Glaucoma - Surgery

Modern operations used for glaucoma include:

1. improving the outflow of intraocular fluid;
2. decrease in the production of intraocular fluid.

If the production of intraocular fluid decreases, innervation is disrupted, corneal dystrophy develops, etc. On the seeing eye, operations on the ciliary body are undesirable.

To increase the intraocular fluid, surgical interventions are performed at the site of intraocular fluid retention.

Another concept is to create new outflow paths:

1. anastomoses near the angle of the anterior chamber and the veins of the porticosus bed;
2. myocleisis - part of the internal rectus muscle with a vascular bundle is transplanted into the angle of the anterior chamber;
3. part of the episclera together with the vessels is immersed in the angle of the anterior chamber;
4. insert various tubes (drainage), create valves.

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Preparing the patient for surgery

1. They lower intraocular pressure as much as possible and reduce high blood pressure. Anticholinergic drugs are discontinued 2-3 weeks before, as they increase bleeding.
2. Diphenhydramine with promedol and glycerol are prescribed 30 minutes before the operation.
3. General anesthesia (and combined anesthesia) is desirable.
4. Rational anesthesia - retrobulbar, aminesia (motor muscles are activated).
5. Slow opening of the anterior chamber:
   • steroid anti-inflammatory therapy during surgery;
   • prevention of infection (broad-spectrum antibiotics under the conjunctiva).

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Types of Glaucoma Surgeries

1. Angular retention - relative and absolute; differential diagnosis - Forbes test. In case of functional block - iridectomy, in case of organ synechia - iridocycloretraction.
2. Scleral grafts are cut out by 2/3, then they are inserted into the angle of the anterior chamber, which creates additional drainage.
3. Pretrabecular block - goniotomy,
4. Trabecular retention - trabeculotomy, destruction of the inner wall of Schlemm's canal.
5. Intrascleral retention - sinusotomy; sinustrabectomy - a flap of sclera, Schlemm's drops, trabecula are excised. The effectiveness of this operation is 95%, long-term results - 85-87%, if it is performed in the initial and advanced stages of glaucoma.

Operations aimed at reducing the production of the ciliary muscle:

1. cycloanemia (diathermocauterization of the ciliary arteries is performed, which leads to atrophy of part of the ciliary body and a decrease in the production of intraocular fluid);
2. It is possible to influence the ciliary body through the sclera with cold (cryopexy) or increased temperature, or with a laser (coagulation of the ciliary body).

Laser microsurgery (surgery) for glaucoma

Laser microsurgery of glaucoma is aimed primarily at eliminating intraocular blocks on the path of internal moisture movement from the posterior chamber of the eye to the episcleral veins. For this purpose, lasers of various types are used, but the most widely used are argon lasers with a wavelength of 488 and 514 nm, pulsed neodymium YAG lasers with a wavelength of 1060 nm, and semiconductor (diode) lasers with a wavelength of 810 nm.

Laser gonioplasty - the basal part of the cornea is coagulated, which leads to widening of the angle of the anterior chamber, pupil, trabecula is stretched and Schlemm's canal is opened. 20-30 coagulants are applied. This operation is effective in case of closed-angle glaucoma with functional block.

Laser iridectomy involves creating a small hole in the peripheral part of the iris. The operation is indicated for functional or organic pupillary block. It equalizes the pressure in the posterior and anterior chambers of the eye and opens the anterior chamber. The operation is performed for preventive purposes.

Laser trabeculoplasty involves applying several cauterizations to the inner surface of the trabecular diaphragm, which improves its permeability to intraocular fluid and reduces the risk of Schlemm's canal blockage. It is used for primary open-angle glaucoma that is not amenable to compensation with medications.

With the help of lasers, other operations (fistulizing and cyclodestructive) can also be performed, as well as operations aimed at correcting microsurgical “knife” operations.

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Argon laser trabeculoplasty

It consists of applying point laser coagulants to the trabecular zone, which increases the outflow of aqueous humor and reduces intraocular pressure,

• Technique

The laser beam is directed to the transition zone of the pigmented and non-pigmented areas of the trabecula, maintaining strict focusing. The presence of a blurred outline of the light spot indicates that the sensor is not aimed perpendicularly enough,

Laser coagulates of 50 µm in size are applied with an exposure time of 0.1 sec and a power of 700 mW. The reaction is considered ideal if a point blanching appears or an air bubble is released at the moment of exposure. If a large bubble appears, the exposure is excessive.

