What is glaucoma?
Glaucoma is a group of eye diseases that damage the optic nerve. It often affects both eyes, usually to varying degrees. As most cases won’t have any symptoms, one of the best ways to detect glaucoma is during a routine eye test – that’s why it’s so important to have one regularly.
What causes glaucoma?
The eyeball contains a fluid called aqueous humour, which is constantly produced by the eye. Any excess fluid is drained from the eye through tiny channels and tubes. When the fluid cannot drain properly, pressure builds up in the eye.
Glaucoma typically develops when this increased pressure damages the optic nerve, which connects the eye to the brain, and harms the nerve fibres from the retina, the light-sensitive nerve tissue that lines the back of the eye.
In acute glaucoma cases this pressure rises rapidly to higher levels, even causing pain.
Risk factors of glaucoma
Anyone can develop glaucoma, but there are several risk factors which make developing it more likely.
- Your risk of developing glaucoma is four times higher if you have a close blood relative who has it
- Age plays a big part. Chronic glaucoma affects up to two in every 100 people over the age of 40 and around five in every 100 people over 80
- Higher levels of short-sightedness are linked to the chronic form of glaucoma, and long-sightedness to the acute form
- Consistently raised pressure in the eye, called ocular hypertension (OHT), is a risk factor
- People of African-Caribbean origin have about a four-times higher risk of developing chronic forms of glaucoma compared to those of European origin
- Acute glaucoma is generally much less common, however people of Asian origin are at higher risk of developing this type of glaucoma compared with those from other ethnic groups
- People with diabetes may be at higher risk of developing glaucoma
- Very high blood pressure can lead to an increase in intraocular pressure, which can increase your risk of developing glaucoma
- Low blood pressure can lead to insufficient blood supply to the optic nerve, which can also cause problems
- Eye conditions, surgeries or injuries: injury to the eye can cause secondary open-angle glaucoma, either immediately after the injury or some years later
- Regular users of steroids are at higher risk of developing glaucoma
High intraocular pressure
Everyone has fluid inside their eyes that is regulated by tiny tubes and drainage channels in the eye. Sometimes these channels don’t work as well as they should or can become blocked, and this can cause the pressure in the eye (intraocular pressure) to rise.
A high intraocular pressure can be a significant risk factor in developing glaucoma. If the pressure is consistently high, it can start to affect the sensitive nerve fibres at the back of the eye.
That’s why having regular eye tests is so important – it means we can keep an eye on your pressure levels every time you see us, along with all the other eye health checks we carry out.
Glaucoma and cataracts
Both glaucoma and cataracts can be a natural part of ageing, but are they connected at all? The answer for most people is generally no, and if you have both, it is likely to be because both become more common with age.
However, in some situations cataracts can make a less common type of glaucoma worse, as they can cause the pressure in the eye to rise. This happens because as a cataract develops, it generally causes the lens inside the eye to become thicker. As the lens thickness increases, it can make it more difficult for the eye’s natural fluid (the aqueous humour) to circulate and drain from the eye.
The majority of people with the most common types of glaucoma are not at a higher risk of cataracts. However, a minority of people who have less-common types of glaucoma, perhaps due to eye trauma, eye inflammation or steroid use, may find they are at higher risk of cataracts. What’s more, people with rare developmental conditions such as congenital rubella (when the mother had rubella while the baby was in the womb) can be at higher risk of both cataracts and glaucoma.
Glaucoma and diabetes
Research confirms a link between glaucoma and diabetes — and though the risk for glaucoma increases with age for everyone, if you do have diabetes, you’re at a higher risk of developing the condition.(1)
A study in Australia of more than 3,500 older people found a significant association between diabetes and glaucoma, while another study of almost 5,000 older people in the US found that open-angle glaucoma is more common in people with older-onset diabetes.(2,3)
A separate study of more than 4,000 older people in the Netherlands, which looked for signs of diabetes and glaucoma, found that newly diagnosed diabetes and high levels of blood glucose are linked to glaucoma.(4)
These studies looked at one type of glaucoma, primary open-angle glaucoma, which is more common in those with Type 2 diabetes. There is also another type of glaucoma, neovascular glaucoma, which is related to abnormal blood vessel growth in the eye which blocks the natural drainage of the eye. This type of glaucoma can affect people with Type 1 and Type 2 diabetes equally, according to a Danish study.(5)
What you should do
If you have diabetes, it’s recommended that you have routine eye tests to check for diabetic eye diseases. In England, eye tests are free under the NHS for all diabetics, and as part of this eye test you will be tested for glaucoma.
