Trabeculectomy and treatment of glaucoma

Fistulizing surgery - trabeculectomy is most often performed to reduce intraocular pressure in patients with glaucoma. Trabeculectomy reduces intraocular pressure, because during the operation it creates a fistula between the inner parts of the eye and the subconjunctival space with the formation of a filtration pad.

Cairns reported on the first operations in 1968. A number of existing techniques allow the creation and maintenance of filtration pads in a functioning state, avoiding complications.

Description trabeculectomy

Currently, any kind of regional anesthesia is used (retrobulbar, peribulbar, or administration of anesthetic under the tenon capsule). Perhaps local anesthesia using lidocaine gel 2%, 0.1 ml lidocaine solution 1% intracameral and 0.5 ml lidocaine solution 1% subconjunctivally from the upper temporal quadrant so as to form a conjunctival cushion over the upper straight muscle.

Trabeculectomy is best done in the upper limb, since low-lying filtration pads are associated with a greater risk of developing infectious complications. The eyeball can be rotated downwards using the upper straight traction suture (black silk 4-0 or 5-0) or the corneal traction suture (black silk 7-0 or 8-0 or vicryl on the atraumatic needle).

The conjunctival flap with the base to the limbus or the arch is formed with the help of Vescott's scissors and anatomical tweezers (without teeth). A flap with a base to the arch is preferable in cases when the limb already has scars from previous operations; such a flap is more likely to be associated with cystic pads. When forming a flap with a base to the limb, the conjunctival incision is performed 8-10 mm posterior to the limbus. The incision on the conjunctiva and tenon capsule should be extended by about 8-12 mm. Then the flap is mobilized anteriorly so as to open the root-scleral groove. When creating a flap base to the vault, the conjunctiva and the tenon capsule are separated. It is enough to make limbal peritomy for approximately 2 hours (6-8 mm). Posteriorly perform blunt dissection.

The scleral flap should completely cover the fistula formed in the sclera to provide resistance to the outflow of moisture. The fluid will flow around the scleral flap.

Differences in the shape and size of scleral flaps are likely to have little effect on the outcome of the surgery. The thickness of the flap should be from half to two thirds of the thickness of the sclera. It is important to dissect the flap in the anterior direction (approximately 1 mm of the cornea) in order to make sure that the fistula reaches the scleral spur and the ciliary body. Before opening the eyeball, a corneal paracentesis is performed with a 30 or 27G caliber needle or a sharp pointed blade. Then a tissue block is cut out in the region of the corneoscleral junction.

First, with a sharp blade or scalpel make two radial incisions, starting from the transparent cornea, they extend back approximately 1-1.5 mm. The radial cuts made are spaced about 2 mm apart. To connect them, use the blade or scissors of Baths, thus separating the rectangular flap of fabric. Another method involves the anterior corneal incision parallel to the limbus and perpendicular to the axis of the eye, allowing you to get into the anterior chamber. For tissue excision, use a Kelly or Gass punch.

When performing iridectomy, damage to the iris root and ciliary body, as well as bleeding should be avoided. The scleral flap is first sutured with two single interrupted sutures with 10-0 nylon (in the case of a rectangular flap) or one suture (if the flap is triangular).

Slip knots are used to achieve tightness of the scleral flap and the normal outflow of moisture. Additional seams can be used to better control the outflow of fluid. After suturing the scleral flap, the anterior chamber is filled through the paracentesis, the outflow goes around the flap. If the outflow seems excessive or the depth of the anterior chamber decreases, the sliding nodes tighten or impose additional seams. If the moisture does not flow through the scleral flap, the surgeon can loosen the sliding knots or stitch tight, letting some of them go.

We can loosen seams. The loosening sutures removed to the outside can be easily removed, they are effective in cases of inflamed or hemorrhagic conjunctiva or thickened tenon capsule.

With a flap with a base on the limb, the conjunctiva is sutured with a double or simple continuous suture with an absorbable 8-0 or 9-0 suture or 10-0 nylon. Many surgeons prefer to use round needles. With a flap base to the arch, it is necessary to create a dense conjunctival-corneal joint. To do this, you can use two stitches with 10-0 nylon or a mattress stitch along the edges of the incision.

After the wound is closed, the anterior chamber is filled with a balanced salt solution through the paracentesis using a 30G cannula to lift the conjunctival pad and evaluate the leakage. In the area of the lower arch can enter antibacterial drugs and glucocorticoids. The eye patch is applied individually, depending on the patient's vision and the method of anesthesia used.

