Glaucoma

What is glaucoma?

In a normal eye, a clear transparent fluid called 'aqueous humor' is secreted and continuously drained out via microscopic channels inside and then into the blood circulation. If the channels are blocked due to any reason, the fluid starts accumulating within the eye and pressure starts building up. If this pressure is not controlled, it causes damage to the optic nerve of the eye.
Glaucoma is a condition where the intra-ocular pressure of the eye is sufficiently high to cause damage to the optic nerve. It is one of the leading causes of blindness. It is common in adults over the age of forty. Blindness from glaucoma can be prevented if the condition is diagnosed at an early stage.

How does glaucoma affect normal lifestyle?

Whenever we look at an object, the image of that object falls on the retina (neurosensory layer of the eye). From there, it is carried to the brain via the optic nerve. The optic nerve is like an electric cable with millions of nerve fibers. With increase of pressure within the eye, these nerve fibers die, resulting in damage to the optic nerve. This is usually not noticed by the patients until the damage becomes quite advanced. However, an eye specialist can diagnose it by some special tests like:

Tonometry: Eye-pressure check up
Slit-lamp examination: Microscopic examination of the eye.
Retinal examination: Optic nerve examination to check for the damage.
Perimetry: Visual field testing
OCT- Optical Coherence tomography- for optic Nerve Head analysis & measurements of the thickness of the nerve fibre layer for detection of early Glaucoma & study the progress of glaucoma.

What are the different types of Glaucoma?

Glaucoma can be of many types depending on cause and mechanism of the disease. It can be broadly divided into the following categories:

Chronic simple glaucoma or open angle glaucoma
Acute / closed angle glaucoma
Secondary glaucoma
Congenital glaucoma

1. 'Chronic simple glaucoma' or 'Open Angle Glaucoma' :
It is the most common type where the loss of vision is gradual and painless. Usually it is detected when patients come to the eye doctor for a routine eye check up.

Symptoms indicating 'Open Angle Glaucoma':

Gradual diminution of vision with blurred or foggy vision.
Frequent change of eye-glass with no significant improvement in vision.
Mild chronic headache, scotomas in peripheral visual field.
Coloured halos around lights.

2.What is 'Acute / Closed Angle Glaucoma' :
In certain individuals, the angle from where fluid drains from the eye is genetically narrow. It can be blocked suddenly due to many reasons resulting in sudden increase in eye pressure. It usually occurs in one eye at a time causing some of the following symptoms.

Symptoms of acute or closed angle glaucoma :

Severe pain in the eye with headache and facial pain.
Sudden blurring of vision.
Cloudy vision with halos around the lights.
Redness in the eye with nausea and vomiting.

3. What is 'Secondary Glaucoma'?
The intra-ocular pressure in the eye can increase secondary glaucoma due to

Systemic diseases, eg. diabetes.
Eye diseases, eg. tumours, iridocyclitis.
Injuries, eg. a fist injury.
Overuse of certain drugs, eg. cortico-steroids.

4.What is 'Congenital Glaucoma'?
It is a hereditary condition often present at birth or occurring within the first few years of life. In congenital glaucoma, the drainage channels in the eye are defective from birth itself.

What are the symptoms of congenital glaucoma?

Excessive watering of the eyes.
Abnormal sensitivity to normal light.
The cornea may become white and cloudy or enlarged in size resulting in loss of vision.

Glaucoma treatment :

The aim is to reduce the eye pressure to a level that will not cause damage to the optic nerve. This prevents further loss of vision but the damage already done cannot be reversed.

The modalities of treatment are:

Instilling eye drops regularly as prescribed by the eye doctor to reduce and control intra-ocular fluid pressure.
Using tablets over a short span of time to decrease the pressure during acute attacks or to help in bringing down the pressure when eye drops alone are not sufficient.
Laser treatment - two types :

Laser iridotmy :
This procedure is done for acute or narrow angle glaucoma with laser. A 'hole' or opening is made in the iris to relieve the blockage of the drainage channels.

Laser trabeculoplasty :
This is useful in open angle glaucoma cases. Here the laser is used to open the blocked passages in the eye, thereby facilitating the aqueous fluid from within to reach the outside of the eye.

Surgery for Glaucoma or Trabeculectomy :
It is an operation where an additional channel is created surgically to drain the excess fluid bypassing the abnormally blocked channels. It is useful for most types of glaucoma.

Iridotomy trabeculectomy:
The best defense against glaucoma is a regular eye check-up, especially after the age of forty. All adults should have a regular eye checkup especially if they belong to families with a history of glaucoma.
Timely diagnosis can prevent glaucoma blindness.

The risk factors for glaucoma include:

Age factor, especially for people over forty.
Family history of glaucoma, diabetes and far sightedness to name a few
Use any medication without an eye doctor's approval.
Continuous use of different types of steroid eye-drops can cause glaucoma.
Once diagnosed, a glaucoma patient needs periodic eye check-up.