If the reaction is insufficient, the power is increased by 200 mW. In case of hyperpigmentation, 400 mW is sufficient, in case of non-pigmented UPC, the power can be increased to 1200 mW (on average 900 mW).

25 coagulates are applied at equal intervals in the visualization zone from one edge of the mirror to the other.

The goniolens is rotated clockwise by 90 and the laser action is continued. The number of coagulates: from 25 to 50 in a circle of 180. Continuous visual control of adjacent sectors is important. Good skill allows performing laser trabeculoplasty with continuous rotation of the goniolens, controlling the light beam through the central mirror.

Some ophthalmologists initially prefer coagulation over 180° and later, if there is no sufficient effect, the remaining 180°. Others suggest circular coagulation with the initial application of up to 100 coagulates.

After the procedure, 1% iopidine or 0.2% brimonidine is instilled.

Fluorometholone is used 4 times a day for a week. The previously developed hypotensive regimen is not cancelled.

• Observation

The result is assessed after 4-6 months. If the intraocular pressure is significantly reduced, the hypotensive regimen is reduced, although complete drug withdrawal is rare. The main goal of argon laser trabeculoplasty is to achieve controlled intraocular pressure and, if possible, reduce the instillation regimen. If the intraocular pressure remains high and laser intervention is performed only on 180 UAC, it is necessary to continue treatment for the remaining 180. Usually, repeated laser trabeculoplasty over the entire circumference of the UAC is rarely successful in the absence of an effect, then the issue of filtration surgery is discussed.

• Complications

1. Goniosynechiae may occur if the coagulation application area is displaced posteriorly or the power level is too high. In most cases, this does not reduce the effectiveness of laser trabeculoplasty.
2. Microhemorrhages are possible when the vessels of the iris root or ciliary body are damaged. When the eyeball is compressed with a goniolens, such bleeding is easily stopped.
3. Severe ophthalmic hypertension is possible in the absence of preliminary prophylactic instillation of apraclonidine or brimoniline.
4. Moderate anterior uveitis resolves on its own and does not affect the outcome of the intervention.
5. The lack of effect suggests a filtration intervention, but the risk of developing encapsulated filtration pads after previously performed laser trabeculoplasty is 3 times higher.

• Results

In the initial stage of POAG, the effect is achieved in 7^-85% of cases. The average decrease in intraocular pressure is about 30%, and with initially high ophthalmotonus, the effect is more pronounced. In 50% of cases, the result is maintained for up to 5 years and in about 53% - for up to 10 years. The lack of effect from laser trabeculoplasty becomes clear already during the first year. If the intraocular pressure is normalized during this period, the probability of normalization of intraocular pressure after 5 years is 65%, and after 10 years - about 40%. If laser trabeculoplasty is performed as the primary stage in the treatment of POAG, in 50% of cases additional hypotensive treatment is required for 2 years. Subsequent laser trabeculoplasty is effective in 30% of cases after 1 year and only in 15% - after 2 years after the first intervention. The effect of laser trabeculoplasty is worse in people under 50 years of age, does not differ between Europeans and people of the Negroid race, but in the latter it is less stable.

In normotensive glaucoma, a good result is possible in 50-70% of cases, but the absolute reduction in intraocular pressure is significantly less than in POAG.

In pigmentary glaucoma, laser trabeculoplasty is also effective, but its results are worse in older patients.

In pseudoexfoliative glaucoma, high efficiency was noted immediately after the intervention, but later, a rapid decrease in the result was noted, compared to POAG, with a subsequent increase in intraocular pressure.

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Diode laser trabeculoplasty

Its results are similar to laser trabeculoplasty with less destructive impact on the hemato-ophthalmic barrier. The main differences between these methods are:

• Higher laser power (800-1200 mW).
• Postcoagulation burn is less pronounced, in this area there is blanching, and a cavitation bubble does not form.
• The size of the light spot is 100 microns, and can be reduced to 70 microns using a special contact lens.
• Pulse duration: 0.1-0.2 sec.

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NdrYAG laser iridotomy

Indications:

• Primary angle-closure glaucoma: acute attack, intermittent and chronic course.
• Acute attack of glaucoma in the fellow eye.
• Narrow "partially closed" angle.
• Secondary angle-closure glaucoma with pupillary block.
• POAG with a narrow angle and a combined mechanism of glaucoma development.

