Glaucoma and Vision Loss

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Are you experiencing problems with your peripheral or side vision? Do you have to turn your head to see what’s to your immediate right or left? Do you have blurred vision, nausea, and headaches? Do you see “halos” around bright lights? Do you have a family history of blindness or low vision? It is important for you to have a comprehensive eye exam to ensure you do not have a disease called glaucoma.

Glaucoma is a group of eye diseases that can lead to blindness by damaging the optic nerve. In a healthy eye, fluid called the aqueous humor is continuously produced and drained appropriately to maintain healthy eye pressure. However, in some cases, the production of aqueous is too high, or the drainage system is blocked, causing pressure to build within the eye. Over time, this increased pressure can damage the optic nerve.

The optic nerve transmits information from the eye to the brain. For example, you can think of the eye as a camera that obtains information from the outside world and the brain as a computer that processes that information. In this example, the optic nerve is like a cable connecting the eye (or the camera) to the brain (or the computer), allowing information to be processed.

With periods of elevated pressure in the eye, damage first occurs in the outskirts of the optic nerve, resulting in peripheral (or side) vision loss. The effect can be like looking through a tube or into a narrow tunnel, making walking difficult without bumping into objects off to the side, near the head, or at the foot level. As the disease progresses and the optic nerve damage continues, the field of vision constricts until complete vision is lost. This is why glaucoma is often called the “sneak thief of sight,” as the symptoms or early warning signs of glaucoma are very subtle.

Glaucoma can happen in 1 eye or both eyes. 

Early detection through a comprehensive eye exam, appropriate and ongoing treatment, and the availability of specialized low vision and vision rehabilitation services can help people with glaucoma live productive and satisfying lives.

Facts About Glaucoma

Glaucoma is a group of eye diseases that can lead to blindness by damaging the optic nerve. The eye continuously produces an aqueous fluid that must drain from the eye to maintain healthy eye pressure.

• Glaucoma affects more than 3 million people living in the United States.
• Glaucoma is a leading cause of blindness in African Americans, who should begin glaucoma tests as early as age 35.
• Glaucoma has many causes, and elevated eye pressure is a factor in most. Pressure builds up in the eye due to problems with the drainage of aqueous, a fluid produced in the eye.
• Glaucoma can cause irreversible damage to the optic nerve if left undetected and untreated. The optic nerve transmits information from the eye to the brain for processing.
• Glaucoma results in a loss of peripheral or side vision initially, which affects your ability to move about safely. Over time, glaucoma can damage your central vision as well.
• Glaucoma can also affect reading because losing the visual field can reduce the number of words you can see simultaneously.
• Glaucoma is particularly dangerous to your vision because there are usually no noticeable symptoms initially. A comprehensive dilated eye exam is critical to detect changes that occur early in the optic nerve.
• A dilated eye exam is recommended every one to two years for people at higher risk for glaucoma, including African Americans age 40 and older, everyone over age 60 (especially Mexican Americans), and people with a family history of glaucoma.
• Early treatment for glaucoma can usually (but not always) slow the progression of the disease. However, as of yet, there is no cure for glaucoma.

How Would You Describe the Eyesight of One with Glaucoma?

Glaucoma results in peripheral field loss, which can progress to the point of total blindness if left untreated. An individual with loss of peripheral vision has some degree of “tunnel vision” making it difficult to gather comprehensive visual information in an environment. He or she will benefit from learning visual efficiency skills such as scanning an environment in an organized manner and possibly using a reverse telescope to minimize the appearance of an image and see its entirety within the remaining field of vision.

Additionally, the individual is likely to bump into side-lying and low-lying obstacles; he or she should utilize orientation and mobility skills, such as the use of a cane, to avoid obstacles.

If your child’s vision loss progresses to near-total or total loss of sight, he or she must be taught to complete tasks without the use of vision. Your child may be taught braille, screen-reading software to use the computer, and techniques for performing life-skills and academic tasks from the teacher of students with visual impairments and orientation and mobility specialist.

It is common for bright sunlight and glare to cause significant discomfort and inability to see (this is known as a “whiteout”) in one with glaucoma. Your child may benefit from specialized sunglasses (amber-tinted lenses), use of a brimmed hat while outdoors as well as shutting blinds while indoors if glare is present.

Your child’s teacher of students with visual impairments should perform a functional vision assessment to determine how your child uses his or her vision in everyday life and a learning media assessment to determine which senses your child primarily uses to get information from the environment. These assessments, along with an orientation and mobility assessment conducted by a mobility specialist, will give the team information needed to make specific recommendations for your child to best access learning material and his or her environment.