Types of glaucoma
The main types of glaucoma are as follows:
Chronic or primary open-angle glaucoma
Chronic or primary open-angle glaucoma is the most common type of glaucoma. It develops gradually and painlessly, so an eye test is usually the only way to detect it.
Primary angle-closure glaucoma
Sometimes known as acute glaucoma, primary angle-closure glaucoma is usually treated as a medical emergency.
This is because, unlike chronic open-angle glaucoma, primary angle-closure glaucoma happens quickly due to a sudden rise in eye pressure, and if it’s not treated quickly, it can lead to sight loss.
Traumatic glaucoma can develop after an eye injury – either a blunt trauma or something that penetrates the eye. It can happen either at the time of the injury or some time later.
There is at least a four-times higher risk of developing glaucoma if you have a close blood relative who has it.
Studies(6) have shown that if members of your immediate family (a parent or a sibling) have glaucoma, your risk of developing early-onset glaucoma increases by almost 10 times. Your risk of developing glaucoma also increases if you have an identical twin who has the condition.
Congenital means a condition is present at birth and congenital glaucoma does affect a very small number of babies. The onset of congenital glaucoma happens before the age of three and is caused by mutations in two genes (CYP1B1 or LTBP2).
These genes are inherited as an autosomal recessive trait, where both parents are carriers of the mutation but do not have glaucoma themselves. Their children can inherit both copies of the mutation, one from each parent, leading to the development of glaucoma.
What are the symptoms of congenital glaucoma?
Some of the signs of possible eye trouble in children can be difficult to spot. For childhood glaucoma, symptoms may include:
- Unusually large eyes due to increased pressure
- The cornea (the transparent front section of the eye) may appear cloudy
- The child may display excessive tearing and photosensitivity, like closing one or both eyes in bright conditions
- There may be signs and symptoms that indicate poor peripheral (side) vision, for example running or bumping into objects
- Some children with childhood glaucoma may complain of discomfort or pain in the eye if there is a rapid increase in intraocular pressure
- Babies with this condition may become irritable and refuse to feed(7)
Developmental glaucoma is another type of childhood glaucoma that appears between the ages of 10 and 20 years. It is associated with mutations in genes involved in the development of the eye — particularly in the front part of the eye and in structures that drain fluid from the eye.
These developmental issues are usually inherited from one of the parents who is carrying a dominant gene, and may be associated with other developmental anomalies. For example, someone with developmental glaucoma may also have abnormal teeth or hearing loss.
People diagnosed with glaucoma before the age of 35 may have a form of glaucoma associated with a mutation in a myocilin gene. Mutations in this gene are also inherited as autosomal dominant traits, meaning there’s a chance that parents with this form of glaucoma could pass it on to half of their children.
However, any form of glaucoma can have multiple gene variants that can place you in the risk group. It’s also important to note that even if someone in your immediate family has glaucoma, it doesn’t necessarily mean you will develop it yourself.
What are the symptoms of glaucoma?
There are various types of glaucoma and symptoms will differ depending on which type you have.
If you have chronic glaucoma, you might not realise you have it because it’s painless and affects your peripheral (outer) vision. Without regular checks you may not notice there’s a problem until your start to lose your more central vision.
Acute glaucoma develops much faster as a result of sudden pressure build-up in the eye. Although rare, it is usually painful and is often accompanied by:
- Blurred vision
- Haloes around lights
- A red eye
If you get these symptoms, it is important to seek immediate assistance. Contact your optician or local accident and emergency department.
Even if the symptoms go away you should contact your optician as soon as possible as repeat episodes can cause damage to your eyesight.
How will glaucoma affect my vision?
Many people with early-stage glaucoma have enough vision to work, read, drive, and live independently. However, if you’ve been diagnosed with glaucoma, it’s important to use the eye drops you’ve been prescribed exactly as instructed.
Neglecting treatment, including missing medications, can make your vision worse, and in some cases can even lead to vision loss(8).
