Silent thief of sight

Glaucoma is a common eye ailment that can lead to severe loss of vision and blindness. Because of its potential to take away sight and leading to darkness in afflicted person's life, it is also referred to as ‘kala motia’ in local population. 

In reality glaucoma is not one entity; it is a group of many conditions that result in causing blindness through a common pathway. Vision is usually lost due to slow and progressive damage to the optic nerve. Optic nerve is the connection between the eye and the brain. Eyes capture the image and send it to the brain for recognition and further interpretation, through the optic nerve.  If  the optic nerve is damaged, the brain will not receive any image and one will not see anything even if rest of the eye is normal. 

The optic nerve damage in glaucoma can be due to many reasons. But mostly it happens due to increased pressure inside the eyes. Eyes are like a ball. It needs to be inflated with some pressure to maintain its shape otherwise it will collapse. But when this pressure becomes too high then it damages the eye. So, like blood pressure, eye pressure also needs to remain normal.

Glaucoma is a silent disease, as  patients show no symptoms until the disease is quite advanced. For this reason it is also known as ‘silent thief of sight’. If left undetected and untreated, it can lead to irreversible blindness due to permanent damage to the optic nerve. As glaucoma has no symptoms, it remains undetected until it is too late. It is estimated that 90 per cent of glaucoma patients in our country remain undiagnosed. This puts a large population at risk of going blind.

According to World Health Organisation (WHO) estimates, about 314 million people around the world have impaired vision, due either to eye diseases or need for glasses (uncorrected refractive errors). Of these, 45 million are blind. More than 82 per cent of all blind are 50 years of age or older and more than 90 per cent of these visually impaired live in developing countries like India. Top five causes of blindness are cataract, refractive errors, glaucoma, age-related macular degeneration and diabetic retinopathy. These account for 75 per cent of all visual impairment. 

Glaucoma is the third major cause of blindness after cataract and uncorrected refractory errors. However, blindness due to cataract and refractive errors is reversible; in contrast, blindness due to glaucoma is irreversible. Glaucoma cannot be cured but blindness due to glaucoma can be prevented in majority by timely diagnosis and treatment.

Currently, around 60 million people suffer from glaucoma. This number is expected to increase to 80 million by 2020 mainly due to increase in the ageing population. And India will be home to about one sixth of these patients.

Who is at risk of developing glaucoma?

 Glaucoma can occur at any age but generally it affects people above 40 years of age and the risk increases with advancement of age. People over 60 years of age are six times more at risk than population at large. People with high ‘eye pressure’ and with a family history are particularly at risk of developing glaucoma. Certain ethnic groups and people with diabetes are also prone to glaucoma. 

Can it be prevented?

All glaucomas cannot be prevented, but visual impairment and blindness can be prevented by early detection and treatment. Since glaucoma may not have any symptoms, periodic eye check-up is of utmost importance for early detection. Some people may see coloured halos around lights and have mild blurring of vision in the evening. Such people should consult an eye doctor without delay otherwise, whenever you visit your eye doctor for reading glasses, you must insist on check-up for glaucoma, which includes measuring ‘eye pressure’,  examining the optic disc for any damage and evaluation of drainage angles of the eye. This check-up should be done by an eye specialist. Opticians who make glasses for you are generally not trained to do this.

How is glaucoma treated? 

The aim of treatment is to prevent further damage and preserve the remaining visual function. This is best achieved by reducing ‘eye pressure’. In most cases ‘eye pressure’ can be reduced by using eye drops. As glaucoma is a chronic disease, the treatment is life-long. The number and nature of eye medication is likely to change over a period of time, therefore, regular periodic checkups are important. Some people need lasers or surgery to control the disease.

Glaucoma not only increases burden of blindness in society, it also causes enormous difficulties due to direct as well as indirect cost of treatment.  Research conducted a few years ago at the Advanced Eye Centre at PGI revealed that families of glaucoma patients incur significant burden of care and loss of quality of life. 

KALA KOTIA

GLAUCOMA  

• Global cases 64.3 million (2013), expected 111.8 million (2040)
• The second leading cause of blindness 
• In India 12 million affected by it and 12 million blind 
• More than 90% cases of glaucoma remain undetected  

What is it? 

Glaucoma is a group of diseases generally caused by an increase in the fluid pressure within the eyeball that damages the nerve of the eye.

Types 

• Open-angle glaucoma is the most common, happens silently  
• Angle-closure occurs when exit of aqueous humor fluid is blocked

Warning signs 

• Frequent change of reading glasses
• Poor sight in dim light 
• Bumping into things in unfamiliar places
• Angle closure glaucoma is extremely painful 
• Colored rings around lights with blurred vision 
• One sided headache
• Poor sight in dim light, tunnel vision 

RISK GROUP

• If you are over 40
• Have a family history of glaucoma, diabetes or thyroid disorder

Detection 

• Fundus examination : Whether nerve of your eye is damaged 
• Field charting : Your field of view is complete 
• Intraocular pressure (IOP): Pressure inside your eye

Treatment 

• Prevent further sight loss by medications, laser or surgery

Medicines 

• Eye-drops to reduce pressure within the eye 
• Caution if suffering from asthma, bronchitis or heart problems

Laser  

• For angle-closure glaucoma laser takes a short  time, totally painless 
• In open-angle, laser can be used to reopen the drainage channels partially

Surgery  

• Needed if pressure not controlled with medication or laser 
• Usually done under local anaesthesia

Self-care 

• Visual field examination every 6 months, if defective 
• Take drop strictly as prescribed without a gap
• If multiple drops required, wait 10 minutes between drops 
• Must remember names of your medicines and doses 
• Moderate exercise, walking or jogging three or more times a week
• Benefits from exercise last only as long as you 

continue exercising

• Yoga is beneficial. Avoid inverted positions that may increase IOP

Source: AIIMS, www.wgweek.net, Internet

BLINDNESS

51% Cataract 

8% Glaucoma

5% Age-related macular degeneration

4% Corneal Opacities

4% Childhood blindness

3% Trachoma

3% Uncorrected refractive error

1% Diabetic retinopathy

21% Other causes

(Source: http://www.who.int)

— Prof Jagat Ram is Director of Post Graduate Institute of Medical Education & Research, Chandigarh, and Prof Surinder Pandav is the Chief of Glaucoma Service at the Advanced Eye Centre, PGI