Resources for Families of Children with Glaucoma

Lighthouse Guild for the Blind offers a free national tele-support network for parents of children with visual impairment to connect you with parents whose children also have glaucoma so that you can share resources, experiences, strength, and hope. The tele-support groups meet by phone every week and are facilitated by a psychologist or social worker with input from professionals knowledgeable about children’s eye conditions.

For more information or to enroll in a tele-support group, call 800-562-6265 or write to [email protected].

What Will Happen at My Eye Appointment?

Because glaucoma can begin to develop without noticeable symptoms, the best way to protect your sight from glaucoma is to have regular comprehensive eye examinations to assess your eye pressure, optic nerve health, thinning of the cornea, and other signs of potential problems. An ophthalmologist or optometrist diagnoses glaucoma by doing a comprehensive medical eye examination, which should include all of the following components:

A Health and Medication History

• Your overall health and that of your immediate family
• The medications you are taking (prescription and over-the-counter)
• Questions about high blood pressure (hypertension), diabetes, smoking, and sun exposure

A Vision History

• How well you can see at present, including any recent changes in your vision
• Eye diseases that you or your family members have had, including macular degeneration and glaucoma
• Previous eye treatments, surgeries, or injuries
• The date of your last eye examination

Visual Acuity Testing

• Distance and near vision acuity tests to determine the sharpness or clarity of your reading and distance vision
• Testing your vision with different lenses (sometimes contained in a machine called a phoropter), pictured at right) to determine if your vision can be improved or corrected with regular glasses or contact lenses. This can indirectly help your doctor determine the size of your eye to determine whether you are at risk for particular types of glaucoma.

Basic Visual Field Testing

• This test determines how much side (or peripheral) vision you have and the surrounding area you can see.
• The most common type of visual field test in a regular eye exam is a confrontation field test. This test measures only the outer edge of the visual field and will not reveal changes in early glaucoma. See Perimetry (below) for more detailed and precise visual field testing for glaucoma.

An Eye Health Evaluation

• A penlight is used to assess for a relative afferent pupillary defect, which can indirectly help your doctor determine if there is a nerve dysfunction in one eye as compared to the other eye.
• A tonometer, a machine used to check pressure, assesses the amount of aqueous humor or pressure within your eyes. There are various ways and instruments to measure the pressure inside your eyes, including a machine that ejects a puff of air, a pen-like probe that taps the surface of your eye, or a tool on the slit-lamp itself that taps the surface of your eye. Your doctor might also refer to this pressure as intraocular (“within the eye”) pressure or IOP.
• A special microscope called a slit lamp is used to examine the anterior segment of the eye (a front third of the eyeball), including the cornea, pupil, iris, lens, and aqueous drainage structures.
• A dilated eye (or fundus) examination that can be achieved with special lenses will allow your doctor to see inside your eye and examine the retina and optic nerve. Your doctor might use eye drops to see the retina and optic nerve more clearly.

Additional Tests for Glaucoma

If your eye doctor suspects that you may have glaucoma, you will need to undergo additional testing that can help your doctor make a more definitive diagnosis of glaucoma:

Gonioscopy

• Examining the eye’s drainage system is an important aspect of the assessment for glaucoma as decreased drainage of the fluid (aqueous humor) can increase eye pressure. This drainage system, or drainage angle, is formed between your cornea and iris. As it is located around a “corner” of your cornea, the doctor cannot see this structure by looking directly into your eye.
• To view the drainage system of the eye, a mirrored contact lens test called a gonioscopy must be done. To do this exam, the doctor will numb the surface of your eye with an anesthetic drop. Then a lens, called a gonioscope, is placed on the surface of your eye like a large contact lens. The doctor will have you look straight ahead, then use the slit lamp to look through the lens and assesses the angle.

Pachymetry

• This test uses a probe that emits an ultrasonic wave to measure the thickness of your cornea. Thicker-than-normal corneas can give IOP readings that are inaccurately high, while thinner-than-normal corneas can give IOP readings that are inaccurately low.
• To measure your corneal thickness, the doctor will numb the surface of your eye with an anesthetic drop. Then will have you look straight and touch the tip of the pachymeter probe to the surface of your cornea. The probe emits a painless ultrasound wave that measures your corneal thickness.