Glaucoma will usually be diagnosed during a normal eye test. As well as looking at the overall health of your eye and the structures within it, you’ll have a series of quick and painless tests that help to spot any signs of glaucoma.
Tests for glaucoma
Eye pressure test (tonometry)
An instrument called a tonometer is used to measure the pressure inside your eye – the intraocular pressure.
Tonometry can be useful in identifying ocular hypertension (OHT – raised pressure in the eye), which is a risk factor for chronic open-angle glaucoma.
Other forms of tonometry might be used that measure eye pressure differently, for example by using drops and a probe.
Visual field test
You will be shown a sequence of light spots and asked which ones you can see.
Some dots will appear in your peripheral vision, which is where glaucoma begins.
If you can’t see the spots in your peripheral vision, it may indicate the glaucoma has damaged your vision.
Digital retinal photography
This involves taking a picture of your eye with a specialist camera that gives the optician a good view of the retina and your optic nerve at the back of the eye.
Your optician will pay special attention to the optic nerve, as that’s typically where glaucoma presents itself.
The images from your previous visits are compared against the current appearance of the eye to check for any changes that may indicate glaucoma.
Optic nerve assessment
Your optic nerve connects your eye to your brain. This can be assessed in a variety of ways during your examination and it is also photographed using a retinal camera.
Digital retinal photography (DRP) captures an image of your optic nerve which can be used as reference for future visits and to track any changes that may occur over time.
OCT (Optical Coherence Tomography)
OCT scans are similar to MRI and ultrasound scans and can help our opticians detect signs of glaucoma and other conditions up to four years earlier than more traditional imaging methods. Early detection means that treatment with prescribed eye drops, laser treatment or surgery can be started before you experience any significant sight loss.
How does optical coherence tomography work?
Much like an ultrasound scan uses sound waves, OCT uses light waves to take thousands of images of your retina, the layer of nerve fibres at the back of the eye. In order to carry out an OCT scan, you’ll be asked to sit with your chin on a support in front of a compact machine. The equipment will scan your eye without touching it. You will need to look at a light inside the machine, and you may see a flash of light.
The test is carried out on both eyes, one at a time. Overall, scanning takes just a few minutes. You may feel a little dazzled for a few moments after the test, but this will quickly pass — this is completely normal and is similar to what happens after having your photo taken with a bright camera flash.
What is optical coherence tomography used for?
While your first OCT scan can pick up signs of glaucoma, for most people this first test will provide baseline data about what your eye looks like when it’s healthy.
The clever thing about OCT is that it can pick up subtle changes in the thickness of the nerve fibre layers over time, giving your optometrist information that may indicate very early signs of conditions like glaucoma.
By repeating the OCT scan at every eye test, your optometrist can see if the nerve fibre thickness is changing outside of the normal age-related levels and can take action if it is.
Understanding gonioscopy: how can it diagnose glaucoma?
Gonioscopy refers to one of the tests an ophthalmologist will use to determine whether you have glaucoma and, if so, which type. Here, you’ll find information on the gonioscopy test, so you can feel reassured and comfortable if or when you have one.
What is gonioscopy?
During the test, an ophthalmologist uses a lens which is placed in contact with your eye to assess the health of the angle where fluid drains from your eye. The lens is able to do this because it incorporates mirrors and a prism which bends light, giving the ophthalmologist a clear view.
What happens during gonioscopy?
Gonioscopy is used to view the angle at the place where the coloured part of your eye (your iris) joins the cornea (the clear layer at the front of your eye).
The reason why it’s important to assess this angle, and how wide it is, is because this is where fluid drains out of your eye, and the balance of fluid pressure inside the eye is crucial in diagnosing, managing and treating glaucoma.
During your visit to the hospital, your ophthalmologist will ask you to place your chin on the rest of a slit lamp, which is a microscope designed to examine the front of your eye.
You’ll then be given some anaesthetic eye drops before the gonioscopy lens is placed on the front surface of your eye. The light from the slit lamp, shining through the gonioscopy lens, will allow the eye doctor to assess the drainage angle.
How corneal thickness can help diagnose glaucoma
How does corneal thickness affect glaucoma?
