A Complete Guide to Glaucoma

Glaucoma is a major cause of irreversible blindness worldwide and affects over 700,000 people in the UK, although many more may be undiagnosed. It comprises a group of eye diseases that gradually damage the optic nerve, usually due to increased pressure within the eye. Known as the "silent thief of sight," glaucoma often progresses without symptoms until vision loss is advanced.

This guide is designed to help you understand what glaucoma is, how it is diagnosed and treated, and how to manage the condition in daily life.

1. What Is Glaucoma?

The optic nerve, located at the back of the eye, is crucial for vision as it transmits images from the retina to the brain. Glaucoma causes damage to this nerve, most commonly due to high intraocular pressure (IOP), although some types can occur with normal pressure levels.

Glaucoma usually develops in both eyes, although one eye may be more severely affected. If left untreated, it can lead to permanent peripheral vision loss and eventually central vision loss and blindness.

2. Types of Glaucoma

Primary Open Angle Glaucoma (POAG)

● Prevalence: The most common form in the UK.

● Cause: The drainage channels in the eye become clogged over time, causing a gradual increase in IOP.

● Progression: Slow and symptomless in early stages, making regular eye exams vital.

● Impact: Progressive loss of peripheral vision.

Angle Closure Glaucoma

● Cause: The iris bulges forward to block the drainage angle between the cornea and the iris.

● Symptoms: Sudden onset of symptoms such as severe eye pain, headache, blurred vision, halos around lights, and nausea.

● Emergency: This type is a medical emergency and requires immediate treatment to prevent permanent vision loss.

Normal Tension Glaucoma

● IOP: Optic nerve damage occurs despite normal eye pressure.

● Risk factors: More common in people with a family history, poor circulation, or conditions like sleep apnoea.

● Diagnosis: Often harder to detect, requiring thorough optic nerve imaging and visual field analysis.

Secondary Glaucoma

● Cause: Develops because of another eye condition e.g. uveitis, trauma, or prolonged use of steroid eye drops.

● Treatment: Depends on managing the underlying cause as well the glaucoma.

Congenital and Childhood Glaucoma

● Onset: Present at birth or within the first few years of life.

● Signs: Watery eyes, light sensitivity, enlarged eyes, and cloudy corneas.

● Treatment: Requires prompt surgical intervention to preserve vision.

3. Causes and Risk Factors

Glaucoma is often caused by inefficient drainage of aqueous humour, the fluid that fills the front part of the eye. When fluid cannot drain properly, pressure builds up, damaging the optic nerve.

Key Risk Factors:

● Age (risk increases after 40)

● Family history of glaucoma

● African, Caribbean, or Asian heritage

● Short-sightedness (myopia) or long-sightedness (hyperopia)

● Diabetes and cardiovascular disease

● Long-term use of corticosteroid medications

● Eye injuries or surgeries

4. Symptoms of Glaucoma

Primary Open-Angle Glaucoma:

● Usually asymptomatic in early stages

● Gradual peripheral vision loss

● Tunnel vision in advanced stages

Angle-Closure Glaucoma:

● Sudden eye pain

● Severe headache

● Nausea and vomiting

● Blurred vision and halos

● Redness in the eye

When to Seek Help:

Any sudden change in vision, especially accompanied by pain or discomfort, should be treated as an emergency. Contact NHS 111 or visit A&E.

5. Diagnosis

Early detection is crucial. Comprehensive eye tests are typically done by an optometrist and may include:

● Tonometry: Measures IOP using an ICare or Goldmann tonometer.

● Ophthalmoscopy: Examines the shape and colour of the optic nerve.

● Perimetry (Visual Field Test): Maps peripheral vision to detect blind spots.

● Gonioscopy: Examines the angle where the iris meets the cornea.

● Optical Coherence Tomography (OCT): Uses light waves to capture cross-sectional images of the retina and optic nerve.

● Pachymetry: Measuring corneal thickness which relates to IOP measurement.

6. Treatment Options

While vision loss from glaucoma cannot be reversed, treatment can halt or slow its progression.

Eye Drops

● Types: Prostaglandin analogues, beta-blockers, alpha agonists, and carbonic anhydrase inhibitors.

● Function: Lower IOP by either reducing fluid production or increasing fluid drainage.

● Side Effects: May include redness, irritation, or systemic effects like lowered blood pressure.

Laser Treatment

● Selective Laser Trabeculoplasty (SLT): Improves drainage of fluid in the anterior chamber angle in POAG.

● Laser Peripheral Iridotomy: Used for angle closure glaucoma.

● Procedure: Usually quick and performed under local anaesthesia.

Surgery

● Trabeculectomy: Creates a new channel for fluid to drain.

● Glaucoma Drainage Devices: Implanted to help fluid leave the eye.

● Minimally Invasive Glaucoma Surgery (MIGS): Less invasive with quicker recovery, suitable for early to moderate glaucoma.

Monitoring and Follow-Up

● Regular appointments to monitor IOP, optic nerve health, and vision.

● Adjustments to treatment plan as needed.

7. Living With Glaucoma

Medication Adherence

● Use drops at the same time daily.

● Set reminders or use apps to track dosages.

Lifestyle Adjustments

● Eat a healthy diet rich in leafy greens, omega-3s, and antioxidants.

● Exercise regularly to improve blood flow to the optic nerve.

● Avoid smoking and limit caffeine.

Driving

● If glaucoma affects both eyes, notify the DVLA.

● A visual field test will be required to determine driving eligibility.

Emotional Wellbeing

● Diagnosis can be distressing; support groups and counselling may help.

● Organisations like Glaucoma UK offer helplines and peer support.

8. Prevention and Eye Health

While not all cases can be prevented, you can reduce your risk by:

● Getting regular eye tests (every two years or more frequently if at risk)

● Managing chronic conditions like diabetes and hypertension

● Avoiding eye trauma and wearing protective eyewear

● Informing your optometrist about your family history

9. FAQs

Q: How often should I get my eyes tested?
 A: Every two years, or more often if advised by your optometrist.

Q: Can glaucoma be cured?
 A: No, but early treatment can manage it effectively.

Q: Is glaucoma painful?
 A: Open-angle glaucoma is typically painless, but angle-closure glaucoma can cause severe pain.

Q: Are there benefits available for those with vision loss?
 A: Yes, you may be eligible for registration as vision impaired and support such as a Disabled Persons Railcard or PIP.

Managing Glaucoma

Glaucoma is a serious but manageable condition. The key to protecting your sight is early detection, consistent treatment, and regular monitoring. By staying informed and working closely with your eye care team, you can lead a full, independent life while preserving your vision.

If you're over 40 or have a family history of glaucoma, book an eye test today with your eye specialist. It could save your sight.