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| Glaucoma |
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| Glaucoma service includes Applanation tonometer, disc photography, automated perimeter and provocative tests. |
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| An automated perimeter (OCTOPUS 301) with field analysis management of the glaucoma patient which is very essential in the present context of the consumer protection Act. |
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| Besides medical and surgical management, facilities for laser iridotomy, laser trabeculoplasty and laser cyclophotocoagulation and a non contact tonometer is available. |
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| About Optic Nerve |
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| The optic nerve is the nerve of sight. It is like an electric cable containing a million wires. Each "wire" or nerve fibre carries electrical impulses from the light sensitive retina, at the back of eye, to the brain. In brain the electrical impulses are put together to form a picture. Glaucoma can damage nerve fibres causing small blind spots to develop in the field of vision. These areas of missed vision are not straight ahead. People seldom notice these small blind areas until they are required to identify these early defects. When the entire nerve is destroyed, blindness results. Early detection and treatment are the keys to prevent optic nerve damage and blindness from glaucoma. |
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| The nerve gets directly damaged due to increased pressure inside the eye ball. The extent of damage to the nerve correlates directly to the eye pressure. An increased or abnormal pressure may be taken as that pressure where the structure and/or functions of the eye are adversely affected. |
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| About pressure |
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| A clear liquid called the 'aqueous humour' flows continuously within the eye. This liquid is not a part of the tears on the out surface of the eye. The aqueous humour is produced behind the iris. It then flows through the pupil and drains out of the eye through a mesh work of drainage canals around the outer edge of the iris. Under normal circumstances, the amount of fluid produced in the eye, balances the amount of fluid that flows out of the eye. As a result, the pressure inside the eye remains stable and within "safe" range. If the drainage of aqueous is hampered, the fluid pressure within the inner eye increases to a level that can damage the optic nerve. |
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| About Rise In Pressure |
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| The drainage potion of the eye, called the 'drainage angle' is like a sieve and can be blocked in different ways. |
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- It may get blocked suddenly. It is as though a sheet of paper floating near the drain suddenly drops over the opening and blocks all outflow. In the eye, the iris may act like a sheet of paper and close off the drainage angle. Eye pressure increases rapidly, resulting in symptoms of acute angle-closure glaucoma: blurred vision, severe eye pain, headache, rainbow halos around light and nausea and vomiting. Unless an ophthalmologist treats this condition quickly, blindness can result. A more gradual and painless blockade of the angle is called chronic angle-closure glaucoma. It occurs more frequently in people of Asian and African ancestry.
- Sometimes, the sieves out of which the fluid exits, can be blocked by debris caused by inflammation or aging. This leads to an insidious rise in pressure, known as 'Chronic open angle glaucoma'. It can damage vision so gradually and painlessly that a person is unaware of trouble until the optic nerve is badly damaged. This type of glaucoma is much more common.
- Glaucoma can also occur if there is increase in production of fluid. Glaucoma may rarely be present at birth. It results from maldevelopment of sieve. The parents may notice their baby's eye enlarging (since a baby's eye is more elastic than an adult), becoming cloudy with watering and increased sensitivity to light. The infant or child should be taken to an ophthalmologist immediately.
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| The Range of Normal Pressure |
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| Average intra-ocular pressure in adults is 16mmHg(mercury). The range varies from 9 mmHg to 21mmHg. The actual upper limit of normal pressure, however, is difficult to pinpoint. |
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| If the pressure is consistently above 21mmHg, the chances of eye damage are probably around ten percent. When the pressure inside the eye is above 26mmHg, the likelihood increases to about fifty percent. When the intra-ocular pressure persists above 30mmHg, the damage will eventually develop. |
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| What constitutes normal intra-ocular pressure is an individual matter for each person. For example, some persons with an intra-ocular pressure of 16 mmHg may need surgery while others with a pressure of 30mmHg may be kept under observation only. |
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| All types of glaucoma thus have three features in common. These are used to diagnose glaucoma, measure the extent of damage, and monitor it's progression. These are : |
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- Increased Intra-Ocular Pressure (I.O.P. or Tension) : The pressure inside eye is measured with Goldmann Applanation tonometer. Your doctor touches a prism with blue lights on the eye after putting anaesthetic drops.
- Cupping or Atrophy of the Optic Nerve : The drying up of the nerve of sight as it suffers damage due to high pressure inside the eye. It is assessed by examination of Fundus of the eyes.
- Visual Field Defect : The presence of missing areas in the field of sight, though person may seeing well otherwise. This is measured on instrument called perimeter. The modern perimeter is computerized to measure, self analyze, compare and report the defects.
