- Email: [email protected]
Optimum time for angle visualization during ab interno glaucoma surgery: Before or after phacoemulsification
615
ARTICLE
Optimum time for angle visualization during ab interno glaucoma surgery: Before or after phacoemulsification Rebecca S. Epstein, MD, Anthony T. Scott, BA, MHI, Cara E. Capitena Young, MD, Jennifer L. Patnaik, PhD, Mina B. Pantcheva, MD, Jeffrey R. SooHoo, MD, Malik Y. Kahook, MD, Leonard K. Seibold, MD
Purpose: To determine whether it is more advantageous to perform ab interno glaucoma surgeries involving the angle before or after phacoemulsification. Setting: University of Colorado Health Eye Center, Aurora, USA. Design: Retrospective case series. Methods: Video recordings were taken of eyes having phacoemulsification with or without angle surgery. From the videos, still images of the angle before and after cataract surgery were obtained. Four glaucoma physicians independently reviewed the images and were masked to whether the images presented sideby-side were captured before or after cataract surgery. The reviewers used a 5-point rating scale to assess which of the 2 presented images showed the best visualization of the angle. Patient and ocular characteristics were analyzed to determine predictive factors for better view before or after phacoemulsification.
I
t is estimated that 64.3 million people in the world’s population have glaucoma.1 Vision loss from glaucomatous retinal nerve fiber layer damage is irreversible. Glaucoma therapy centers on the reduction of intraocular pressure (IOP) through topical medications, laser trabeculoplasty, or surgery. Although effective, traditional glaucoma filtering surgery has a substantial number of vision-threatening complications,2,3 creating the need for safer surgical options with less risk for vision loss. As a result, several ab interno angle-based procedures and minimally invasive glaucoma surgery procedures have become commercially available in recent years. These procedures provide new surgical options with an improved
Results: Twenty side-by-side comparisons (20 eyes of 20 patients) were reviewed and rated. The mean rating of all surgeons was 2.93, nearing the “3-no difference” response. The most common response was “3-no difference” between each photograph (32.5%), followed by “4-post phacoemulsification image somewhat better” (30%), and “2-pre-phacoemulsification image somewhat better” (27.5%). No ocular characteristic, including anterior chamber depth, angle pigmentation, or cumulative dissipation energy, was found to be predictive of surgeon preference.
Conclusion: In combination phacoemulsification and anglebased glaucoma procedures, there appears to be no significant angle visualization difference whether the surgeon chooses to complete angle surgery before or after phacoemulsification; therefore, the decision of surgical order should rely on surgeon preference. J Cataract Refract Surg 2019; 45:615–619 Q 2019 ASCRS and ESCRS
safety profile and a rapid postoperative recovery due to smaller incisions and quicker operative times.4 Most of these procedures also spare the conjunctiva and facilitate aqueous outflow through physiologic outflow pathways. These include devices that bypass the juxtacanalicular trabecular meshwork to increase trabecular outflow.5 These techniques are a suitable option for patients who have difficulty with medication adherence or tolerance, a concern for disease progression, or uncontrolled IOP despite medical therapy alone. Most of these procedures target outflow pathways residing in the anterior chamber angle and must be performed through direct gonioscopic visualization of angle
Submitted: November 28, 2018 | Final revision submitted: January 4, 2019 | Accepted: January 4, 2019 From the Department of Ophthalmology, University of Colorado School of Medicine, Aurora, USA. Presented at the annual meeting of the American Glaucoma Society, San Diego, California, USA, March 2017. Corresponding author: Leonard K. Seibold, MD, University of Colorado Health Eye Center, 1675 Aurora Court, Aurora, CO 80045, USA. Email: leonard.seibold@ ucdenver.edu. Q 2019 ASCRS and ESCRS Published by Elsevier Inc.
