Glaucoma: Symptoms, Causes, and Treatment

Today, glaucoma is one of the most prevalent eye diseases. There are two main forms of the condition: primary open-angle glaucoma (POAG), the most common, and secondary glaucoma. There are several subtypes of secondary glaucoma. Worldwide, an estimated 57.5 million people are affected by POAG. By 2040, estimates show the number of people with glaucoma will rise to 111.8 million.

Glaucoma is strongly correlated with age and tends to be more common in certain ethnicities, such as being Hispanic, Latinx, or black. A positive family history of glaucoma also increases the chance that an individual will develop the disease.

Symptoms

Glaucoma is sometimes referred to as the “silent thief” because it can cause irreversible damage to the eyes before any symptoms show. It tends to progress slowly, causing damage over many years. As the disease progresses, it can eventually cause a noticeable decrease in peripheral vision. But by this time, the condition is rather advanced. Another reason that symptoms may not be noticeable is glaucoma tends to cause asymmetric damage, meaning one eye suffers more vision loss than the other. The brain is exceptionally good at compensating for this, and therefore one may not notice that one eye has lost vision until quite late.

Angle-closure glaucoma, one of the secondary types of glaucoma, may cause more symptoms than POAG. These include eye pain, blurry vision, halos around light sources, and nausea or even vomiting. Angle-closure glaucoma tends to cause damage much more quickly than POAG. Because of the risk of rapid and permanent vision loss, it should be treated as an emergency.

Causes

Glaucoma is a multifactorial disease of the optic nerve, the conduit that transmits information from the eye to the brain. In most types of glaucoma, the pressure inside the eye, called intraocular pressure (IOP) rises, causing damage to the optic nerve and surrounding retinal cells. POAG tends to have no identifiable root for this rise in IOP, while secondary glaucoma often has a recognizable cause. One subtype of secondary glaucoma, called normal-tension glaucoma (NTG), does not involve increased IOP. This finding reinforces the multifactorial nature of the disease and the need for more research.

The diagnosis of glaucoma involves multiple screening tests.

  • The measurement of IOP is one facet of the evaluation.
  • The drainage system for the fluid inside the eye should be examined using a technique called gonioscopy.
  • The optic nerve is examined after pupil dilation.
  • Visual field testing is performed to check for any areas of missing or diminished vision.
  • A specialized machine is also generally used to scan the nerve layers of the eye; this helps check for any damage.

It sometimes takes multiple visits to make the diagnosis of glaucoma. It is imperative to continue with regular follow-up if there is suspicion of glaucoma, to make a diagnosis, and initiate treatment promptly if it’s needed.

Treatments

The following treatment options are available for those with glaucoma. They include:

  • Prescription eye drops: This is the primary treatment for glaucoma. Several different types of medication can be used, depending on the patient's needs. The goal of these medications is to decrease IOP. If one medication does not control IOP sufficiently, additional medication(s) may be added until an acceptable level is achieved.
  • A laser procedure: Called selective laser trabeculoplasty (SLT) or Argon laser trabeculoplasty (ALT), it is an alternative to eye drops. These laser therapies don’t work for everyone, but they can be useful for those that don’t wish to take eye drops or don’t tolerate their side effects. Laser trabeculoplasty is not a permanent treatment for glaucoma and must be repeated periodically to maintain IOP control. In addition, the procedure tends to become less effective the more times it’s repeated.
  • A different type of laser: Called laser peripheral iridotomy (LPI), it is sometimes used in angle-closure glaucoma.
  • Surgery: In particularly aggressive cases of glaucoma, surgery may be necessary. Patients who have glaucoma surgery often still need to use medication(s).

Summary

Glaucoma is one of the reasons that it’s so important to seek regular eye care, even if one doesn’t have any eye symptoms. Those between the ages of 40-64 should get their eyes examined every two years if asymptomatic. After the age of 65, eye exams should be annual. If you have symptoms, or if your eye doctor recommends it, more frequent follow-up may be necessary.

Although glaucoma is treatable, the damage the condition causes is irreversible. The goal of glaucoma treatment is to initiate it early and slow down the condition's progress as much as possible to preserve vision.

With regular dilated eye exams, you can be sure that you’ll get the treatment you need as soon as possible.

References:

Allison K, Patel D, Alabi O. Epidemiology of Glaucoma: The Past, Present, and Predictions for the Future. Cureus. 2020;12(11):e11686. Published 2020 Nov 24. doi:10.7759/cureus.11686

Comprehensive eye exams. Aoa.org. https://www.aoa.org/healthy-eyes/caring-for-your-eyes/eye-exams?sso=y.

Glaucoma | National Eye Institute. Nei.nih.gov. https://www.nei.nih.gov/learn-about-eye-health/eye-conditions-and-diseases/glaucoma.

Glaucoma: The 'silent thief' begins to tell its secrets | National Eye Institute. Nei.nih.gov. https://www.nei.nih.gov/about/news-and-events/news/glaucoma-silent-thief-begins-tell-its-secrets. Published 2014.

Khazaeni B, Khazaeni L. Acute Closed Angle Glaucoma. In: StatPearls. Treasure Island (FL): StatPearls Publishing; April 30, 2022.

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