times range from 10 to 20 ms. Some surgeons use up to 8 J. Because of the varying amounts of energy delivered by each type of laser instrument, it is advisable to obtain recommendations from a surgeon experienced with the particular instrument being used.

Although repeat treatments often are needed, 60–70% of cases can be controlled, maintaining IOPs of 22 mmHg or lower. Complications include reduced visual acuity, uveitis, pain, hemorrhage, and phthisis bulbi. All of these complications, especially pain and inflammation, seem less severe than those experienced after cyclocryotherapy.

Contact trans-scleral cyclophotocoagulation (TCP) (Fig. 32-3) has been accomplished using the same laser energy levels but deliv-

ered with a fiber-optic probe lightly pressed onto the conjunctiva (Tables 32-1 and 32-2).14–17 Slightly lower energy levels than those

Fig. 32-3  Superior conjunctiva immediately after contact TCP. Small depressions in the conjunctiva disappear within minutes and the eye often appears essentially normal in 24 hours.

Table 32-1  Trans-scleral contact cyclophotocoagulation techniques

used for non-contact procedures are advisable because the contact pressure increases the transparency of the sclera. Retrobulbar anesthesia is necessary, as is a speculum to separate the eyelids.The probe should be placed 0.5–1.0 mm from the limbus and held as perpendicular to the sclera as possible. Probes made especially for cyclophotocoagulation such as the G-Probe™ of Gaasterland make placement easier and more uniform.18

All forms of trans-scleral laser cyclophotocoagulation may damage ciliary muscle as well as ciliary epithelium, adjacent iris, and retina. Extreme care must also be taken to avoid excessive destruction of the ciliary body, which could lead to hypotony and possibly phthisis.To target the ciliary epithelium more accurately, some physicians favor the use of an endoscopic probe and laser delivery fiber introduced via a limbal incision.19 This allows the surgeon to directly visualize and destroy the ciliary processes.20 This is an invasive technique, however, that requires sterile technique but is gaining in popularity.

Endocyclophotocoagulation procedures are currently under clinical and laboratory investigation. Endocyclophotocoagulation may be most useful for aphakic and pseudophakic eyes or in combination with phacoemulsification procedures.21,22 Following endocyclophotocoagulation, some surgeons inject sub-Tenon’s dexamethasone over the perilimbal area treated by the laser; others use topical steroids and atropine drops alone.

Since immediate postoperative pressure spikes are common with all types of cyclophotocoagulation, often an oral carbonic anhydrase inhibitor (acetazolamide 500 mg, methazolamide 50– 100 mg) is administered immediately preor postoperatively. It is important to monitor patients closely in the short-term postoperative period.

The operated eye is usually patched postoperatively overnight or until the anesthetic wears off. Long-acting anesthetics such as bupivacaine help with immediate postoperative pain control. The patient should be sent home with an adequate supply of major analgesic medication as the eye may be quite painful after the anesthetic wears off. Topical regimens typically include prednisolone acetate 1% four times daily and atropine sulfate 1% twice daily. Medications are tapered gradually until inflammation has disappeared. Preoperative glaucoma medications may be continued as needed, except for miotics. Repeat cyclodestructive procedures are often necessary, although fewer spots should be treated to avoid hypotony and phthisis.

These procedures are alternatives to cyclocryotherapy. All cyclodestructive procedures may cause side effects of pain, phthisis, and reduced vision, although laser techniques may cause less pain and allow for more precise control of energy delivery.

Table 32-2  Trans-scleral non-contact cyclophotocoagulation techniques

Other laser procedures

Lasers have also achieved widespread use in conjunction with surgical procedures such as trabeculectomy. Laser suture lysis, for example, can safely sever trabeculectomy flap sutures to increase filtration. Laser bleb reopening and remodeling may reduce the need for further invasive filtration surgery. Finally, lasers provide a safe and often effective approach to closing cyclodialysis clefts, removing peripheral anterior synechiae from the angle or cornea, and enlarging miotic pupils. Laser procedures are safer than surgical alternatives in all of these capacities.

