Glaucoma is an eye disease in which damage to the optic nerve can lead to loss of vision and person can be blind. It is the primary cause of blindness. It can only be diagnosed when patient go for regular eye examinations. Intraocular pressure increases when either too much fluid is produced in the eye or the drainage or outflow channels (trabecular meshwork) of the eye become blocked. Though any person can have glaucoma, but some people are at high risk. There are two types of glaucoma. These are open-angle glaucoma, which has several variants and is a chronic condition and closed-angle glaucoma, which is a sudden (acute) condition. If there is injury in the optic nerve and impairment of vision from glaucoma, it can not be corrected. Several easy tests that find out the intraocular pressure, the status of the optic nerve and drainage angle, and visual fields are done to diagnose glaucoma. Many researchers are engaged to identify the causes and treatment of glaucoma throughout the world. Early diagnosis and treatment is necessary to prevent from blindness in people with glaucoma. In some cases, glaucoma may occur in the presence of normal eye pressure. This form of glaucoma is caused by poor regulation of blood flow to the optic nerve.
Symptoms: In glaucoma, patients do not show any symptoms early in its course. As optic nerve fibers are damaged by glaucoma, small blind spots may begin to develop, usually in the peripheral or side vision. If the entire optic nerve is destroyed, it results in blindness. Other symptoms are sudden increases in IOP, particularly with acute angle-closure glaucoma, and may include blurred vision, halos around lights, severe eye pain, headache, abdominal pain, nausea, and vomiting.
Causes: Major cause of glaucoma is the elevated pressure in the eye that damage to the eye nerve. Through the optic nerve, people see objects in the environment. This nerve transmits the images that a person sees back to the brain for interpretation. The eye is firm and round, like a basketball. Its tone and shape are maintained by a pressure within the eye (the intraocular pressure). When the pressure is too low, the eye becomes softer, while a too high pressure causes the eye to become harder. It turns out that the optic nerve is the most susceptible part of the eye to high pressure because the delicate fibers in this nerve are easily damaged.
Risk factors glaucoma can occur in people who are above 45 years, having family history of glaucoma, black racial ancestry, diabetes use of cortisone (steroids), either in the eye or systemically (orally or injected) Farsightedness (hyperopia), which is seeing distant objects better than close ones (Farsighted people may have narrow filtering angles, which predispose them to acute (sudden) attacks of closed-angle glaucoma.)
Diagnosis- An ophthalmologist can identify person who are at risk for glaucoma before nerve damage occurs. The doctor also can diagnose patients who already have glaucoma by observing their nerve damage or visual field loss. He recommends various tests for evaluation which are generally painless. The test, Tonometry, verify the pressure in the eye by measuring the tone or firmness of its surface. Several types of tonometers are available for this test, the most common being the applanation tonometer. After the eye has been numbed with anesthetic eye drops, the tonometer's sensor is placed against the front surface of the eye. The firmer the tone of the surface of the eye, there are higher the pressure reading. Another test referred as Pachymetry is done to detect the disease. It is a comparatively new test which is used for glaucoma. Pachymetry determines the thickness of the cornea. After the eye has been numbed with anesthetic eye drops, the pachymeter tip is touched lightly to the front surface of the eye (cornea). Thicker corneas may give falsely high eye pressure readings and thinner corneas may give falsely low pressure readings. Furthermore, thin corneas may be an additional risk factor for glaucoma. The purpose of Gonioscopy test is to examine the filtering angle and drainage area of the eye. It is done by numbing the eye with anesthetic drops and placing a special type of thick contact lens with mirrors inside on the eye. The mirrors allow the doctor to view the interior of the eye from different directions. In this procedure, the doctor can find out whether the angle is open or narrow. Gonioscopy can also determine if anything, such as abnormal blood vessels, might be blocking the drainage of the aqueous fluid out of the eye. Ophthalmoscopyis an assessment in which the doctor uses a handheld device to look directly through the pupil (the opening in the colored iris) into the eye. This procedure is done to examine the optic nerve (seen as the optic disc) at the back of the eye. Damage to the optic nerve, called cupping of the disc, can be detected in this way. Visual Field testing maps the visual fields to detect any early (or late) signs of glaucomatous damage to the optic nerve. This test can be done by having the patient look straight ahead and count the fingers shown by the examiner from the side. More typically, however, visual fields are measured by a computerized assessment. For this procedure, one eye is covered and the patient places his or her chin in a type of bowl. Then, when the patient sees lights of various intensities and at different locations, he or she pushes a button. This process produces a computerized map of the visual field.
Treatment- Doctors are helpless to cure nerve damage and visual loss from glaucoma because it cannot usually be reversed. But glaucoma can generally be controlled. Treatment can make the intraocular pressure normal and, therefore, prevent or retard further nerve damage and visual loss. For treatment, doctors advise the use of eye drops, pills (rarely), laser, or surgery. Eye drops are usually recommended in early stage of treatment of most types of open-angle glaucoma. In some cases pills are prescribed. The drops can be varied to best suit the patient and the type of glaucoma. One or more types of eye drops may have to be taken up to several times a day to lower intraocular pressure. These drops work either by reducing the production of the aqueous fluid (shutting the faucet) or by increasing the drainage of the fluid out of the eye. Every remedy has advantages and side effects. In many cases, doctors advise laser or surgery is recommended at initial stage. Laser (laser trabeculoplasty) is performed when eye drops do not stop deterioration in the field of vision. In many cases eye drops will need to be continued after laser. In Laser treatment, patient is not hospitalized. Surgery (trabeculectomy) is done when eye drops and laser do not control the eye pressure. A new channel for the fluid to leave the eye is created. Treatment can save remaining vision but it does not improve eye sight.
Prevention: To prevent glaucoma, person must go for early eye check up. If detection is done early, vision loss and blindness may be prevented. Anyone older than 20 years should have a glaucoma screening. Periodic eye examinations are helpful for the rest of person’s life to prevent and identify glaucoma, especially if he has certain risk factors such as having a family history of glaucoma.
Note: This information is just for knowledge of disease. If such type of medical condition develops, consult your doctor.
