FAQs & follow-up for glaucoma 

Glaucoma is a chronic lifelong condition, and we hope to be with you along the whole way. Typically, it is best to have a check-up every year or so. This may vary if there are any changes or progression in the disease. 

Useful reading and resources.  

The Royal College of Ophthalmologists, Royal National Institute for the Blind, and Glaucoma UK have some excellent resources for further information. These are available online. 
 

Glaucoma Surgery FAQs 

 
Glaucoma is a progressive eye disease where the nerve at the back of the eye (the optic nerve) may become damaged, and this can cause permanent vision loss. Glaucoma is often (but not always) associated with high pressure in the eyes. 
 
Glaucoma has been termed the ‘silent thief of sight’ as it can cause permanent vision loss before the disease is even detected. In its early stages, glaucoma does not typically present with any symptoms that would make you feel you need to visit your optician or ophthalmologist to raise concerns over changes in your vision. If not diagnosed and treated early, some vision loss may have already occurred by the time you eventually see your eye specialist. 
 
We often don’t know exactly what causes the high pressure. Pressure may build within the eye because of a problem in the eye’s drainage system. In a healthy eye, the aqueous fluid is produced within the eye— and as it drains out of the eye through the anterior chamber angle, new aqueous fluid is produced. This process repeats continuously, and if effective, will maintain a normal level of eye pressure. 
 
When a problem occurs within the drainage system, and the eye’s natural drain becomes clogged, the fluid builds up in the eye, and consequently causes a build-up of pressure within the eye. 
 
If glaucoma is not effectively controlled at an early stage, the disease can cause severe peripheral vision loss— resulting in a condition called ‘tunnel vision’. Tunnel vision blocks your ‘side vision’ and limits your field of vision to strictly seeing images in your central vision, or straight ahead. 
 
Glaucoma affects more than 70 million people, worldwide. It is a leading cause of irreversible blindness and is the third most common cause of blindness in the world (after cataract, and uncorrected refractive error), accounting for more than 12% of global blindness. 
 
Glaucoma affects up to 5% of adults ages 70 and above and increases to over 9% for those 80 and older. 
 
Glaucoma is most often associated with high levels of pressure in the eye (not to be confused with high blood pressure). This high intra-ocular pressure (IOP) may cause damage to the optic nerve eventually leading to permanent vision loss if left untreated. 
 
Typically, if the vision is affected at all, it is more likely the peripheral vision that is affected first. If not effectively controlled at this point, glaucoma can result in progressive ‘tunnel vision’. As the disease progresses, central vision is next to be affected, leaving the person with partial, or complete permanent vision loss. 

Is there only one type of glaucoma? 

There are different types of glaucoma: 
 
1. Ocular hypertension is the most common form. This is where the pressure in the eyes is high, however there are no signs of optic nerve damage and no changes in the visual field. Often low-risk, ocular hypertension may still lead to early glaucoma and does often need treatment with either regular eye drops or laser (SLT). 
 
2. Chronic open-angle glaucoma is caused by IOP build-up over time, typically as a result of aging. Chronic angle-closure glaucoma is the most common type of glaucoma in South-East Asia. 
 
3. Acute (angle-closure) glaucoma is a rare form that requires immediate medical attention. It develops as a result of sudden pressure build-up. Symptoms include blurred vision, seeing halos around lights, severe eye pain and headaches, nausea and vomiting. 
 
4. Secondary glaucoma can develop from complications of medical conditions such as diabetes, and other ocular conditions including inflammation (uveitis), pigment dispersion, and pseudoexfoliation (PXF/PEX). Secondary glaucoma may develop from side effects of some medications (particularly steroids), or trauma to the eye. Secondary glaucoma accounts for 10% of all glaucoma cases. 
 
5. Normal-tension (or normal-pressure) glaucoma develops when the optic nerve is damaged, in the presence of ‘normal’ IOP. The cause of this type of glaucoma is still unknown. Normal tension glaucoma accounts for around 30% of all patients diagnosed with glaucoma. 

How is glaucoma diagnosed? 

Glaucoma is diagnosed during a comprehensive eye exam, using specific diagnostic tools and assessments: 
 
Eye pressure test 
 
An eye pressure test (tonometry) uses an instrument called a tonometer to measure the pressure inside your eye. 
 
The optometrist or ophthalmologist will put some anaesthetic drops and dye into the front of your eye. They will then shine a light into your eye and gently touch the surface of it with the tonometer. 
 