Intraocular pressure measurement can be affected by the thickness of the cornea. During the tonometry test, a small amount of pressure is applied to the cornea, and any resistance to the pressure helps measure IOP. A thick cornea may not ‘give’ as easily when pressure is applied, giving the impression of a high IOP. Similarly, a thin cornea may ‘give’ more than usual, which can give an impression of an abnormally low IOP.
What is the normal thickness of the cornea?
A normal range of corneal thickness is between 540µm and 560µm – µm represents measurements in micrometres, i.e. one-millionth of a metre. A thick cornea is 565µm or more, with a very thick cornea being greater than 600µm.
Typical corneal thickness can vary by race, with African-Caribbean people typically having a thinner cornea. For anyone with a thinner cornea, the risk is that lower IOP readings will potentially result in an underestimation of the actual level of intraocular pressure (IOP).(9, 10, 11)
This risk, if unrecognised, can lead to misdiagnosis. This makes it even more critical that the ophthalmologist has an overall picture of your eye health, including your optic disc appearance, your nerve fibre layers, and your visual field test results. Thankfully, technology now is incredibly advanced, meaning glaucoma misdiagnosis is an extremely rare occurrence.
Should you be referred to an ophthalmologist due to being glaucoma suspect (showing signs and symptoms of the condition), the test your eye doctor will perform to measure corneal thickness is called a pachymetry test.
What is a pachymetry test?
The pachymetry test is a procedure used to measure central corneal thickness (CCT) and determine if it could be affecting the accuracy of your IOP measurements. A pachymeter can use light or ultrasound to assess the thickness of your cornea.
For Alan, it was during his normal eye test at Specsavers that his opticians spotted the early signs of glaucoma.
Now, after a quick referral, he can manage his glaucoma and protect his sight with some daily eye drops.
Glaucoma can be treated but early detection is important. If left untreated, glaucoma can cause visual impairment and damage that cannot be reversed. But if it’s detected and treated early enough, further damage to vision can be minimised or prevented.
So regular eye tests are essential. You should have an eye test at least every two years or more frequently if advised by your optometrist. For example, they may suggest you have more frequent eye tests if you have a close relative with glaucoma, such as a parent, brother or sister.
If your optometrist suspects glaucoma, you will be referred to an ophthalmologist for further tests. If the ophthalmologist confirms a diagnosis of glaucoma, they will also be able to explain:
- How far the condition has developed
- How much damage the glaucoma has had on your eyes
- What may have caused the glaucoma
They will then be able to advise on treatment which in most cases is simply an eye drop used on a daily basis coupled with regular follow-up appointments.
When will treatment start? How long will it last?
Glaucoma is a lifelong disease that progresses slowly, and treatment usually begins soon after the diagnosis is made. Treatment for glaucoma usually continues indefinitely. Early detection and appropriate treatment are critical to preserving your vision.
Treatment may be started in one eye first. This is typically the ‘worse’ eye, with the higher intraocular pressure. A single drug may be tried to see if it works. Later, your doctor may test different combinations of medications to find a solution that works best for you.
Regular follow-ups with your doctor are required while being treated with glaucoma medication. This helps your doctor to quickly detect any progression of the disease.
If your vision is found to be worsening despite treatment, you may need an increased dose of your current medication or to change the medication that you’re taking. You may also be recommended for laser treatment and/or surgery. Stable patients are usually examined at three- to six-month intervals, depending on the severity of the disease and the rate that it is progressing(12).
Can glaucoma treatment affect cataracts?
Cataracts are not treated using medication, but eye drops for glaucoma can occasionally cause issues if you have cataracts. Some glaucoma eye drops make the pupil larger and can give someone with cataracts increased problems with glare. Other eye drops can make the pupil smaller, which allows less light into the eye – for someone who also has cataracts, this can cause a drop in the level of vision.
If you notice problems with glare, or with how much you can see, after starting eye drops for glaucoma, it’s important to talk to your ophthalmologist. If you have both conditions and need surgery, your ophthalmologist’s priority will be to control the glaucoma first, which may be with medication or surgery. If you need surgery for both glaucoma and cataracts, your ophthalmologist will advise whether it would be best to do both at the same time or one followed by the other.