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| About Symptoms |
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| Unfortunately there are no symptoms in early stages. A person with chronic glaucoma is usually unaware of the disease. Like the hands of a clock, chronic glaucoma moves so slowly that it's progress is not noticed. Thus it is a silent snatcher of vision. |
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| On the other hand, acute glaucoma, in which the pressure rises rapidly, causes severe symptoms which force the patient to consult a doctor. Symptoms that suggest the presence of chronic or acute glaucoma include : |
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- Poor night vision.
- Sensation of a blind area.
- Headaches in the early morning of after dusk.
- Pain in eye, particularly when associated with smoky vision
- Halos around light
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| About Risk Factors |
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| People with high pressures have a higher risk of developing optic nerve damage. Other important risk factors include advancing age. Severe myopia (near sighted), a family history of glaucoma of diabetes, past injury to the eye, surgery or a history of severe anaemia or shock. |
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| Your ophthalmologist will weigh all these factors before deciding whether you need treatment for glaucoma or not. If your risk of developing glaucoma is higher than normal but there is no optic nerve damage, you will be monitored periodically as a 'glaucoma suspect'. |
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| About Early Detection |
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| Regular eye examination by an ophthalmologist is the best way to detect glaucoma. During a complete work up for glaucoma. Your ophthalmologist will measure the intra-ocular pressure (tonometry), inspect the drainage angle of the eye (gonioscopy), evaluate for optic nerve damage (ophthalmoscopy), and test the visual field of each eye (perimetry). |
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| Some of these tests may not be necessary for every person. These tests must be repeated on a regular basis to monitor the progress of disease. |
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| Management |
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| Strictly speaking glaucoma cannot be cured but it can be controlled and further optic nerve damage can be slowed and halted. |
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| Achieving this goal required a life long commitment to treatment and regular visits to the ophthalmologist, your eye doctor will decide if, when and how the treatment should start. |
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| Eye drops, pills, laser and surgical operations are available to manage glaucoma. |
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| Medical treatment : The first attempt to control glaucoma is made with eye drops instilled twice/several times a day, sometimes in combination with pills. These medications act to decrease eye pressure either by slowing the production of aqueous fluid within the eye or by improving the flow through the drainage angle. To be affective, these medications must be taken regularly at prescribed intervals. |
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| Some medicine may occasionally result in unwanted side effects. Some drops may sting, redden the eye and cause blurring of vision or headaches. Such side effects usually disappear after a few weeks. Rare side effects of may be changes in pulse, heart beat and breathing (Now, specially designed drops for people with cardiac problems and bronchial asthma are available). Medication should never be stopped or changed without consulting your ophthalmologist. Frequent eye examinations and tests are crucial to monitor your glaucoma condition for any changes. Pills sometimes cause tingling sensation in finger tips and toes, drowsiness, loss of appetite, bowel irregularities or kidney stones. Inform your ophthalmologist immediately if you think you are experiencing side effects. |
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| Laser surgery may be effective for some types of glaucoma. In chronic open angle glaucoma, when the drain itself is treated (trabeculoplasty), the laser may help (or replace) the medications to control the pressure. In angle-closure glaucoma, a hole is made in the iris (iridotomy) to restore the flow of aqueous fluid to the drainage angle. |
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| Sometimes, surgery (trabeculectomy) is necessary to control glaucoma. The ophthalmologist uses miniature instruments to create a new drainage channel for fluid to leave the ye, thus lowering the pressure in advanced cases. If surgery fails, special glaucoma valves can be implanted. Fortunately, serious complications of modern glaucoma surgery are rare. Surgery for glaucoma would be recommended only if the medicines fail to prevent damage to the optic nerve. |
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| Whatever may be the approach, the objective of the treatment is to lower the eye pressure to a level at which optic nerve damage does not develop or worsen. Although eye pressure is important, the condition of your optic nerve and peripheral vision are equially or more important. Normal pressure means tat all the medicines are adequate and not that glaucoma has been cured. |
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| The success of your treatment depends entirely on the team work put in by you and your ophthalmologist. It is therefore important to communicate with your doctor. Finally, remember to keep the follow-up appointments with your ophthalmologist. If you don't, glaucoma could be stealing your sight without your knowledge.. |
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| Suggested Glaucoma screening schedule in High Risk groups |
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- People with high intra-ocular pressure (I.O.P) : Regular visit to eye specialist with Tonometry, Fundus and Visual field testing.
- People over the age of forty years with no previous glaucoma : At least once every two years, specially whenever there is a change of reading glasses.
- Family history of glaucoma : Regular screening from younger age for people with parents or close blood relatives suffering from glaucoma.
- People having minus or plus numbered glasses : Once a year.
- Other high risk factors : Like diabetes, injury to eye, a major eye surgery, prolonged steroid use etc. need more frequent screening as advised by the treating physician.
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