Glaucoma, an eye condition that affects the optic nerve, usually due to increased intraocular pressure (IOP), affects about 80 million people worldwide. In the United States alone, more than 3 million Americans have glaucoma.
Interestingly, half the people who have glaucoma do not even know it, and this is why it is often dubbed the silent thief of sight. Typically, in its early stages, glaucoma progresses without noticeable symptoms. When patients begin to notice that their vision is not what it used to be, it is often too late.
Understanding the different types of glaucoma is crucial, as each type has its unique characteristics and mechanisms that affect the progression of the disease.
While all forms of glaucoma can lead to optic nerve damage and vision loss if left untreated, the underlying causes and patterns of development vary. The most common types of glaucoma include open-angle glaucoma, angle-closure glaucoma and normal-tension glaucoma, but there are also secondary and congenital forms of the disease.
Open-angle glaucoma is the most prevalent form of glaucoma, responsible for approximately 90 per cent of cases. In this condition, the drainage angle of the eye, where the cornea and iris meet, appears normal. However, the eye’s drainage system gradually becomes less effective, resulting in a slow build-up of IOP. Over time, this pressure can damage the optic nerve. The progression is typically gradual and painless, often without noticeable symptoms until substantial vision loss has occurred.
Angle-closure glaucoma is a less common but more critical form of glaucoma that requires immediate attention. It occurs when the iris (the coloured part of the eye) moves too close to the drainage angle, suddenly blocking the eye’s drainage system. This blockage causes a rapid and severe rise in IOP. Symptoms may include intense eye pain, headache, nausea, vomiting, blurred vision and halos around lights. Because of its urgency, angle-closure glaucoma is considered a medical emergency and demands prompt treatment.
Normal-tension glaucoma is a condition where damage to the optic nerve occurs despite IOP remaining within the normal range. While the exact cause is not fully understood, it may be linked to reduced blood flow to the optic nerve or other factors that increase the nerve’s vulnerability to damage. Similar to open-angle glaucoma, it often progresses silently, with no noticeable symptoms until significant vision loss has taken place. Treatment typically aims to lower IOP and protect the optic nerve from further damage.
Secondary glaucoma encompasses any form of glaucoma that arises due to another medical condition or injury. Causes can include eye trauma, inflammation, tumours, or systemic diseases such as diabetes or cataracts.
Additionally, certain medications, such as corticosteroids, can elevate the risk of developing this condition. Treatment focuses on addressing the underlying cause while also managing IOP to prevent further damage.
Congenital glaucoma is a rare form of glaucoma present at birth, caused by improper development of the eye’s drainage system during foetal growth. This results in elevated IOP.
Symptoms in infants may include excessive tearing, sensitivity to light and a cloudy cornea. Early diagnosis and intervention are critical to prevent permanent vision loss, with surgery often required to address the drainage problem.
The Glaucoma Research Foundation emphasises that vision loss from glaucoma is silent, gradual, progressive and irreversible, but it is treatable. Early detection is crucial for managing the disease and preventing permanent vision loss. Regular eye exams are essential, especially for individuals at higher risk.
During these exams, tests like tonometry (to measure IOP), visual field tests (to detect vision loss) and optic nerve imaging (to assess damage) can identify glaucoma in its early stages, often before symptoms appear.
Those at greater risk, such as individuals over 60, people with a family history of glaucoma, or those with conditions like diabetes, should prioritise regular screenings. Early detection allows for more effective treatment options to preserve vision.
While glaucoma progresses silently, it is not without solutions. Understanding the different types of glaucoma and committing to routine eye care are vital steps toward protecting long-term vision health.
Don’t let glaucoma take you by surprise; take charge of your sight with awareness and regular screenings.