Some opticians use a different instrument, which uses a puff of air and doesn't touch the eye, to check pressure. 
Visual field test 
 
The visual field test is sometimes called perimetry. It is a sequence of flashing lights which when seen will require you to click on a hand-held button. The test maps out what each eye can see and checks for missing areas of vision or the ‘visual field’. 
 
You may be shown a sequence of light spots and you will be asked to click a button to indicate which ones you can see. Some dots will appear at the edges of your vision (your peripheral vision), which is often the first area to be affected by glaucoma; and some dots will appear very dim. 
 
If you can't see the spots in the periphery, it may mean glaucoma has damaged your vision. Mr Dean will talk through all of your test results with you. 
Optic nerve assessment 
 
At the back of the eye is the optic nerve. It connects your eye to your brain, and may become damaged in glaucoma, so an assessment may be carried out to see if it's healthy. 
 
For the test, eyedrops may sometimes be used to enlarge your pupils. Your eyes are then examined using either: 
 
A slit lamp (a microscope on a table with a chin rest and with a bright light) 
Optical coherence tomography (OCT) – a type of scan where special rays of light are used to scan the back of your eye and produce an image of it 
 
The eyedrops used to widen your pupils can temporarily affect your ability to drive (for up to 4-6 hours), so you'll need to plan your journey home after your appointment. 
Gonioscopy 
 
Gonioscopy is an examination to look at the front part your eye – the fluid-filled space between the coloured part (iris) and the clear window of the front of the eye (cornea). This is where the fluid should drain out of your eye. 
 
During this test, your eye doctor will be able to determine if the angle is open or closed, and detect the presence of abnormal blood vessels, adhesions (synechiae), or any damage from previous eye trauma. 
 
To enable a clear view of the angle and its drainage system, your eyes will be numbed with anaesthetic drops, and a special contact lens prism will be placed on the surface of your eye. This test is relatively quick, and does not cause any pain, though you may feel some pressure from the contact lens, and it may feel a bit ticklish on the eyelids. 

How is glaucoma treated? 

Unfortunately, there is no cure for glaucoma, and the ability to reverse any damage to the eye that has already occurred has yet to be discovered. However, there are treatments available to help stop, or at least reduce the progression of the disease by lowering or controlling IOP: 
 
Anti-glaucoma eye drops are often the first plan of action, and many cases of glaucoma can be controlled with eye drops. Your eye doctor will prescribe a specific type of eye drop, depending on the type of glaucoma you have. 
Types of eye drops: 
 
Prostaglandins relax the muscles in the eyes to allow better fluid drainage, reducing build-up of IOP. These are the most common initial drops used. 
Beta-blockers are used in a variety of glaucoma eye drops. They decrease the amount of aqueous fluid production and are often prescribed in combination with prostaglandins. They cannot be used if you have asthma, COPD, or a slow heart rate. 
Carbonic anhydrase inhibitors decrease the rate of fluid production and are used in combination with other anti-glaucoma eye drops. 
Alpha-adrenergic agonists decrease the rate of fluid production. They can be used alone or in combination with other anti-glaucoma eye drops. 
Parasympathomimetics are used to control IOP in narrow-angle glaucoma. They work to increase ocular fluid drainage by opening the narrow angle where drainage occurs. 
Combination glaucoma drugs include two different anti-glaucoma medicines. Many times, patients with glaucoma require more than one type of medication to control IOP. 
 
Selective laser trabeculoplasty (SLT) is the primary laser treatment performed for ocular hypertension or open angle glaucoma, as it effectively lowers intra-ocular pressure by 20-30%, and is successful in about 80% of patients. This laser procedure stimulates a biochemical change that improves the aqueous fluid drainage from the eye. Improved pressure after an SLT treatment may last 3 to 5 years and can be repeated if needed. According to recent research, SLT has similar results to the most effective glaucoma eye drops. 
 
Other surgery techniques used to treat angle closure glaucoma: 
 
Iridotomy is performed for angle-closure glaucoma. During this YAG laser procedure, a tiny hole is created in the peripheral iris to release the build fluid and allow it to flow properly out of the regular drainage angle. 
Trabeculectomy is a surgical procedure that is performed in cases of progressive or advanced glaucoma, where there is already optic nerve damage and uncontrollable IOP levels. During this procedure, an artificial opening in the eye for ocular fluid drainage is created, to decrease IOP levels. 
 
What is minimally invasive glaucoma surgery (MIGS)? 
 
Minimally invasive glaucoma surgery (MIGS) uses microscopic tools and devices to lower your risk of surgical complications and is often performed in combination with cataract surgery. 
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