0886-3350/$ - see frontmatter https://doi.org/10.1016/j.jcrs.2019.01.012
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ANGLE VISUALIZATION DURING AB INTERNO GLAUCOMA SURGERY BEFORE OR AFTER PHACOEMULSIFICATION
structures. Optimum visualization of these structures is paramount to accurate tissue targeting and precise placement of devices. In recent years, there has been much debate on whether it is advantageous to perform ab interno angle-based procedures before or after phacoemulsification when the 2 procedures are combined. Although to our knowledge no previous studies have examined angle visualization at different times of a combined procedure, several potential advantages to each approach have been proposed. Performing the angle procedure first might cause less corneal edema secondary to phacoemulsification; such edema can cloud the view of the angle. Performing the angle surgery before phacoemulsification also guarantees that the glaucoma procedure will be completed, regardless of any surgical complications that might occur with cataract surgery. Alternatively, completing an angle-based procedure after cataract surgery achieves a deeper angle, potentially improving the surgeon’s view of the angle anatomy as well as providing a greater anterior chamber depth (ACD) within which to work. In addition, reflux of blood into the canal of Schlemm might further delineate the location of the trabecular meshwork in eyes with little to no pigmentation. Despite the growing availability and utilization of anglebased glaucoma procedures, to our knowledge, no study has addressed this issue to date. In this study, we sought to determine whether there is an optimum sequence for a combined cataract surgery and angle-based glaucoma procedure in terms of angle visualization. PATIENTS AND METHODS This retrospective single-center study included intraoperative video recordings of eyes that had cataract surgery with or without angle-based surgery between September 2016 and May 2017 at the University of Colorado Health Eye Center, Aurora. The study was approved by the Colorado Multiple Institutional Review Board. Three fellowship-trained glaucoma surgeons experienced in intraoperative gonioscopy and angle-based procedures performed the surgical cases used in the recordings. All patients had routine phacoemulsification and intraocular lens (IOL) implantation in the capsular bag. Before surgery, patients were given 3 doses each of flurbiprofen, moxifloxacin, and a mixture of phenylephrine 10.0%, cyclopentolate 1.0%, and tropicamide 1.0% spaced 10 minutes apart in the preoperative holding suite. Immediately before surgery in the operating room, topical anesthesia was administered as follows: tetracaine drops given 3 times 1 minute
apart followed by lidocaine gel 1.0%. The eye was then sterilely prepped in the usual ophthalmic fashion using povidone–iodine 5.0% (Betadine). All surgeries were performed using an OPMI Lumera T ophthalmic microscope (Carl Zeiss Meditec AG). During surgery, a 2.4 mm temporal clear corneal incision was made and the anterior chamber was adequately deepened with a dispersive ophthalmic viscosurgical device (OVD) (sodium hyaluronate 3.0%–chondroitin sulfate 4.0% [Viscoat]). The microscope was tilted approximately 45 degrees toward the surgeon, and the patient’s head was turned approximately 45 degrees away from the surgeon. Using the OVD as a coupling agent, a Swan Jacob direct gonioprism (Ocular Instruments) was placed on the corneal surface so the surgeon could view the anterior chamber angle. Care was taken to achieve the best view of the angle by manipulating the gonioprism and focusing the microscope. The cataract was removed by phacoemulsification performed using a combination of the divide-and-conquer technique and chopping technique per the surgeon’s preference. Irrigation/aspiration of the remaining cortical material was completed, and a 1-piece acrylic IOL was implanted in the capsular bag. After IOL insertion, the anterior chamber was deepened with a cohesive OVD. The microscope and patient’s head were again rotated in the same fashion as before cataract removal, and the angle was visualized using the same gonioprism coupled with OVD. Effort was again directed toward achieving the best view of the angle structures. The angle-based procedure was then performed as indicated for each patient. Some patients did not have glaucoma and therefore did not have a glaucoma procedure after the cataract was removed; however, the angle in these cases was visualized before and after cataract extraction, as in cases with glaucoma. Demographic data were gathered from the patients’ medical records and included age, sex, race, surgical eye, glaucoma type, and gonioscopic findings before surgery. Ocular biometry measurements, including ACD and axial length (AL), as well as the cumulative dissipated energy (CDE) data were collected to determine whether these measurements influenced the grader’s choice. Surgical video recordings were reviewed for each case, and the clearest still images before and after phacoemulsification were selected (Figure 1). The before and after phacoemulsification images were randomized and placed side by side. Four glaucoma surgeons were then asked to rate each set of images individually based on which image provided superior visualization of the angle. All image graders were masked to whether the images were obtained before or after phacoemulsification. A 5-point scale and comment section were used to rate reviewer preference for each set of images. The scale used was as follows: 1 Z the image on the left is significantly better, 2 Z the image on the left is somewhat better, 3 Z no difference, 4 Z the image on the right is somewhat better, and 5 Z the image on the right is significantly better. After completion of the survey, an independent masked reviewer decoded the image ratings according to the appropriate timing of each masked image. The same masked
Figure 1. Direct gonioscopic image of the angle before (left) and after (right) cataract surgery in a patient with marked pigmentation. Note the similar quality of the view in the 2 photographs.
