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J Glaucoma  Volume 00, Number 00, '' 2010 typical glaucomatous visual field loss. Primary filtration threshold 24-2 Humphrey perimetry tests, the last of which surgery was indicated in each participant, all of whom were was carried out within 2 weeks before surgery.
on maximal tolerated ocular hypotensive medications and Complications, both intraoperative and postoperative had an intraocular pressure (IOP) in the study eye of 18 mm (early, through day 7, and late, beyond 1 wk), were classified Hg or higher, as measured with a Goldmann applanation according to severity and their relationship to the studied tonometer during 3 consecutive visits over a 90-day period device. In addition, the incidence of intraoperative macro- before enrollment. In addition, inclusion criteria were a perforations, defined as perforations accompanied by iris phakic or pseudophakic study eye with a Shaffer angle prolapse or anterior chamber shallowing or both, was wider than grade 2, no associated ocular disorders other than cataract, and no earlier surgical or laser interventionin the study eye other than clear corneal incision cataract Surgical Technique All the operations were performed under subconjuncti- Patients with a history of an earlier intraocular surgery val anesthesia with 2% lidocaine without epinephrine. A but clear corneal cataract extraction, a history of ocular 5.5-mm superior fornix-based incision was made and the laser procedures, or with a history of severe eye trauma Tenon capsule was dissected to expose the sclera. A partial were excluded from the study. Patients with any media thickness (one-third to one-half) rectangular limbal-based opacity, which may interfere with optic nerve evaluation, 5 5-mm superior scleral flap was dissected at the limbus into and patients with a pupillary dilation diameter of <2 mm, the clear cornea. The desired scanning area and the shape a best-corrected visual acuity of 20/200 or less in the fellow were set, the laser beam was focused, and the area to be eye, known allergy to the study medications, with severe treated was verified with a red laser (HeNe)-aiming beam systemic disease or disabling conditions, or pregnant or (Fig. 1A). The CO2 laser beam was then applied over an area nursing women were excluded from the study. Data from that included the Schlemm canal until the outer wall of the patients, who were followed up for less than 6 months, were canal was ablated and a scleral bed was formed. The residual excluded from the study.
charred tissue was wiped away with a BSS damp Weck-Cel The patients underwent a baseline examination within sponge and ablation was continued until sufficient percola- 2 weeks before surgery, and 1 day, 1, 2, 4, and 6 weeks, and tion was achieved along a region of at least 3 mm in length 3, 6, and 12 months after surgery. Baseline examination (Figs. 1B–D). The scleral flap was repositioned and secured included refraction, best-corrected visual acuity measured with 2 interrupted 10-0 nylon sutures and a high-molecular with a Snellen chart, comprehensive biomicroscopy, IOP weight ophthalmic viscosurgical device (Healon 5; Abbott assessment with a calibrated Goldmann applanation tono- Medical Optics, Santa Ana, CA) was applied beneath the meter (average of 3 repeated measurements taken at the flap. The conjunctiva was adequately secured with 10-0 nylon same time of the day ± 1 h), and fundus examination buried sutures (2 to 4), and the eye was patched with including optic disc evaluation. The patients also under- antibiotic and steroid ointments.
went gonioscopy, assessment of central corneal thickness The application of mitomycin C (MMC) and its (average of 3 repeated measurements), and 3 consecutive concentration were left to the surgeon's discretion. The FIGURE 1. Surgical steps: (A) a carbon dioxide laser beam is applied under a scleral flap. Red aiming beams indicate the area to beablated. When the lateral anterior dots are positioned at the surgical limbus (transition of transparent to gray zones) the ablated area willinclude the Schlem canal. B, Percolating aqueous is beginning to be seen at the ablated area. C, The desired surgical endpoint isachieved, percolation without scleral perforation. D, The superficial flap is sutured to its original position. E, Postoperative image of theconjunctival bleb 1 month later in the patient.