[1], [2], [3], [4], [5]

Intraoperative use of antimetabolites

To reduce postoperative subconjunctival fibrosis, which is especially important at high risk of unsuccessful surgery. Mitomycin-C and 5-fluorouracil are used. The use of antimetabolites is associated with great success, and with a high incidence of complications in primary trabeculectomy and high-risk operations. The risk / benefit ratio should be considered for each patient individually.

Mitomycin-C (solution of 0.2-0.5 mg / ml) or 5-fluorouracil (solution of 50 mg / ml) is applied for 1-5 minutes with a cellulose sponge soaked in a solution of the drug. The entire sponge or a piece of it of the required size is located above the episclera. It is possible to apply the drug under the scleral flap. The conjunctival tenon layer is thrown onto the sponge so as to avoid contact of mitomycin with the edges of the wound. After application, the sponge is removed, the entire area is thoroughly washed with a balanced salt solution. Plastic devices that collect the outflowing fluid are replaced and disposed of in accordance with the rules for the disposal of toxic waste.

[6], [7], [8], [9], [10]

Postoperative care

Local installations of glucocorticoids (prednisone 1% solution 4 times a day) are gradually canceled after 6-8 weeks. Some doctors use nonsteroidal anti-inflammatory drugs (2-4 times a day for 1 month). Appointment of antibacterial drugs should be within 1-2 weeks after surgery. In the postoperative period, cycloplegic drugs are used individually in patients with shallow anterior chamber or severe inflammation.

With a high probability of developing early complications (vascularized and thickened filtration pads), it is recommended to perform repeated subconjunctival applications of 5-fluorouracil (5 mg in 0.1 ml of solution) during the first 2-3 weeks.

Finger pressure on the eyeball in the lower part of the sclera or cornea through the closed lower eyelid, as well as a point pressure on the edge of the scleral flap with a moistened cotton swab can be useful for raising the filtration pads and reducing intraocular pressure in the early postoperative period, especially after laser lysis of the sutures.

Lysis of sutures and removal of loosening sutures are necessary for high intraocular pressure, a flat filtration pad and a deep anterior chamber. Before conducting a laser monitoring, it is necessary to perform a gonioscopy to make sure that the sclerostomy is open and that there is no tissue or blood clot in its lumen. Lysis of stitches and removal of loosening stitches should be carried out in the first 2-3 weeks after surgery, the result can be successful, even a month after surgery to receive mitomycin-C.

[11], [12], [13], [14], [15], [16], [17]

Complications of trabeculectomy

Complication	Treatment
Conjunctival holes	Kissetny seam thread 10-0 or 11-0 on a round ("vascular") needle
Early superfiltration	If the anterior chamber is shallow or flat, but there is no contact of the lens with the cornea, use cycloplegic preparations, reduce the load and avoid taking Valsalva. If there is contact between the lens and the cornea, an urgent restoration of the anterior chamber is necessary. Attach stitches to scleral flap
Choroidal effusion (choroidal detachment)	Observation, cycloplegic drugs, glucocorticoids. Drainage is indicated with a copious effusion, which is associated with a shallow anterior chamber.
Suprahoroid hemorrhage
Intraoperative	Try to take eye and gently fill the prolapse choroid. Intravenous mannitol and acetazolamide.
Postoperative	Observation, control of intraocular pressure and pain. Drainage is shown after 7-10 days in cases of continuing shallow anterior chamber and unbearable pain
Incorrect flow direction	Initial drug treatment - intensively topical cycloplegic medications and mydriatics, local and oral liquid suppressants and osmotic diuretics. In pseudophakic eyes - hyaloidotomy with neodymium YIG laser or anterior vitrectomy through the anterior chamber In phakic eyes - phacoemulsification and anterior vitrectomy. Vitrectomy through pars plana
Pads encapsulation	First observation. Suppressants fluid at elevated intraocular pressure. Consider the possibility of using 5-fluorouracil or surgical revision
Late fistula filtration pads	In case of small leaks, monitoring and local use of antibacterial drugs. If the leakage is prolonged - surgical revision (conjunctival plasty)
Chronic hypotension	With maculopathy and loss of vision - subconjunctival blood or surgical revision of the scleral flap
Inflammation filtration pads, endophthalmitis	Infection pads without the involvement of intraocular structures - intensive treatment of strong antibacterial drugs with a broad spectrum of action. Infection pads with a moderate cellular reaction of the anterior segment - intensive local treatment with strong antibacterial drugs. Infection pads with a pronounced cellular response of the anterior segment or the involvement of the vitreous body: sampling the vitreous body and the introduction of antibacterial drugs intravitreal

[18], [19], [20], [21], [22], [23], [24]