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Table 1. Demographic and clinical factors by image rating. Parameter Patients, n Sex, n (%) Male Female Race/ethnicity, n (%) White Hispanic African-American Unknown Glaucoma type (n Z 14), n (%) CACG POAG PXF/pigmentary Mean age (y) G SD Mean ACD (mm) G SD Mean AL (mm) G SD Mean CDE† G SD Pigmentation grade, n (%) Absent to light Moderate to heavy
Mean Rating %2.75
Mean Rating >2.75 to <3.25
Mean Rating R3.25
8
5
7
2 (25.0) 6 (75.0)
2 (40.0) 3 (60.0)
5 (71.4) 2 (28.6)
6 (75.0) 1 (12.5) 0 1 (12.5)
2 (40.0) 2 (40.0) 1 (20.0) 0
5 (71.4) 1 (14.3) 1 (14.3) 0
0 2 (50.0) 2 (50.0) 72.2 (9.1) 3.3 (0.5) 24.3 (1.5) 2.1 (1.1)
1 (33.3) 2 (66.7) 0 70.8 (10.2) 2.8 (0.5) 23.3 (1.1) 3.4 (3.8)
1 (14.3) 6 (85.7) 0 69.0 (6.3) 3.3 (0.5) 24.7 (1.3) 4.6 (2.3)
2 (25.0) 6 (75.0)
3 (60.0) 2 (40.0)
2 (28.6) 5 (71.4)
P Value* d .27
.65
.20
.77 .22 .27 .17 .50
ACD Z anterior chamber depth; AL Z axial length; CACG Z chronic angle-closure glaucoma; CDE Z cumulative dissipated energy; POAG Z primary openangle glaucoma; PXF Z pseudoexfoliative *Fisher exact testing for categorical variables and analysis of variance for continuous variables † Cumulative dissipated energy was not normally distributed, and nonparametric tests were performed; the P value was not significant
reviewer graded angle pigmentation according to the Spaeth gonioscopic grading system.6 The mean image ratings were then calculated for each reviewer and the group as a whole. Descriptive statistics were used to analyze surgeon preferences for images before and after cataract surgery. The mean ratings for each image were grouped into the following 3 categories: preference for before phacoemulsification (mean rating %2.75), no difference (mean rating O2.75 and !3.25), or preference for after phacoemulsification (mean rating R3.25). Demographic and clinical characteristics were compared across these 3 categories with Fisher exact testing for categorical variables, analysis of variance testing for normally distributed continuous variables and the Wilcoxon-rank sum test for CDE as a nonparametric continuous variable. Interrater agreement among the 4 surgeons was assessed with the k statistic7 after ratings of 1 and 2 were combined and ratings of 4 and 5 together were combined, yielding the following 3 groups: preference for image before phacoemulsification, no difference, and preference for image after phacoemulsification.
RESULTS The study comprised 20 eyes of 20 patients. Table 1 shows the patients’ demographic data by image rating. The mean age of all patients was 70.75 years, and 11 (55%) were women. The majority of patients (13 [65%]) identified as white followed by Hispanic (4 [20%]) and AfricanAmerican (2 [10%]). One patient’s race was unidentified. Ten images were of the right eye and 10 of the left eye. Most patients in the study had been previously diagnosed with primary open-angle glaucoma (10 [50%]); however, 6 patients (30%) had no history of glaucoma. The remaining patients had pigmentary glaucoma (1 [5%]),
pseudoexfoliative glaucoma (1 [5%]), or chronic angleclosure glaucoma (2 [10%]) without significant peripheral anterior synechiae formation. Figure 2 shows the frequency of each reviewer rating option. The most common response was “no difference” between each before phacoemulsification image and after phacoemulsification image (26/80 [32.5%]). This was followed in frequency by “after phacoemulsification
Figure 2. Frequency of masked surgeon image preference ratings (1 Z the pre-phacoemulsification image is significantly better; 2 Z the pre-phacoemulsification image is somewhat better; 3 Z no difference; 4 Z the post-phacoemulsification image is somewhat better; 5 Z the post-phacoemulsification image is significantly better).