Technique:

1. Instill brimondip 0.2% to reduce intraocular pressure.
2. Pilocarpine is instilled to achieve maximum miosis, although after an acute attack of glaucoma this is usually impossible.
3. Local installation anesthesia is administered.
4. A special contact lens such as the Abraham lens is used.
5. An area of the iris is selected, preferably in the superior segment, so that this area is covered by the eyelid to prevent monocular diplopia. Iridotomy should be performed as peripherally as possible to prevent damage to the lens, although this is not always possible due to the presence of the arcus senilis. The crypt area is convenient for iridotomy, but this recommendation is not mandatory.

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Abraham lens for laser iridectomy

1. The light beam is turned so that it is not perpendicular, but directed towards the periphery of the retina to prevent accidental burning of the macula.
2. Laser coagulants vary depending on the type of laser. Most lasers have a power of 4-8 mJ. For thin blue irises, a power of 1-4 mJ is required for one coagulation, after 2-3 coagulations an “explosive” effect is achieved. For thick, “velvet”, brown irises, a higher energy level or more coagulants are required, but there is a greater risk of intraocular damage.

Usually the conventional application of 3 coagulates with a power of 3-6 mJ is effective.

1. Laser action is performed after precise focusing of the beam. A successfully performed procedure is characterized by pigment release. On average, up to 7 coagulates are performed to achieve the desired effect (Fig. 9.145), although in practice it can be reduced to 1-2.
2. After the intervention, 1% aproclonidine or 0.2% brimonidine is instilled.

Topical application of steroids according to the following schedule: every 10 minutes for 30 minutes, then every hour during the treatment day and 4 times a day for 1 week.

Possible technical problems:

If the first action is ineffective, the application of pulses is continued, retreating from this area, shifting laterally and increasing the power. The possibility of continuing coagulation in the same area depends on the degree of pigment release and hemorrhage caused by the previous pulse. In case of a thick brown iris, incomplete iridotomy is characterized by the appearance of a cloud of scattered pigment, which complicates visualization and focusing in this area. Further manipulations through the pigment cloud often increase the amount of pigment and hemorrhage, preventing the desired result from being achieved. In this situation, after the pigment has settled, pulses are applied to the same area, increasing the energy of action, or they act on the adjacent area. If the effect is insufficient, a combination with an argon laser is possible.

Too small iridotomy opening. In this case, it is sometimes easier and more appropriate to make an additional iridotomy in another area, rather than trying to enlarge the first opening. The ideal diameter is 150-200 µm.

Complications:

• Microhemorrhages occur in approximately 50% of cases. They are usually minor, and the bleeding stops within a few seconds. Sometimes, minor compression of the cornea with a contact lens is enough to speed up hemostasis.
• Iritis resulting from laser exposure is usually mild. More severe inflammation associated with hyperexposure to laser energy and inadequate steroid therapy may result in posterior synechiae.
• Corneal burn if no contact lens is used or the anterior chamber depth is shallow.
• Photophobia and diplopia if the iridotomy hole is not located under the upper eyelid.

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Diode laser cyclocoagulation

As a result of coagulation of the secretory ciliary epithelium, intraocular pressure decreases, which leads to a decrease in the production of aqueous humor. This organ-preserving intervention is used in terminal glaucoma, accompanied by pain syndrome and usually associated with organic synechial blockade of the angle.

Technique:

• peribulbar or sub-Tenon anesthesia is performed;
• use laser pulses with an exposure of 1.5 sec and a power of 1500-2000 mW;
• the power is adjusted until a “popping” sound is heard and then reduced below this level;
• apply approximately 30 coagulates in a zone 1.4 mm posterior to the limbus over a distance of more than 270;
• Active steroid therapy is prescribed in the postoperative period: every hour on the day of surgery, then 4 times a day for 2 weeks.

Complications. The most common are moderate pain and signs of inflammation of the anterior segment. More serious (rare): prolonged hypotension, thinning of the sclera, corneal dystrophy, retinal and ciliary body detachment. Since the purpose of the procedure is to relieve pain, possible complications are not comparable to complications after conventional filtering interventions.

Results depend on the type of glaucoma. Sometimes the procedure needs to be repeated. Even when pain relief is achieved, it is usually not associated with compensation of intraocular pressure.

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Trabeculectomy

This surgical procedure is used to reduce intraocular pressure by creating a fistula to drain aqueous humor from the anterior chamber into the sub-Tenon space. The fistula is covered with a superficial scleral flap.

