ORIGINAL STUDY
A Comparison of Resident-performed Argon and Selective Laser Trabeculoplasty in Patients With Open-angle Glaucoma Eugene A. Lowry, MD,* Daniel A. Greninger, MD,*w Travis C. Porco, MPH, PhD,*zy Ayman Naseri, MD,*z8 Robert L. Stamper, MD,*8 and Ying Han, MD, PhD*z8
Purpose: To compare intraocular pressure (IOP) reduction and complications of resident-performed argon laser trabeculoplasty (ALT) and selective laser trabeculoplasty (SLT). Patients and Methods: This was a retrospective, interventional, comparative case series performed at the San Francisco Veterans Affairs Hospital. The study included 77 patients each undergoing 1 resident-performed ALT procedure from April 2006 through November 2009, and 81 patients each undergoing 1 resident-performed SLT procedure from November 2009 through December 2011. Reduction in IOP at 12 months and a longitudinal analysis across 24 months was determined. Secondary outcomes investigated included additional interventions of either repeat trabeculoplasty or trabeculectomy as well as change in eye drop medications. Results: There was no evidence of a difference between IOP reductions in patients undergoing ALT compared with SLT at 12 months (P = 0.41, linear modeling) or across all follow-up appointments (P = 0.62, linear-mixed effects regression). Patients undergoing ALT had a significantly increased number of eye drops (+ 0.6 vs. 0.1 drops, P < 0.001, Wilcoxon rank-sum test) and trend toward increased rates of additional interventions (P = 0.06, Weibull regression). There was no difference in immediate postprocedure IOP rise between the 2 groups (P = 0.75, Wilcoxon rank-sum test) or any evidence of change in visual acuity. Conclusions: We found no difference in IOP reduction between patients undergoing resident-performed ALT compared with SLT. However, patients undergoing ALT had a significant increase in eye drop medications and trend toward additional interventions compared with patients undergoing SLT. Key Words: laser trabeculoplasty, resident education, glaucoma, ALT, SLT
Received for publication December 23, 2013; accepted November 27, 2014. From the *Department of Ophthalmology; zFrancis I. Proctor Foundation; yDepartment of Epidemiology and Biostatistics, Division of Preventive Medicine and Public Health, University of California San Francisco; 8Department of Ophthalmology, San Francisco Veterans Affairs Medical Center, San Francisco, CA; and wDepartment of Ophthalmology, Oregon Health and Science University, Portland, OR. Conception and design: E.A.L., D.A.G., A.N., R.L.S., Y.H.; acquisition of data: E.A.L., D.A.G.; analysis and interpretation of the data: E.A.L., D.A.G., T.C.P., Y.H.; drafting the article: E.A.L.; critical revision: E.A.L., D.A.G., T.C.P., A.N., R.L.S., Y.H.; and final approval: E.A.L., D.A.G., T.C.P., A.N., R.L.S., Y.H. Disclosure: The authors declare no conflict of interest. Reprints: Ying Han, MD, PhD, Department of Ophthalmology, University of California San Francisco, 10 Koret Way, San Francisco, CA 94143 (e-mail: [email protected]). Copyright r 2015 Wolters Kluwer Health, Inc. All rights reserved. DOI: 10.1097/IJG.0000000000000207
J Glaucoma
Volume 25, Number 3, March 2016
(J Glaucoma 2016;25:e157–e161)
L
aser trabeculoplasty is a core part of the treatment algorithm for open-angle glaucoma because of its ability to reduce intraocular pressure (IOP) and/or dependence on daily medications without the higher risks of invasive surgery.1 Laser trabeculoplasty has been performed with argon laser trabeculoplasty (ALT) for decades, whereas the Nd:Yag laser or selective laser trabeculoplasty (SLT) has been more recently developed.2 SLT has the theoretical advantage of targeting only the pigmented cells of the trabecular meshwork, therefore requiring significantly less energy and generating less tissue damage.2,3 In the studies by experienced surgeons, there remains controversy over the comparative effectiveness of SLT compared with ALT with many studies showing no difference4–8 and a recent meta-analysis favoring SLT.9 There are few studies investigating resident-performed laser trabeculoplasty. These studies suggest that residentperformed ALT can achieve good IOP reductions albeit lower than the reduction achieved by more experienced surgeons.10,11 Resident-performed SLT likely achieves similar IOP reductions with complication rates similar to those seen in the literature for more experienced surgeons.12 From a technical perspective, SLT may be easier for training ophthalmologists to master as it uses larger laser spots applied in a confluent pattern on the trabecular meshwork compared with the smaller, discrete laser spots of ALT.2,3 However, we are not aware of any studies that compare effectiveness or complication rates between resident-performed ALT and SLT despite the rising popularity of laser trabeculoplasty and persistence of ALT in some institutions.13 Our study investigates the IOP reduction and complication rates associated with resident-performed ALT compared with SLT. We also compare changes in eye drop medications and number of additional interventions for patients undergoing resident-performed ALT compared with SLT.
PATIENTS AND METHODS This study is an interventional, retrospective, comparative case series. Permission was obtained from the Research and Development Committee at the San Francisco Veterans Affairs Medical Center and the UCSF Institutional Review Board to perform the study. The study www.glaucomajournal.com |
Copyright r 2016 Wolters Kluwer Health, Inc. All rights reserved.
