:
- Patchy blind spots in the side or central vision, often in both eyes
- Tunnel vision (advanced stages)
Symptoms of acute angle-closure glaucoma should be treated immediately. They are:
- Severe headache
- Eye pain
- Nausea and vomiting
- Blurred vision
- Halos around lights
- Eye redness
Untreated, glaucoma will lead to blindness. Even after seeking treatment, 15 percent of people become blind in one or both eyes within 20 years.
Causes of Glaucoma
Glaucoma, which runs in families, results from damage to the optic nerve. As the optic nerve deteriorates, blind spots develop in the visual field. The deterioration is caused by increased pressure in the eye, although it is not fully understood why.
Elevated eye pressure is due to a buildup of aqueous humor fluid, which flows throughout the inside of the eye. This fluid normally drains through a tissue called the trabecular meshwork in the area where the iris meets the cornea. When too much fluid is produced or the eye is not draining the fluid properly, the fluid cannot flow at a normal rate and it causes pressure in the eye.
Risk Factors of Glaucoma
Risk factors include:
- Having high internal eye pressure
- Being over 60 years old
- Being black, Asian, or Hispanic
- Having a family history of glaucoma
- Having underlying health conditions, including diabetes, heart disease, hypertension, and sickle cell anemia
- Having corneas that are thin in the center
- Being extremely near- or farsighted
- Having had an eye injury or certain types of eye surgery
- Having taken corticosteroid medications, including eyedrops, for a long period of time
Preventing Glaucoma
Early detection is important and can help prevent vision loss or slow its progress. Self-care steps include:
- Get regular eye examinations with dilation: The American Academy of Ophthalmology recommends comprehensive eye exams every 5–10 years for people under age 40; every 2–4 years for people ages 40–54; every 1–3 years for people ages 55–64, and every 1–2 years for people over age 65.
- Know your family health history
- Exercise safely
- Take prescribed eyedrops as directed
- Wear eye protection
Herrick Library Resources
The following resources on glaucoma and eye health are available from Herrick Library to request and check out through curbside pickup:
- The Aging Eye: Preventing and Treating Eye Disease, by Laura Fine, ed.
- EyeFoods: The Complete Eye Health & Nutrition Guide, by Laurie Capogna
- Glaucoma: What Every Patient Should Know, by Harry Quigley
- Living with Glaucoma, by BrightFocus Foundation and the Glaucoma Research Foundation
- Vision: Your Annual Guide to Sight-Saving Therapies, by Colin McCannel
Sources: Bright Focus Foundation, What Is Neovascular Glaucoma?, https://www.brightfocus.org/glaucoma/article/what-neovascular-glaucoma; Glaucoma Research Foundation, January Is Glaucoma Awareness Month, https://www.glaucoma.org/news/glaucoma-awareness-month.php; Glaucoma Research Foundation, Types of Glaucoma, https://www.glaucoma.org/glaucoma/types-of-glaucoma.php; Mayo Clinic, Glaucoma, https://www.mayoclinic.org/diseases-conditions/glaucoma/symptoms-causes/syc-20372839
Credits: Glaucoma Research Foundation, https://www.glaucoma.org/news/glaucoma-awareness-month.php
