Glaucoma

• Glaucoma is a serious eye condition that damages the optic nerve.
• It is frequently associated with elevated pressure inside the eye.
• There are several types of glaucoma, with open-angle and angle-closure being the most common.
• Many forms of glaucoma progress without noticeable symptoms until vision loss is significant.
• Early and accurate diagnosis through comprehensive eye exams is crucial for managing the condition and preserving vision.

What is Glaucoma?

Glaucoma is a complex group of eye diseases characterized by progressive damage to the optic nerve. This nerve transmits visual information from the eye to the brain, and its damage can lead to irreversible vision loss and, if left untreated, blindness. While high intraocular pressure (IOP) is a primary risk factor, glaucoma can also occur with normal eye pressure. The condition often progresses without early warning signs, earning it the nickname “the silent thief of sight.” According to the World Health Organization (WHO), glaucoma is the second leading cause of blindness globally, affecting millions of people.

Understanding what is glaucoma involves recognizing that it’s not a single disease but rather a spectrum of conditions that share a common outcome: optic nerve damage. Regular eye examinations are essential for early detection, especially for individuals at higher risk, as early intervention can significantly slow its progression and preserve remaining vision.

Types of Glaucoma, Symptoms, and Causes

There are several distinct types of glaucoma explained, each with specific characteristics, symptoms, and underlying causes. The two most prevalent forms are primary open-angle glaucoma and angle-closure glaucoma.

• Primary Open-Angle Glaucoma (POAG): This is the most common type, accounting for at least 90% of all glaucoma cases. It develops gradually when the eye’s drainage canals become clogged over time, leading to increased intraocular pressure. POAG often presents with no pain or immediate vision changes, making early detection challenging. Vision loss begins with peripheral vision and slowly progresses inward.
• Angle-Closure Glaucoma (ACG): Also known as narrow-angle or acute glaucoma, this type occurs when the iris (the colored part of your eye) bulges forward, blocking the drainage angle formed by the cornea and iris. This blockage causes a sudden, sharp increase in eye pressure. ACG can be acute, causing severe symptoms, or chronic, developing more slowly.

The primary glaucoma symptoms and causes vary depending on the type. In the early stages of open-angle glaucoma, there are typically no symptoms. Vision loss is gradual and often goes unnoticed until the disease is advanced. However, acute angle-closure glaucoma can present with sudden and severe symptoms, including:

• Severe eye pain
• Blurred vision
• Halos around lights
• Redness in the eye
• Nausea and vomiting

Causes of glaucoma are multifaceted. Elevated intraocular pressure is a significant risk factor, but other factors contribute, such as genetics, age (over 60), ethnic background, certain medical conditions (e.g., diabetes, heart disease, high blood pressure), severe eye injury, and prolonged use of corticosteroid medications. Family history of glaucoma significantly increases an individual’s risk.

How Glaucoma is Diagnosed

Diagnosing glaucoma involves a comprehensive eye examination by an ophthalmologist. Since many forms of glaucoma are asymptomatic in their early stages, regular check-ups are critical for timely detection and intervention. The process of how is glaucoma diagnosed typically includes several key tests:

• Tonometry: This test measures the intraocular pressure (IOP) inside your eye. While high IOP is a significant indicator, it’s not the sole diagnostic factor.
• Ophthalmoscopy: The doctor examines the optic nerve at the back of your eye for signs of damage or changes in its appearance, such as cupping.
• Perimetry (Visual Field Test): This test assesses your peripheral vision to detect any blind spots or areas of vision loss caused by optic nerve damage.
• Gonioscopy: This procedure allows the ophthalmologist to examine the drainage angle of your eye to determine if it is open or closed, which helps classify the type of glaucoma.
• Pachymetry: This measures the thickness of your cornea, as corneal thickness can influence IOP readings and glaucoma risk.
• Optical Coherence Tomography (OCT): OCT provides detailed cross-sectional images of the optic nerve and retina, allowing for precise measurement of nerve fiber layer thickness and detection of subtle changes over time.

Early diagnosis is paramount because vision loss from glaucoma is irreversible. Once diagnosed, treatment typically focuses on lowering eye pressure to prevent further damage to the optic nerve. This may involve eye drops, oral medications, laser treatment, or surgery.