What Is 'Glaucoma'?
Glaucoma is a condition in which the pressure of fluid in the eye-ball is abnormally high - higher than the eye can tolerate over a long period of time. Glaucoma usually occurs in both eyes, but it may start much sooner in one eye than in the other. When the eye pressure is abnormally high over a long period of time then it causes the slow death of nerve fibrils inside the optic nerve leading to a gradual reduction in vision. Eye-sight thus lost can never be regained.
What Causes Glaucoma?
It is caused by the build-up of the fluid 'aqueous humour' which circulates within the eye. This occurs because either too much fluid is being formed or the channel through which it normally drains - 'the canal of Schlemm' - is blocked. Since new fluid continues to be formed the pressure continues to rise.
Can Glaucoma Damage Sight?
If it goes untreated, YES. Raised pressure can constrict blood vessels that nourish the sensitive visual cells in the back of the eye resulting in the slow death of these cells causing gradual, slowly progressive loss of vision. Blurring of side vision and reduced vision in low light conditions is usually noticed first. As the condition progresses, more nerve cells are damaged and the range of vision becomes narrower. If left unchecked, this process will definitely lead to total blindness.
How Can You Tell if You Have Glaucoma?
Usually you can't. Glaucoma is insidious: the vast majority of cases develop slowly over a period of months or years. In most cases there are no symptoms. Damage can progress so slowly that the person is not aware of the gradual loss of sight. Some people do experience vague symptoms and these are important warnings that a proper eye examination is needed. Symptoms can include a need for frequent change of glasses, difficulty in adjusting to dark rooms, loss of side vision, and generally blurred vision. Rarely, other symptoms, such as appearance of halos or rainbow colours around lights and severe headache or pain associated with blurred vision and red eyes may occur.
Who Gets Glaucoma?
It most often appears in people in middle and later years of life. That is why it is important for everyone above 40 to have a proper eye examination at a well equipped eye clinic every two years. A very rare form of glaucoma can occur in infants. These infants usually have one or both eyes that look abnormally big .They have difficulty in opening their eyes in bright light and a lot of watering from the affected eye. People at high risk include those with diabetes or those who have relatives with glaucoma. Those who have a positive family history should be all the more vigilant and should be sure to have their eyes checked regularly.
Are There Different Types of Glaucoma?
Yes, there are several. The most common types are CHRONIC, ACUTE, CONGENITAL and SECONDARY. All of them require attention over a long period of time, often for the whole life.
Simple or chronic open-angle glaucoma: This accounts for 80 per cent of the cases. It progresses slowly and often goes unnoticed for many months or years, causing a gradual deterioration of vision. Signs that suggest that a person has this type of glaucoma include: frequent change of glasses, none of which seem to help; aching or discomfort around the eyes; blurring of side vision and difficulty in adjusting to darkly lit surroundings. This type of glaucoma usually responds well to medication, although resistant cases are always there. Therapy is usually continued for life so that the pressure is kept under control. Surgery is the only treatment for resistant cases.
Acute or angle-closure glaucoma:
It is much less common. In this there is an acute and drastic rise in eye pressure causing severe pain and reduction in vision. If not treated at once it can permanently damage vision in a very short time. Unlike chronic open-angle glaucoma, acute glaucoma has very marked symptoms such as severe pain, blurred vision, appearance of halos around lights and nausea and vomiting.
Secondary glaucoma:
This type is caused as a complication of certain pre-existing eye problem such as iritis, retinal detachment, over-ripe cataract or a tumour in the eye.
Congenital glaucoma:
This is very rare and occurs in babies who are born with defective drainage canals. This makes the eye appear cloudy and causes the eye to become abnormally large. The baby may shy away from light and keep its eyes closed to avoid light. There may also be excessive watering from the baby's eyes. These symptoms indicate the need to get the baby's eyes examined by an eye specialist.
How is Glaucoma Diagnosed? What are the Special Tests for Glaucoma?