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Lowry et al
was conducted in compliance with the Health Insurance Portability and Accountability Act. Consecutive patients treated with laser trabeculoplasty by resident ophthalmologists at the San Francisco Veterans Affairs Hospital during a 5-year period from April 2006 to December 2011 were identified from laser log books and by the retrospective review of scheduling logs for the glaucoma laser clinic. If a single patient underwent >1 procedure either in the same or opposite eye, only outcomes of the first procedure were included in this analysis. Patients receiving trabeculoplasty from April 2006 through November 10, 2009 underwent ALT, whereas all subsequent patients after from November 11, 2009 through December 2011 after acquisition of an SLT device were treated with SLT. Exclusion criteria included attending physician participating directly in the procedure, inadequate charting, and patients who never had follow-up visits after treatment. Each included patient in the study had been previously examined by an attending glaucoma specialist (R.L.S. and Y.H.) and had been referred for trabeculoplasty to be performed by a PGY-2 resident ophthalmologist. All laser procedures were performed under the supervision of an attending physician, and each resident worked under the direct observation of an attending glaucoma specialist through the assistant scope until the resident felt comfortable to perform the procedure alone. Typically, patients received 1 drop of topical proparacaine and iopidine 0.5% in the operative eye before surgery. Visual acuity and preoperative IOP were recorded before eye drops were administered. For some patients, 1% pilocarpine was added to improve the visualization of angle structures. A Latina SLT lens or Goldmann 3-mirror ALT lens was placed on the operative eye with a gonioscopic gel and laser treatment was applied. In the ALT procedure, laser energy was applied to a 50 mm spot at the junction of the pigmented and nonpigmented trabecular meshwork for 0.1 seconds. In the SLT procedure, laser energy was applied to a 400 mm spot at the junction of the pigmented and nonpigmented trabecular meshwork for 3 10 9 seconds. The degree of treatment ranged from 180 to 360 degrees. One drop of iopidine 0.5% was administered after the procedure. Postoperative IOP was checked approximately 1 hour postprocedure, 6 weeks postprocedure, and at regular intervals thereafter as indicated by the clinical history. Visual acuity, repeat interventions defined as trabeculoplasty or trabeculectomy, and number of eye drop medications were also recorded at each follow-up appointment. Combination eye drop medications were counted as 2 separate eye drop medications in our analysis due to their separate pharmacologic properties. Patient records were followed for 2 years, until glaucoma filtration surgery was performed, or until the end of the study, whichever came first. IOP was measured by Goldmann applanation in the vast majority of patients. Reduction in IOP at 12 months from baseline was the primary outcome. Analysis of difference in IOP reduction at 12 months between the ALT and SLT cohort was conducted with linear modeling. In addition, a longitudinal linear-mixed effects regression was used to determine whether IOP reductions were significantly different between the SLT and ALT cohorts across all follow-up appointments at 1, 3, 6, 12, and 24 months. These linear models for IOP change adjusted for the expected effect of baseline IOP and number of treatment drops at time of trabeculoplasty when calculating P-values. Baseline IOP was defined as the
J Glaucoma
Volume 25, Number 3, March 2016
average IOP over the 2 preoperative appointments and success was defined as a 20% IOP reduction without subsequent surgical intervention to maintain consistency with the current literature.14–19 Our major secondary outcome was the number of repeat interventions. We conducted interval-censored Weibull regression to assess whether or not first retreatment times were different between the 2 groups. Significance was assessed using the Wald P-value for the coefficient for the indicator of the type of treatment. Additional outcomes included medication burden, success rates, and complication rates including change in visual acuity and postoperative IOP rises. These were assessed with the Wilcoxon rank-sum testing for discrete variables and the Fisher exact test for dichotomous outcomes.
