What Is Glaucoma ?
A watery fluid known as aqueous humor fills the spaces in the front one third of the eye. This fluid nourishes the cornea and the lens and gives the front of the eye its form and shape. The aqueous humor is continually produced by the ciliary body and drains through channels located in the trabecular spaces of the angle of the eye. In a normal eye the rate of production should be balanced by an equal rate of drainage. This keeps the pressure inside the eye (intraocular pressure) stable. In some individuals, with advancing age, these channels get blocked; disrupting the outflow of this fluid. This results in raised pressure within the eye. This raised pressure then starts damaging the optic nerve. The optic nerve carries the signals of sight from the eye to brain, thus making vision possible. Damage caused to the Optic Nerve leads to decrease in the field of vision and sight. This condition is called GLAUCOMA or KALA MOTIA.
What are the types of Glaucoma?
There are three major categories of Glaucoma. These are:
Primary Open Angle or Chronic Glaucoma: This is the most common form of glaucoma. Damage to the vision in this type of glaucoma is gradual and generally painless. The affected person might not develop significant symptoms and may be entirely unaware of this disease until the optic nerve has been severely damaged.
Normal Tension Glaucoma: A special type of glaucoma where even at lower intraocular pressure there may be damage to the optic nerve due to factors such as decreased blood flow into the eye.
Closed Angle or Acute Glaucoma: In this type of glaucoma, the intraocular pressure increases very rapidly due to a sudden and severe block of fluid drainage within the eye. Significant symptoms such as pain, haloes, headache and decreased vision may develop, indicating the presence of acute glaucoma. This condition has to be treated urgently by an ophthalmologist to prevent permanent visual damage.
Other types of Glaucoma: Congenital Glaucoma and Secondary Glaucoma.
Most types of Glaucoma have three common features. These are:
Increased intraocular pressure: This is measured with Goldmann Applanation Tonometer. This instrument is pressed against the patient's eye to determine the intra-ocular pressure.
Cupping or Atrophy of the Optic Nerve: This is a measure of loss of the nerve fibre layer of the optic nerve due to damage caused by the raised pressure in the eye. This is assessed by examination of the fundus. Newer imaging modalities like the optical coherence tomography (OCT), GDx, HRT are now available for measuring the status of the nerve fibre layer and documenting the extent and progression of the damage.
Visual Field Defects: This is the measure of missing areas in the field of sight even though the person may be seeing well otherwise. The visual field is assessed by an instrument called the Perimeter.
What are the symptoms of Glaucoma?
Glaucoma in early stages generally does not show noticeable symptoms. It is possible for a person suffering from chronic glaucoma to be completely unaware of the disease. Chronic Glaucoma generally progresses too slowly to get noticed. Some common symptoms of chronic glaucoma could be:
- Inability to adjust the eyes to darkened rooms such as theaters.
- Frequent changes in near (reading) eyeglass prescription.
- Gradual loss of peripheral vision.
- Blurred vision.
- Poor night vision.
- Difficult in Driving
In the case of Acute Glaucoma resulting from rapid increase in the intraocular pressure, there could be severe symptoms. Common symptoms suggesting the presence of acute glaucoma could be:
- Seeing rainbow coloured halos around lights.
- Severe eye pain, facial pain.
- Red eye.
- Cloudy vision with halos around light.
- Nausea and vomiting.
- Feeling of a blind area in the eye.
Tests for Glaucoma: How are they done?
- Perimetry: Must for making diagnosis of all glaucoma patients. This test is essential not only to assess the extent of the existing damage, but also to document and measure the progression of the disease and the response to treatment. This test requires sophisticated machinery with advanced software. This exercise takes time and may have to be repeated at timely intervals.
- Tonometry: Recording of pressure is done using Goldmann Applanation Tonometer or any other Tonometer.
- Gonioscopy: A lens is applied on the eye and angle is examined to see if it is open or closed type of glaucoma.
- Other sophisticated tests: OCT (Ocular Coherence Tomography), CCT (pachymetry) etc. The OCT is a noninvasive test. This means that nothing touches the eye. The patient is simply asked to focus onto a light as the advanced machine and its software assess the status of the optic nerve and the nerve fibre layer. Pachymetry or CCT is measured with the application of an ultrasonic probe onto the cornea.
Which are the high- risk groups, who can get Glaucoma?
- People belonging to families with a history of glaucoma.
- People suffering from diabetes.
- People having high minus or plus numbered glasses.
- People suffering from hypertension.
- People who have undergone any kind of eye surgery.
- People with thyroid gland related ailments.
- People with over - mature cataracts.
- People with any injury to the eye.
- People with a history of prolonged use of steroid eye drops.
Is Glaucoma curable?
Glaucoma cannot be cured. But it can be controlled and further damage to the optic nerve can be slowed down or halted. This control can only be sustained by a very thorough and regular treatment. It is a life long process.
What are the treatment options for Glaucoma?
Primary objective of the treatment is to reduce the intraocular pressure. Depending upon the type of glaucoma, this is achieved by medications or by surgery. Usually special eye drops are prescribed. These drops reduce the intraocular pressure. These are used once or several times a day depending upon the type and stage of glaucoma. Medications may also be given orally or intravenously. An emergency laser Iridotomy may be required for the treatment of acute glaucoma. This creates a drainage hole in the iris to relieve the pressure build up. This technique can be performed by laser surgery without making an incision in the eye. Surgery is generally the next step. A surgery called Trabeculectomy is performed to control glaucoma. In this technique a new drainage channel is created for the fluid to exit, thus lowering the pressure build up.
How to prevent Glaucoma?
In most cases, it is difficult to prevent development of glaucoma. If detected early, further vision loss and blindness may be prevented with treatment. It is always suggested that excessive smoking should be avoided. Regular eye check up especially for the people falling under the high - risk groups is a must and above 40 years.
Must remember facts about Glaucoma
- There is no prevention for the development of glaucoma.
- Sometimes the symptoms of glaucoma are simply not noticeable.
- Glaucoma can silently snatch away your vision.
- Timely detection of glaucoma is a must.
- Timely treatment of glaucoma may prevent further loss of vision and blindness.
Immediately get in touch with an eye specialist, if you experience any of the following:
- Severe eye pain
- Sudden loss of vision
- Coloured Halos
- Nausea and / or vomiting
- Poor night vision
- Persistent redness of the eye.