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J Glaucoma  Volume 00, Number 00, '' 2010 CO2 Laser-assisted Sclerectomy Surgery, Part II patients were treated postoperatively with prednisolone deep, causing perforation, or too small). In 1 of these acetate 1% drops (Pred Forte; Allergan, Irvine, CA) 6 times 4 cases the ablation zone was larger than the dissected flap, daily for 4 weeks and with moxyfloxacin 0.5% drops and in the other 3 cases the surgeons opted to convert to (Vigamox; Alcon Laboratories, Fort Worth, TX) 4 times conventional trabeculectomy. One patient was excluded daily for 2 weeks.
as he underwent laser treatment (iridectomy) before this Surgeons working on their first cases with the CLASS procedure, a major violation of the protocol. Moreover, procedure were permitted to convert to conventional this patient had Fuch endothelial dystrophy leading to trabeculectomy at any stage of the operation.
corneal decompensation, which was another protocolviolation. Although all 5 patients were excluded from the Postoperative Analysis performance analysis, those who had received at least "Complete success" was defined as IOP values partial laser treatment were included in the safety analysis.
measured at the 6-month visit and 12-month endpoint, All the patients were followed in the prospective ranging between 5 and 18 mm Hg and IOP reduction prescribed manner apart from 1 patient who was lost to Z20% compared with baseline IOP without additional follow-up 6 weeks after the procedure and another patient hypotensive medication or repeat filtration surgery. The who died, 4 weeks after the procedure, from causes same finding, but also including patients who required unrelated to the glaucoma surgery (complications of long- hypotensive medications postoperatively, was defined as standing severe diabetes mellitus).
"qualified success." Failure was defined as an IOP value MMC was used in 25 patients (83.3%), of which 15 <5 mm Hg and >18 mm Hg, IOP reduction of <20% patients at a concentration of 0.02% for 2 minutes and 10 compared with baseline IOP, severe loss of vision, or the patients at a concentration of 0.04% for 1 minute. Shallow need to undergo additional glaucoma surgery other than diffuse blebs were observed in all the cases (Fig. 1E).
goniopuncture or needling. Goniopuncture and needlingwere not considered to be failures or adverse events, as both are commonly used as normal postoperative interventions Data on all 37 enrolled patients were used in the that are required to maintain or augment the operative analysis of safety outcomes. No device malfunctions results of glaucoma surgeries.13–15 The number of hypo- occurred. There were no device-related macroperforations.
tensive medications being used by each patient at the time Four cases of microperforation, defined as small trabeculo- of the 6-month and the 12-month visits was compared with Descemet holes with no loss of depth of the anterior the baseline situation.
chamber, and no iris prolapse, were recorded. The anteriorchamber remained deep and stable in all cases.
Statistical Methods Mild transitory complications were recorded in some Continuous variables were summarized in terms of of the 30 patients who were included in the final analysis.
the mean, median, standard errors, and minimum and maxi- These included 4 cases of superficial punctuate keratitis, mum values. Categorical variables were derived from fre- microhyphema (1 case), infectious conjunctivitis (1 case), quency counts and percentages.
wound dehiscence (1 case), and wound leaks (2 cases, both The 95% confidence intervals (CIs) were calculated for at 1 surgical center in which the surgeon did not suture the the mean IOP measurements and for the success rates at scleral flap in half of the procedures, including those 6-month follow-up and the 12-month endpoint. A paired 2 cases). All complications resolved spontaneously or with t test was used to determine the significance of the changes conservative treatment in 1 month after the surgery. None in IOP. All the tests applied were 2 tailed, and a P value of of these ill effects was attributed specifically to the laser r0.05 was considered significant. The data were analyzed treatment. One patient developed choroidal detachment using the SAS software (SAS Institute, Cary, NC).
1 week postoperatively; this was treated by drainage andwas completely resolved.
Performance Analysis Between December 2007 and June 2008, 37 consecu- The preoperative IOP of 26.3 ± 7.8 mm Hg (mean ± tive patients (37 eyes) who met the inclusion/exclusion SD) dropped to 14.4 ± 3.4 mm Hg at 6 months and 14.3 ± criteria were enrolled in the study. Demographic data and 3.1 mm Hg at 12 months postoperatively (Fig. 2), yielding baseline information on the recruited patients are summar- average IOP reductions at 6 and 12 months of 11.9± ized in Table 1.
7.4 mm Hg (42.4%) and 11.6 ± 8.4 mm Hg (40.7%), Five patients were excluded from the performance respectively (P<0.001). Kaplan-Meier survival curves for analysis; in 4 cases because of inappropriate size and probability of CLASS success are presented in Figure 3.
configuration of the manually performed scleral flap (too The patterns of IOP reduction were similar at all 3 surgical TABLE 1. Demographic Details and Baseline Data Hispanic, 14 (37.8%); Indian, 13 (35.2%); Caucasian, 10 (27%) CCT indicates central corneal thickness; C/D, cup-to-disc ratio; PEXG, pseudoexfoliative glaucoma; POAG, primary open-angle glaucoma.
r 2010 Lippincott Williams & Wilkins Copyright Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited.
