FAQ GLAUCOMA

Why is it important to know about glaucoma?

Damage due to glaucoma is preventable, not curable. It is therefore necessary that the disease should be detected and treated at its earliest stage to prevent blindness.

What is glaucoma?

Glaucoma is a group of diseases that can damage the eye’s optic nerve and result in vision loss and blindness. The most common form of the disease is open-angle glaucoma. With early treatment, you can often protect your eyes against serious vision loss.

 My vision is good, then why do you say I have glaucoma?

In glaucoma the central vision is not lost till the very late stages. It starts with damage to your peripheral vision and gradually comes to the centre. When the central vision is affected it is too late and nothing can be done to restore vision. In a way, a good vision is misleading as far as severity of glaucoma and extent of damage is concerned.

What is the optic nerve?

The optic nerve transmits the electrical signals from the retina (light sensitive tissue at the back of the eye) to the brain allowing us to ‘see’. It consists of a bundle of millions of ‘nerve fibres’ with each fibre carrying information about different parts of the image. It is the gradual loss of these fibres which ultimately leads to loss of vision in glaucoma.

What is the normal pressure for an eye?

Normal pressure for an eye is one which does not cause any damage to the optic nerve. In most normal people the eye pressure is around 17 to 20 mm of mercury. Some people have higher pressure than this, but that does not cause damage to the nerve for years. However, such patients need careful monitoring so that damage to the nerve is detected at its earliest stage. On the other hand, some patients have a much lower eye pressure, say 12 or 14 mm Hg, but this low pressure is not tolerated by the eye and the nerve is damaged. This is a special type of glaucoma and needs more careful monitoring and treatment.

Does increased eye pressure mean that I have glaucoma?

Not necessarily.  Increased eye pressure means you are at risk for glaucoma, but does not mean you have the disease.  A person will only be diagnosed with glaucoma if the optic nerve is damaged.  If you have increased eye pressure but no damage to the optic nerve, you do not have glaucoma, however, you should be regularly monitored.  Follow the advice of your eye care professional. 

Will I develop glaucoma if I have increased eye pressure?

Not necessarily. Not every person with increased eye pressure will develop glaucoma.  Some people can tolerate higher eye pressure better than others. Also, a certain level of eye pressure may be high for one person but normal for another.

Can I develop glaucoma without an increase in my eye pressure?

Yes. Glaucoma can develop without increased eye pressure. This form of glaucoma is called normal-tension glaucoma.  It is a form of open-angle glaucoma.

Why does the eye pressure (IOP) rise?

‘Aqueous humour’ is a clear fluid constantly formed by a structure in the eye called ciliary body and bathes a space in the front of the eye called the ‘anterior chamber’. The fluid then drains out of the chamber through the angle of the eye where it flows out through a spongy meshwork (trabecular meshwork) and leaves the eye. Eye pressure rises when this drainage system of the eye is not functioning properly and the fluid (aqueous humour) starts collecting inside raising the pressure. In ‘Open Angle Glaucoma’, the trabecular meshwork is not functioning properly and doesn’t allow the fluid to drain out easily.

In ‘Angle Closure Glaucoma’ the angle of the eye itself is blocked and the fluid is unable to reach the trabecular meshwork for drainage.

In ‘Normal Tension Glaucoma’ there is no build-up of eye pressure and the fluid is draining properly, but the nerve of the eye is too sensitive to even normal pressure and gradually develops glaucoma.

In ‘Congenital Glaucoma’ the trabecular meshwork is defective since birth and the child develops increase eye pressure soon after birth.

What causes damage to the “Optic Nerve”?

The eye is filled with a clear fluid called ‘Aqueous Humour’ which nourishes the eye and keeps it healthy. Similar to blood pressure, it also exerts a pressure in the eye called Intraocular Pressure (IOP). For reasons not clearly understood, excessive pressure within the eye can cause damage to the nerve. Usually it happens when the fluid builds up within the eye raising IOP. Sometimes the nerve gets damaged inspite of normal IOP due to increased sensitivity of the nerve itself.

Who gets glaucoma?

Risk factors for ‘Open Angle Glaucoma’ include older age, black race, family history of glaucoma, high pressure in the eyes, diabetes, hypertension and near-sightedness (myopia).

‘Angle Closure Glaucoma’ is more common in patient of ‘Asian’ origin including Indians and far sightedness (hypermetropes) or anybody with a narrow angle of the eye.