1. The pupil should be constricted.
2. The conjunctival flap and underlying Tenon's capsule are separated with the base towards the limbus or superior fornix.
3. The episcleral space is released. The area of the proposed superficial scleral flap is delimited by coagulation.
4. The sclera is cut along the coagulation marks to 2/3 of its thickness, creating a bed that is covered with a triangular or rectangular scleral flap measuring 3x4 mm.
5. The superficial flap is separated to the area of transparent cornea.
6. Paracentesis is performed in the superior temporal segment.
7. The anterior chamber is opened along the entire width of the scleral flap.
8. A block of deep layers of the sclera (1.5x2 mm) is excised with a blade, Vannas scissors or a special “punch” instrument. Peripheral iridectomy is performed to prevent blockage of the internal scleral opening by the root of the iris.
9. The scleral flap is loosely fixed with sutures in the distal corners of the scleral bed from the cornea.
10. The sutures can be adjusted to reduce excess filtration if necessary and prevent the formation of a shallow anterior chamber.
11. The anterior chamber is restored via paracentesis with a balanced solution, checking the function of the created fistula and identifying areas of leakage under the scleral flap.
12. The conjunctival incision is sutured. Irrigation through paracentesis is repeated to check the functioning of the filtration pouch and to exclude external filtration.
13. Instillation of 1% atropine solution is performed.
14. A subconjunctival injection of steroid and antibiotic is performed into the inferior fornix of the conjunctiva.

Combination of trabeculectomy and phacoemulsification

Trabeculectomy and phacoemulsification can be performed through the same conjunctival and scleral approaches.

Excision of a deep block with Vannas scissors

1. A conjunctival flap is formed.
2. A 3.5 x 4 mm scleral flap is cut out with the base towards the limbus.
3. The phaco tip is inserted into the anterior chamber with a width of 2.8-3.2 mm.
4. Phacoemulsification is performed using traditional techniques.
5. A soft intraocular lens is implanted. With a rigid IOL, the size of the conjunctival and scleral flap is determined at the beginning of the operation.
6. A block of deep layers of the sclera is excised.
7. Peripheral iridectomy is performed.
8. The scleral flap is fixed.
9. Tenon's capsule and conjunctiva are sutured.

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Patient behavior after glaucoma surgery

Modern methods of antiglaucoma surgery significantly reduce the risk of postoperative complications, so the patient can return to normal life within a few days after the operation. Depending on the visual acuity, the patient may still be unable to drive a car for some time.

Taking a shower and washing your head (without tilting it) is permitted as early as the third day after the operation.

The question of returning to work is decided individually, depending on the effectiveness of the operation and the patient's profession. Heavy physical labor is prohibited.

In many types of work, such as office work, it is possible to resume it fairly quickly if the unoperated eye has sufficient visual functions. Caution is necessary in situations where stereoscopic vision is required by the type of work.

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Complications after glaucoma surgery

• ciliochoroidal detachment, since transudates accumulate in the suprachoroidal space;
• small anterior chamber;
• low intraocular pressure;
• low vision;
• with low intraocular pressure - "ciliary body shock".

Treatment of complications

1. hospitalization, injections of caffeine, steroids, mydriatics, pressure bandages on the filtration area;
2. surgical treatment - posterior trepanation of the sclera in the projection of the flat part of the ciliary body;
3. according to Fedorov - it is necessary to create new paths for fluid outflow;
4. SAAR - scleroangulo reconstruction is done at 6 o'clock, two flaps are separated at the limbus - the episclera (where there are many vessels) and a deep flap, then they are swapped (the superficial vascular plexuses are brought to the fluid of the anterior chamber);
5. internal sclerectomy (STE according to Fedorov) - resection of the internal layers of the sclera and their excision.

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Postoperative period after glaucoma surgery

1. sick leave for at least 2 months;
2. "pupil gymnastics";
3. treatment of postoperative iridocyclitis;
4. for posterior synechiae and hyphema - resorption therapy;
5. in case of hyperfiltration - a pressure bandage with a roller for 2-3 hours a day;
6. if filtration is insufficient - massage;
7. after surgery - local instillations of antibiotics, during the first weeks - anti-inflammatory drugs in doses corresponding to the degree of the inflammatory reaction. Non-steroidal anti-inflammatory drugs are used more often;
8. if intraocular pressure remains high for several weeks after surgery or is maintained at a normal level due to concomitant antihypertensive therapy, removal of sutures in the corneoscleral tunnel is necessary;
9. With prolonged reduction of intraocular pressure, vision can be seriously impaired, but with normalization of pressure, in almost all cases, its complete restoration is observed.