J Glaucoma  Volume 00, Number 00, '' 2010 Average IOP by site
FIGURE 2. Cumulative intraocular pressure (IOP) ± SD measure- ments of 33 patients taken from the preoperative stage up to 12 months postoperatively. Average IOP reduction at 12 months = FIGURE 4. Intraocular pressure results at each of the participat- 41%. Dashed line indicates preoperative IOP level minus 20%.
ing surgical centers. The intraocular pressure patterns are almostidentical in the 3 centers in the 3 different continents.
Nonpenetrating filtration surgery is a promising surgical centers in Asia (India), America (Mexico), and Europe procedure for open-angle glaucoma treatment. A review of (Russia) (Fig. 4). Defining success as 5rIOPr18, and 20% the literature shows contradictory findings, however, with IOP reduction, the complete success rates after 6 and 12 some studies describing NPDS as superior2–4 and others as months were 76.7% (95% CI, 0.58-0.90) and 60% (95% CI, similar or inferior-to-standard trabeculectomy.16–18 Despite 0.40-0.77), respectively, whereas qualified success were its possible advantages, mainly its higher safety profile 83.3% (95% CI, 0.65-0.94) and 86.6% (95% CI, 0.69- compared with those of other filtration procedures, many surgeons are reluctant to use this procedure. A meta-analysis The complete success rates after 12 months with and of the results of manual NPDS19 showed that a mean IOP of without MMC were 68.2% and 42.9%, respectively, not 21 mm Hg or lower at a mean follow-up of 31.3 months was showing statistically significant difference (P = 0.375), achieved by 48.6% of patients without any implant or whereas the rates of qualified success were 95.5% and antimetabolite medications, by 68.7% of patients with an 71.4%, respectively, not showing statistically significant implant, and by 67.1% of patients on use of antimetabolites.
difference either (P = 0.136).
The use of laser technology to improve surgical accuracy is The preoperative use of hypotensive medications per therefore a highly appealing option.12 patient dropped from an average of 2.5 ± 1.3 to 0.1 ± 0.4 at The CO2 laser is most commonly used in laser-assisted 6 months and 0.6 ± 0.9 at 12 months (P<0.001) (Fig. 5).
operations.20 It has been used for tissue dissection in Eight needling procedures were carried out in 7 filtration procedures using either a continuous wave or a patients between 1 and 4 weeks (mean, 3.8 wk) after rapid superpulse mode.21 The CLASS technique is con- surgery. Two patients needed to undergo YAG laser venient because the microdissection is performed under goniopuncture procedures, carried out 2 and 4 weeks after direct microscopic observation, and the safety profile is the initial surgery.
high as the anterior chamber is not penetrated.
FIGURE 3. Kaplan-Meier survival curves for probability of CO2laser-assisted sclerectomy surgery success. Solid line indicates FIGURE 5. Average number of hypotensive medications ± SD qualified success and dashed line indicates complete success.
from the preoperative stage up to 12 months postoperatively.
r 2010 Lippincott Williams & Wilkins Copyright Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited.
J Glaucoma  Volume 00, Number 00, '' 2010 CO2 Laser-assisted Sclerectomy Surgery, Part II The CO2 laser has certain qualities that confer The limitations of this study include the absence of a significant advantages when it is used specifically to facilitate control group and the limited follow-up period (12 mo).
deep sclerectomy filtration surgeries. These include photo- Longer-term follow-up is required to further evaluate and ablation of dry tissues, coagulation of bleeding vessels, and substantiate the safety and long-term efficacy of the CLASS, almost complete absorption of the laser energy by even and to assess its usefulness in a wider spectrum of indications.
minute amount of water. As the emitted radiation is readily Despite these limitations, the results are sufficiently promising absorbed by the percolating aqueous humor, the trabecular to suggest that the CLASS is a simple surgical procedure to meshwork is effectively protected from the laser energy perform, which appears to be relatively safe and effective in when percolation takes place. Thus, perforation of the thin the short and intermediate term.