RESULTS Seventy-seven patients underwent 1 ALT procedure each from April 2006 through November 2009. Eighty-one patients underwent 1 SLT procedure each from November 2009 through December 2011. There was no significant difference between the SLT and ALT cohort in terms of baseline IOP, age, sex, diagnoses, number of eye drop medications, visual acuity, or treatment degree. Both populations consisted primarily of older, male patients on multiple medications with an average baseline IOP of approximately 18.5 mm Hg. The details of the procedure differed between ALT and SLT patient groups with the SLT cohort receiving more laser shots at lower energy than the ALT cohort, consistent with the standard operating parameters of the respective lasers (Table 1). At 12 months’ follow-up, there was no significant difference between IOP reduction in the ALT cohort compared with the SLT cohort, with respective IOP reductions of 2.44 mm Hg (95% CI, 1.20-3.67) and 2.13 mm Hg (95% CI, 0.88-3.39) (P = 0.41, linear modeling). A longitudinal analysis likewise showed no difference in IOP reduction across all timepoints in follow-up from baseline to 24 months (P = 0.62, linear-mixed effects regression). Both analyses controlled for baseline IOP and number of eye drops at the time of treatment (Fig. 1). As a guide to the statistical power of our study, 71 subjects per group would provide approximately 80% power to detect a change of 2 mm Hg (assuming a SD of 4 mm Hg in each cross-sectional measurement, and a correlation of 0.5 between baseline and follow-up measurements). We investigated the need for additional interventions, success rates, and changes in eye drop medications as secondary outcomes. Over the 24-month follow-up period, there was a strong, but not statistically significant, trend for patients undergoing ALT to need more interventions sooner after treatment (P = 0.06, Weibull regression). At 12 months, 18% of those following up in the ALT cohort had undergone repeat interventions (9 trabeculoplasties and 1 trabeculectomy) compared with 9% (4 trabeculoplasties and 1 trabeculectomy) of those following up in the SLT cohort (Fig. 2). The success rate of ALT varied from 44% to 52% over follow-up compared with 36% to 50% in the SLT cohort. There was no significant difference in success rate between the 2 groups at any timepoint in follow-up (all P > 0.25, Fisher exact test) (Fig. 3). Patients in the ALT cohort had an average increase in eye drop medications of 0.6 medications from pretrabeculoplasty levels at 12 months’ follow-up. In contrast, patients in the SLT cohort
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J Glaucoma
Volume 25, Number 3, March 2016
Resident-performed ALT Versus SLT in Open-angle Glaucoma
TABLE 1. Baseline Characteristics of Included Patients and Treatments No. patients Baseline IOP Age Sex (male) [n (%)] Diagnoses [n (%)] Primary open-angle glaucoma Pseudoexfoliative glaucoma Normal tension glaucoma Pigment dispersion glaucoma Traumatic Unknown No. drops on day of treatment LogMar visual acuity in treatment eye Treatment shots Treatment degree [n (%)] 180 270 360 Unknown Treatment energy per shot (mJ)
ALT Treatment Group
SLT Treatment Group
77 18.45 ( ± 4.33) 75.90 ( ± 11.12) 74 (95)
81 18.52 ( ± 4.19) 75.54 ( ± 10.67) 78 (97)
64 6 2 1 2 2 2.35 0.37 78.1
(83) (8) (3) (1) (3) (3) ( ± 0.86) ( ± 0.38) ( ± 26)
71 5 1 3 1 0 2.62 0.31 95.8
(88) (6) (1) (4) (1) (0) ( ± 1.15) ( ± 0.40) ( ± 50.7)
45 3 26 3 63.7
(58) (4) (34) (4) ( ± 13.2)
41 0 31 9 0.82
(51) (0) (38) (11) ( ± 0.13)
P N/A 0.855 0.571 1.00 0.64
0.08 0.14 0.41 0.09
< 0.001
Treatment power was significantly different for patients in the ALT compared with SLT cohort. There was no evidence of a difference in all other baseline variables. Continuous values are provided with SD and were analyzed for significance with Wilcoxon rank-sum testing. Dichotomous values are provided with percentage in parentheses and were analyzed for significance with r c Fisher exact test. ALT indicates argon laser trabeculoplasty; IOP, intraocular pressure; SLT, selective laser trabeculoplasty.
had a decrease of 0.1 medications at 12 months’ follow-up (P < 0.001, Wilcoxon rank-sum test) (Fig. 4). We also investigated complications. There was no evidence of visual acuity change in either group after trabeculoplasty or any difference between the 2 groups (P = 0.87, Wilcoxon rank-sum test). The IOP increase immediately after trabeculoplasty was 0.25, Fisher exact test). ALT indicates argon laser trabeculoplasty; IOP, intraocular pressure; SLT, selective laser trabeculoplasty.
procedures, but that patients who underwent ALT were more likely to have increased need for eye drop medication and had a strong trend toward having earlier additional interventions. The literature comparing IOP reductions after ALT and SLT among more experienced surgeons shows either no significant difference or significant favorability for SLT leading to larger IOP reductions.4,5,8,9,20,21 We originally anticipated that any benefit in terms of enhanced IOP reduction with SLT seen in this literature was likely to be larger at the resident level given the
FIGURE 4. Change in number of eye drop medications after resident-performed trabeculoplasty. *There was a statistically significant increase in eye drop use in the ALT cohort compared with the SLT cohort across all timepoints in follow-up (P < 0.001, Wilcoxon rank-sum test). Error bars show SE of the mean. ALT indicates argon laser trabeculoplasty; SLT, selective laser trabeculoplasty.
