Glaucoma

What is glaucoma?

Glaucoma is an eye disease in which there is damage to the optic nerve which is usually due to increase in eye pressure.

What is optic nerve?
Optic nerve is responsible for sending signals from the eye to the brain. It sends signals of the images seen by the eye to the brain to interpret it.

What is eye pressure?
Like blood pressure is the pressure of the flow of blood in our blood vessels, eye pressure is the pressure exerted by the fluid present in the eye.

What is normal eye pressure ?
The eye pressure is normally between 11-21mm of Hg. Pressure above 21mm Hg does not always mean that one has glaucoma but it needs to be monitored more closely depending on other clinical findings.

Why does eye pressure increase?
The fluid in the eye is being produced constantly and also being drained out through drainage channels. If there is an increase in fluid production or blockage of the drainage channels then the fluid gets accumulated in the eye which leads to raised eye pressure.

What is the relation between eye pressure and optic nerve?
If eye pressure is high , it affects the blood supply to the optic nerve causing optic nerve damage.

Who is at risk of glaucoma?
Anyone above the age of 40 years is at risk of glaucoma. Those who have a family member affected by glaucoma are at higher risk.Certain types of glaucoma maybe seen in childhood, following injury, certain medications, or even at birth.

What are the symptoms of glaucoma?
Glaucoma is rightly termed as the 'Silent thief of sight' as there are no obvious symptoms in early stages of the disease. One may notice decrease in the side vision which may affect activities like driving , crossing the road etc. By the time glaucoma affects central vision it has come to an advanced stage. Redness,pain, watering maybe present if there is sudden increase in the eye pressure to very high levels. However if there is slow rise in the eye pressure one may not feel any pain.

How can I know if I'm suffering from glaucoma?
If you are above 40 years of age, ideally you should get a comprehensive eye check up by an ophthalmologist. We check your eye pressure and optic nerve status to know if you are suffering from or at risk of glaucoma.

What is he importance of early detection of glaucoma? Or Is glaucoma treatable?
The optic nerve damage which occurs in glaucoma cannot be reversed, however once we start treatment we can prevent further damage to the nerve. Hences it is very important to be detected early.

What are the ways to measure eye pressure?
There are various techniques to measure the eye pressure. Most commonly a Non-contact method is used to measure the eye pressure in all patients. This uses a puff of air to measure the pressure however it is a screening test with limited accuracy. For all patients of glaucoma or those who have raised pressure by the screening test we perform Applanation tonometry which is the Gold standard for eye pressure measurement. This involves the instrument touching the eye surface hence is not done in all patients.

What are the various glaucoma tests?
What is glaucoma work up?
The various tests for glaucoma are:

• Eye Pressure Check
• Optic Nerve Examination
• Perimetry - It is a computerised testing of the visual field of the eye. It gives us a report of how good the side vision is when looking at a central point. It should be done once a year atleast or advised by the doctor to look for any worsening or stability
• OCT - It is a scanning test of the optic nerve. It measures the thickness of nerve fibres and gives us a detailed analysis report.
• Gonioscopy - It is performed by placing a lens over the eye and observing the drainage passage in all quadrants of the eye. It gives us information whether the outflow channels are open or are narrowed or blocked.
• CCT -This is the measurement of the thickness of the central part of the cornea (black part of the eye) . It is measured by a small probe placed on the centre of the cornea. It helps to know the accuracy of the eye pressure measured. Thicker corneas show falsely high pressure readings and vice versa. Hence this test is important to correlate with the eye pressure.

What is the treatment for glaucoma?
There are various treatment modalities:

• Medical management - Eye drops are used to lower the eye pressure so that it does not increase and damage the nerve. Like medicines for sugar and B.P. this is also a Lifelong treatment. This is usually the preferred first line of management.
• Laser treatment- In patients who have narrow drainage channels, there is a laser procedure done to make a small opening in the eye which gives more space for the fluid to drain. After this procedure again eye pressure needs to be checked and then decided whether medical management is required or not.
• Surgery- Glaucoma surgery is usually done only if the pressure is not being controlled by medicines. The results are not as predictable as cataract surgery and the patient may need medicines even after surgery

What happens if we do not treat Glaucoma?
If left untreated there will be gradual progressive decrease in the side vision which will eventually come upto centre and cause vision loss.