Glaucoma Cause, Prevention, Risks and Treatment
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Glaucoma is a condition of the eyes that damages the optic nerve leading to an irreversible vision loss. It is one of the leading causes of blindness each year in the United States, with approximately 10% of the patients experiencing loss of vision even after the Glaucoma treatment takes place. Understanding, detecting and managing glaucoma is therefore a major concern to the eye doctors.
Glaucoma is not simply a disease but a collection of eye problems which lead to increase in the pressure within the eyes and serious impediments to vision. Its onset is often furtive and very gradual over the course of several years during which time people may seldom have any symptoms to alert them of their elevated eye pressure. Even the loss of peripheral vision (the first sign of its onset) may take several years and is virtually unnoticeable.
Types of Glaucoma
The type of glaucoma depends on the specific obstruction that's hampering the aqueous fluid's drainage from the eye. There are two major types- closed-angle glaucoma (also called narrow-angle glaucoma or angle-closure glaucoma) and the more common condition, open-angle glaucoma.
1. Closed-angle Glaucoma- Closed-angle glaucoma is an obstruction in the drainage of aqueous fluid due to a narrowing in the angle of the anterior chamber of the eyes. It can be best identified during a comprehensive eye examination with a technique known as gonioscopy, using a specially designed contact lens with angled mirrors. Farsighted people having smaller eyeballs are more prone to developing closed-angle glaucoma. Treatment involves eye drops, pills, and occasionally intravenous eye injections. In the acute stages of an attack, it may also be necessary to operate if medical treatment fails to lower the eye pressure. Laser or surgical treatment is used to make a hole or opening in the iris so that the fluid can escape and relieve the pressure. This procedure is called a peripheral iridectomy.
2. Open-angle Glaucoma- Unlike closed-angle glaucoma, there's no single anatomical problem resulting in drainage block in the eyes. Instead, many conditions can lead to open-angle glaucoma, such as inflammation or bleeding in the anterior portion of the eyes etc.
Although glaucoma can occur in eyes with normal eye pressure, the relationship between elevated eye pressure and vision loss was, however, discovered centuries ago. In fact, eye pressure has been one of the most foolproof methods for diagnosing glaucoma for hundreds of years. Over the years many tonometry techniques have been developed, all of them measuring how much force is required to indent or flatten the cornea. This measurement, in turn, allows the ophthalmologist to estimate the pressure in the eye.
Determining what is a ‘normal’ intraocular pressure is not possible since ‘normal’ varies from person to person. Other variable factors to be kept in mind include age, the presence of myopia, family history of glaucoma, medications (such as antihistamines, steroids), hypertension, high blood pressure etc.
Most common risk factors include-
- Being over age fifty-five,
- Having a family history of glaucoma,
- Being very nearsighted,
- Having diabetes etc.
Because glaucoma is a diverse collection of disorders with a common endpoint, i.e. a damaged optic nerve resulting in loss of vision, there is no one preferred form of treatment. In general, the basic goal of managing glaucoma is to lower someone's intraocular pressure and keep it lowered sufficiently to prevent further nerve damage and loss of vision.
At the beginning of a new antiglaucoma medication or changing to a new regimen, you may require weekly or monthly monitoring of your intraocular pressures. Depending upon a regimen which works in controlling eye pressure and stabilizing visual field, your eye doctor will probably lengthen the time between visits to every three to six months or so. Visual field testing may be performed less often, depending on such factors as your eye health, the degree of vision loss, intraocular pressure readings, and the appearance of the optic disc. If you have severe glaucoma, this testing may be done more frequently.
Since eye pressure is not constant, frequent eye checks prove very helpful in treating glaucoma. Another reason for frequent monitoring is that many patients become resistant over a period of time to the effects of a particular antiglaucoma medication and their intraocular pressure gradually sneaks back up to where it was before treatment. For such patients, it's clearly important to detect this problem as soon as possible, so that they can be switched to a different type of medication. Also, your eye doctor needs to make sure that your vision isn't deteriorating by watching for any significant changes in the appearance of the optic disc. Because eye pressures fluctuate constantly, even from morning to afternoon, it's a good idea to schedule your office visits at different times of the day. Also, be sure to report any changes in your general health, any other medications you may be taking, or any other visual or medical symptoms that you feel may be important.