external trabeculotomy

The principle of external trabeculectomy is to cut the trabecular meshwork and the internal wall of the scleral sinus from the external path, and establish a direct aqueous drainage channel between the anterior chamber and the venous sinus. Wide range of indications and high success rate. The anatomical positioning is precise and the complications are few. Curing disease: Indication 1. Simple trabecular dysplasia. 2, corneal opacity can not see the congenital glaucoma of the anterior chamber angle structure. 3, uveitis secondary glaucoma, there are anterior chamber corneal adhesions, some patients have also achieved success. 4, not suitable for the angle of the incision and the previous angle of the incision failed. Preoperative preparation 1. Preoperative medication and anesthesia are the same as anterior chamber angle incision. 2, the microscope is enlarged 4 to 20 times, and the coaxial or oblique axis illumination can be used. Special equipment is: (1) Trabecular incisor: Harm type incisor is two metal needles arranged in parallel with a diameter of 0.3mm, separated by 3mm, 9mm in length, and the bending radius is about 6mm. It is the same as the curvature of the sinus of the cornea, and the front end is used. Cut in the trabecula, the latter is used to position the two in the left and right direction, with a 90 ° handle. McPherson trabeculectomy: The same as the Harm type, the handle has a 30° angle. (2) Lynn-Berry trabecular slitter: consists of two metal rings of different diameters, three metal bars between the two rings are welded and fixed into a conical shape, the large ring is used for hand-held, and the small ring has a 60° notch. A 9mm long incision needle is welded underneath for trabecular incision. (3) anterior chamber angle mirror: used for intraoperative observation of trabecular incision. Other instruments are the same as trabeculectomy. Surgical procedure 1. Open and fix the eyeball. The opener opens the eyelid and the upper rectus muscle is fixed. 2, incision: the microscope is aimed at the upper angle of the scleral margin, and the conjunctival flap with the iliac crest as the base is placed slightly above the nose, the superficial sclera is separated, and the surface of the sclera is burned to stop bleeding. A scleral flap (triangular or square) with a length of 3 mm is placed around the angle of the nose (1 or 11 o'clock). The thickness of the flap is 1/2 to 2/3, and the scleral flap is turned to the cornea. . Determine the gray-white scleral junction of the scleral plate level. 3, scleral sinus positioning and external wall incision. Increase the microscope to a multiple of 16 times. Make a vertical incision on the gray-white boundary line. The length of the 1mm is gradually deepened by careful observation until there is clear or reddish liquid in the incision, but the anterior chamber does not become shallow. At this point, the outer wall of the scleral sinus has been cut. The tip of the knife is upward, and the incision is enlarged to reveal the broken end of the outer wall of the scleral sinus. Finding the scleral sinus is the key to successful surgery. Due to the influence of the limbal scleral staphyloma and previous surgical scars, the position of the scleral sinus often varies greatly. A variety of methods can be used to detect the position of the sinus cavity. (1) Transillumination method: It is often used for direct transillumination of optical fibers during surgery after anesthesia is started. Turn off the microscope illumination. Under the magnification of the high magnification microscope, the fiber head is placed directly at the 6-point clock angle, the interface between the outermost opaque and the light-transmissive area is the front of the ciliary body, and then the inner angle of the sclera is gray. The area presents a bright, circularly scattered strip of light that is wider above. There is a relatively brighter reflective area in the scattered light band about 0.5mm inward in the opaque area, which is in the form of a thin line, which is the scleral sinus. The surface of the sclera corresponding to this line is marked, and the sclera is cut vertically to cut the outer wall of the scleral sinus. (2) Radial incision method: as described above. When the outer wall of the sinus is cut, two small black spots are visible on both sides of the front side, which are more obvious under the oblique axis illumination, and are elliptical or crack-like, and can be inserted by a nylon thread. If the main resistance is inserted, the nylon thread is swung back and forth at the incision, and the end of the anterior chamber is not seen in the anterior chamber. It is basically confirmed that the nylon thread is in the scleral sinus. If you check it again by transillumination, you can see the exact position of the black nylon thread. (3) Schlemm's sinus congestion: When the scleral sinus is still not found after radial sclerectomy, the anterior chamber puncture can be performed, the intraocular pressure can be reduced, the scleral venous sinus can be passively congested, and there will be a pale blood flow out near the incision. The oozing site is the sinus cavity. (4) Wide incision method: The scleral sinus cavity after radial incision is mostly fissure-like, and it is difficult to insert the nylon thread and the trabeculectomy device into the lumen. At this time, a parallel cut of 1 to 2 mm can be added to the outer wall, or a 2 mm × 2 mm scleral resection can be performed in the scleral inner layer, and the outer wall of