Glaucoma is the leading cause of irreversible blindness and affects 76 million people worldwide. It is estimated that half a million people are affected with glaucoma in the UK, with 1 in 50 people over the age of 40 and 1 in 10 of those above the age of 80.

 

Glaucoma is a progressive optic nerve disease and is usually marked by high pressure inside the eye. It is often asymptomatic initially as the off-centre (peripheral) vision is lost first. If left untreated, the optic nerve damage gets worse leading to loss of the central detailed vision and eventually blindness.

 

The eye pressure is controlled by a clear liquid called the aqueous humour, which fills the front part of the eye. Aqueous humour passes through the pupil and drains through tiny channels (the trabecular meshwork) in the angle between the cornea and iris, called the drainage angle.

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Types of glaucoma

 

Glaucoma can be classified into open angle or angle closure types depending on the drainage angle. It can be subdivided into primary when no cause has been found, or secondary when a cause has been identified.

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• Primary open angle glaucoma is the most common form of glaucoma. The trabecular meshwork in the open drainage angle becomes blocked leading to a gradual increase in eye pressure. Certain risk factors have been identified such as increasing age, high eye pressure, family history and ethnicity.

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• Primary angle closure glaucoma occurs when the drainage angle narrows and becomes blocked, causing an increase in eye pressure. This may occur gradually or suddenly with symptoms such as severe eye pain, blurred vision, red eye, haloes around lights, nausea and vomiting.

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• Secondary glaucoma is when a cause has been identified and these include uveitis (inflammation in the eye), pxeudoexfoliation, pigment dispersion syndrome, trauma or after surgery for other eye diseases, such as retinal detachment surgery or corneal transplantation.

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A formal assessment by Dr Yu-Wai-Man will be able to determine the presence and type of glaucoma.

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Assessment

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Although any vision which has been lost from glaucoma cannot be recovered, with early diagnosis, careful monitoring and regular use of the treatments, the majority of patients can retain useful sight for life. Dr Yu-Wai-Man will perform a number of tests to assess for glaucoma including:

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• Measuring the eye pressure (tonometry). Eye pressure is the only modifiable risk factor in glaucoma and it will assist diagnosis and assessing the response to treatment.

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• Assessment of the drainage angle (gonioscopy). This will be used to determine the type of glaucoma (open angle or angle closure) and to discuss the different treatments available.

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• Measuring the central corneal thickness (pachymetry). If a patient's cornea (clear window at the front of the eye) is thicker or thinner than average, it can affect the eye pressure measurement.

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• Disc assessment. This will be used to assess the degree of optic nerve damage due to glaucoma and to monitor the progression over time.

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• Testing the field of vision (perimetry). The degree and pattern of visual field loss will assist diagnosis and monitoring the progression of glaucoma.

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• Imaging. Different imaging techniques, e.g. optical coherence tomography (OCT), can be used to assist diagnosis and monitoring the progression of glaucoma.

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Treatment

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The options can be divided into medical, laser and surgical treatments.

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1.   Medical Treatment

 

Most patients who are diagnosed with glaucoma will be offered treatment with eye drops to lower the eye pressure. There are five different classes of eye drops and they can be associated with local and systemic side effects.

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2.   Laser Treatment

 

• Laser peripheral iridotomy (LPI) is used to treat and prevent angle closure. A laser is used to create a small hole in the outer edge of the iris (coloured part of the eye). This allows aqueous humour to flow from the back to the front of the iris and vice versa, thereby widening the drainage angle. If the patient already has significant cataract, lens extraction surgery can also be performed to widen the drainage angle. Please refer to the section on cataract surgery for more information.

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• Selective laser trabeculoplasty (SLT) is used to treat open angle glaucoma and ocular hypertension. The laser is applied to the trabecular meshwork and allows the aqueous humour to drain out of the eye more readily, thereby decreasing the eye pressure. The treatment has a low risk of complications and could allow patients to remain drop-free for a significant period of time.

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• Cyclodiode is a type of laser that is applied to the sclera (white part of the eye) and it decreases the production of aqueous humour by the ciliary body. It can be used to decrease the eye pressure in refractory cases (when other treatments have failed), blind painful eyes and eyes with good vision but high pressures.

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• Endoscopic cyclophotocoagulation (ECP) is a type of cyclodiode laser when a small endoscopic camera is inserted into the eye and the laser is applied directly to the ciliary body to decrease the production of aqueous humour. ECP is often combined with cataract surgery to decrease the eye pressure in glaucoma patients undergoing cataract surgery.​​

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3.   Surgical Treatment

 

Surgery may be required if eye drops and laser treatment do not lower the eye pressure adequately or the patient is intolerant to multiple eye drops or if there is progression of glaucoma despite treatment.

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• Trabeculectomy

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• Aqueous shunt/ tube

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• Minimally invasive glaucoma surgery

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If you would like to discuss glaucoma assessment and the treatments in more detail, please arrange a consultation with Dr Yu-Wai-Man by clicking here.