trabeculo-Descemet membrane during deep sclerectomy,which is the most frequent intraoperative complication of manual NPDS, is substantially minimized.7,11 Study group: Svetlana Anisimova, MD, Ehud I. Assia, The feasibility and safety of the earlier CO2 laser MD, Michael Belkin, MD, Felix Gil Carrasco MD, Elie prototype (model OT-133) for CLASS procedure were Dahan, MD, Noa Geffen, MD, Orna Geyer, MD, Dvora examined in experimental models12 and in a clinical trial.22 Kidron, MD, Guy Kleinman, MD, Shimon Kurtz, MD, Shoba Although the results were usually satisfactory, localized Naveen, MD, Mark Sherwood, MD, Ravi Thomas, MD, heating and tissue photocoagulation resulted in several Yokrat Ton, MD, Mauricio Turati, MD, and Miriam Zalish, cases in early fibrosis and adhesions, with consequent failure of the filtration. The improved version (OT-134)provides faster scanning, higher power focused laser beam, evenly distributed over the scanned area with somebeam overlap to ensure uniform, effective ablation with 1. Krasnov MM. Microsurgery of glaucoma: indications and minimal coagulative thermal damage to adjacent tissues.
choice of technique. Am J Ophthalmol. 1969;67:857–864.
The energy is deposited using a scanner, which rapidly 2. Zimmerman TJ, Kooner KS, Ford VJ, et al. Effectiveness of nonpenetrating trabeculectomy in aphakic patients with scans the focused laser beam across the treatment zone.
glaucoma. Ophthalmic Surg. 1984;15:734–740.
The scanner is designed to move the focused beam such that 3. Fyodorov SN, Kozlov VI, Timoshkina NT. Non penetrating the dwell time of the focused beam at each point is less deep sclerectomy in open-angle glaucoma. IRTC Eye Micro- than the thermal relaxation time, the characteristic heat surgery (Moscow). 1989;3:52–55.
conduction time is constant in the tissue. The laser energy 4. Stegmann R, Pienaar A, Miller D. Viscocanalostomy for open- absorbed by the sclera locally heats the tissue above angle glaucoma in black African patients. J Cataract Refract evaporation temperature, causing local vaporization of the sclera at the laser deposition area. It has been shown 5. Demailly P, Jeanteur-Lunel MN, Berkani M, et al. La in a preclinical study (part I of this study) that the sclere´ctomie profonde non perforante associe´e a la pose d'unimplant de collage´ne dans le glaucome. J Fr Ophtalmol.
lateral walls of the ablation zone showed a thin layer of thermal damage, 200 to 250 mm thick, whereas the thermal 6. Sourdille P, Santiago P-Y, Villain F, et al. Reticulated damage was minimal or absent at the bottom of the hyaluronic acid implant in nonperforating trabecular surgery.
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pected in some cases, but this did not interfere with the 9. Camras CB. Diagnosis and Management of Complications of safety or efficacy of the surgical outcome and might even Glaucoma Filtration Surgery: Focal Points: Clinical Modules for have improved filtration. The simplicity of performance is Ophthalmologists. San Francisco: American Academy of an appealing advantage, as it obviates the prolonged Ophthalmology; 1994. Module 3.
learning curve characteristic of manual NPDS, and thus 10. Sarodia U, Shaarawy T, Barton K. Nonpenetrating glaucoma can be confidently performed by surgeons with a wide range surgery: a critical evaluation. Curr Opin Ophthalmol. 2007;18: of experience in filtration surgery. The surgeon does not need to manually dissect layers of sclera and the drainage 11. Khaw PT, Siriwardena D. "New" surgical treatments for system or locate the orifice of the Schlemm canal, as in glaucoma. Br J Ophthalmol. 1999;83:1–2.
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and MMC was used in 73.5% of the patients. The results of 16. Jonescu-Cuypers C, Jacobi P, Konen W, et al. Primary this study may be further improved by the use of scleral viscocanalostomy versus trabeculectomy in white patients with implants, such as hydrogel, reticulated hyaluronic acid, or open angle glaucoma: a randomized clinical trial. Ophthalmo- autologous scleral implants.6,7,19,22–24 r 2010 Lippincott Williams & Wilkins Copyright Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited.
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r 2010 Lippincott Williams & Wilkins Copyright Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited.

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