the scleral sinus can be cut off to directly expose the inner surface of the sinus cavity. This method is very beneficial for inserting a trabecular slitter. Among the above four methods, the radial scleral incision method is most commonly used, and the wide incision incision or excision method is second. As long as the anatomical structure variation is not very large, the operation is accurate and light, and most of the scleral sinus can be found smoothly. (5) The main reasons for not finding the scleral sinus are: the anatomical landmark of the limbus is blurred and the variation is large; the previous fibrosis caused by surgery and trauma, the difficulty in finding the scleral sinus during surgery; the scleral sinus hypoplasia The diameter of each segment is different, and some parts are completely occluded. If the incision is made here, the sinus cavity cannot be found; the high intraocular pressure presses the inner and outer sinus walls of the scleral venous sinus together, and when the outer wall is cut, the inner wall is affected. When the intraocular pressure changes, the sinus cavity is closed, it is sometimes difficult to find the sinus cavity diaphragm; the nylon thread is blocked by the diaphragm in the lumen, and the insertion cannot be continued. It is often mistaken that the nylon thread is located outside the sinus cavity and is repeatedly inserted; the operation error enters the ciliary shape. The superior choroid or the trabecular meshwork enters the anterior chamber. The latter is more common. In case the surgery can not find or damage the scleral sinus, in order to strengthen the effect, a trabeculectomy can be added. 4. The trabeculae are cut open. The curved surface of the trabeculectomy is parallel to the limbus, and the sinus cavity is inserted from the sinus sinus end, and the trabeculectomy device is moved in the direction of the limbus to make the anterior portion enter the sinus cavity 8 to 9 mm. Gently turn the handle back to determine if the front end of the slitter is actually inside the sinus cavity. If there is greater resistance after the rotation, the position of the incisor is correct; if the posterior rotation is easy, and there is bleeding in the anterior chamber, the incision device is located outside the sinus cavity and is transferred to the upper cavity of the ciliary body. At this time, the original device should be withdrawn from the incision and the sinus cavity should be inserted again. After determining that the incisor is located in the sinus cavity, the right hand-handle and the iris are rotated parallel to the front atrial side by about 45° to separate the inner wall of the Schlemm's sinus and the trabecular meshwork. At this time, there will be bleeding in the anterior chamber, and the anterior chamber will become shallow. At this time, the incision should be withdrawn in time to avoid damage to the iris or lens. When the trabecula is incision, the incisor will have a slight resistance, but if the resistance is large, the corner structure and even the surrounding cornea are deformed, indicating that the front end of the incisor has been inserted into the posterior elastic layer or the parenchyma. At this time, you can exit a little and try to separate again. After the trabecula is cut open, there will be a small amount of bleeding in the anterior chamber, but generally it will have little effect on the second incision. If there is more bleeding, you can rinse the anterior chamber first. The second incision is the same as the first, but in the opposite direction, the total incision angle is 120° to 180°. 5, Lynn and Berry designed a trabecular slitter, because of the hand-held ring, easy to operate, does not interfere with intraoperative direct observation. At the same time, it is easier to keep the incision needle parallel to the plane of the limbus. After the scleral sinus incision, the surgeon holds a large ring and cuts the distal end of the sinus. The small ring is located outside the limbus, and the large ring is gently rotated. The needle is inserted into the sinus cavity. When the incision needle completely enters the sinus cavity, gently swing the large ring to the left and right. The front end of the incision can be seen through the angle of the sclera, and the incision is the axis of rotation, and the large ring is rotated to the cavity area, that is, the corresponding opening is performed. The trabecular meshwork and the inner wall of the scleral sinus, with the curvature of the arc exiting the incision. 6, stitching. The scleral sinus incision does not require suturing. 10-0 nylon suture scleral flap 4 ~ 5 needles, intermittent suture ball conjunctiva. complication 1. The shallow or disappearance of the anterior chamber during surgery is mostly caused by excessive traction of the eyeball or insufficient anterior chamber perfusion. Care should be taken to prevent the incision and the lens from being cut. You can exit the cutting knife first and inject a small amount of viscoelastic into the front room. Then try again. 2, after the anterior chamber of the trabecular trabecula, a small amount of bleeding in the anterior chamber, most of the impact is not significant. The scleral sinus implant positioning on both sides can be done in advance. Even if one side of the trabecula is bleeding after cutting, it will not affect the other side of the incision. If there is more bleeding, a small amount of viscoelastic agent can be injected into the front room to push the blood to ensure that the second incision can be seen.