About Eye Diseases 
Glaucoma
Glaucoma is one of the leading causes of blindness
in Hong Kong. For every one hundred adults above
the age of 40, three or more may have glaucoma.
If we can diagnose glaucoma early enough,
visual impairment or even blindness can often be
prevented.
Leading Cause of Permanent Blindness
Symptoms may not be very obvious in early stages of glaucoma, therefore the condition is often undetected. By the time the patient realises that he/she has an eye problem, the disease may already be very advanced. Therefore, glaucoma is also known as “the silent killer of vision”.
What Causes Glaucoma?
Within the eyeball, there is a continuous flow of a transparent fluid called “aqueous humour”. The flow of the aqueous humour is like a sink with a faucet turned on at all times. If the flow is too fast or if the drainpipe gets clogged, the pressure within the eye increases. The increased eye pressure will damage the eye and its optic nerve, leading to poor vision and even blindness.
The diagnosis of glaucoma includes state-of-the-art tests and careful examinations by experienced eye specialists.
Types of Glaucoma
Glaucoma can be classified according to the type of onset or underlying etiology as acute or chronic, congenital or acquired, primary or secondary, and normal tension or hypertensive.
Acute Glaucoma
Patients with acute glaucoma will experience a sudden onset of eye pain, redness, blurred vision and halos. It is usually associated with headache, nausea and vomiting. This is an ophthalmologic emergency, and medical attention should be sought immediately. Oral medications, injections or eye drops should be given in order to decrease eye pressure as quickly as possible, after which treatment can be administered via laser or other surgical methods.
Chronic Glaucoma
Chronic glaucoma is more insidious in onset. There are no telltale symptoms. Vision deteriorates and the field of vision narrows gradually. Patients are often unaware of their problem until the disease becomes very advanced, by that time most of their vision is lost and irreversible. Hence glaucoma is also known as “the thief of sight”.
Congenital and Acquired Glaucoma
While many patients are first diagnosed with glaucoma after the age of 40 (acquired glaucoma), there are also children who are born with a defective aqueous drainage system, resulting in congenital glaucoma. Congenital glaucoma usually presents itself during infancy or early childhood. Patients have large watery eyes which are sensitive to light.
Primary and Secondary Glaucoma
While primary glaucoma refers to glaucoma not caused by other underlying diseases, secondary glaucoma is caused by other underlying eye or systemic diseases, such as hypermature cataract, uveitis, eye tumours, diabetic disease or long-term use of steroid eye drops. It is vital to treat the underlying disease before the secondary glaucoma can be treated.
Details of Annual Glaucoma Screening
Normal Tension Glaucoma
Some patients can have glaucoma even with normal eye pressure. This is called “normal tension glaucoma” in which the optic nerve apparently cannot withstand the normal level of eye pressure. Thus, more investigations are usually required for diagnosis.
Hypertensive Glaucoma
In general, glaucoma is caused by increased eye pressure, thus damaging the optic nerve and resulting in vision deterioration and narrowing of the field of vision.
If you have the following conditions, you are at a higher risk for glaucoma and you should undergo regular eye check-ups:
Treatment of Glaucoma
Depending on the type of glaucoma, eye drops, oral medications, laser or surgery may be used to control the eye pressure. For some patients with narrow angle glaucoma in one eye, prophylactic laser peripheral iridotomy or medications may also be advised for the other eye to prevent acute glaucoma.
Glaucoma may cause permanent blindness, which can be prevented by early diagnosis and treatment. Adults over 40 years of age, especially those who have the above risk factors, are recommended to undergo eye examination every one to two years to facilitate early detection and prevent deterioration.
Leading Cause of Permanent Blindness
Symptoms may not be very obvious in early stages of glaucoma, therefore the condition is often undetected. By the time the patient realises that he/she has an eye problem, the disease may already be very advanced. Therefore, glaucoma is also known as “the silent killer of vision”.
What Causes Glaucoma?
Within the eyeball, there is a continuous flow of a transparent fluid called “aqueous humour”. The flow of the aqueous humour is like a sink with a faucet turned on at all times. If the flow is too fast or if the drainpipe gets clogged, the pressure within the eye increases. The increased eye pressure will damage the eye and its optic nerve, leading to poor vision and even blindness.
The diagnosis of glaucoma includes state-of-the-art tests and careful examinations by experienced eye specialists.
Types of Glaucoma
Glaucoma can be classified according to the type of onset or underlying etiology as acute or chronic, congenital or acquired, primary or secondary, and normal tension or hypertensive.
Acute Glaucoma
Patients with acute glaucoma will experience a sudden onset of eye pain, redness, blurred vision and halos. It is usually associated with headache, nausea and vomiting. This is an ophthalmologic emergency, and medical attention should be sought immediately. Oral medications, injections or eye drops should be given in order to decrease eye pressure as quickly as possible, after which treatment can be administered via laser or other surgical methods.
Chronic Glaucoma
Chronic glaucoma is more insidious in onset. There are no telltale symptoms. Vision deteriorates and the field of vision narrows gradually. Patients are often unaware of their problem until the disease becomes very advanced, by that time most of their vision is lost and irreversible. Hence glaucoma is also known as “the thief of sight”.
Congenital and Acquired Glaucoma
While many patients are first diagnosed with glaucoma after the age of 40 (acquired glaucoma), there are also children who are born with a defective aqueous drainage system, resulting in congenital glaucoma. Congenital glaucoma usually presents itself during infancy or early childhood. Patients have large watery eyes which are sensitive to light.
Primary and Secondary Glaucoma
While primary glaucoma refers to glaucoma not caused by other underlying diseases, secondary glaucoma is caused by other underlying eye or systemic diseases, such as hypermature cataract, uveitis, eye tumours, diabetic disease or long-term use of steroid eye drops. It is vital to treat the underlying disease before the secondary glaucoma can be treated.
Details of Annual Glaucoma Screening
Normal Tension Glaucoma
Some patients can have glaucoma even with normal eye pressure. This is called “normal tension glaucoma” in which the optic nerve apparently cannot withstand the normal level of eye pressure. Thus, more investigations are usually required for diagnosis.
Hypertensive Glaucoma
In general, glaucoma is caused by increased eye pressure, thus damaging the optic nerve and resulting in vision deterioration and narrowing of the field of vision.
If you have the following conditions, you are at a higher risk for glaucoma and you should undergo regular eye check-ups:
- Family history of glaucoma
- High nearsightedness / farsightedness
- Diabetes mellitus
- Ischemic heart / cardiovascular disease
- Sleep Apnea
- Migraine
- Underlying eye conditions, e.g. uveitis, history of eye injury
Treatment of Glaucoma
Depending on the type of glaucoma, eye drops, oral medications, laser or surgery may be used to control the eye pressure. For some patients with narrow angle glaucoma in one eye, prophylactic laser peripheral iridotomy or medications may also be advised for the other eye to prevent acute glaucoma.
Glaucoma may cause permanent blindness, which can be prevented by early diagnosis and treatment. Adults over 40 years of age, especially those who have the above risk factors, are recommended to undergo eye examination every one to two years to facilitate early detection and prevent deterioration.