OCT

• As glaucoma progresses, the optic nerve thins. This can be assessed by your doctor subjectively by looking at the optic nerve and measuring the thinning of the nerve itself. However, your doctor may want to assess this objectively with a machine that measures the thickness of the optic nerve. This test is done through a non-invasive imaging test called Optical Coherence Tomography, or OCT.
• The technician or ocular photographer will have you rest your head on a chinrest and look straight at a target. The machine will then focus on your optic nerve and scan the area to measure the thickness in each direction. Your doctor will be able to view these results and assess the progression of glaucoma by comparing these results with any past or future test results.

Perimetry

• This test measures and maps your visual fields. Perimetry testing can draw a map of your visual fields and show you where you may have lost vision, especially your peripheral (or side) vision, which is the vision usually affected by early damage to the optic nerve from glaucoma.

• The Humphrey Field Analyzer (pictured at right) is the most commonly used perimetry test. The machine resembles a large bowl. One eye is covered with a patch while the other remains stationary and focused straight ahead. Small white lights of varying sizes and intensities will flash at different locations around the bowl. You will be instructed to press a button whenever you see a flashing light. Recording which lights you see and which you do not creates a visual field map.

Updated by Sefy Paulose, M.D., March 2022

What are some Risk Factors with Glaucoma?

• Elevated eye pressure:
  • Eye pressure can vary considerably over 24 hours. So, one eye pressure measurement taken in the office does not provide an accurate assessment of eye pressure as elevated eye pressure may occur intermittently in glaucomatous eyes. However, most eye care professionals define the normal eye pressure range as between 10 and 21mmHg (millimeters of mercury which is a pressure measurement).
• Age:
  • Over age 60
• Ethnic Background:
  • People of Black African and/or Black Caribbean descent, Hispanics, and Asians have an increased risk of developing glaucoma, developing it at an earlier age and a more advanced stage than those White individuals.
• Family History:
  • Family history of glaucoma, such as a sibling or parent with glaucoma. The most common type of glaucoma, primary open angle glaucoma, is more common in people with a family history of glaucoma.
• Refractive error:
  • High myopia, or nearsightedness, has put patients at a greater risk for the most common type of glaucoma, primary open-angle glaucoma.
  • High hyperopia, or farsightedness, increases the risk for glaucoma related to a blocked drainage system of the eye also called narrow-angle glaucoma or angle closure glaucoma.
• Corneal thickness:
  • Cornea is the structure in the front of the eye that gives a particular refract. A thin cornea can increase the risk of glaucoma, specifically corneas with a central corneal thickness of less than 0.540 millimeters.
• Medical conditions:
  • Diabetes mellitus: Patients with uncontrolled diabetic mellitus can result in diabetic retinopathy, which can block the drainage system of the eye and cause a specific kind of glaucoma
  • Injuries or Surgeries: Injuries to the eye, such as blunt trauma and sports injuries, or a history of multiple eye surgeries for chronic eye conditions can cause secondary glaucoma. Blunt trauma can create inflammation in the eye or alter the anatomy of the eye’s drainage system and place the patient at increased risk for the development of glaucoma. Inflammation occurs with any eye surgery but is usually limited and causes very minimal alteration of the anatomy of the eye’s drainage system. Rarely, more inflammation and/or damage to the drainage structures in the eye can occur, putting the person at increased risk for glaucoma.
  • Other conditions: Several conditions may increase the risk of glaucoma, but further research is still needed to stratify this risk: sleep apnea, thyroid disorders, migraine headaches, low blood pressure, and hypertension.

Ways to Reduce Your Risks

• The best ways to reduce your risk of experiencing permanent vision loss from glaucoma are to get regular comprehensive eye exams and to follow the treatment regimen prescribed by your eye care professional.
• If you have problems with the eye drops prescribed for your glaucoma, do not stop taking them. Instead, contact your eye doctor immediately to determine if you need to change your medication.
• The onset of glaucoma usually does not cause noticeable symptoms, so early detection, informed management of your glaucoma, and ongoing follow-up exams are crucial to limiting vision loss.

Updated by Sefy Paulose, M.D,, March, 2022

Different Types of Glaucoma

Glaucoma is a group of eye diseases that can lead to blindness by damaging the optic nerve. The eye continuously produces a fluid called aqueous humor that must drain through the eye’s drainage system, or angle, to maintain healthy eye pressure. The different types of glaucoma are described by whether this drainage system is open or narrow. One cause of increased eye pressure is when the drainage system, or angle, is narrow or blocked.

