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Glaucoma
 
Glaucoma is one of the world's leading causes of blindness. Glaucoma is not curable, but blindness is preventable if the glaucoma is diagnosed early and treated quickly. While there are usually no warning signs regular eye tests will help detect onset of the disease.
What is glaucoma?
Glaucoma is an eye condition characterised by loss of vision due to damage of the optic nerve. The optic nerve carries sight images to the brain and any damage to the nerve results in damaged sight. Normally, the fluid of the eye (aqueous) is secreted in the eye and drained out of the eye. In glaucoma the fluid is accumulated in the eye due to decreased drainage leading to increased pressure. This damages the optic nerve.
There are 2 main types of glaucoma:
? Open Angle Glaucoma
? Angle Closure Glaucoma

Aqueous circulates through the anterior chamber and passing through the angle exits from the eye into the Canal of Schlemn . In open angle glaucoma the passage to the canal of Schelmn offers resistance to the flow of aqueous. In angle closure glaucoma the angle of the chamber is narrow or becomes closed, preventing the drainage of aqueous from the eye. Both these situations lead to an increase in intra-ocular pressure.
Who are the people at risk of developing Glaucoma?
The following are the risk factors for Glaucoma:
? Family history of glaucoma (particularly in parents and siblings)
? Refractive errors (Myopia or Hypermetropia)
? Diabetes mellitus
? Thyroid Diseases
? Injudicious use of steroids, especially steroid eye drops.
? Certain eye conditions, e.g. Retinal Vein Occlusions, Pseudo-exfoliation, Pigment Dispersion Syndrome, etc.
Glaucoma usually effects people in their 50s, or later, but it can occur at any age. Glaucoma can occur even in young children and infants (Developmental Glaucoma). If it occurs before the age of 3 years it is called Congenital Glaucoma and between the age of 3 and 30-35 years it is called Juvenile Glaucoma. Treatment of glaucoma is more difficult in young patients and operations are more freqently required.
What are the signs & symptoms?
Open angle type of glaucoma does not usually give rise to any symptoms in its early stages. In its later stages patients may feel eye pain and discomfort. Some individuals may notice field defects (an inability to see certain areas of the field of vision). Usually, an eye specialist diagnoses this type of glaucoma on examination when he suspects it because of risk factors or during the course of a routine examination.
Angle closure type glaucoma can give rise to pain in the eye, headache, vomiting, seeing colored rings (haloes) around lights and redness in the eyes.
How is Glaucoma detected?
Glaucoma can be detected by performing the following tests:
Tonometry: A tonometry test measures the pressure inside the eye; the intraocular pressure (IOP). Tonometry measures IOP by determining the resistance of the cornea to indentation. Eyedrops are used to numb the surface of the eye for most methods used to measure IOP.

Gonioscopy: An anaesthetic drop is given to numb the front of the eye. The ophthalmologist then holds a special lens against the cornea to give a better view of the inside of the eye and assist further examination.

Disc Examination: Optic disc examination with the indirect ophthalmoscope is frequently used in the assessment of pediatric glaucoma cases. If the usual viewing eyepieces are removed from the headgear and loupes are worn instead a greatly magnified view of the disc is seen with little change in technique or ease of examination.

Visual Field Analysis: The visual field is the range of sight we have on each side of an object we look at. The extent of the visual field can be measured. The field test takes about 15 minutes per eye. Patients are asked to sit at a screen and keep their gaze fixed on a central light source. They then need to indicate (by pressing a button) if they can see a series of other lights, no matter how dim, used during the test. They are not expected to see all the lights. This test detects if there are any missing areas in the visual field caused by damage to the optic nerve.
Can Glaucoma be treated?
Glaucoma can be treated. Damage done by the disease cannot be reversed or undone but further damage to the eye caused by glaucoma can be stopped. Consequently, it is of the utmost importance that glaucoma is diagnosed and treated early and before significant damage has been done.

If you have been diagnosed with glaucoma this does not mean you will go blind, especially if you have been diagnosed with glaucoma at an early stage in the disease. Drops and sometimes operations can stabilise the glaucoma and, with regular check-ups, you will be able to manage the condition. You will experienc some degree of sight loss but it will be minimised by effective treatment.
What is the treatment of glaucoma?
The treatment options of glaucoma includes:
Drugs: Generally the first stage of glaucoma treatment is beta-blocker eyedrops which lower fluid production in the eye. These may not be used in people with heart conditions as they can affect heart and/or lung function. Other pressure-lowering drops like alpha-2 agonists and prostaglandin analogs are used in such cases. Many of the drugs used for glaucoma interact with common medications. Most cases of glaucoma can be controlled with a single drug or a drug combinations but some patients may require, or select, surgery. About 70% of patients need new or extra medications within two years after the commencement of drug treatment compared with 56% of those who choose laser surgery. Patients should discuss these issues with both the family physician and the eyecare practitioner.

Operation: In some forms of glaucoma an operation may be necessary. The most common operation is a trabeculectomy where a small piece of tissue is removed to make a new opening that allows the aqueous fluid to escape from the eye. The escaping fluid is absorbed into the tissues that form the outer coat of the eye.

Laser: For persons with severe glaucoma damage that has not been successfully managed by standard glaucoma surgery, or for types difficult to treat such as neovascular glaucoma, there is a surgical technique available that may prove to be effective - endoscopic laser surgery. Endoscopic laser surgery is a type of cyclodestructive surgery - surgery that actually destroys part of the ciliary body, the part of the eye that produces intraocular fluid. This helps to lower eye pressure.
The treatment is decided by many factors:
Type of glaucoma.
Stage of glaucoma.
Damage done.
Status of the other eye.
Response to other treatment(s) already taken.
Patient compliance and reliability for taking drugs/attending follow up examinations.
Decisions regarding the most appropriate treatment should be left to the judgment of the consulting eye surgeon.
Detected early and treated properly, glaucoma is perfectly compatible with life long good vision. If neglected it can end in blindness.