Jun 145 min read

Glaucoma

Updated: Aug 28

Introduction

Glaucoma is a group of eye conditions that damage the optic nerve, leading to irreversible sight loss. It is the leading cause of blindness in the United States and the second leading cause of blindness in the world. Over 2 million people are affected with the more common forms of this disease: open-angle glaucoma and angle-closure glaucoma. This disease, in particular, is horrifying because those who develop it over time are generally asymptomatic, thus explaining its common nickname, “the silent sneak of sight”. Because the changes in vision of a person with glaucoma over time are so miniscule, almost unidentifiable, it almost always gets recognized in the later stages of its progression. Although the signs of glaucoma's presence are few, there are some patterns that it follows regarding its victims. So, what is glaucoma and why is it such a big deal?

Background

Glaucoma usually occurs when the fluid pressure inside the eye rises over time and slowly causes damage to the optic nerve. Although unlikely, if caught in the early stages it can be treated and vision can be preserved for longer. Without treatment, however, blind spots start to appear and peripheral vision begins to disappear, causing vision as if looking through a tunnel. Eventually, this tunnel vision will decrease until complete blindness is reached. Although there is no cure as of now, there are measures that can control glaucoma and slow blindness from taking over completely. Eyedrops, medicines, laser treatments, and surgery are some methods of mitigating the effects of glaucoma. Because there are many types of glaucoma caused by many differing variables, some treatments are more favorable for some, than they are for others. Due to the lack of research and knowledge regarding glaucoma treatments, there is room for growth in this area to more efficiently target the glaucoma at the source.

Types of Glaucoma

Primary Glaucoma is a category of glaucoma that accounts for instances when a pre-existing condition of the patient is not the cause of the blindness. The most common type of glaucoma in this category, so much so that 90% of people who have glaucoma have this type, is Open-angle glaucoma. When the pressure that builds in their eye can’t drain fast enough and pushes the optic nerve into the back of their eye. This pressure causes distress to the nerve and the nerve loses its function, which is why blindness occurs over time.

Normal-tension glaucoma is the second type of primary glaucoma. This type of glaucoma is peculiar to experts because it occurs without intraocular pressures (IOP) exceeding a normal range. Not much is known regarding the causes of normal-tension glaucoma but it has been known to cause bilateral blindness.

Angle-closure glaucoma (AKA narrow-angle or acute glaucoma) occurs when the outer edge of the iris blocks any buildup of fluid from draining, thus causing rapid growth of IOP. This is a medical emergency if left untreated, it can cause blindness in just a few days. Symptoms of this include sudden intense eye pain, red eyes, nausea, or blurry vision.

Congenital glaucoma is the last type in the primary glaucoma category. This occurs when babies are born with the inability to drain fluid from their eyes normally. This condition is extremely rare (around 1 in 10,000 babies are born with it in the U.S.) It is fairly easy to discern because the child has cloudy eyes, is sensitive to light, makes extra tears, and has abnormally large eyes. Surgery for this type of glaucoma has a high success rate and permanent vision loss is usually not a concern after the surgery.

Secondary glaucoma is caused by pre-existing medical conditions. Neovascular glaucoma occurs when blood vessels cover the area where fluid is supposed to drain from your eye. This blockage of the draining path is common in people with diabetes or high blood pressure. This complicates the treatment process because to target the glaucoma, the underlying causes must be addressed to relieve the eye of built-up pressure.

Pigmentary glaucoma is when the iris pigment flakes off and blocks the drainage site in the eye, causing a build-up in IOP. This phenomenon is generally referred to as pigment dispersion syndrome (PDS) and occurs when zonules, fibers that hold the Iris’s pigment in place, start to rub against the eye lens and flake off. This type of glaucoma is generally found in near-sighted white men. If you see rainbow-colored rings around lights, especially during exercise, you may have this type of glaucoma.

Exfoliation glaucoma, a type of open-angle glaucoma, occurs in people with exfoliation syndrome: when extra material deposits on regions of the eye and causes blockage of the draining site. Although rare, exfoliation syndrome is genetic, so this type of glaucoma likely follows within the family tree. This type of glaucoma can build in IOP at a faster rate, thus those at risk of it must get their eyes checked often.

Finally, Uveitic glaucoma is common in people with uveitis: a condition causing swelling and inflammation in the eyes. It is thought that because the inflammation occurs in the middle of the eye and leaves scar tissue beyond, it blocks or damages the drainage site in the eye and increases IOP. Around 20% of people with uveitis develop uveitic glaucoma in their lifetime, so it is quite rare.

Patterns

Those of older age (generally above 40), Asian/ African/ Hispanic descent, and female sex fit into the categories of most likely to suffer from visual impairment caused by glaucoma. People with a family history of glaucoma are at high risk of primary open-angle glaucoma. The risk of obtaining it is 4-9 times larger if seen in family history. Heart problems, migraine, low blood pressure, Japanese ancestry, sleep apnea, Alzheimer's dementia, and raised intraocular pressure (IOP) are a few more things that make one at a higher risk for this disease. It is hard to determine who is more at risk of glaucoma because each type of glaucoma has varying target groups, some favoring certain pre-existing conditions and others simply relying on the patient's gene pool.

Conclusion

Glaucoma research has been making headway as we travel down the possible path of integrating stem cells into the retina to better control glaucoma. Additionally, catching glaucoma in its earlier stages is an area of focus for researchers because the sooner it is caught, the better the chances are to stop it before total blindness takes over. Clinical applications are in the discussion of glaucoma treatments, furthering the likeliness that there is a chance of finding a cure in the near future.

Sources

Glaucoma

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