What is Glaucoma?

Glaucoma is a group of eye diseases that cause progressive damage of the optic nerve at the point where it leaves the eye to carry visual information to the brain.

If left untreated, most types of glaucoma progress, without warning nor obvious symptoms to the patient, towards gradually worsening visual damage and could eventually lead to blindness. And if sight is lost to glaucoma, the visual damage is mostly irreversible. This is why glaucoma has also been labeled as the “silent blinding disease” or the “sneak thief of sight”.

Types of glaucoma

There are several types of glaucoma. Some may occur as a complication of other visual disorders (the so-called “secondary” glaucomas), but the vast majority is “primary”, i.e. they occur without a known cause. It was once believed that the cause of most, or even all glaucomas, was high pressure within the eye; known as intraocular pressure, sometimes abbreviated as IOP. It is now established, however, that even people without an abnormally high IOP may suffer from glaucoma. Therefore, intraocular pressure is considered one of the risk factors, yet there are additional factors to consider such as racial ancestry, family history, high myopia and age.

While there is no clearly established difference in glaucoma incidence between men and women, some forms of glaucoma may occur at birth (congenital) and some others during infancy and childhood (juvenile). In most cases, however, glaucoma appears after the 4th decade of life, and its frequency may increase with age.

The most common types of adult-onset glaucoma are ‘Primary Open Angle Glaucoma (POAG)’, a form most frequently encountered in patients of Caucasian and African ancestry, and ‘Angle-Closure Glaucoma (ACG)’, which is more common in patients of Asian ancestry. Angle-Closure Glaucoma is often chronic, just like POAG, but can sometimes be acute, in which case it usually appears as a very painful ocular condition leading to rapid vision loss.

Furthermore, ‘Exfoliation Syndrome (XFS)’[1] is the most common recognizable cause of open-angle glaucoma worldwide, accounting for the majority of cases in several countries and is estimated to affect 60-80 million people. It is also associated with angle-closure and numerous systemic diseases. It has also recently been associated with inguinal hernia, chronic obstructive pulmonary disease, skin cancer, and atrial fibrillation. It is potentially preventable and a significant amount of research into its genetics, biochemistry and cell biology is underway.

Who is at risk?

There are people who are more vulnerable to getting glaucoma. This includes:

• People over the age of 40
• People with family members who have glaucoma
• Those who are of African, Hispanic or Asian heritage
• People with high eye pressure
• People who are farsighted or nearsighted
• Those who have suffered from an eye injury
• People who use long-term steroid medications
• Those who have thin corneas
• People who have a thinning optic nerve
• People living with diabetes, migraines, high and low blood pressure, poor blood circulation or other health problems that affect the whole body

The current state of glaucoma worldwide

Facts and figures

• Glaucoma is the second most common cause of blindness worldwide; the third most common in Europe and the USA
• An estimated 78 million individuals are currently living with glaucoma (2020)^[2]
• It is predicted that 111.8 million individuals will have glaucoma by 2040
• 90% of glaucoma is undetected in developing countries
• An estimated 11 million individuals will be bilaterally blind due to glaucoma by 2020 (13% of glaucoma cases)
• At least 1 billion people have no access to eye care, due to it being unfairly distributed globally
• Africa accounts for 15% of the worlds blindness due to glaucoma^[3]
• 90% of blindness is found in the developing world, and 75% of that is treatable or preventable
• Global prevalence of glaucoma for persons ages 40 – 80 years is 3.54%
• Family members of those with glaucoma have a ten-fold risk of getting glaucoma themselves
• Every one in 200 people aged 40 have glaucoma, which rises to one in eight by age 80
• Poor public awareness, knowledge and misconceptions associated with glaucoma is a challenge for public health professionals.^[4]

Prevention, diagnosis and treatment

Currently, there is no cure for glaucoma, and vision loss due to glaucoma is irreversible; however, medication or surgery (traditional or laser) can halt or slow down any further vision loss. Early detection is paramount to limiting visual impairment and preventing the progression towards severe visual handicap or blindness. Eye professionals can detect glaucoma in its early stages and advise on the best course of action.

Prevention

To eliminate glaucoma blindness, we have to tackle three facts:

• Glaucoma usually gives no warning until it is advanced
• The damage to vision it causes is ongoing
• The damage is irreversible

For most people living with glaucoma, treatment can prevent further damage. That means, the earlier the diagnosis, the more vision there is to save and the less likely it is that the person will become visually handicapped. The World Glaucoma Week (WGW) alerts members of the broad community to the need for regular simple eye checks, allowing for earlier detection.

While you may not be able to fully control the onset of glaucoma, you can take preventative steps to help minimize the risk of glaucoma, including:

• Routine eye checks
• Following a nutritious and well-rounded diet
• Exercising regularly to promote blood flow
• Not smoking
• Regulating caffeine intake
• Protecting your eyes from injury, trauma and the sun (wear eye protection)

Diagnosis

Glaucoma tests are painless and do not take too long. The best way to spot glaucoma early on is through regular eye exams with your eye-care professional, including:

• Using drops to dilate your pupils and examine your eyes
• Do a test called tonometry to measure your intraocular pressure (IOP) and see if your levels are within the normal range.
• Perform a field vision test to check your peripheral vision and ensure you are not losing any side vision.
• Check your optic nerve for any signs of glaucoma. At times, photographs are taken so that they can spot any changes during your next visit.

Treatment

While glaucoma damage cannot be reversed, and it is not always possible to fully stop the progression of the disease, it can almost always be slowed with proper treatment. Treatment is dependent on your specific case and type of glaucoma, but can include:

• Prescription eye-drops
• Surgery and special therapies
• Laser therapy
• Filtering therapy (Trabeculectomy)
• Inserting drainage tubes
• Minimally invasive glaucoma surgery (MIGS)

New treatment research is focused on lowering pressure inside the eye, finding medications to protect and preserve the optic nerve from the damage that causes vision loss, and the role of genetic factors.

The future of glaucoma

The impact of glaucoma on the world is expected to grow in the coming years. It is staggering that the number of people living with this disease is projected to increase to more than 111 million by 2040.

However, healthcare professionals are gradually getting closer to understanding the genetics of glaucoma and the reason vision is damaged on a cellular level. This advancement will pave the way for new treatment strategies with the tantalizing possibility of actually being able to reverse damage caused by the disease.

Furthermore, artificial intelligence (AI) driven interpretations of images of a person’s optic nerve promises to revolutionize early detection on a large scale. This is most exciting, as it will allow more accurate diagnosis and earlier onset of effective treatment.

To learn more about glaucoma, visit www.glaucomapatients.org

^[1] Robert Ritch MD, Systemic Association of Exfoliation Syndrome, Asia Pac J Ophthalmol 2016;5: 45–50

^[2] https://www.glaucomapatients.org/basic/statistics/

^[3] Tham YC, Li X, Wong TY, Quigley HA, Aung T, Cheng CY. Global prevalence of glaucoma and projections of glaucoma burden through 2040: a systematic review and meta-analysis. Ophthalmology. 2014;121(11):2081–90.

^[4] Livingston PM, Lee SE, De Paola C, Carson CA, Guest CS, Taylor HR. Knowledge of glaucoma, and its relationship to self-care practices, in a population sample. Aust N Z J Ophthalmol. 1995;23(1):37–41.