About Glaucoma

Glaucoma - "the silent thief of sight"

Introduction

Glaucoma is a group of eye diseases that cause damage to the optic nerve, often due to elevated intraocular pressure (IOP). It is one of the leading causes of irreversible blindness worldwide. The optic nerve, which connects the eye to the brain, becomes damaged over time due to increased pressure inside the eye. If left untreated, glaucoma can result in permanent vision loss. There are different types of glaucoma, with open-angle glaucoma being the most common. Other forms include angle-closure glaucoma, normal-tension glaucoma, and congenital glaucoma.

Illustration: To check for glaucoma, we look at the optic nerve head, a structure at the back of the eye where the nerve fibres travel through and eventually lead to the brain.

Signs and Symptoms

Open-Angle Glaucoma:

• It typically develops slowly, and symptoms may not be noticeable until significant damage to the optic nerve has occurred.

• Gradual loss of peripheral (side) vision, which can lead to tunnel vision in advanced stages.

• No noticeable pain or discomfort in the early stages.

Angle-Closure Glaucoma (also called narrow-angle glaucoma):

• Sudden and severe eye pain.

• Redness in the eye.

• Blurred vision or halos around lights.

• Headaches, nausea, and vomiting are common, which may be associated with a sudden increase in eye pressure.

• This is a medical emergency and requires immediate treatment.

Normal-Tension Glaucoma:

• Like open-angle glaucoma, it causes optic nerve damage but without the elevated eye pressure.

• Symptoms develop gradually and are usually not noticed until at a later stage, eventually leading to a significant amount of peripheral vision loss.

  
  

Congenital Glaucoma:

• In infants, symptoms can include enlarged eyes (buphthalmos), light sensitivity, and tearing.

• Prompt diagnosis and treatment are crucial to prevent vision loss.

Equipment to test for visual field defects

Diagnosis

Glaucoma is diagnosed through a series of tests, including:

Comprehensive eye exam:

A thorough examination at an ophthalmology clinic, which if screening for glaucoma is done then usually eye pressure, visual fields, and a scan or photograph of the optic nerve head is done.

Tonometry:

Measures the pressure inside the eye to determine if it is elevated. Both the non-contact air puff tonometry and the Goldmann Applanation Tonometry (GAT) may be done.

Dilated Fundus Examination:

Eyedrops are used to dilate the pupils, alllwing for the eye doctor (ophthalmologist) to observe and examine the optic nerve head for damage or changes.

Visual Field Test (Perimetry):

This test seeks to detect the sensitivity of the periphery retina, which then shows the extent of loss of peripheral vision (if any), which can be indicative of glaucoma, and can be used to check the progression of glaucomatous changes.

Gonioscopy:

A special lens is used to examine the angle where the iris meets the cornea to check for the presence of angle-closure glaucoma. This angle is where fluid in the eye drains out.

Optic Nerve Head Imaging:

Techniques like OCT (Optical Coherence Tomography) can assess the optic nerve head and assist in detecting early signs of glaucomatous damage.

Regular eye exams are crucial, especially for those at higher risk, as early-stage glaucoma often has no noticeable symptoms, and the glaucomatous damage is often significant by the time symptoms appear, resulting in a lower quality of life due to the visual field reduction. This is also why glaucoma is known as the silent thief of sight, due to the initial lack of symptoms for the patient who suffers from this condition.

Risk Factors for Glaucoma

• Elevated intraocular pressure (IOP) – the most important modifiable risk factor

• Age – risk increases over 40, especially over 60

• Family history of glaucoma

• Race/ethnicity – higher risk in people of African, Hispanic/Latino, or Asian descent (varies by glaucoma type)

• Thin central cornea

• High myopia (for open-angle glaucoma)

• Hyperopia (for angle-closure glaucoma)

• Diabetes mellitus

• Hypertension or vascular disease

• Prolonged corticosteroid use (topical, oral, inhaled, or injected)

• Previous eye injury or trauma

• History of eye surgery

• Conditions causing poor blood flow to the optic nerve (e.g., migraine, vasospasm)

Eye drops that control the eye pressure may be used to manage glaucoma.

Treatment

The goal of treatment is to lower intraocular pressure (IOP) to prevent further damage to the optic nerve.

Medications:

Eye drops are the most common treatment for glaucoma. These work by reducing the production of fluid in the eye, thus lower the pressure within the eye. Common types include beta-blockers, prostaglandin analogs, and alpha agonists.

Oral medications may be prescribed in some cases if eye drops are not enough to control IOP.

Laser therapy:

Laser trabeculoplasty is used for open-angle glaucoma to improve fluid drainage.

Laser iridotomy or laser iridoplasty is used in cases of angle-closure glaucoma to help open the drainage angle.

Surgical treatment:

If medications and laser treatments are ineffective, surgery may be required to create a new drainage pathway or implant a drainage tube.

Trabeculectomy and tube shunt surgery are common surgical options to reduce IOP.

The use of minimally invasive glaucoma surgeries (MIGS) is becoming increasingly popular for treating glaucoma with fewer complications.

Drainage devices may be implanted to help maintain proper eye pressure.

Prognosis

The prognosis for glaucoma largely depends on the type of glaucoma, the extent of damage to the optic nerve, and how early the condition is diagnosed and treated.

Open-angle glaucoma:

With early detection and treatment, most people can manage the condition and avoid significant vision loss. However, the disease is progressive, so long-term treatment is necessary.

Angle-closure glaucoma:

This form is more acute, and if left untreated, it can result in rapid vision loss. Immediate treatment is crucial to preserve vision.

Normal-tension glaucoma:

Although the pressure is not elevated, the optic nerve can still be damaged, and managing IOP is essential for slowing progression.

Congenital glaucoma:

Early treatment is essential for preserving vision. Without treatment, children may experience significant visual impairment or blindness.

Regular monitoring and consistent treatment are necessary to slow the progression of glaucoma and minimise vision loss, to ensure good quality of life in the long term.

Conclusion

Glaucoma is a serious eye condition that can lead to permanent vision loss if not diagnosed and treated early. Elevated intraocular pressure (IOP) causes damage to the optic nerve, and while the condition is generally progressive, it can be managed with medications, laser treatments, and surgery.

Regular eye exams are essential, particularly for those at higher risk, such as people over the age of 60, those with a family history of glaucoma, and individuals with other risk factors (e.g., diabetes).

Though glaucoma often develops without noticeable symptoms, early intervention can prevent severe vision loss and improve long-term outcomes.

Check for Glaucoma at The Ophthalmology Practice