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Volume 25, Number 3, March 2016
relatively greater skill required to accurately apply the smaller laser spots of ALT to the correct zone of the trabecular meshwork. However, this study did not find any significant difference in IOP reduction, but rather found greater increases in eye drop medications. This increase in eye drop medications after ALT compared with SLT is consistent with the literature for experienced surgeons.4,9,20,21 This may reflect the real-world proactive process of physicians responding to inadequate IOP control after trabeculoplasty by increasing the number of eye drop medications and as well as using additional interventions as needed in patients undergoing ALT compared with SLT. These interventions would tend to drive down the IOP in the ALT cohort and reduce potential differences in IOP reductions between the 2 cohorts. The average IOP reductions in our study were in the 2 to 4 mm Hg range across follow-up for both the ALT and SLT cohorts. This is notably lower than the 6 to 7 mm Hg reductions seen in many studies of trabeculoplasty performed by more experienced surgeons.4,5,8,20,21 However, the baseline IOP for all patients in this study was much lower than that seen in corresponding studies with more experienced surgeons. Baseline IOP has previously been shown to be the strongest predictor of IOP reduction and the reductions here are similar to published results seen in populations with similar baseline IOP.22 In addition, the majority of the patients in this population had well-established glaucoma with visual field defects and evidence of optic nerve head damage and had been on multiple medical treatments for years before trabeculoplasty was recommended, which may have influenced the lower reduction figures seen in our study. This study had several limitations. The study was retrospective and has the inherent limitations of this study design including differential medical management of study subjects according to their disease history. Most of the patients in this study were male as it was conducted at a Veterans Affairs medical center. Patients in this study were not randomized to treatment groups, which allows the possibility of nonrandom distributions of clinical confounders between the 2 study populations. We believe this possibility is reduced by the fact that a given patient’s procedure was selected solely on the basis of procedure date (ALT before November 11, 2009 and SLT after) and not on clinical factors. The IOP measurements in this study were taken during clinic business hours, but not controlled more specifically for time of day although IOP is known to fluctuate on a circadian pattern.23 The phakic status of patients was not specifically recorded and we cannot comment on how phakic status may change trabeculoplasty effectiveness. The majority of IOP measurements were obtained using Goldmann applanation tonometry (87%); however, pneumotonometry (7%) and tonopen (6%) were used in a small number of cases, and this variability could have affected the results. In addition, although follow-up in both arms was approximately 70% at our primary 1-year outcome, there was a low rate of follow-up in the SLT group at 2 years of 41%. In summary, we found that resident-performed ALT compared with SLT required a greater increase in eye drop medications and additional interventions to achieve similar levels of reduction in IOP. These reductions were consistent with more experienced surgeons after adjusting for the lower baseline in our study population. Additional prospective studies are warranted to verify these findings,
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J Glaucoma
Volume 25, Number 3, March 2016
which suggest that resident-performed SLT may have better outcomes for medication burden and repeat interventions compared with resident-performed ALT. REFERENCES 1. Rolim de Moura C, Paranhos A Jr, Wormald R. Laser trabeculoplasty for open angle glaucoma. Cochrane Database Syst Rev. 2007;4:CD003919. 2. Samples JR, Singh K, Lin SC, et al. Laser trabeculoplasty for open-angle glaucoma: a report by the American Academy of Ophthalmology. Ophthalmology. 2011;118:2296–2302. 3. Realini T. Selective laser trabeculoplasty: a review. J Glaucoma. 2008;17:497–502. 4. Damji KF, Bovell AM, Hodge WG, et al. Selective laser trabeculoplasty versus argon laser trabeculoplasty: results from a 1-year randomised clinical trial. Br J Ophthalmol. 2006;90: 1490–1494. 5. Russo V, Barone A, Cosma A, et al. Selective laser trabeculoplasty versus argon laser trabeculoplasty in patients with uncontrolled open-angle glaucoma. Eur J Ophthalmol. 2009;19:429–434. 6. Rosenfeld E, Shemesh G, Kurtz S. The efficacy of selective laser trabeculoplasty versus argon laser trabeculoplasty in pseudophakic glaucoma patients. Clin Ophthalmol. 2012;6: 1935–1940. 7. Martinez-de-la-Casa JM, Garcia-Feijoo J, Castillo A, et al. Selective vs. argon laser trabeculoplasty: hypotensive efficacy, anterior chamber inflammation, and postoperative pain. Eye (Lond). 2004;18:498–502. 8. Kent SS, Hutnik CM, Birt CM, et al. A randomized clinical trial of selective laser trabeculoplasty versus argon laser trabeculoplasty in patients with pseudoexfoliation. J Glaucoma. 2013. [Epub ahead of print]. 9. Wang H, Cheng JW, Wei RL, et al. Meta-analysis of selective laser trabeculoplasty with argon laser trabeculoplasty in the treatment of open-angle glaucoma. Can J Ophthalmol. 2013;48:186–192. 10. Khan KA, Lederer CM Jr, Willoughby L. Argon laser trabeculoplasty in a residency program. Ophthalmic Surg. 1986;17:343–350.
Copyright
r
Resident-performed ALT Versus SLT in Open-angle Glaucoma
11. Brodell G, Lass J, Bruner W, et al. Results of laser trabeculoplasty performed by residents. Ann Ophthalmol. 1986;18:236–239. 12. Greninger DA, Lowry EA, Porco TC, et al. Residentperformed selective laser trabeculoplasty in patients with open-angle glaucoma. JAMA Ophthalmology. 2014;132: 403–408. 13. Ramulu PY, Corcoran KJ, Corcoran SL, et al. Utilization of various glaucoma surgeries and procedures in Medicare beneficiaries from 1995 to 2004. Ophthalmology. 2007;114: 2265–2270. 14. Babighian S, Caretti L, Tavolato M, et al. Excimer laser trabeculotomy vs. 180 degrees selective laser trabeculoplasty in primary open-angle glaucoma. A 2-year randomized, controlled trial. Eye (Lond). 2010;24:632–638. 15. Lai JS, Chua JK, Tham CC, et al. Five-year follow up of selective laser trabeculoplasty in Chinese eyes. Clin Experiment Ophthalmol. 2004;32:368–372. 16. Latina MA, Sibayan SA, Shin DH, et al. Q-switched 532-nm Nd:YAG laser trabeculoplasty (selective laser trabeculoplasty): a multicenter, pilot, clinical study. Ophthalmology. 1998;105: 2082–2088; discussion 2089-90. 17. McIlraith I, Strasfeld M, Colev G, et al. Selective laser trabeculoplasty as initial and adjunctive treatment for openangle glaucoma. J Glaucoma. 2006;15:124–130. 18. Nagar M, Luhishi E, Shah N. Intraocular pressure control and fluctuation: the effect of treatment with selective laser trabeculoplasty. Br J Ophthalmol. 2009;93:497–501. 19. Schwenn O, Yun SH, Troost A, et al. Glaucoma studies from 1996 to 1999 in peer-reviewed journals. Graefes Arch Clin Exp Ophthalmol. 2005;243:629–636. 20. Bovell AM, Damji KF, Hodge WG, et al. Long term effects on the lowering of intraocular pressure: selective laser or argon laser trabeculoplasty? Can J Ophthalmol. 2011;46:408–413. 21. Liu Y, Birt CM. Argon versus selective laser trabeculoplasty in younger patients: 2-year results. J Glaucoma. 2012;21:112–115. 22. Heijl A, Peters D, Leske MC, et al. Effects of argon laser trabeculoplasty in the early manifest glaucoma trial. Am J Ophthalmol. 2011;152:842–848. 23. Bagga H, Liu JH, Weinreb RN. Intraocular pressure measurements throughout the 24 h. Curr Opin Ophthalmol. 2009;20: 79–83.
