The leading cause of glaucoma is a build-up of pressure within the eye.
The eyeball contains a fluid called aqueous humour which is continuously produced by the eye, with any excess drained through special tubes. Glaucoma develops when the fluid cannot drain properly, and pressure, known as the intraocular pressure, builds up. This can damage the optic nerve ( the part of the eye which connects the eye to the brain) and the nerve fibres from the retina (the light-sensitive nerve tissue that lines the back of the eye).

Glaucoma symptoms and lifestyle impacts
Different types of glaucoma have varying symptoms.

Chronic open-angle glaucoma
In cases of chronic glaucoma, there are usually no noticeable symptoms because the condition develops very slowly. People don’t often realise their sight is being damaged because the first part of the eye to be affected is the outer field of vision (peripheral vision). Vision is lost from the outer rim of the eye, slowly working inwards towards the centre.
Changes in vision are often linked to getting older, which is why it is so important to have your eyes checked regularly. You should have an eye test at least every two years unless you are advised by your optometrist to return more frequently.

Acute angle-closure glaucoma
Acute angle-closure glaucoma develops rapidly. Symptoms are often severe. They include:
• Intense pain
• Redness of the eye
• Headache
• Tender eye area
• Seeing halos or ‘rainbow-like’ rings around lights
• Misty vision
• Loss of vision in one or both eyes that progresses very quickly
As a result of these symptoms, some people may feel sick or be sick.
Symptoms of acute glaucoma are not constant. They can last for one or two hours before disappearing again. However, each time the symptoms occur, your vision is damaged a little more. This is an emergency, and you should seek urgent advice.
It’s essential to seek professional help straight away if you have any of the above symptoms because early treatment can prevent further damage occurring.

Secondary glaucoma
Secondary glaucoma is caused by other conditions, such as uveitis (inflammation of the middle layer of the eye). It can also be caused by eye injuries and certain treatments, such as medication or operations.
The symptoms of glaucoma can be confused with the symptoms of other conditions. For example, uveitis often causes painful eyes and headaches.
Glaucoma may also cause misty vision and rings or halos around lights.

Developmental glaucoma
Recognising the symptoms of developmental glaucoma (also known as congenital glaucoma) can be difficult due to the young age of the baby or child. However, your child may display symptoms, such as:
• Large eyes due to the pressure in the eyes causing them to expand
• Sensitive to light (photophobia)
• Having a cloudy appearance to their eyes
• Watery eyes
• Jerky movements of the eyes
• A squint, which is an eye condition that causes one of the eyes to turn inwards, outwards or upwards, while the other eye looks forward

Treatment aims to control the condition and minimise future damage by reducing the pressure in the affected eye. We can treat glaucoma with eye drops, laser treatment or surgery.

Eye drops
Chronic open-angle glaucoma is often treated using eye drops. There are several different types of eye drops available; the type prescribed may depend on:
• How your condition is progressing
• Whether you have other medical conditions
• Whether you are taking any other medications
• Whether the eye drops cause side effects when you use them

Other treatments
If the use of eye drops does not improve your symptoms, we may recommend a different type of treatment, such as laser treatment or surgery.

Selective Laser Trabeculoplasty (SLT)
Selective Laser Trabeculoplasty (SLT) is one type of Laser Trabeculoplasties and helps to reduce the intraocular pressure in patients with glaucoma. It works by Applying a cold laser to the drainage tissue inside the eye. There is a combination of biological changes and chemical transformation in the tissue allowing Enhancement of the drainage of fluids from the eye. The results might take up to 3 months to show. SLT laser uses very low heat energy which mean that it is less likely to cause damage to the tissue and the pain is very minimal.
Selective laser trabeculoplasty or SLT is becoming the first line treatment for patients with a primary or secondary open angle glaucoma. There is a growing evidence to support that SLT laser is effective as a first-line therapy as well as being safe and well tolerated by patients. It allows for no or less need for topical eyedrops to control the glaucoma.
SLT laser has potential to lower the eye pressure by more than 30%. This is far more powerful than the most commonly used topical eyedrops. The effect of high-pressure control can last up to 5 years. There are cases where there is no or little benefit from the laser. This is usually known by monitoring the eye pressure for 6 to 12 months after the treatment. If the effect of the SLT laser has worn off often after several years then it would be advisable to repeat the treatment.
More and more surgeons are choosing SLT as a first line treatment for their patience. It will save the patients from installing too many drops in their eyes for life. The use of SLT laser has transformed the management of glaucoma for the better.
Selective Laser Trabeculoplasty (SLT) laser should not be confused with other types of laser treatments such as Argon laser trabeculoplasty (ALT) and micropulse laser trabeculoplasty (MLT). Finally, an alternative to laser trabeculoplasty is cyclodiode laser treatment. This involves destroying some of the tissue in the eye that produces aqueous humour. It creates less fluid in the eye, which reduces the intraocular pressure.
SLT laser can be used as sole therapy or as additional therapy to help other anti-glaucoma medications.

