GONIOTOMY TREAT CONGENITAL GLAUCOMA
Category: Ophthalmology
Abstract : A goniotomy is a surgical procedure primarily used to treat congenital glaucoma, first described in 1938. It is caused by a developmental arrest of some of the structures within the anterior (front) segment of the eye. These structures include the iris and the ciliary body, which produces the aqueous fluid needed to maintain the integrity of the eye. These structures do not develop nor- ma
A goniotomy is a surgical procedure primarily used to treat congenital glaucoma, first described in 1938. It is caused by a developmental arrest of some of the structures within the anterior (front) segment of the eye.
These structures include the iris and the ciliary body, which produces the aqueous fluid needed to maintain the integrity of the eye.
These structures do not develop nor- mally in the eyes of patients with isolated congenital glaucoma. Instead, they overlap and block the trabecular meshwork, which is the primary drainage system for the aqueous fluid. As a result of this blockage, the trabecular meshwork itself becomes thicker and the drainage holes within the meshwork are narrowed. These changes lead to an excess of fluid in the eye, which can cause pressure that can damage the internal structures of the eye and cause glaucoma.
All types of congenital glaucoma are caused by a decrease in or even a complete obstruction of the outflow of intraocular fluid. The ocular syndromes and anomalies that predispose a child to congenital glaucoma include the following: Reigers anomaly; Peters anomaly; Axenfelds syndrome; and Axenfeld-Riegers syndrome. Systemic disorders that affect the eyes in ways that may lead to glaucoma include Marfans syndrome; rubella (German measles); and the phacomatoses, which include neurofibromatosis and Sturge-Weber syndrome. Since these disorders affect the entire body as well as the eyes, the childs pediatrician or family doctor will help to diagnose and treat these diseases.
Purpose
The purpose of a goniotomy is to clear the obstruction to aqueous outflow from the eye, which in turn lowers the intraocular pressure (IOP). Lowering the IOP helps to stabilize the enlargement of the cornea and the distension and stretching of the eye that often occur in congenital glaucoma. The size of the eye, however, will not return to normal. Most importantly, once the aqueous outflow improves, damage to the optic nerve is halted or reversed.
The patients visual acuity may improve after surgery. Goniotomies are commonly performed to treat the following eye disorders:
• Congenital glaucomas.
• Aniridia. Aniridia is a condition in which the patient lacks a visible iris. A goniotomy is performed as a preventivemeasure, as 50% - 75% of patients with aniridia will develop glaucoma.
• Uveitic glaucoma associated with juvenile rheumatoid arthritis.
• Maternal rubella syndrome.
• JOAG.
Demographics
The congenital glaucomas affect 1: 10,000 infants, with boys affected twice as often as girls. Both eyes are affected in 75% of patients. These glaucomas are differentiated from the secondary glaucomas caused by such medical conditions as juvenile rheumatoid arthritis (JRA), Marfans syndrome, or diabetes; or caused by intraocular tumors, cataract surgery, or trauma. Many of the secondary glaucomas respond better to medical treatment than to surgical treatment. Ninety-five percent of developmental or congenital glaucoma appears before age three. Another type of pediatric glaucoma is usually diagnosed between ages 10 and 35 and resembles the type of glaucoma seen in adults more closely than the congenital glaucomas, although some developmental anomalies may be present. This type of glaucoma is referred to as juvenile-onset open angle glaucoma (JOAG). Congenital glaucoma is a polygenic disorder; that is, it involves more than one gene. Since this type of glaucoma is inherited and the genes for JOAG and congenital glaucoma have been mapped, genetic testing is available to determine whether a specific child is at risk for these disorders.
Description
Before the surgeon begins the procedure, the patient is given miotics, which are drugs that cause the pupil to contract. This partial closure improves the surgeons view of and access to the trabecular meshwork; it also protects the lens of the eye from trauma during surgery. Other drugs are administered to lower the intraocular pressure. Once the necessary drugs have been given and the patient is anesthetized, the surgeon uses a forceps or sutures to stabilize the eye in the correct position. The patients head is rotated away from the surgeon so that the interior structures of the eye are more easily seen. Next, with either a knife-needle or a goniotomy knife, the surgeon punctures the cornea while looking at the interior of the eye through a microscope or a loupe. An assistant uses a syringe to introduce fluid into the eyes anterior chamber through a viscoelastic tube as the surgeon performs the goniotomy.
A gonioscopy lens is then placed on the eye. As theeye is rotated by an assistant, the surgeon sweeps the knife blade or needle through 90 - 120 degrees of arc in the eye, making incisions in the anterior trabecular meshwork, avoiding the posterior part of the trabecular meshwork in order to decrease the risk of damage to the iris and lens.
Once the knife and tubing are removed, saline solutionis introduced through the hole to maintain the integrity of the eye and the hole is closed with sutures. The surgeon then applies antibiotics and corticosteroids to the eye to prevent infection and reduce inflammation. The head is then rotated away from the incision site so that blood cannot accumulate. The second eye may be operated on at the same time. If the procedure needs to be repeated, another area of the eye is treated.
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