Glaucoma eye drops
The purpose of the eye drops is to lower the eye pressure, either by reducing the amount of fluid (aqueous humour) that is produced or by helping it to drain better from the eye.
How do eye drops treat glaucoma?
This is dependent on the type of glaucoma. Some eye drops do both, and, sometimes, doctors can prescribe a combination of eye drops to reduce the risk of vision loss or to try and stop vision getting any worse. In addition to providing more effective treatment, another combination of eye drops may be given to reduce side effects.
How to administer eye drops for glaucoma?
It’s important that you administer the eye drops correctly for your glaucoma treatment correctly, to make sure the medication is fully effective. While the number of drops you use may vary depending on the medication you’ve been prescribed, the process for administering them is usually the same.
Firstly, you should make sure you face the ceiling when putting your drops in — you can do this by tilting your head right back, or it might be easier to administer your drops by lying down. When you have the eye drops ready and your head is tilted back, you can administer them, using as many the number of drops you’ve been as prescribed.
Once administered, you should then apply pressure to the inner corner of your eye, where the tear ducts are. Hold your finger there for several seconds after instilling putting the drops in. This ensures that the medication doesn’t not drain away by the ducts, and allows the drops to be effective.
Types of eye drops used to treat glaucoma
Prostaglandin analogues (PGAs) are usually the first type of glaucoma treatment recommended by doctors. This is because they are effective at reducing IOP, have an easy once-daily dosage, and minimal side effects.(13)
What are prostaglandin analogues?
PGAs are a synthetic version of the body’s natural compound, and come in the form of eye drops.
It’s the eye drop that binds to the receptor in order to stimulate the desired effect and help drain the fluid efficiently.
Types of prostaglandins used to treat glaucoma
Currently, there are four different types of prostaglandin analogue eye drops available for glaucoma treatment in the UK:
Typically, these medications are used to help reduce IOP in people with open-angle glaucoma or ocular hypertension.
Latanoprost was the first PGA eye drop developed to lower IOP, and remains the most commonly prescribed.
Are there any common side effects for PGAs?
Generally, all of the PGAs mentioned above share some common side effects, however these tend to be localised to the eyes:
- Dry eyes
- Red (stinging) eyes
- Increased pigmentation of the iris
It’s usually recommended that if you are pregnant or breastfeeding you do not take any PGAs for glaucoma treatment.(15,16,17,18) If you are suffering from any side effects, contact your ophthalmologist as they will be able to analyse why you might be responding to a specific PGA in a certain way and can adjust your treatment plan accordingly.
Combination therapy with prostaglandin analogues
Although PGAs are considered the most effective class of drug for reducing IOP, they are frequently combined with other medications such as beta blockers, adrenergic agonists or carbonic anhydrase inhibitors for increasing the efficacy of treatment. Studies have shown that the fixed combinations are as effective as individual medications administered separately.(19)
Alpha-adrenergic agonists work by stimulating a response from the adrenergic receptors that make up part of the body’s autonomic nervous system, which controls vital bodily functions. The adrenergic receptors, when stimulated, can cause a number of responses, including:
- Dilated pupils
- Elevated heart rate
- Mobilisation of energy
- Diversion of blood flow from non-essential organs to skeletal muscles
Importantly, however, a key response is the reduction in eye fluid production, as well as increased drainage of the fluid from the eye — making alpha-adrenergic agonists a popular choice for treating glaucoma with eye drops.
Adrenergic agonist medication
The types of adrenergic agonist drugs that can affect adrenergic receptors can be split into two types: non-selective and selective. Selective drugs target and affect their intended site alone. Non-selective, on the other hand, can affect multiple tissues and organs.
This class of glaucoma eye drops works by reducing the production of fluid in the eye, and a commonly used medication that does this is Timolol (Timoptic). Other examples of beta blockers include:
- Levobunolol (Betagan)
- Carteolol (Ocupress)
- Betaxolol (Betoptic)
- Metipranolol (OptiPranolol)
It is worth noting that beta blockers can cause some systemic (whole body) side effects such as slow pulse, asthma, dizziness, and fatigue.(20) Your ophthalmologist can help you with some techniques to minimise these risks.(21)
These eye drops are generally used once or twice a day. They can also be prescribed in combination with other types of medication for the best results.
