Cyclodestructive surgery for glaucoma

Increased intraocular pressure is the main risk factor for the development of glaucoma, which ophthalmologists can control.

In order to effectively reduce the intraocular pressure due to a decrease in moisture production or an increase in its outflow, medicines (eye drops or tablets) are used. Most surgical and laser interventions, trabeculotomy, filter operations, tubular shunts, goniotomy, iridectomy, laser trabeculoplasty and laser iridotomy reduce intraocular pressure, increasing outflow. Cyclodestructive surgery is aimed at destroying the processes of the ciliary body, reducing the production of intraocular fluid. Due to the unpredictability of these operations with respect to reducing intraocular pressure and the complications associated with their use, cyclodeutulative operations are used last.

[1], [2], [3], [4], [5], [6]

Indications for cyclodeasures

Cycloidal destruction of the ciliary body is usually left as a backup method for patients not amenable to medical or surgical treatment. Exceptions to this rule are patients who can not be subjected to surgical treatment for medical contraindications or in underdeveloped countries. In these countries, where medical treatment is expensive and rarely available, the diode contact CTF, portable and relatively easy to conduct, may in the future be the first-line treatment for glaucoma. Such interventions are useful for relieving the pain associated with glaucoma and lack of vision, which will help the patient avoid enucleation until a malignant tumor is detected during ultrasound diagnosis. With the help of these methods, terminal stages of open-angle glaucoma, neovascular glaucoma, blind sore eyes, glaucoma after penetrating keratoplasty, progressive closure of the angle, simultaneously primary and secondary to glaucoma, traumatic glaucoma, malignant glaucoma, glaucoma induced by silicone oil, congenital glaucoma , pseudophakic and aphakic open-angle glaucoma, as well as secondary open-angle glaucoma. Alternative therapies that can be used in these patient groups include fistulizing operations using antimetabolites or tubular shunts.

Contraindications to cyclodextraction

There are few contraindications to these operations. A direct contraindication is the patient's lens and good eyesight. In these cases, alternative treatment methods should be used first. Expressed uveitis is a relative contraindication, since after inflammation there is a pronounced inflammation: before the procedure, careful care is necessary. Nevertheless, uveitis glaucoma is one of the secondary glaucomas, which is successfully treated by the described method. For all the above procedures, with the exception of endoscopic cyclophotocoagulation, the patient's assistance is necessary, and his absence may be a contraindication.

Methods of cyclodextraction

Several methods are used for cyclodestruction: non-contact transscleral cyclophotocoagulation (CTC), cyclocryotherapy, contact transcleral CT, transpupillary CT and endoscopic cyclophobic coagulation. If the desired level of pressure has not been reached, these interventions can be repeated the required number of times, usually at intervals of 1 month.

Non-contact transscleral cyclophobic coagulation

To perform this operation, a neodymium AIG laser is used. Previously, a semiconductor diode laser was used. A microlaser was also used. Conduct a retrobulbar anesthetic. Insert the eyelid expander if you do not use a contact lens. Sometimes use a contact lens, developed by Bruce Shields (Bruce Shields). Advantages of such a lens: marks with an interval of 1 mm for more accurate determination of the distance to the limb, blocking part of the laser beams from entering the pupil, as well as anemia of the inflamed conjunctiva to reduce the surface burn. At a distance of 1 to 3 mm from the limb (optimally 1.5 mm), 8-10 burns are applied over 180-360 °, avoiding meridians at 3 and 9 h, in order not to coagulate the long posterior ciliary arteries and thus not cause necrosis of the anterior segments. The energy is 4-8 J. The laser beam is focused on the conjunctiva, but the laser is scattered so that its effect falls just 3.6 mm below the surface of the conjunctiva, most of the energy is absorbed by the ciliary body. In general, the higher the levels of energy used, the more inflammation.

