Closed Angle Closure is also known as Angle Closure Glaucoma or Narrow Angle Glaucoma and is one the two main categories of Glaucoma. Although Closed Angle Glaucoma affects less than ten per cent of all patients diagnosed with glaucoma, it is the most serious form of the disease and in some cases comes on progressively in a matter of just hours or days, rather than over months or years, as open angle glaucoma typically does.
Closed Angle Glaucoma is often inherited and is more common in women and elderly people, especially those who are far-sighted. Like all types of glaucoma, the aqueous humour which the eye naturally creates, fails to drain and pressure builds up in the eye. This pressure causes damage to the optic nerve and loss of vision and eventual blindness occurs. Only an eye doctor can detect glaucoma by several eye tests which are described in the article on Glaucoma Diagnosis. Similarly only a specialist can detect the cause of the blockage to the aqueous humour to decide whether the patient has open angle glaucoma, or the more unusual closed angle glaucoma.
What Causes Closed Angle Glaucoma?
If the iris bulges and blocks the drainage angle between the iris and the cornea, then this is known as Closed Angle Glaucoma. If the onset is gradual, it is called Chronic Angle Closure Glaucoma. However, if the closure is sudden it is known as Acute Angle Closure Glaucoma. This type may be triggered by a sudden dilation of the pupil caused as it reacts to sudden darkness, stress, excitement or certain medications and drugs. Some antihistamines and antidepressants are known to cause this sudden dilation in the pupil. Eyedrops used in eye examinations also dilate the pupils to allow a thorough check of the optic nerve to be performed. Diabetes can also be a cause of this type of glaucoma.
If the iris blocks the drainage angle, the fluid builds up behind the iris, eye pressure increases, sometimes very rapidly, and damage to the optic nerve may result.
Symptoms of Closed Angle Glaucoma
Although glaucoma is known as the 'Silent thief of sight' closed angle glaucoma can be very painful because of the suddenness of the build up of pressure within the eye. Sometimes blurred vision may be the result of a partially closed or blocked angle. Halos may appear around lights and other changes to sight may be noticed in these warning attacks. An acute attack with severe pain and other side effects such as nausea and vomiting should be treated as a medical emergency. Time may be critical if the patient's sight is not to be irreversibly damaged and lost.
Treatment of Closed Angle Glaucoma
A Peripheral Iridectomy is usually performed once closed angle glaucoma has been diagnosed. This is a surgical procedure using a laser which creates a new drainage channel in the angle between the iris and the cornea to allow the build-up of aqueous humour to drain out. A peripheral iridectomy is normally performed in the doctor's office and is likely to be performed on both eyes, as the problem is likely to occur in both. An iridectomy involves the doctor removing a tiny part of the iris to drain the fluid, whereas an iridotomy creates a tiny hole in the iris by laser, to drain the fluid.
If Closed Angle Glaucoma is diagnosed at an early stage, possibly during a regular eye check up, or due to a swift response to the symptoms, then it can be successfully controlled and treated. If it is left untreated, the result will be damage to the optic nerve which will be permanent, and other parts of the eye may develop secondary types of glaucoma, leading to irreversible blindness.
Patients who are at a high risk of developing Closed Angle Glaucoma should take particular care if there is a family history of this disease. Those who are over 60 years of age also fall into this category. Read the warnings on all medications, including over-the-counter preparations. It is also imperative that regular eye checks are made, at least once every two years, and any changes in eyesight should immediately be reported to your eye doctor.
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