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e161
A Comparison of Resident-performed Argon and Selective Laser Trabeculoplasty in Patients With Open-angle Glaucoma Eugene A. Lowry, MD,* Daniel A. Greninger, MD,*w Travis C. Porco, MPH, PhD,*zy Ayman Naseri, MD,*z8 Robert L. Stamper, MD,*8 and Ying Han, MD, PhD*z8
Purpose: To compare intraocular pressure (IOP) reduction and complications of resident-performed argon laser trabeculoplasty (ALT) and selective laser trabeculoplasty (SLT). Patients and Methods: This was a retrospective, interventional, comparative case series performed at the San Francisco Veterans Affairs Hospital. The study included 77 patients each undergoing 1 resident-performed ALT procedure from April 2006 through November 2009, and 81 patients each undergoing 1 resident-performed SLT procedure from November 2009 through December 2011. Reduction in IOP at 12 months and a longitudinal analysis across 24 months was determined. Secondary outcomes investigated included additional interventions of either repeat trabeculoplasty or trabeculectomy as well as change in eye drop medications. Results: There was no evidence of a difference between IOP reductions in patients undergoing ALT compared with SLT at 12 months (P = 0.41, linear modeling) or across all follow-up appointments (P = 0.62, linear-mixed effects regression). Patients undergoing ALT had a significantly increased number of eye drops (+ 0.6 vs. 0.1 drops, P < 0.001, Wilcoxon rank-sum test) and trend toward increased rates of additional interventions (P = 0.06, Weibull regression). There was no difference in immediate postprocedure IOP rise between the 2 groups (P = 0.75, Wilcoxon rank-sum test) or any evidence of change in visual acuity. Conclusions: We found no difference in IOP reduction between patients undergoing resident-performed ALT compared with SLT. However, patients undergoing ALT had a significant increase in eye drop medications and trend toward additional interventions compared with patients undergoing SLT. Key Words: laser trabeculoplasty, resident education, glaucoma, ALT, SLT
Received for publication December 23, 2013; accepted November 27, 2014. From the *Department of Ophthalmology; zFrancis I. Proctor Foundation; yDepartment of Epidemiology and Biostatistics, Division of Preventive Medicine and Public Health, University of California San Francisco; 8Department of Ophthalmology, San Francisco Veterans Affairs Medical Center, San Francisco, CA; and wDepartment of Ophthalmology, Oregon Health and Science University, Portland, OR. Conception and design: E.A.L., D.A.G., A.N., R.L.S., Y.H.; acquisition of data: E.A.L., D.A.G.; analysis and interpretation of the data: E.A.L., D.A.G., T.C.P., Y.H.; drafting the article: E.A.L.; critical revision: E.A.L., D.A.G., T.C.P., A.N., R.L.S., Y.H.; and final approval: E.A.L., D.A.G., T.C.P., A.N., R.L.S., Y.H. Disclosure: The authors declare no conflict of interest. Reprints: Ying Han, MD, PhD, Department of Ophthalmology, University of California San Francisco, 10 Koret Way, San Francisco, CA 94143 (e-mail: [email protected]). Copyright r 2015 Wolters Kluwer Health, Inc. All rights reserved. DOI: 10.1097/IJG.0000000000000207
J Glaucoma
Volume 25, Number 3, March 2016
(J Glaucoma 2016;25:e157–e161)
L
aser trabeculoplasty is a core part of the treatment algorithm for open-angle glaucoma because of its ability to reduce intraocular pressure (IOP) and/or dependence on daily medications without the higher risks of invasive surgery.1 Laser trabeculoplasty has been performed with argon laser trabeculoplasty (ALT) for decades, whereas the Nd:Yag laser or selective laser trabeculoplasty (SLT) has been more recently developed.2 SLT has the theoretical advantage of targeting only the pigmented cells of the trabecular meshwork, therefore requiring significantly less energy and generating less tissue damage.2,3 In the studies by experienced surgeons, there remains controversy over the comparative effectiveness of SLT compared with ALT with many studies showing no difference4–8 and a recent meta-analysis favoring SLT.9 There are few studies investigating resident-performed laser trabeculoplasty. These studies suggest that residentperformed ALT can achieve good IOP reductions albeit lower than the reduction achieved by more experienced surgeons.10,11 Resident-performed SLT likely achieves similar IOP reductions with complication rates similar to those seen in the literature for more experienced surgeons.12 From a technical perspective, SLT may be easier for training ophthalmologists to master as it uses larger laser spots applied in a confluent pattern on the trabecular meshwork compared with the smaller, discrete laser spots of ALT.2,3 However, we are not aware of any studies that compare effectiveness or complication rates between resident-performed ALT and SLT despite the rising popularity of laser trabeculoplasty and persistence of ALT in some institutions.13 Our study investigates the IOP reduction and complication rates associated with resident-performed ALT compared with SLT. We also compare changes in eye drop medications and number of additional interventions for patients undergoing resident-performed ALT compared with SLT.