Glaucoma Screening
The American Academy of Ophthalmology’s recommended intervals for eye exams are:

• Age 20-29: Individuals of African descent or with a family history of glaucoma should have an eye examination every three to five years. Others should have an eye exam at least once during this period.

• Age 30-39: Individuals of African descent or with a family history of glaucoma should have an eye examination every two to four years. Others should have an eye exam at least twice during this period.

• Age 40-64: Individuals should have an eye examination every two to four years.

• Age 65 or older: Individuals should have an eye examination every one to two years.

Which age does glaucoma affect?

Although glaucoma is most common above the age of 40 years, it may affect any age group. A special type of glaucoma called Congenital Glaucoma may affect even a new-born or a child. Any eye that appears bigger than normal in a child should be shown to an eye specialist.

What are the symptoms of glaucoma?

Most people who have glaucoma don’t have any symptoms. By the time a patient notices loss of vision, the eye damage is severe. This makes it essential to have regular screening to detect glaucoma at an early treatable stage. The loss of nerve fibres in glaucoma is irreversible and therefore early detection and treatment is essential to prevent further loss.

Loss of nerve fibres in the ‘Optic Nerve’ cause loss of field of vision. The central vision remains clear till the last stage but there is a gradual loss of peripheral vision. In the later stages only a ‘Tunnel Vision’ may be left.

In some patients with ‘Angle Closure Glaucoma’ there will be an acute (sudden or short-term) rise in eye pressure or attack of glaucoma. In these cases, the eye becomes red and extremely painful. Nausea, vomiting, headache and blurred vision may also occur. These attacks usually occur in the evening time though it can occur at any time of the day. Sometimes these attacks are preceded by smaller milder attacks which are associated with mild to moderate pain. The patient may also observe rainbow like coloured halos around lights. These attacks usually resolve without any treatment within a few hours and can be missed by the patient. Treatment at this stage is very easy and can prevent a full-blown attack and need for lifelong medications or surgery.

What is open-angle glaucoma?

Open-angle glaucoma is the most common form of glaucoma. In the normal eye, the clear fluid leaves the anterior chamber at the open angle where the cornea and iris meet. When the fluid reaches the angle, it flows through a spongy meshwork, like a drain, and leaves the eye. Sometimes, when the fluid reaches the angle, it passes too slowly through the meshwork drain, causing the pressure inside the eye to build.  If the pressure damages the optic nerve, open-angle glaucoma – and vision loss – may result.

Who is at risk for open-angle glaucoma?

Anyone can develop glaucoma. Some people are at higher risk than others. They include people:

• With a family history of glaucoma
• Over 40 years of age
• With diabetes or high blood pressure
• Who suffer from migraines; Raynaud’s phenomenon, heart attack or stroke
• Who are short sighted
• Who have suffered a previous eye injury
• Who use or have used steroids

Is Glaucoma hereditary?

Yes, blood related family members of glaucoma patients are likely to develop glaucoma more often than the general population. It is advisable that family members of glaucoma patients should get their eyes review to rule out glaucoma.

How can I prevent the disease from occurring?

At this time, we do not know how to prevent glaucoma.  However, studies have shown that the early detection and treatment of glaucoma, before it causes major vision loss, is the best way to control the disease.  So, if you fall into one of the high-risk groups for the disease, make sure you have a complete glaucoma screening once every 3 – 5 years depending upon your age group. Also make sure your eyes are thoroughly examined through dilated pupils every two years by an eye care professional.

What are the symptoms of glaucoma?

At first, open-angle glaucoma has no symptoms.  It causes no pain.  Vision seems normal.

Without treatment, people with glaucoma will slowly lose their peripheral, or side vision.  They will feel as if they are looking through a tunnel. Over time, straight-ahead vision may decrease until no vision remains.

How is glaucoma detected?

Glaucoma is detected through a comprehensive eye exam that includes a visual acuity test, visual field test, dilated eye exam, tonometry, and pachymetry.

Can glaucoma be cured?

No. There is no cure for glaucoma, but appropriate treatment and regular monitoring will usually minimize vision loss. Vision lost from the disease cannot be restored.

Can glaucoma be treated?

Yes. Immediate treatment for early stage, open-angle glaucoma can delay progression of the disease.  That’s why early diagnosis is very important.  Glaucoma treatments include medicines, laser surgery, conventional glaucoma surgery, or a combination of any of these.  While these treatments may save remaining vision, they do not improve sight already lost from glaucoma.