Combination eye drops
Some people need more than one type of medication in order to control their intraocular pressure, and this is where combination eye drops can help.
These also reduce exposure to preservatives and potential allergic reactions.(21)
If you are prescribed a combination eye drop, your ophthalmologist will go into detail as to why and how they fit into your treatment plan.
More treatment options for glaucoma
Depending on the type of glaucoma, different types of laser treatment can be effective. In an acute case, a procedure called an iridotomy is often used to quickly relieve the pressure and keep it lower. In non-acute cases, a selective laser trabeculoplasty (SLT) can be used to help lower the pressure – this is especially useful for people with open-angle glaucoma who have tried eye drops to lower the pressure, but they haven’t worked.
Selective Laser Trabeculoplasty (SLT)
A selective laser trabeculoplasty is usually recommended for people with open-angle glaucoma that continues to progress despite treatment with pressure-lowering eye drops.(22) In a single outpatient laser procedure, SLT reduces intraocular pressure by increasing aqueous outflow through the trabecular meshwork. This, in turn, helps reduce intraocular pressure and prevent or slow down further vision loss in glaucoma patients.
SLT has minimal recovery time, is comparable to medical treatment, and can even delay or prevent the need for eye drops, thereby avoiding the associated side effects. Importantly, the effect of SLT is not permanent, but the procedure can be repeated.
Eye drops will often be the first treatment to try, but surgery is an option. Trabeculectomy surgery helps to slow the development of glaucoma and lower eye pressure. Many other procedures can be used, depending on the stage and type of glaucoma.
Types of surgery
- Trabeculectomy (tra·bec·u·lec·to·my) — this procedure involves creating a small flap in the sclera. The scleral opening is covered with a thin trapdoor that allows fluid to drain out of the eye, but also prevents it from draining too quickly.
- Trabeculotomy (tra·bec·u·lo·to·my) — the procedure of choice in children with congenital glaucoma. This involves the removal of a small piece of tissue from the drainage angle in the eye to create an artificial opening. This allows fluid to drain out of the new opening, lowering the intraocular pressure.
- Viscocanalostomy (vis·co·can·al·os·to·my) — involves the injection of a viscoelastic material into the eye. This injection dilates the canal and disrupts the layers of the trabecular meshwork. This procedure allows the fluid to slowly percolate out of the anterior chamber.
- Deep sclerotomy (scler·o·to·my) — this is an innovative, minimally invasive surgical procedure for open-angle and juvenile glaucoma, which allows the intraocular pressure to be lowered without opening the anterior chamber or entering the eye. The procedure removes some of the tissue responsible for limiting the rate of aqueous outflow, which aims to allow more fluid to drain out of the eye. This, in turn, lowers eye pressure.
- Trabecular stent bypass — involves the placement of a stent (tiny tube) to directly drain aqueous humour from the anterior chamber into Schlemm’s canal (a vessel in the eye that collects aqueous humour from the anterior chamber), thereby bypassing the obstruction at the level of the trabecular meshwork.
Recovery and aftercare following glaucoma surgery
The recovery time for invasive procedures can be several weeks and it’s advisable to keep water out of the eye during recovery. Patients should also avoid reading, bending, heavy lifting and driving for as long as advised by their ophthalmologist. The aftercare for each type of glaucoma surgery can be different, so you should always check with your ophthalmologist and follow their specific advice.
Here are some tips to ensure the best recovery(23):
- Leave the padding/eye patch in place over the operated eye for the first day to prevent external injury
- To prevent infection, keep your face clean and avoid touching the eye
- Avoid using eye make-up for as long as directed
- Avoid activities that expose the eye to water (for example, showering)
- Wash your hands before using eye drops
- Use the postoperative antibiotic and anti-inflammatory eye drops as instructed
- Protect the eye with goggles, especially in windy weather and during sports
- Be alert for signs of postoperative complications (for example, sudden changes in vision, severe pain, redness, pus discharge, or halos around light bulbs)
- Keep all your follow-up appointments
Secondary glaucoma treatment
Secondary glaucoma is when there is an identifiable reason for the pressure in your eye increasing, which has led to glaucoma developing. As with primary glaucoma (where we don’t know the cause), secondary glaucoma can be of the open-angle or angle-closure type, and can occur in one or both eyes.