Primary Open Angle Glaucoma

The most common type of glaucoma in the United States is Primary Open Angle Glaucoma (POAG). In POAG, the eye’s drainage system appears to be normal or open, yet the eye has high pressure. This is due to the increasing fluid production in the eye or aqueous humor. If the fluid in your eye can’t drain fast enough, it creates pressure that pushes on the optic nerve in the back of your eye.  Over time, the pressure damages the optic nerve, which affects your vision. People often do not have symptoms until they start losing their vision, and they may not notice vision loss immediately.

Open-angle glaucoma is termed “primary” if no other underlying factors could cause the elevated pressure. If there is an identifiable cause for increased eye pressure, the condition is called Secondary Open Angle Glaucoma (see below).

POAG is treated by decreasing the production or by increasing the drainage of aqueous humor. This can be achieved with medications (eye drops or pills), specific kinds of laser treatments, or by surgery.

Primary Angle Closure Glaucoma

Primary Angle Closure Glaucoma is much less common than POAG in the United States. In this type of glaucoma, the aqueous humor cannot drain properly because the entrance to the drainage canal is either too narrow or closed completely. In this case, eye pressure can occur episodically, mainly when triggered by pupil dilation, which happens intermittently throughout the day with changes in light. If the angle is narrow but not completely closed, symptoms can be vague such as pain, headaches and blurry vision. Symptoms of sudden angle-closure glaucoma can include sudden eye pain, nausea, headaches, and blurred vision. If you experience these symptoms, you should seek immediate medical treatment.

Normal-Tension Glaucoma

In this type of glaucoma, also called low-pressure glaucoma, the eye’s drainage system appears normal, and the eye pressure is not elevated. Yet, there is still evidence of optic nerve damage. This type of glaucoma is treated much like POAG, but the eye pressure needs to be kept even lower to prevent the progression of vision loss. According to the NEI, “You may be at higher risk for normal-tension glaucoma if you:

• Are of Japanese ancestry
• Have a family history of normal-tension glaucoma
• Have had certain heart problems, like an irregular heartbeat
• Have low blood pressure”

Secondary Glaucomas

Secondary glaucomas develop as secondary to, or as complications of, other conditions such as eye trauma, cataracts, diabetes, eye surgery, inflammation, or tumors. Treatment of these would include treating the underlying cause of glaucoma and eye-pressure lowering medication as above. As in the other types of glaucoma, the sooner eye pressure is normalized, the more functional vision can be preserved.

• Facts About Glaucoma by the National Eye Institute
• Glaucoma Research Foundation
• Glaucoma by the American Optometric Association
• Glaucoma by AFB’s VisionAware

What Can I do if I have Severe Vision Loss from Glaucoma?

• Consider having a low vision exam. Doing so will help you learn how to use your existing vision to your best advantage. A magnifier or prism glasses may help expand your visual field, but only a low-vision specialist can determine what products and technology will work best with your vision.
• Consider vision rehabilitation services to help you learn how to manage everyday tasks more easily. Preparing meals, performing personal self-care tasks, making home repairs, and enjoying leisure activities are easier with appropriate training in techniques that use your remaining vision and other senses combined with specialized products.
• Work with an orientation and mobility specialist to learn to use a long white cane if you have problems detecting curbs, crossing the street, or finding your way in poor lighting or unfamiliar surroundings. Independent travel is possible with training and persistence.
• Because glaucoma affects your peripheral (or side) vision, remember to scan your environment to ensure you are not missing things. The brain often fills in blind spots in the visual field, making it difficult to be aware of the extent of your vision loss.
• It is important to identify the boundaries of your visual field loss and learn to locate objects in your environment more easily. One helpful technique is to place a contrasting-colored strip of tape or a sticker on the left and right side of each doorway or cupboard to help you find the edges.
• Consistency and organization are helpful principles for many people with glaucoma and other types of vision loss. Leave things in the same place so you can find them again, and tell your family members to do the same.
• If reading print is difficult for you, use a small digital recorder to keep track of your appointments and medications.
• Talk to your family about what you are experiencing and how they can help you. Remember, you are ultimately responsible for managing your glaucoma and ensuring you adhere to your doctor’s advice and medical regimen. Ask questions and solicit help when you need it.

Managing Your Glaucoma Medications

You must adhere to your glaucoma medication regimen. Here are some tips to make it easier for you:

• Keep your glaucoma medications in the same place at all times so that you can find them easily.
• Use a medication organizer with an alarm or similar device to keep track of the times you need to use your medications.
• Write a sticky note reminder in large print with a wide-tip marker and put it on your bathroom mirror.
• If your hands shake and make it difficult to administer your eye drops, many adaptive devices can help you.