How serious is my glaucoma problem?

It depends upon the amount of optic nerve damage that has already been caused. The damage can be measured by visual field analysis (VFA) and GDx (which measures the thickness of nerve). As the damage is permanent, appropriate measures are taken to prevent or slow down further damage.

What can I do to protect my vision?

If you are taking medicines for glaucoma, be sure to take them every day as directed by your eye care professional.  People at risk for glaucoma should have a dilated eye exam at least every two years. If you have been diagnosed, you may need to see your eye care professional more often.

What can I do if I have already lost some vision from glaucoma?

If you have lost some sight from glaucoma, ask your eye care professional about low vision services and devices that may help you make the most of your remaining vision. In most cases, slight vision loss will not be noticeable.

If you have experienced significant vision loss, ask for a referral to a specialist in low vision. Many community organisations and agencies offer information about low vision counselling, training, and other special services for people with visual impairments.  A nearby school of medicine or optometry may provide low vision services.

What should I do for a family member or friend who may be at risk of glaucoma?

Encourage them to have a comprehensive dilated eye exam at least once every two years.  Remember – lowering eye pressure in the early stage of glaucoma slows progression of the disease and helps save vision.

Glaucoma Surgery FAQs

What is a trabeculectomy? 

It is an operation performed to treat glaucoma. The operation entails forming a small channel through the white part of the eye.  This channel will allow fluid – made naturally in the eye – to drain away. Some patients will require a special medication (Mitomycin C) to be placed around the incision site to try to ensure that the hole does not scar over. The drainage site is under the upper eyelid and will not be seen, and once settled should not cause you discomfort. The fluid will drain from the channel and be absorbed by conjunctival vessels in the skin of the eye.

Do I have to have an operation, or can I have other forms of treatment? 

Glaucoma can be treated with eye drops, which have to be instilled every day throughout the patient’s life time.  If treatment with eye drops fails to control the pressure in the eye, an operation may be necessary.  In other cases, an operation may not be essential, but may be offered as an alternative to instilling eye drops constantly. 
Laser treatments are suitable for some patients but are not always permanently effective in lowering pressure.

Will I be awake or asleep during the surgery? 

The majority of patients having this surgery have it under local anaesthetic (the eye is numbed with special fluid drops and the patient is awake). For some patients this is not appropriate and they will have a general anaesthetic or some sedation. 

How long will I be in hospital after the operation? 

Most local anaesthetic patients can go home the same day of surgery assuming they have good vision in the other eye or have someone with them that evening. Many patients choose to stay overnight if this is difficult. Patients having a general anaesthetic may have to stay overnight.

Will the operation improve my sight? 

Unfortunately, the operation cannot bring back any sight that has been lost.  After the operation, your sight may be blurred and seem worse.  This is only a temporary situation, and is to be expected after an operation.  Your eye will need time to heal and settle down following surgery.  
This generally takes about 6-8 weeks in total. 

How successful is the operation?

 
Evidence shows that surgery is most effective at lowering eye pressure and the lower the eye pressure the lower the risk of blindness from glaucoma!
It is quite a successful operation, which will in most cases, save the remaining sight of the eye.  Following surgery, in 70% of cases no further treatment is necessary.  In 15-20% of cases, drops to reduce pressure will still be needed.  In 10-15% of cases, a further operation or treatment is necessary.  

Following surgery do: –

• read
• watch TV
• go for walks
• cook
• wear glasses/sun glasses in the day
• wear an eye shield for 2 weeks at night
• rest and take things easy

Following surgery,: –

• do not rub your eye
• do not undertake strenuous exercise
• do not do heavy gardening or housework

What are antimetabolites and why are they used?

Mitomycin C and 5-FU decrease the amount of scar tissue formed around the new drainage site, thereby increasing the flow of fluid in this new channel, and helping to keep the pressure low. They can be used during and/or after surgery. They do carry a small increased risk of infection, and corneal complications, but can dramatically increase your chances of success.

What are the alternative surgical procedures?

Non penetrating surgery is an option but can be less effective than a trabeculectomy. A minimally invasive trabeculectomy with a Express micro-shunt implant gives the benefit of both as it lower pressure effectively and reduces complications, and surgery time, but can significantly increase the costs of the procedure. 

Q Do I need to come for follow up after laser / surgery?

Treatment of glaucoma is life-long. Even after laser or surgery one may need additional medication and a lifetime of follow up to monitor the progress of the disease.