The dictionary definition of Glaucoma is:
"Any of a group of eye diseases characterized by abnormally high intraocular fluid pressure, damaged optic disk, hardening of the eyeball and partial to complete loss of vision."
What the dictionary does not say is that glaucoma is almost impossible to detect, except by an ophthalmologist, until the disease has already damaged the optic nerve. Although most diseases can be diagnosed early on by certain symptoms alarming the sufferer, glaucoma is known as 'the silent thief of sight'. It is only detected when it is in an advanced stage, after it has already caused loss of vision. Knowing and recognizing some of the symptoms of glaucoma may make the difference between getting treatment before it is too late, or not.
Normal intraocular pressure is between 10mmHg and 20 mmHg. When pressure builds up within the eye, damage to the optic nerve can occur. Unfortunately this loss of vision is so gradual that sufferers may not notice it for a long time. Intraocular pressure is caused by the build-up of fluid called aqueous humor. This fluid normally drains away from the front of the eye through a drainage system between the cornea and the iris. If for any reason the fluid is prevented from draining away, pressure begins to build up in the eye.
To complicate matters further, not all sufferers of high intraocular pressure will develop glaucoma, and not all glaucoma sufferers have intraocular pressure. About one third of glaucoma suffers have what is known as low-tension glaucoma. If eye pressure is found to be above normal, or on the increase, it can actually be controlled using eye drops, or occasionally with surgery. This early control may prevent glaucoma from developing. Regular eye examinations which include the measurement of eye pressure are the only way to diagnose the problem early on.
Intraocular Pressure is caused by different problems within the eye and each cause has its own symptoms.
Symptoms of Open-Angle Glaucoma
Primary open-angle glaucoma is caused when the drainage channel between the iris and the cornea is clear, but the drainage channels within the angle, known as the Trabecular meshwork, are partly obstructed. This pressure may damage the optic nerve leading to a gradual loss of sight.
Open-angle glaucoma is painless and has no early symptoms. The development of blind spots or patches of vision loss may occur over months and years. These are symptoms to be aware of and get checked out immediately. The blind spots gradually grow larger and eventually coalesce. Peripheral vision is generally lost first and the sufferer is left with tunnel vision, but if left untreated even the tunnel vision is lost and the person becomes blind. It is therefore imperative that even the slightest loss of vision or blind spots are taken as early warning symptoms of glaucoma. An eye test and consultation should be immediately arranged to check for glaucoma.
Symptoms of Closed-Angle Glaucoma
Closed-angle glaucoma occurs when the drainage angle within the eye is blocked by a bulge in the iris. Once again, the aqueous humor cannot drain away and causes pressure to build up in the eye. This type of glaucoma may occur gradually, when it is known as chronic angle-closure glaucoma. Sometimes it occurs suddenly and is then known as acute angle-closure glaucoma. It is sometimes triggered by a sudden dilation of the pupil due to stress, excitement, sudden darkness, medication such as antidepressants, or eyedrops which are used to dilate the pupil before an examination.
Acute angle-closure glaucoma may cause a sudden severe pain in the eye, headache, blurred vision, rainbow halos around lights and even a sudden loss of vision. The sudden increase in eye pressure may even cause nausea and vomiting. These early symptoms should be immediately treated as a medical emergency. If the condition is not recognized and acted upon quickly, blindness can occur just a few hours after the onset of the acute angle-closure glaucoma.
Risk Factors for Developing Glaucoma
Glaucoma is the second leading cause of blindness in America, after cataracts. Among blacks and Hispanics, glaucoma is even more prevalent, and is the leading cause of blindness. People who suffer from glaucoma in one eye have a high risk of developing glaucoma in the other eye. Those with a higher than normal risk for developing glaucoma should be aware of the early symptoms, and even if they experience no problems, should get a regular eye check.
People with the highest risk of developing glaucoma are those with any of the following:
- Age over 40
- African-American race
- Previous eye injury
- Family members who have been diagnosed with glaucoma
- Farsightedness or nearsightedness previously
- Long-term users of corticosteroid drugs
Anyone suffering with one or more of the above risks should have a comprehensive eye examination every 1 to 2 years. Early detection may be the only way to stall this disease, by having eye pressure monitored and a thorough examination by a professional for damage to the optic nerve.
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