How is it done?
The treatment is painless and easy to do. We will place anaesthetic eye drops into your eye and place a special lens in front of your eye. The laser will be shone through the lens and will be focused on the trabecular meshwork. This allows more fluid to drain out of your eye and reduces the intraocular pressure.
Laser treatments are usually quick and painless, although, during the procedure, you may feel a brief twinge of pain or heat. You may still need to use eye drops after having laser treatment.

Surgery
A trabeculectomy is the most common type of glaucoma surgery. It involves removing part of the trabecular meshwork to allow fluid to flow through the eye’s drainage system. The procedure will be carried out under local anaesthetic or general anaesthetic.
Other types of surgery include:
• A viscocanalostomy – this operation removes part of the sclera (the white outer covering of the eyeball), enabling the fluid to filter out of your eye and into your body.
• A deep sclerectomy operation – this operation involves implanting a tiny device inside your eye to widen the trabecular meshwork.
• An aqueous shunt implant – this operation involves placing a tube device into your eye to increase the drainage of fluid out of your eye.
If you are having surgery, your Eye Clinic London surgeon may choose to use anti-scarring medicine. These can improve the success of the operation by preventing scar tissue forming as your eye heals.

Minimally Invasive Glaucoma Devices (MIGS)
MIGS procedures work by using microscopic-sized equipment and tiny incisions.
The MIGS group of operations are divided into several categories:
• Miniaturized versions of trabeculectomy
• Trabecular bypass operations
• Totally internal or suprachoroidal shunts
• Milder, gentler versions of laser photocoagulation

Acute angle-closure glaucoma
As acute glaucoma develops rapidly, we need to treat the condition quickly. The most common forms of treatment for this type of glaucoma include:
• Eye drops – see above for further details
• Systemic medicines – these are injected into your bloodstream to reduce the pressure in your eye quickly
• Laser treatment (called laser iridotomy) – this uses high-energy beams of light to create holes in your iris (coloured part of the eye) to open the angle and enable fluid to flow. Both eyes may need to be treated, even if only one has acute angle-closure glaucoma. This is because this form of glaucoma may develop in both eyes at some point.
• Surgery – a trabeculectomy (surgery to remove part of the drainage tubes) is the most common form of surgery for acute glaucoma.
If you also have a cataract (a cloudy patch in the lens of your eye), removing it may open the angle in your eye and control the intraocular pressure.

Miotics
We can also treat acute angle-closure with a medication called a miotic, such as pilocarpine. Miotics work by opening up the blocked trabecular meshwork, which should improve the drainage of aqueous humour out of your eye. You may need to use these eye drops for up to four times a day.
Miotics can also cause side effects, such as:
• Headaches, which may be severe during the first two to four weeks of treatment
• Burning or itchy eyes
• Blurred vision, which may affect your ability to drive

Treating other types of glaucoma
For other types of glaucoma, we usually recommend eye drops, laser treatment or surgery. Your treatment will depend on the type of glaucoma you have and how advanced it is.

Monitoring your condition
If you are diagnosed with glaucoma, your condition will be closely monitored to check for further damage to your vision.
Depending on how your glaucoma is progressing, you may need further appointments every one to four months, or up to 12-24 months apart with an experienced member of the team.