Only a qualified eye specialist will have the expertise and the equipment to properly diagnose this condition. It is therefore important for everyone to visit an ophthalmologist at around the age of 40 years to have a complete eye exam. The most important part of this eye exam is the measurement of eye pressure using an instrument called the TONOMETER. This is usually referred to as "taking the tension". This test takes only a few seconds and is absolutely painless.
If the eye pressure is found to be raised, only then a set of confirmatory tests are done to find out if the person really has the disease or not. These include the following:
Gonioscopy:
With this test the doctor comes to know about the type of glaucoma that the patient is suffering from. A special 'contact lens' called the 'gonioscope' is placed on the eye and the inner structures are visualised using a special microscope called the 'slit-lamp bio-microscope'. This test is not painful and takes a few minutes only.
Field Test (Perimetry):
This test is done on a special, computerised machine and provides information about the amount of damage that has been caused to the optic nerve by the disease. This is a very sensitive test and it can help diagnose the disease in its earliest stages when a significant amount of damage has not occurred. It needs to be repeated frequently every 3 to 6 months in order to keep a close track of the disease and to see if it is in control or not. It helps tell how much treatment you need and how well it is working.
Refraction:
Refers to the testing for glasses and it is routinely done for all patients who have glaucoma whenever they come for their follow-up visits to the doctor. This helps to know if the vision is being maintained or not.
Are Regular Eye Check-Ups Important?
If the diagnosis of glaucoma is established then the tension test, the field test and the refraction test have to be periodically repeated in order to know if the disease is under control or not. That is why it is very important for the patient not to miss his appointments with his eye doctor. If home or work responsibilities, lack of money or difficulty in travelling interfere with your visits to the hospital or in getting your medicine then you should talk with your doctor freely. He may be able to guide you to the right places for assistance.
Can Glaucoma Be Cured?
Although glaucoma cannot be cured it can usually be controlled with proper treatment. Glaucoma is a chronic life-long condition requiring continual observation and management of the patient to keep elevated intra-ocular pressure under control and to help prevent loss of vision. The earlier the condition is detected and treated, the greater the success in preventing visual loss.
How Is Glaucoma Treated?
Eye drops and tablets:
It is usually controlled by using special eye drops. If one eye type of drop is not producing the desired effect then it may have to be supplemented or replaced by another one. Sometimes tablets have to be taken also. It is very important to use the medicine regularly and exactly as instructed by the doctor. As the effect of the medicine lasts for only a few hours the drops must be instilled on schedule to keep glaucoma under control.
How many drops to put:
Only one drop of the medicine is enough for the desired effect so do not put more. After putting the drop close your eye and wait for at least 5 minutes before putting the next medicine, if any. Do not use the drops if they are discoloured. Keep all medicines out of reach of children as they are toxic if taken orally.
Side-effects of tablets
If pills have been prescribed they may cause tingling sensation in the fingers and toes. They can also cause drowsiness and stomach upset. These side effects are usually mild.
Although these side effects of the medicines may be a nuisance, but they are worth the trouble to save the eye-sight. So they should not be stopped without the doctor's advice or permanent damage to sight can occur!
Surgery:
When glaucoma is not being adequately controlled with medicines, surgery is necessary. It is usually possible with the help of surgery to bring the pressure down to normal levels and to halt permanently the reduction of vision. However, the amount of sight that has already been lost can never be recovered. Sometimes even after the operation one eye drop may be needed to keep the pressure under control. This will have to be continued life-long. As with any other surgical procedure there are risks involved in the operation of glaucoma also and the benefits of the surgery have to be weighed against the risks before a decision to operate is made. After operation when the eye has stabilised and the pressure is under control the patient will still be required to get his eye pressure tested periodically to make sure that the operation is performing well. Field test may also be required once a year for the same reason.
Laser Treatment
Laser therapy is a very effective new form of treatment in selected cases of glaucoma. It does not replace medical or surgical methods of treatment, but it has been found to be a valuable adjunct in the treatment.