Severing of sutures

Subconjunctival trabeculectomy flap sutures can be lysed with the laser postoperatively if there is inadequate filtration. Dark nylon or proline sutures can usually be severed with the argon laser using settings of 200–1000 mW for 0.02–0.15 second with a 50–100- m spot size.23 This allows the surgeon to suture the wound more securely at the time of surgery.24,25 Tighter suturing maintains the integrity of the eye better and reduces the incidence of flat chambers and hypotony in the early postoperative period. The procedure is feasible from about 3–15 days after surgery or up to at least 2 months or more after mitomycin-C use.26

Laser suture lysis (LSL) is accomplished by first anesthetizing the eye with an appropriate topical agent and then compressing the conjunctiva overlying the suture with the flat corner of a fourmirror gonioprism or specially designed laser suture lens such as that described by Hoskins.23 Phenylephrine 2.5% or apraclonidine 0.5% (Iopidine®) is useful to blanch the superficial vessels of the conjunctiva. Gentle but constant pressure with the lens will displace fluid from the most edematous conjunctiva and provide a clear view of the underlying suture, which usually can be lysed with one or two laser applications. If possible, sutures should be lysed close to their tissue penetration site to prevent the loose ends from springing up and potentially disrupting the conjunctiva.Very edematous flaps may require 1–2 minutes of sustained gentle pressure over the suture before the suture is clearly visible (Figs 32-4 and 32-5). Dense hemorrhage in the tissues overlying the suture will absorb the energy, prevent treatment, and possibly cause conjunctival perforation. Similarly, fluorescein-stained conjunctiva limits argon laser energy transmission to the sutures and may cause conjunctival perforation. Therefore eyes with conjunctival hemorrhage obscuring the suture cannot be treated with this technique.

A thick, inflamed Tenon’s capsule may also preclude successful LSL.This is unfortunate because these eyes commonly suffer from inadequate filtration. After the suture is cut, gentle pressure on the scleral edge of the incision will elevate the bleb and increase flow.

Fig. 32-4  Laser suture lens. The device has a small convex lens that compresses the edematous conjunctiva, permitting a clear view of the tiny nylon suture underneath the conjunctiva. This suture then can be cut easily with a 50- m spot laser beam using 400 mW of energy for 0.1 second.

(Photo courtesy of John Hetherington Jr, MD, University of California, San Francisco.)

Topical steroids are often useful postoperatively to reduce external scarring. An important point to remember is that only one suture should be severed at a time because excessive filtration might occur,23 leading to a flat anterior chamber. The eye should be examined carefully after the LSL session to ensure that the wound is intact. Additional sutures can be lysed 1 or 2 days later if filtration is still inadequate.

Reopening failed filtration sites

Filtering sites can close because of fibrosis on the external side beneath the conjunctiva or because of membrane formation or iris incarceration on the internal side of the sclerostomy. In any case, if the bleb is to be salvaged, reopening should be attempted early, before the episclera has completely closed the external opening at the sclerostomy because of lack of aqueous flow.

A Goldmann three-mirror goniolens or specially designed laser goniolens is used to view the internal site. If pigmented tissue is

obstructing the sclerostomy, the argon or Q-switched Nd:YAG laser can vaporize it.27–29 With the argon laser, settings of 300–

1000 mW at 0.1–0.2 second with a 50–100- m spot are used. If the obstruction is a pillar of iris, the laser is directed toward one side of the anterior edge of the iridocorneal adhesion. If the attachment is

(A)

(B)

Fig. 32-5  (A) When lasering sutures, the flange of the Hoskins laser suture lens holds up the lid. The suture is located under the laser slit lamp. (B) The lens is pressed steadily against the conjunctiva, displacing edema until a clear image of the suture is seen (upper right). The suture usually is treated near the knot. The long end of the suture will then retract into the sclera (lower right).