PATIENTS AND METHODS This study is an interventional, retrospective, comparative case series. Permission was obtained from the Research and Development Committee at the San Francisco Veterans Affairs Medical Center and the UCSF Institutional Review Board to perform the study. The study www.glaucomajournal.com |
Copyright r 2016 Wolters Kluwer Health, Inc. All rights reserved.
e157
Lowry et al
was conducted in compliance with the Health Insurance Portability and Accountability Act. Consecutive patients treated with laser trabeculoplasty by resident ophthalmologists at the San Francisco Veterans Affairs Hospital during a 5-year period from April 2006 to December 2011 were identified from laser log books and by the retrospective review of scheduling logs for the glaucoma laser clinic. If a single patient underwent >1 procedure either in the same or opposite eye, only outcomes of the first procedure were included in this analysis. Patients receiving trabeculoplasty from April 2006 through November 10, 2009 underwent ALT, whereas all subsequent patients after from November 11, 2009 through December 2011 after acquisition of an SLT device were treated with SLT. Exclusion criteria included attending physician participating directly in the procedure, inadequate charting, and patients who never had follow-up visits after treatment. Each included patient in the study had been previously examined by an attending glaucoma specialist (R.L.S. and Y.H.) and had been referred for trabeculoplasty to be performed by a PGY-2 resident ophthalmologist. All laser procedures were performed under the supervision of an attending physician, and each resident worked under the direct observation of an attending glaucoma specialist through the assistant scope until the resident felt comfortable to perform the procedure alone. Typically, patients received 1 drop of topical proparacaine and iopidine 0.5% in the operative eye before surgery. Visual acuity and preoperative IOP were recorded before eye drops were administered. For some patients, 1% pilocarpine was added to improve the visualization of angle structures. A Latina SLT lens or Goldmann 3-mirror ALT lens was placed on the operative eye with a gonioscopic gel and laser treatment was applied. In the ALT procedure, laser energy was applied to a 50 mm spot at the junction of the pigmented and nonpigmented trabecular meshwork for 0.1 seconds. In the SLT procedure, laser energy was applied to a 400 mm spot at the junction of the pigmented and nonpigmented trabecular meshwork for 3 10 9 seconds. The degree of treatment ranged from 180 to 360 degrees. One drop of iopidine 0.5% was administered after the procedure. Postoperative IOP was checked approximately 1 hour postprocedure, 6 weeks postprocedure, and at regular intervals thereafter as indicated by the clinical history. Visual acuity, repeat interventions defined as trabeculoplasty or trabeculectomy, and number of eye drop medications were also recorded at each follow-up appointment. Combination eye drop medications were counted as 2 separate eye drop medications in our analysis due to their separate pharmacologic properties. Patient records were followed for 2 years, until glaucoma filtration surgery was performed, or until the end of the study, whichever came first. IOP was measured by Goldmann applanation in the vast majority of patients. Reduction in IOP at 12 months from baseline was the primary outcome. Analysis of difference in IOP reduction at 12 months between the ALT and SLT cohort was conducted with linear modeling. In addition, a longitudinal linear-mixed effects regression was used to determine whether IOP reductions were significantly different between the SLT and ALT cohorts across all follow-up appointments at 1, 3, 6, 12, and 24 months. These linear models for IOP change adjusted for the expected effect of baseline IOP and number of treatment drops at time of trabeculoplasty when calculating P-values. Baseline IOP was defined as the
J Glaucoma
Volume 25, Number 3, March 2016
average IOP over the 2 preoperative appointments and success was defined as a 20% IOP reduction without subsequent surgical intervention to maintain consistency with the current literature.14–19 Our major secondary outcome was the number of repeat interventions. We conducted interval-censored Weibull regression to assess whether or not first retreatment times were different between the 2 groups. Significance was assessed using the Wald P-value for the coefficient for the indicator of the type of treatment. Additional outcomes included medication burden, success rates, and complication rates including change in visual acuity and postoperative IOP rises. These were assessed with the Wilcoxon rank-sum testing for discrete variables and the Fisher exact test for dichotomous outcomes.
