Open angle glaucoma means that there is an elevated rise in the patient's eye pressure without any apparent obstruction to the drainage area In essence, the part of the patient's eye that drains the internal fluid, called the trabecular meshwork (TM), does not seem to be functioning properly. Because there is no obvious blockage to the TM, your surgeon tries to decrease pressure by either decreasing the amount of fluid the eye makes, or by artifically stimulating the TM to drain more fluid. In the United States, the most common initial measure to alter the internal production and/or drainage of aqueous is through the use of antiglaucoma medications. These medications are applied directly to the ocular surface in the form of drops. When medications fail to produce a desirable level of eye pressure control, the next level of treatment is typically a laser treatment called a trabeculoplasty. Laser trabeculoplasty is an office-based procedure where light energy is delivered to the drainage area of the eye and stimulates the TM to drain more fluid. Usually, the procedure takes 4-6 weeks for the patient to experience a lowering of the eye pressure.
When all other treatment measures fail, the next step is surgical control of intraocular pressure. The reasoning is, if medical and laser therapy are not capable of stimulating the TM to drain enough aqueous to keep the eye pressure low, then a new route of egress for the fluid needs to be made in order to lower the patient's eye pressure to an appropriate level. The most common form of glaucoma surgery is called trabeculectomy. In a trabeculectomy, a microscopic canal is made through the wall of the eye to permit the aqueous to leave the eye with low resistance. The procedure is performed under a local anesthetic, on an outpatient basis.
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