(B)

Fig. 32-6  (A) Before Nd:YAG laser therapy. Despite what appeared to be a healthy bleb, the pressure was 30 mmHg in this eye. Note the dense white membrane existing beneath the bleb surface. (B) After Nd:YAG laser therapy. The Nd:YAG laser was focused deep into the bleb with four applications at 8 mJ. Note the dark area where the whitish membrane had been. Intraocular pressure fell immediately to 18 mmHg, and the bleb enlarged.

not too solid, the synechiae can be dissected away from the sclerostomy site with similar settings on the argon laser by freeing up one edge of the synechia with laser applications and gradually working across the line of iridocorneal adhesion with additional laser applications. Pigmented tissue within the site should also be vaporized.

The Nd:YAG laser is also useful in opening an obstructed sclero- stomy.5,30–33 Single bursts of 2–4 mJ are delivered via a Nd:YAG-

coated goniolens to disrupt any translucent membrane obstructing it. Lower power levels (i.e., 1–2 mJ) should be used initially to dissect any iris adhesions. Bleeding may obscure the view, requiring a delay between treatments, but this is rarely serious.

Laser treatment may produce an instantaneous lowering of IOP, or approximately 1 day may be required for the pressure to fall. Digital pressure applied three to four times daily may be helpful. An increase in the size of the bleb indicates that the sclerostomy has indeed been opened and that the pressure decline is not simply a result of inflammation.

Blockage occurring on the episcleral side of the bleb rarely can be opened.The Nd:YAG laser can be used through translucent tis-

sue to rupture pigmented or non-pigmented membranes overlying sclerostomy sites.34,35 It is essential that the laser be focused at least

0.5 mm internal to the surface of the bleb or else the shock wave, which expands toward the surgeon from the point of focus, will rupture the overlying bleb (Fig. 32-6). This is especially true with thin blebs such as those seen after mitomycin-C use.

In all of these situations it is advisable to start with a lower power level, increasing it as indicated by the tissue reaction. Success with

any of these procedures is limited, but their simplicity encourages an attempt.

Cyclodialysis and laser

Cyclodialysis clefts have been both opened and closed with laser.36 Most reports are limited to a relatively small number of cases because cyclodialysis is rarely seen.37–39 A variety of successful techniques have been employed.40,41 One patient undergoing a cyclodialysis in conjunction with trabeculectomy had the cyclodialysis reopened 2 months after filtering surgery. A hyaline membrane covering the cleft was divided with a Q-switched Nd: YAG laser using a single pulse of 3.8 mJ. Postoperative treatment included strong miotics and corticosteroids.42

Argon laser photocoagulation using thermal burns of 0.1 second, 100- m spot size, and 500 mW can be used to close cyclodialysis clefts and reduce hypotony (Fig. 32-7).Three patients have reportedly had successful long-term effects.43 In these patients, up to 100 burns were delivered to the area in and around the clefts posterior to the scleral spur.43 Postoperative treatment should include topical steroids and cycloplegics.

Sudden rises of IOP often occur after closure of cyclodialysis clefts.These usually require aqueous suppression therapy.43

Laser synechialysis

The argon laser can be used to pull early or lightly adherent peripheral anterior synechiae away from the angle or cornea. Settings similar to those used for iridoplasty (400–800 mW, 0.1–0.2 second, 50–100- m spot size) are used. If used early, this may be helpful to break and arrest formation of iridocorneal adhesions after penetrating keratoplasty or other forms of peripheral anterior synechiae.This procedure is most likely to work if it is performed very soon after the synechiae have formed. Chronic synechiae can be very resistant to argon iridoplasty. If it is obvious after the first few applications that the iris is firmly adherent, it is useless to persist because this will only cause additional iritis.44

The Nd:YAG laser can lyse iris adhesion. This technique may be useful in early irido–corneal–endothelial (ICE) syndrome to disrupt synechiae, although bleeding may occur. This procedure is also used for reopening filtration blebs and sometimes for preventing further peripheral anterior synechiae after penetrating keratoplasty.45 Nd:YAG lysis of posterior synechiae has been used