Glaucoma – the silent thief of sight

Dr Sachindra Laishram *

Acute angle closure glaucoma of the right eye (intraocular pressure was 42 in the right eye). Note the mid sized pupil on the left that was not reactive to light and conjunctivitis :: Pix - Wikipedia/James Heilman, MD

Glaucoma is a condition that causes damage to your eye's optic nerve and gets worse over time. Glaucoma usually occurs when pressure in your eye increases. This can happen when eye fluid isn't circulating normally in the front part of the eye. Normally, this fluid, called aqueous humour, flows out of the eye through a mesh-like channel. If this channel becomes blocked, fluid builds up, causing glaucoma.

The increased pressure, called intraocular pressure, can damage the optic nerve, which transmits images to the brain. If damage to the optic nerve from high eye pressure continues, glaucoma will cause permanent loss of vision. Without treatment, glaucoma can cause total permanent blindness within a few years.

Because most people with glaucoma have no early symptoms or pain from this increased pressure, it is important to see your eye doctor regularly so that glaucoma can be diagnosed and treated before long-term visual loss occurs.

Glaucoma is the second leading cause of blindness in the world, according to the World Health Organization. According to Indian Journal of Community Medicine 2013 edition, it is estimated that there are more than 60 million cases of glaucoma worldwide and it will increase to 80 million by 2020. The estimated prevalence of glaucoma is 2.65% in people above 40 years of age. In India, the estimated number of cases of glaucoma is 12 million, around one fifth of the global burden of glaucoma.

In the 10th century, Al-Tabari was the first to suggest association of glaucoma with raised intraocular pressure. Mackenzie finally established this in 1835. Since then it has widely been accepted that glaucoma is essentially a disease caused by intraocular pressure.

Glaucoma can cause permanent damage to your vision before you even suspect that something is wrong. That is why glaucoma is called "silent thief of sight". Glaucoma doesn't mean the end of your productive life. Advances in therapy have enabled people to maintain their normal lives, regardless of the disease. With an early diagnosis and early initiation of therapy, most people with glaucoma do not go blind.

Types of Glaucoma

There are several types of glaucoma. Because their causes and the people they affect are so diverse, they may require different forms of treatment.

Open angle glaucoma: Also called wide-angle glaucoma, this is the most common type of glaucoma. The structures of the eye appear normal, but fluid in the eye does not flow properly through the drain of the eye Closed angle glaucoma: Also called acute or chronic angle-closure or narrow-angle glaucoma, this type of glaucoma is less common in the West than in Asia. Poor drainage is caused because the angle between the iris and the cornea is too narrow and is physically blocked by the iris. This condition leads to a sudden build-up of pressure in the eye.

Normal tension glaucoma: also called low-tension glaucoma is a unique condition in which optic nerve damage and vision loss have occurred despite a normal pressure inside the eye.

Secondary glaucoma: refers to any form of glaucoma in which there is an identifiable cause of increased eye pressure, resulting in optic nerve damage and vision loss.

Congenital glaucoma: also referred to as Childhood glaucoma, paediatric, or infantile glaucoma — occurs in babies and young children. It is usually diagnosed within the first year of life. This is a rare condition that may be inherited, caused by incorrect development of the eye's drainage system before birth.

Mixed mechanism glaucoma: is a rare, fortuitous combination of open-angle and Closed angle glaucoma.

Risk Factors for glaucoma

Certain conditions put some people at more risk for glaucoma.

Age more than 40
– Family history of glaucoma
– Mongoliod descent
– Diabetes or hypertension
– Myopia or nearsighted-ness
– Regular long term use of steroid
– Previous eye injury

What are the Warning Signs

Unfortunately, most cases of glaucoma do not occur with readily noticeable symptoms that warn of the irreversible optic nerve damage being done. However, the presence of the following warning signs, indicates that you need a thorough examination by an eye doctor:
– Unusual trouble adjusting to dark rooms
– Difficulty focusing on near or distant objects
– Squinting or blinking due to unusual sensitivity to light or glare
– Recurrent pain in or around eyes
– Dark spot at the center of viewing
– Excess tearing or "watery eyes"
– Dry eyes with itching or burning; and
– Seeing spots, ghost-like images

The following may be indications of potentially serious problems that might require emergency medical attention:
– Sudden loss of vision in one eye
– Sudden hazy or blurred vision
– Flashes of light or black spots
– Halos or rainbows around light

The symptoms listed above may not necessarily mean that you have glaucoma. However, if you experience one or more of these symptoms, contact your eye doctor for a complete exam.

Can Glaucoma be prevented?

Glaucoma cannot be prevented, but if it is diagnosed and treated early, the disease can be controlled.

Why is early detection important?

According to the glaucoma foundation, for people aged 40 years and above, exams should be scheduled every 2 years if you have no risk for glaucoma, and every year if you have risk factors for glaucoma. As the damage done by glaucoma are permanent, early detection and initiation of treatment is of prime importance. As the patients are not aware of the symptoms in the early stage, routine and regular check-up is very important.

The doctor will measure the IOP, assess the optic disc and go for Visual field assessment in specific cases. They will be able to pick up the cases of glaucoma at a very early stage with the modern technology available.

Treatment options

The treatment for glaucoma depends upon the nature and severity of each case. In general, glaucoma cannot be cured, but it can be controlled. Eye drops, pills, Laser surgery, eye operations or a combination of these approaches may be used to treat glaucoma. Typically, they all work to help in keeping IOP under control. With any type of glaucoma, regular eye examinations are very important to detect progression and to prevent vision loss. Because glaucoma can worsen without your being aware of it, your treatment will likely need to be changed over time to achieve a lower "target eye pressure."

Take home message

In its early stages, glaucoma has no symptoms and damage caused by glaucoma is irreversible. It is important that you continue to take your drops every day to avoid losing your sight permanently.
– Keep your regular visits to the clinic/hospital without fail.
– Please comply with the doctor's advice and treatment.
– Never change or stop taking your medications without consulting your doctor.
– Whenever you see any other doctor, make sure he knows you have glaucoma.
– Your vision is more precious than the cost of medication.
– If you have a history of glaucoma in your family, please get your relatives examined for the same, as glaucoma is hereditary.
– If you have any problem with your medication, talk to your doctor as soon as possible.