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ANGLE VISUALIZATION DURING AB INTERNO GLAUCOMA SURGERY BEFORE OR AFTER PHACOEMULSIFICATION
Figure 3. Direct gonioscopic image of the angle before (left) and after (right) cataract surgery in a patient with light trabecular pigmentation. The image after phacoemulsification shows blood in the canal of Schlemm, which gives better visualization of the trabecular meshwork.
image somewhat better” (24/80 [30.0%]) and “before phacoemulsification image somewhat better” (22/80 [27.5%]). Only 7.5% (6/80) of ratings showed a strong preference for before phacoemulsification images, and 2.5% (2/80) of ratings showed a strong preference for after phacoemulsification images. After combining “somewhat better” and “strong preference” ratings so that physicians each fell into one of the 3 groups, the k was 0.11 (standard error 0.06), indicating only slight agreement across physicians. The ACD, AL, angle pigmentation, and CDE were similar between the 3 groups. No other clinical or demographic parameter was found to be a significant predictor of image preference. DISCUSSION Minimally invasive glaucoma surgery continues to grow in popularity because of its enhanced safety profile compared with traditional filtration surgery. Although some anglebased procedures can be performed as standalone operations, they are most commonly combined with cataract surgery. Surgical preferences regarding the order of these 2 procedures (ie, whether phacoemulsification should precede or follow an angle-based procedure) largely revolve around anecdotal experiences alone. We believe that our study is the first to objectively grade gonioscopic angle visualization intraoperatively before and after cataract surgery. Several ocular and surgical parameters have the potential to influence surgeon preference for angle surgery before or after phacoemulsification. In eyes with a shorter AL or ACD, surgeons might prefer to wait until after cataract removal to create a deeper anterior chamber within which
to work. Eyes with dense nuclear cataract that require greater amounts of phacoemulsification energy or CDE might be more ideal for angle surgery first to avoid corneal edema and haze after cataract removal. Angle pigmentation might also influence preference because angles with lightly pigmented trabecular meshwork might be better visualized after cataract removal when blood reflux occurs in the canal of Schlemm. In our study, statistical comparisons between groups of eyes with a mean preference for before phacoemulsification image, after phacoemulsification image, or no preference found no significant difference in AL, ACD, or CDE. Despite individual opinions, our masked surgeon observers most often found no difference between before images and after images. The mean rating for all surgeons combined across all patients was 2.93, very near the rating of no difference (3). When observers detected differences, the differences were rated as “slight,” with an even distribution between the before phacoemulsification preference and after phacoemulsification preference. In fact, only 10% of all ratings showed a strong preference for either preference. These results suggest that in the vast majority of cases, there is little to no true visualization advantage in performing an angle procedure before or after phacoemulsification cataract surgery. However, some preliminary conclusions may be drawn from a qualitative analysis of the images from 5 eyes in which surgeons uniformly favored either the before or after phacoemulsification image. Images from 2 patients had an average rating of 4.0 and 3.75, significantly favoring the after-phacoemulsification image. The raters’ rationale for these scores stemmed from blood in the canal of Schlemm,
Figure 4. Direct gonioscopic image of the angle before (left) and after (right) cataract surgery. Viewers favored the pre-phacoemulsification image.
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ANGLE VISUALIZATION DURING AB INTERNO GLAUCOMA SURGERY BEFORE OR AFTER PHACOEMULSIFICATION
which emphasized the trabecular meshwork as a key visual landmark that is often the target in angle-based surgeries (Figure 3). In 2 eyes with a uniform preference for the before phacoemulsification image (mean rating 2), surgeons explained their choice by the clarity of the angle structures compared with that after cataract removal. Lack of clarity in the post-phacoemulsification image might have been the result of corneal edema or to a recording error leading to poor image quality (Figure 4). Images from another eye showed a strong preference for the prephacoemulsification image (mean rating 1.75); however, this appeared to be caused by poor position of the direct gonioprism, leading to poor visualization of angle structures. We acknowledge limitations in the current study. First, the modest sample size might have precluded more subtle trends or significant predictors of better visualization from being recognized. Second, images were extracted from video recordings and do not represent the dynamic visualization experienced in live surgery. Third, visual clues, such as blood reflux into Schlemm canal, might have revealed the timing of images to the masked reviewers, presenting a source of bias. However, this occurred in 8 eyes with a mean reviewer rating of 3.15 (range 2 to 4), suggesting it did not significantly influence overall results. Finally, no complex or dense cataract cases with very high CDE times were included in this sample; their inclusion might have led to more preference for before phacoemulsification images because of the corneal edema that can occur after phacoemulsification. In conclusion, our findings suggest that there is no significant difference between gonioscopic visualization of angle structures before or after routine cataract surgery. Corneal edema and blood reflux in the canal of Schlemm were the 2 main factors leading to a preference in cases in which there was a preference. Therefore, the timing of angle surgery in combination with cataract surgery should be based on surgeon preference and the clinical case scenario.