Contact transscleral cyclophobic coagulation

This technique is currently the most popular environment for cyclodeastructive operations. In this procedure, a contact laser semiconductor probe having a relatively small size (G-probe, IRIS Medical Instruments, Inc., Mountain View, CA) is used. Neodymium AIG and a krypton laser are also used to conduct a contact transscleral DSC.

Procedure: Retrobulbaric anesthesia is performed and the eyelid expander is inserted. The patient is lying on his back. The front end of the probe is placed on the limb.

Due to the construction of the G-probe, the energy actually hits the point 1.2 mm from the limb. Produce 30-40 applications of energy 1.5-2 W for 1.5-2 seconds per 360 °, avoiding positions at 3 and 9 hours. If you hear a clapping sound, the energy is reduced by 0.25 V to prevent a more pronounced inflammation and the formation of hyphema.

Cyclocryotherapy

According to this technique, a probe of 2.5 mm is cooled in liquid nitrogen to -80 ° C. Then it is placed approximately 1 mm behind the limbus for 60 s. The treatment is carried out in 2-3 quadrants, for each one there are four cryoexposures, excluding the positions for 3 and 9 hours.

Transpupillary cyclophotocoagulation

A continuous wave of an argon laser is directed with a biomicroscope. This method is based on the idea of direct action of laser energy on ciliary tracts instead of stimulated action through other structures, such as conjunctiva and sclera. To visualize the processes of the ciliary body, Goldmann's gonioprism, scleral depression and a large sectoral iridectomy are necessary. Points of laser action ranging in size from 50 to 100 microns with an energy of 700-1000 mV, the duration of each exposure is 0.1 s. The amount of energy used is selected so as to cause a blanching of the tissue. Thus, each visible process is treated. The main drawback of this method is the complexity of visualization.

Endoscopic cyclophotocoagulation

This procedure is performed in the operating room under local retrobulbar anesthesia. There are two different accesses: limbal and through pars plana. With limbal access, the pupil is maximally expanded, a cut is made about 2.5 mm in length by the keratom, and viscoelastic is introduced between the lens and the iris until the cili-arnae processes are achieved. Through one incision it is possible to process the processes on the arc at 180 °. To process the remaining 180 ° it is necessary to make a second cut across from the first. After the processing of the appendages, the viscoelastic is washed out and the wound is nylon 10-0. Together with this procedure, you can perform and extraction of cataracts.

Endoscopic cyclophotocoagulation through the pars plana is performed only by aphakic or pseudophakic patients. A typical section of the pars plana is performed at a distance of 3.5-4.0 mm from the limbus, anterior vitrectomy is performed and a laser endoscope is inserted. If you need to process the sprouts for more than 180, then make two cuts. The incisions on the sclera are sutured with the vikril 7-0. The laser endoscope contains a video conductor, light guide and laser conductor in an endosonde of caliber 18 or 20.

The probe of caliber 20 has a field of view 70, the depth of focus is from 0.5 to 15 mm. The probe of caliber 18 has a field of view of 110 °, depth of focus from 1 to 30 mm. The probe is connected to a video camera, a light source, a video monitor and a video recorder. A semiconductor diode laser with a wavelength of 810 nm is connected to a laser conductor. Laser exposures with a power of 500-900 mV lasting from 0.5 to 2 s are used to cause final whitening and wrinkling of each ciliary tract. If you hear a popping sound or the sound of bursting bubbles, then the duration and / or power of the impact should be reduced. The surgeon carries out the operation, watching his actions through a video monitor.

Post-operative care

With all these methods of treatment, glucocorticoids are prescribed topically and under Tenon's capsule to relieve inflammation that occurs in all patients. Sometimes prescribed drops of atropine. With pain, analgesics are applied, ice is applied.

Complications of cyclodestruction

The most dangerous of these complications is chronic hypotension leading to phthisis, which occurs in 8-10% of patients, and to sympathetic ophthalmia, which is observed less often. The expressed soreness is met in approximately 50% of patients, it can last from several hours to several weeks, usually the pain subsides 2-3 days after the procedure. The pain is removed by taking analgesics and applying ice.