Is secondary glaucoma curable?
The treatment plan for secondary glaucoma will usually depend on treating the underlying cause. However, your ophthalmologist may also recommend either medication such as glaucoma eye drops, laser treatment, conventional surgery or a combination of these to manage the glaucoma itself.
With that in mind, let’s explore the different kinds of secondary glaucoma, the treatment options available, and the most effective treatments for each type.
Types of treatment for secondary glaucoma:
- Exfoliative glaucoma — Generally, medical therapy is not used to control this kind of glaucoma. Your ophthalmologist will usually recommend laser trabeculoplasty or incisional surgery.
- Neovascular glaucoma — This is treated with medication, including beta blockers that reduce the production of aqueous humour (the fluid in your eye) and topical steroids that help manage the pain and inflammation.
- Pigmentary glaucoma — Your ophthalmologist will focus on controlling your eye pressure. They will usually do this through a combination of eye-drop medications that reduce the production of fluid within the eye. Alternatively, lasers or incisional surgery may be used to unblock the drainage system in your eye.
- Traumatic glaucoma — A doctor will customarily recommend incisional surgery in order to restore the intraocular structures, and corticosteroids and antibiotics may be immediately prescribed to prevent tissue scarring and infection. In some cases, it’s possible the patient may also need medication in the form of beta blockers and Diamox tablets post-surgery to maintain the intraocular pressure.
- Uveitic glaucoma — While the focus will be on managing the underlying cause, especially in the case of auto-immune disorders, IOP is usually controlled using drainage shunts, lasers and a combination of drugs including beta blockers and carbonic anhydrase inhibitors. Treatment of uveitic glaucoma is usually complex, and your doctors will work closely with each other to devise a safe and effective treatment plan for you.
- Congenital glaucoma — Microsurgery is used to correct the structural deficiencies which originated during the developmental period of the baby. This type of surgery is incredibly advanced, using small tools to create a drainage canal for any excess fluid in the eye. If necessary, the doctor will also implant a small drainage valve or tube which will carry the fluid out of the eye.
Carbonic anhydrase inhibitors
A group of enzymes called carbonic anhydrases are responsible for the secretion of aqueous humour, but sometimes they get carried away and produce too much fluid, causing a rise in intraocular pressure.
Carbonic anhydrase inhibitors are used to suppress the activity of carbonic anhydrase enzymes.
CAIs are available as eye drops as well as oral medication. The difference here often comes down to whether your glaucoma is already being controlled by eye drops.
Acute angle-closure glaucoma treatment
Treatment for acute ACG usually begins with topical eye drops and intravenous medication, both of which aim to reduce IOP and provide pain relief. The eye drops narrow the pupil, which lowers the amount of fluid your eye makes and helps to decrease pressure. Once the IOP has reduced a little, your ophthalmologist may discuss surgical options with you, for further treatment if necessary.
These are common medication types and treatments an ophthalmologist might recommend for acute angle-closure treatment:
- Carbonic anhydrase inhibitors — If someone with acute ACG has an extremely high IOP, Diamox tablets (a common brand of Acetazolamide) is immediately administered.
- Mannitol — Unless the patient has a contradictory health condition, such as kidney disease or dehydration, a Mannitol injection can be given intravenously to reduce the pressure. This diuretic works by decreasing vitreous volume (a clear, colourless fluid that fills the space between the lens and the retina), which ultimately prevents further build-up of IOP.
- Osmotic agents — These can be given topically (such as an eye drop) or taken orally as a pill to help clear corneal swelling (swelling of the clear, protective outer layer of your eye) and bring down a severely high IOP.
- Steroids — Steroids like prednisolone are often used in limited doses to reduce inflammation and pain. These are used sparingly, as steroids have been known to increase IOP.
- Laser peripheral iridotomy —When the angle is partially or completely closed up, a laser is used to make small holes in the peripheral area of the iris to assist drainage of fluid. Your ophthalmologist may also recommend that the procedure be performed in the other eye as a pre-emptive measure.
- Paracentesis —Manual drainage of eye fluid is usually only performed as a final measure to bring down IOP until the medication starts to take effect.
- Filtration surgery — This would usually only happen if laser facilities are unavailable, and if damage to the optic nerve is significant.
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