Trabeculectomy

Initially, the pocket is created in the conjunctiva and Tenon's capsule and the wounds are treated for several seconds to several minutes with a sponge-soaked mitomycin C (MMC, 0.5-0.2 mg / ml) or 5-fluorouracil (5-FU, 50 mg / ml). This chemotherapeutic aid prevents filter bubble failure due to scarring by inhibiting fibroblast proliferation. Alternatively, non-chemotherapeutic adjuvants can be used to prevent the formation of super-scars along the wound modulation border, such as implanted collagen matrices ^{[1] [2] [3] [4] [5]} or biodegradable spacers. Some surgeons prefer to cut the conjunctival flap with the base to the arch, while others prefer the base to the limb at the junction of the sclera with the cornea, which may allow easier access to the eye. Then, a valve is made in the sclera with a base in the corneal-scleral junction, after carefully cauterizing the valve area, a window is created under the valve using the Kelly punch to remove part of the sclera , Schlemm's canal and trabecular network to enter the anterior chamber . Due to the release of fluid, the iris partially falls out due to sclerostomy and therefore, as a rule, forces an excision to be performed under the name iridectomy . This iridectomy will prevent future blockages of the opening in the sclera. The sclera valve is then loosely sutured into place with a few stitches. The conjunctiva closes in a waterproof manner at the end of the procedure.

Intraocular pressure can be reduced by resuming drainage of intraocular fluid inside the eye in the following ways:

• filtering through a sclerostoma around the periphery of the scleral valve into a filter vesicle, which forms under the conjunctiva;
• filtering through the outlet of the channel in the scleral valve under the conjunctiva;
• filtering through the connective tissue of the scleral valve, under the conjunctiva and into the cut ends of the Schlemm canal ;
• water flow at the cut ends of the Schlemm's canal into the collector of canals and episcleral veins;
• into the cyclodialysis gap between the ciliary body and the sclera, if the tissue is dissected posterior to the scleral spurs.

Glaucoma medication usually stops to improve the flow of aqueous humor in the vesicle. Topical medications usually consist of drops of antibiotics four times a day and anti-inflammatory therapy, such as drops of prednisone every two hours. The eye is closed with a blindfold while anesthesia is active (which also anesthetizes the optic nerve) and vision resumes.

Patients are instructed to call immediately in case of pains that are not eliminated by painkillers or if vision is impaired , do not rub your eyes and wear a bandage overnight for several days after surgery.

If 5-FU was used during surgery, or if an antifibrotic agent was not used, 5 mg of 5-FU per day can be administered 7-14 days after surgery. In the following days and weeks, the sutures that hold the valve below the sclera can be removed by laser lysis of the suture to titrate intraocular pressure while improving outflow. Laser lysis of the suture uses a light red laser and contact lenses to penetrate the non-invasively lying conjunctival valve and remove the black nylon suture. Some surgeons prefer an adjustable valve suture during a trabeculoectomy, which can then be loosened with tweezers using a slit lamp in the office.

• A flat bubble is an unsuccessful operation if the bubble does not form in the first postoperative days; if scarring is caused, subconjunctival injection of 5-FU can prevent the conjunctiva from sticking from below from the bottom of the wound.
• Bubble leak - may cause a flat blister. A dressing with a contact lens is installed for several days with the subsequent elimination of leakage, if necessary
• The flat anterior chamber is a measure to prevent corneal decompensation; often can be done in the office under a slit lamp using viscoelastics used in cataract surgery .
• Inflammation of the bladder tissue - if the infectious process progresses to destructive endophthalmitis .
• Suprachoroidal hemorrhage - rupture of a long posterior ciliary artery due to progressive distension with progressive serous choroidal compartment; usually occurs a few days after trabeculoectomy, often with acute pain pain
• Hypotension - wound revision ^[6]
• Cataract formation is cataract surgery, if significant.
• Small encapsulated bladder - the introduction of a subconjunctival MMC and lidocaine can inflate the bladder to the adjacent conjunctiva, followed by a needle piercing the side of the bladder and expanding the bladder; As an alternative or combination, the use of biodegradable pads or a collagen matrix implant can be realized. ^[7]

Trabeculoectomy is the most common invasive glaucoma surgery. It is very effective in the treatment of progressive glaucoma, which has been demonstrated in the main studies of glaucoma . Even if trabeculoectomy failed, a second operation can be performed elsewhere. If scarring is the main cause of failure, antifibrotic and anti-inflammatory therapy should be enhanced in the second operation. Alternatively, a glaucoma valve device insert may be used.

Trabeculoectomy has undergone numerous changes, for example, filtering trepanotrabeculectomy (TTE) is a modification of surgery after J. Fronimopoulos. A triangular scleral valve is created, which is about half the thickness of the sclera. Then trepanation is performed with a 2 mm trepan. The edges of the trepanation opening of the sclera are thermally cauterized. ^[eight]

An additional deep dissection of the sclera can also be performed in the scleral valve of the trabeculoectomy, first introduced T. Dada et al .; ^{[9] A} deep opening of the sclera is performed by a non-penetrating filtering operation, but not by traditional trabeculoectomy. In the space created by the deep opening of the sclera, it is proposed to place a certain biocompatible pad or device to prevent subscleral fibrosis and maintain good filtration results in this modified operation.