Fig. 37-15  Trabeculodialysis. With the spade-shaped goniotomy knife, the trabeculum is incised at Schwalbe’s line (SL) and disinserted from the scleral sulcus. Vertical relaxing incisions at the extremes of the incision allow the trabecular flap to fall away from the scleral wall. sc, Schlemm’s canal; tm, trabecular meshwork; ss, scleral spur.

the long-term outcome of mitomycin-C trabeculectomies was similar to that of Ahmed valve implants, but the complications were greater for the trabeculectomy group, whereas the Ahmed group was more likely to need subsequent medications to control the pressure.22,35

Trabeculodialysis

Glaucoma secondary to juvenile rheumatoid arthritis (Still’s disease) responds relatively well to trabeculodialysis (Fig. 37-15).36,37 Frequently these eyes have been rendered aphakic in childhood. The appeal of this procedure is that nearly half of treated patients obtain pressure control,38 which spares previously operated conjunctiva superiorly in the event that filtration or implant surgery is required later.

The procedure initially described by Haas resembles goniotomy.36 Under the operating microscope, the anterior chamber is filled with viscoelastic and the globe is secured by the assistant. A superficial incision is made with a Barkan knife at the anterior portion of the trabeculum while viewed through a Barkan lens. Incised trabeculum is peeled downward away from the angle wall as a sheet, and the iris root moves posteriorly.

Complications with this procedure have been minimal. Like goniotomy, trabeculodialysis is relatively atraumatic, and failure does not jeopardize the success of other, more conventional procedures.

Miscellaneous procedures

Goniosynechialysis

Goniosynechialysis has successfully reduced IOP in a small number of patients with chronic synechial angle closure.39 It has been recommended for patients who have had extensive synechial angle closure for less than a year. Goniosynechialysis is similar to trabeculodialysis but can be performed with an irrigating cyclodialysis spatula with an attached bottle of irrigating solution.The spatula is introduced through a paracentesis incision 1–2 mm anterior to the limbus after the anterior chamber has been deepened by draining aqueous and replacing it with a viscoelastic substance. The spatula is used to push the synechiae down from the angle wall over an area of approximately one-half the angle circumference. If bleeding occurs, it can be instantly tamponaded by elevating the irrigation

bottle.The procedure is then repeated via a new paracentesis opposite the initial one to open the other half of the angle.The viscoelastic substance is replaced with BSS at the end of the procedure. If no peripheral iridotomy exists, a surgical iridectomy may be needed to prevent recurrence of angle closure.

Pressure has been controlled in some patients for at least a year after the procedure. Patient selection is critical if this is intended as the primary surgical intervention.40 The most appropriate candidates are patients for whom a precise date for the beginning of progressive angle closure can be documented as being relatively recent. Such cases include an onset of an acute angle-closure attack or postoperative synechial closure documented after cataract or retinal surgery. In our hands, the technique is usually relegated to an ancillary maneuver during either filtration or cataract surgery in eyes with known peripheral anterior synechiae of recent onset.

Cyclocryotherapy

Trans-scleral cryoapplication to the underlying ciliary body may lower IOP by producing damage to the ciliary epithelium, thereby reducing aqueous secretion. Cyclocryotherapy is often painful and may induce a chronic, uncomfortable uveitis. We advise cyclocryotherapy use in patients with end-stage glaucoma who are unresponsive to other procedures, or in patients with minimal visual potential, when no laser is available. Cyclocryotherapy may be particularly useful in patients with chronic angle-closure glaucoma.41,42 Because of the greater comfort of trans-scleral laser techniques43 and the precision of endolaser procedures,44,45 cyclocryotherapy should only be used in cases in which such lasers are not available (see Ch. 32).

Complete perioperative analgesia is imperative.We generally combine bupivacaine 0.5% with lidocaine 4% in a 2:1 mixture and wait 15–30 minutes or more before initiating treatment.The bupivacaine/ lidocaine mixture produces a longer acting anesthetic agent, but the interval between injection and full anesthetic effect may be longer than with lidocaine alone. Subconjunctival anesthesia has also been reported to be effective in the majority of cases of cyclophotodestruction and precludes the possibility of subarachnoid injection of anesthetic which is advantageous especially in an outpatient setting.46

A variety of cyclocryotherapy techniques exists. Usually, six equally spaced applications are made circumlimbally with the probe centered 2–3 mm from the limbus. Usually only 180° of the eye is treated at a time. Subsequent procedures can re-treat some areas and total 180°, but such treatments are not necessarily contiguous: one quadrant should remain untreated at all times. For example, the first session may freeze from the 12 to 6 o’clock positions; a second session from 3 to 9 o’clock positions; and a third session from 12 to 3 o’clock and 6 to 9 o’clock positions. In this example, the quadrant from the 9 to 12 o’clock positions remains untouched.

The larger 4-mm glaucoma probe (rather than the smaller cataract probe) attached to a liquid nitrogen supply is used. The tip is held against the conjunctiva with the probe’s center approximately 3 mm from the limbus, and the temperature is lowered to 280°C for 60 seconds in adults and 30 seconds in children.47 The extent of the freeze ball is approximately 10–12 mm and usually extends to the corneal limbus. The probe is allowed to warm until the iceball thaws, and then the probe is removed. Experimental studies indicate that greater tissue damage is produced by a freeze- thaw-freeze technique, and we do not advise its use.

In the immediate postoperative period, there is often a transient, marked elevation in IOP and moderate to severe pain that requires strong analgesics and maximal glaucoma therapy, including oral