RESULTS Seventy-seven patients underwent 1 ALT procedure each from April 2006 through November 2009. Eighty-one patients underwent 1 SLT procedure each from November 2009 through December 2011. There was no significant difference between the SLT and ALT cohort in terms of baseline IOP, age, sex, diagnoses, number of eye drop medications, visual acuity, or treatment degree. Both populations consisted primarily of older, male patients on multiple medications with an average baseline IOP of approximately 18.5 mm Hg. The details of the procedure differed between ALT and SLT patient groups with the SLT cohort receiving more laser shots at lower energy than the ALT cohort, consistent with the standard operating parameters of the respective lasers (Table 1). At 12 months’ follow-up, there was no significant difference between IOP reduction in the ALT cohort compared with the SLT cohort, with respective IOP reductions of 2.44 mm Hg (95% CI, 1.20-3.67) and 2.13 mm Hg (95% CI, 0.88-3.39) (P = 0.41, linear modeling). A longitudinal analysis likewise showed no difference in IOP reduction across all timepoints in follow-up from baseline to 24 months (P = 0.62, linear-mixed effects regression). Both analyses controlled for baseline IOP and number of eye drops at the time of treatment (Fig. 1). As a guide to the statistical power of our study, 71 subjects per group would provide approximately 80% power to detect a change of 2 mm Hg (assuming a SD of 4 mm Hg in each cross-sectional measurement, and a correlation of 0.5 between baseline and follow-up measurements). We investigated the need for additional interventions, success rates, and changes in eye drop medications as secondary outcomes. Over the 24-month follow-up period, there was a strong, but not statistically significant, trend for patients undergoing ALT to need more interventions sooner after treatment (P = 0.06, Weibull regression). At 12 months, 18% of those following up in the ALT cohort had undergone repeat interventions (9 trabeculoplasties and 1 trabeculectomy) compared with 9% (4 trabeculoplasties and 1 trabeculectomy) of those following up in the SLT cohort (Fig. 2). The success rate of ALT varied from 44% to 52% over follow-up compared with 36% to 50% in the SLT cohort. There was no significant difference in success rate between the 2 groups at any timepoint in follow-up (all P > 0.25, Fisher exact test) (Fig. 3). Patients in the ALT cohort had an average increase in eye drop medications of 0.6 medications from pretrabeculoplasty levels at 12 months’ follow-up. In contrast, patients in the SLT cohort
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J Glaucoma
Volume 25, Number 3, March 2016
Resident-performed ALT Versus SLT in Open-angle Glaucoma
TABLE 1. Baseline Characteristics of Included Patients and Treatments No. patients Baseline IOP Age Sex (male) [n (%)] Diagnoses [n (%)] Primary open-angle glaucoma Pseudoexfoliative glaucoma Normal tension glaucoma Pigment dispersion glaucoma Traumatic Unknown No. drops on day of treatment LogMar visual acuity in treatment eye Treatment shots Treatment degree [n (%)] 180 270 360 Unknown Treatment energy per shot (mJ)
ALT Treatment Group
SLT Treatment Group
77 18.45 ( ± 4.33) 75.90 ( ± 11.12) 74 (95)
81 18.52 ( ± 4.19) 75.54 ( ± 10.67) 78 (97)
64 6 2 1 2 2 2.35 0.37 78.1
(83) (8) (3) (1) (3) (3) ( ± 0.86) ( ± 0.38) ( ± 26)
71 5 1 3 1 0 2.62 0.31 95.8
(88) (6) (1) (4) (1) (0) ( ± 1.15) ( ± 0.40) ( ± 50.7)
45 3 26 3 63.7
(58) (4) (34) (4) ( ± 13.2)
41 0 31 9 0.82
(51) (0) (38) (11) ( ± 0.13)
P N/A 0.855 0.571 1.00 0.64
0.08 0.14 0.41 0.09
< 0.001
Treatment power was significantly different for patients in the ALT compared with SLT cohort. There was no evidence of a difference in all other baseline variables. Continuous values are provided with SD and were analyzed for significance with Wilcoxon rank-sum testing. Dichotomous values are provided with percentage in parentheses and were analyzed for significance with r c Fisher exact test. ALT indicates argon laser trabeculoplasty; IOP, intraocular pressure; SLT, selective laser trabeculoplasty.
had a decrease of 0.1 medications at 12 months’ follow-up (P < 0.001, Wilcoxon rank-sum test) (Fig. 4). We also investigated complications. There was no evidence of visual acuity change in either group after trabeculoplasty or any difference between the 2 groups (P = 0.87, Wilcoxon rank-sum test). The IOP increase immediately after trabeculoplasty was 0.25, Fisher exact test). ALT indicates argon laser trabeculoplasty; IOP, intraocular pressure; SLT, selective laser trabeculoplasty.
procedures, but that patients who underwent ALT were more likely to have increased need for eye drop medication and had a strong trend toward having earlier additional interventions. The literature comparing IOP reductions after ALT and SLT among more experienced surgeons shows either no significant difference or significant favorability for SLT leading to larger IOP reductions.4,5,8,9,20,21 We originally anticipated that any benefit in terms of enhanced IOP reduction with SLT seen in this literature was likely to be larger at the resident level given the
FIGURE 4. Change in number of eye drop medications after resident-performed trabeculoplasty. *There was a statistically significant increase in eye drop use in the ALT cohort compared with the SLT cohort across all timepoints in follow-up (P < 0.001, Wilcoxon rank-sum test). Error bars show SE of the mean. ALT indicates argon laser trabeculoplasty; SLT, selective laser trabeculoplasty.
