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August 11, 2024

Understanding Glaucoma: Causes, Symptoms and Treatment Options

Glaucoma is a complex group of eye conditions that harm the optic nerve, which is most important for good vision. Unusual high pressure in the eye is usually the reason for this damage. Glaucoma is one of the main causes of blindness for people over the age of 60. However, it can occur at any age.


What is Glaucoma?

Glaucoma is not a single disease but a group of eye conditions that can lead to optic nerve damage. The optic nerve, composed of over a million nerve fibres, connects the retina to the brain. The health of the optic nerve is vital for clear vision.

Glaucoma often results from increased intraocular pressure (IOP) – a measurement of fluid pressure in the eye. Increased IOP can damage the optic nerve over time.


Types of Glaucoma

There are several types of glaucoma, each with distinct characteristics:

  • Primary Open-Angle Glaucoma (POAG): The most common form, where the drainage angle of the eye remains open, but the trabecular meshwork becomes less efficient at draining fluid, leading to increased IOP.
  • Angle-Closure Glaucoma: The iris bulges forward, narrowing or blocking the drainage angle formed by the cornea and iris in angle-closure glaucoma. This can cause a sudden increase in IOP leading to acute angle-closure glaucoma, a medical emergency.
  • Normal-Tension Glaucoma: In this type, optic nerve damage occurs despite normal IOP. It is believed to be related to poor blood flow to the optic nerve.
  • Secondary Glaucoma: Caused by an underlying condition, such as inflammation, trauma, or steroid use, which increases IOP and damages the optic nerve.
  • Congenital Glaucoma: A rare form present at birth due to abnormal development of the eye’s drainage system.

Causes of Glaucoma

The exact cause of glaucoma is not fully understood, but several risk factors contribute to its development:

  • Increased Intraocular Pressure: Elevated IOP is the primary risk factor for most types of glaucoma. It results from an imbalance between the production and drainage of aqueous humour, the fluid in the eye.
  • Age: The risk of developing this condition increases with age, particularly after 40.
  • Family History: A family history of glaucoma significantly raises the risk of developing the disease.
  • Ethnicity: African Americans, Hispanics, and Asians are at higher risk for different types of glaucoma.
  • Medical Conditions: Conditions such as diabetes, hypertension, and heart disease can increase the risk of glaucoma.
  • Eye Injuries: Trauma to the eye can damage the drainage system, leading to secondary glaucoma.
  • Prolonged Use of Steroids: Long-term use of corticosteroids, especially eye drops, can elevate IOP.

Symptoms of Glaucoma

Glaucoma is often called the “silent thief of sight” because it usually progresses without noticeable symptoms until significant vision loss has occurred. However, depending on the type, some symptoms can indicate the presence of glaucoma.

Primary Open-Angle Glaucoma

  • Gradual loss of peripheral vision, usually in both eyes
  • Tunnel vision in advanced stages

Normal-Tension Glaucoma

  • Symptoms similar to POAG but occur with normal IOP

Acute Angle-Closure Glaucoma

  • Severe eye pain
  • Nausea and vomiting
  • Sudden onset of visual disturbance, often in low light
  • Blurred vision
  • Halos around lights
  • Reddening of the eye

Congenital Glaucoma

  • Cloudiness in the cornea
  • Enlargement of one or both eyes
  • Excessive tearing
  • Sensitivity to light

Diagnosing Glaucoma

Early detection of glaucoma is crucial for preventing vision loss. Comprehensive eye exams are essential and typically include the following tests:

  • Tonometry: Measures intraocular pressure using a device that gently touches the eye or uses a puff of air.
  • Ophthalmoscopy: The optic nerve is examined for damage through a special lens or camera.
  • Perimetry (Visual Field Test): Maps the field of vision to detect peripheral vision loss.
  • Gonioscopy: Inspect the drainage angle to determine whether it is open or closed.
  • Pachymetry: Measures corneal thickness, which can influence IOP readings.
  • Optical Coherence Tomography (OCT): Provides detailed images of the optic nerve and retinal nerve fibre layer.

Treatment Options for Glaucoma

Unfortunately, there is no cure for glaucoma. However, various treatments can help manage the condition, lower IOP, and prevent further optic nerve damage. Treatment options include medications, laser therapy, and surgery.

Medications

Usually, the following medication options are used:

  • Prostaglandin Analogs: Increase the outflow of aqueous humour, reducing IOP. Examples include latanoprost and bimatoprost.
  • Beta-Blockers: Reduce the production of aqueous humour. Examples include timolol and betaxolol.
  • Alpha Agonists: Decrease aqueous humour production and increase outflow. Examples include brimonidine.
  • Carbonic Anhydrase Inhibitors: Reduce aqueous humour production. Examples include dorzolamide and acetazolamide.
  • Rho Kinase Inhibitors: Increase outflow of aqueous humour. An example is netarsudil.
  • Combination Medications: Sometimes two or more medications are combined to achieve better IOP control.

Laser Therapy

Glaucoma can also be treated using laser therapy such as:

  • Laser Trabeculoplasty: Used for open-angle glaucoma, this procedure improves the drainage angle’s function, enhancing fluid outflow.
  • Laser Iridotomy: This procedure is used for angle-closure glaucoma. A small hole is created in the iris to improve fluid drainage.
  • Cyclophotocoagulation: Reduces the production of aqueous humour by targeting the ciliary body.

Surgical Options

  • Trabeculectomy: Creates a new drainage pathway for aqueous humour to reduce IOP.
  • Glaucoma Drainage Devices (Implants): Small tubes implanted in the eye to help drain fluid.
  • Minimally Invasive Glaucoma Surgery (MIGS): Less invasive procedures that lower IOP with fewer risks and quicker recovery times.

A Final Word

Glaucoma is a serious eye condition that requires vigilant management to prevent vision loss. Early detection of glaucoma is crucial for preventing significant vision loss. Since glaucoma often progresses without noticeable symptoms, regular eye exams are the best defence.

Discuss risk factors with your ophthalmologist for more frequent screenings. Be aware of symptoms like vision loss or eye pain and seek medical help promptly.



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