What is Glaucoma

Glaucoma is a group of eye conditions that damage the optic nerve, which is crucial for vision. The damage is often caused by increased pressure in the eye (intraocular pressure or IOP), though normal-pressure glaucoma can also occur. If untreated, glaucoma can lead to irreversible vision loss and is one of the leading causes of blindness worldwide.
Types of Glaucoma
1- Open-Angle Glaucoma (Chronic Glaucoma):
The most common type is where the drainage system of the eye (trabecular meshwork) becomes less efficient over time, causing pressure to build up gradually.
Symptoms: It develops slowly, and there are often no early symptoms, leading to a “silent” loss of peripheral vision.
2- Angle-Closure Glaucoma (Acute Glaucoma):
Occurs when the drainage angle in the eye suddenly becomes blocked, causing a rapid rise in intraocular pressure.
Symptoms: Severe eye pain, headache, nausea, blurred vision, and seeing halos around lights. This is a medical emergency and can lead to blindness if not treated immediately.
3- Normal-Tension Glaucoma:
Optic nerve damage occurs despite normal intraocular pressure. The cause is not fully understood, but poor blood flow to the optic nerve may be involved.
Symptoms: Similar to open-angle glaucoma, with gradual loss of peripheral vision.
4- Secondary Glaucoma:
Results from other conditions such as eye injuries, inflammation, or certain medications (e.g., steroids).
5- Congenital Glaucoma:
A rare form seen in babies, caused by improper development of the eye's drainage channels.
Symptoms of Glaucoma
1- Open-angle glaucoma:
Often no symptoms in the early stages.
Gradual loss of peripheral (side) vision, often unnoticed until it becomes severe.
Tunnel vision in advanced stages.
2- Angle-closure glaucoma (emergency):
Severe eye pain.
Headache, nausea, and vomiting.
Sudden blurred vision.
Halos around lights.
Red eyes.
Causes and Risk Factors
Increased intraocular pressure (IOP): The primary risk factor is elevated IOP due to improper drainage of fluid (aqueous humour) within the eye.
Age: People over 60 are at higher risk.
Family History: A family history of glaucoma increases risk.
Medical Conditions: Conditions like diabetes, hypertension, and heart disease are associated with higher risk.
Ethnicity: African, Hispanic, and Asian populations are at a higher risk of certain types of glaucoma.
Diagnosis
Tonometry: Measures intraocular pressure (IOP).
Ophthalmoscopy: This allows the doctor to examine the optic nerve for damage.
Visual Field Test: Detects any loss of peripheral vision.
Gonioscopy: Examines the drainage angle in the eye to check for blockages.
Optical Coherence Tomography (OCT): A high-resolution scan that measures the thickness of the retinal nerve fibres to assess optic nerve damage.
Treatment of Glaucoma
While glaucoma damage is irreversible, treatment aims to slow or prevent further vision loss:
Medications:
Eye drops to lower IOP (e.g., prostaglandins, beta-blockers, alpha agonists, and carbonic anhydrase inhibitors).
Laser Therapy:
Laser trabeculoplasty: Helps improve fluid drainage for open-angle glaucoma.
Laser iridotomy: Used for angle-closure glaucoma to create a small hole in the iris to improve fluid outflow.
Surgery:
Trabeculectomy: A surgical procedure to create a new drainage channel for the fluid to exit the eye.
Drainage implants: Devices are implanted to help drain excess fluid.
Minimally Invasive Glaucoma Surgery (MIGS):
Newer procedures are designed to lower IOP with fewer risks and shorter recovery times compared to traditional surgery.
When to Seek Help
Routine Eye Exams: Early detection is key because glaucoma can be asymptomatic in its early stages. Regular eye exams, especially if you're over 40 or have risk factors, are important.
Emergency: If you experience severe eye pain, blurred vision, or halos around lights, seek immediate medical attention. These could be signs of angle-closure glaucoma, which requires urgent treatment.
References:
American Academy of Ophthalmology (AAO):
"Glaucoma." Last reviewed: May 2023.
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National Health Service (NHS):
"Glaucoma." Last reviewed: April 2022.
Mayo Clinic:
"Glaucoma: Symptoms and Causes." Last reviewed: August 2023.
National Eye Institute (NEI):
"Glaucoma: What Is Glaucoma?" Last reviewed: November 2021.