J Glaucoma
Volume 25, Number 3, March 2016
relatively greater skill required to accurately apply the smaller laser spots of ALT to the correct zone of the trabecular meshwork. However, this study did not find any significant difference in IOP reduction, but rather found greater increases in eye drop medications. This increase in eye drop medications after ALT compared with SLT is consistent with the literature for experienced surgeons.4,9,20,21 This may reflect the real-world proactive process of physicians responding to inadequate IOP control after trabeculoplasty by increasing the number of eye drop medications and as well as using additional interventions as needed in patients undergoing ALT compared with SLT. These interventions would tend to drive down the IOP in the ALT cohort and reduce potential differences in IOP reductions between the 2 cohorts. The average IOP reductions in our study were in the 2 to 4 mm Hg range across follow-up for both the ALT and SLT cohorts. This is notably lower than the 6 to 7 mm Hg reductions seen in many studies of trabeculoplasty performed by more experienced surgeons.4,5,8,20,21 However, the baseline IOP for all patients in this study was much lower than that seen in corresponding studies with more experienced surgeons. Baseline IOP has previously been shown to be the strongest predictor of IOP reduction and the reductions here are similar to published results seen in populations with similar baseline IOP.22 In addition, the majority of the patients in this population had well-established glaucoma with visual field defects and evidence of optic nerve head damage and had been on multiple medical treatments for years before trabeculoplasty was recommended, which may have influenced the lower reduction figures seen in our study. This study had several limitations. The study was retrospective and has the inherent limitations of this study design including differential medical management of study subjects according to their disease history. Most of the patients in this study were male as it was conducted at a Veterans Affairs medical center. Patients in this study were not randomized to treatment groups, which allows the possibility of nonrandom distributions of clinical confounders between the 2 study populations. We believe this possibility is reduced by the fact that a given patient’s procedure was selected solely on the basis of procedure date (ALT before November 11, 2009 and SLT after) and not on clinical factors. The IOP measurements in this study were taken during clinic business hours, but not controlled more specifically for time of day although IOP is known to fluctuate on a circadian pattern.23 The phakic status of patients was not specifically recorded and we cannot comment on how phakic status may change trabeculoplasty effectiveness. The majority of IOP measurements were obtained using Goldmann applanation tonometry (87%); however, pneumotonometry (7%) and tonopen (6%) were used in a small number of cases, and this variability could have affected the results. In addition, although follow-up in both arms was approximately 70% at our primary 1-year outcome, there was a low rate of follow-up in the SLT group at 2 years of 41%. In summary, we found that resident-performed ALT compared with SLT required a greater increase in eye drop medications and additional interventions to achieve similar levels of reduction in IOP. These reductions were consistent with more experienced surgeons after adjusting for the lower baseline in our study population. Additional prospective studies are warranted to verify these findings,
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J Glaucoma
Volume 25, Number 3, March 2016
which suggest that resident-performed SLT may have better outcomes for medication burden and repeat interventions compared with resident-performed ALT. REFERENCES 1. Rolim de Moura C, Paranhos A Jr, Wormald R. Laser trabeculoplasty for open angle glaucoma. Cochrane Database Syst Rev. 2007;4:CD003919. 2. Samples JR, Singh K, Lin SC, et al. Laser trabeculoplasty for open-angle glaucoma: a report by the American Academy of Ophthalmology. Ophthalmology. 2011;118:2296–2302. 3. Realini T. Selective laser trabeculoplasty: a review. J Glaucoma. 2008;17:497–502. 4. Damji KF, Bovell AM, Hodge WG, et al. Selective laser trabeculoplasty versus argon laser trabeculoplasty: results from a 1-year randomised clinical trial. Br J Ophthalmol. 2006;90: 1490–1494. 5. Russo V, Barone A, Cosma A, et al. Selective laser trabeculoplasty versus argon laser trabeculoplasty in patients with uncontrolled open-angle glaucoma. Eur J Ophthalmol. 2009;19:429–434. 6. Rosenfeld E, Shemesh G, Kurtz S. The efficacy of selective laser trabeculoplasty versus argon laser trabeculoplasty in pseudophakic glaucoma patients. Clin Ophthalmol. 2012;6: 1935–1940. 7. Martinez-de-la-Casa JM, Garcia-Feijoo J, Castillo A, et al. Selective vs. argon laser trabeculoplasty: hypotensive efficacy, anterior chamber inflammation, and postoperative pain. Eye (Lond). 2004;18:498–502. 8. Kent SS, Hutnik CM, Birt CM, et al. A randomized clinical trial of selective laser trabeculoplasty versus argon laser trabeculoplasty in patients with pseudoexfoliation. J Glaucoma. 2013. [Epub ahead of print]. 9. Wang H, Cheng JW, Wei RL, et al. Meta-analysis of selective laser trabeculoplasty with argon laser trabeculoplasty in the treatment of open-angle glaucoma. Can J Ophthalmol. 2013;48:186–192. 10. Khan KA, Lederer CM Jr, Willoughby L. Argon laser trabeculoplasty in a residency program. Ophthalmic Surg. 1986;17:343–350.
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