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WHAT WAS KNOWN Several ab interno angle-based glaucoma procedures have become commercially available in recent years. These procedures are becoming more prevalent because of their efficacy, excellent safety profile, and rapid recovery. Although these procedures are commonly combined with cataract surgery, it is not known whether it is more advantageous to perform angle-based surgery before or after phacoemulsification.
WHAT THIS PAPER ADDS In most cases, gonioscopic angle visualization was similar before and after phacoemulsification. When combining angle surgery with phacoemulsification cataract removal, the optimum sequence should be determined by surgeon preference and the clinical case scenario.
REFERENCES 1. Tham Y-C, Li X, Wong TY, Quigley HA, Aung T, Cheng C-Y. Global prevalence of glaucoma and projections of glaucoma burden through 2040; a systematic review and meta-analysis. Ophthalmology 2014; 121:2081–2090 2. Watson PG, Jakeman C, Ozturk M, Barnett MF, Barnett F, Khaw KT. The complications of trabeculectomy (a 20-year follow-up). Eye 1990; 4:425–438 3. Gedde SJ, Herndon LW, Brandt JD, Budenz DL, Feuer WJ, Schiffman JC, on behalf of the Tube Versus Trabeculectomy Study Group. Postoperative complications in the Tube Versus Trabeculectomy (TVT) Study during five years of follow-up. Am J Ophthalmol 2012; 153:804–814 4. Saheb H, Ahmed IIK. Micro-invasive glaucoma surgery: Current perspectives and future directions. Curr Opin Ophthalmol 2012; 23:96–104 5. SooHoo JR, Seibold LK, Radcliffe NM, Kahook MY. Minimally invasive glaucoma surgery: current implants and future innovations. Can J Ophthalmol 2014; 49:528–533 6. Spaeth GL, Araujo SV, Azuara-Blanco A. Comparison of the configuration of the human anterior chamber angle, as determined by the Spaeth gonioscopic grading system and ultrasound biomicroscopy. Trans Am Ophthalmol Soc 1995; 93:337–347; discussion, 347–351 7. Fleiss JL. Measuring nominal scale agreement among many raters. Psychol Bull 1971; 76:378–382
Disclosures: None of the authors has a financial or proprietary interest in any material or method mentioned.
Volume 45 Issue 5 May 2019
ARTICLE
Optimum time for angle visualization during ab interno glaucoma surgery: Before or after phacoemulsification Rebecca S. Epstein, MD, Anthony T. Scott, BA, MHI, Cara E. Capitena Young, MD, Jennifer L. Patnaik, PhD, Mina B. Pantcheva, MD, Jeffrey R. SooHoo, MD, Malik Y. Kahook, MD, Leonard K. Seibold, MD
Purpose: To determine whether it is more advantageous to perform ab interno glaucoma surgeries involving the angle before or after phacoemulsification. Setting: University of Colorado Health Eye Center, Aurora, USA. Design: Retrospective case series. Methods: Video recordings were taken of eyes having phacoemulsification with or without angle surgery. From the videos, still images of the angle before and after cataract surgery were obtained. Four glaucoma physicians independently reviewed the images and were masked to whether the images presented sideby-side were captured before or after cataract surgery. The reviewers used a 5-point rating scale to assess which of the 2 presented images showed the best visualization of the angle. Patient and ocular characteristics were analyzed to determine predictive factors for better view before or after phacoemulsification.
I
t is estimated that 64.3 million people in the world’s population have glaucoma.1 Vision loss from glaucomatous retinal nerve fiber layer damage is irreversible. Glaucoma therapy centers on the reduction of intraocular pressure (IOP) through topical medications, laser trabeculoplasty, or surgery. Although effective, traditional glaucoma filtering surgery has a substantial number of vision-threatening complications,2,3 creating the need for safer surgical options with less risk for vision loss. As a result, several ab interno angle-based procedures and minimally invasive glaucoma surgery procedures have become commercially available in recent years. These procedures provide new surgical options with an improved
Results: Twenty side-by-side comparisons (20 eyes of 20 patients) were reviewed and rated. The mean rating of all surgeons was 2.93, nearing the “3-no difference” response. The most common response was “3-no difference” between each photograph (32.5%), followed by “4-post phacoemulsification image somewhat better” (30%), and “2-pre-phacoemulsification image somewhat better” (27.5%). No ocular characteristic, including anterior chamber depth, angle pigmentation, or cumulative dissipation energy, was found to be predictive of surgeon preference.
Conclusion: In combination phacoemulsification and anglebased glaucoma procedures, there appears to be no significant angle visualization difference whether the surgeon chooses to complete angle surgery before or after phacoemulsification; therefore, the decision of surgical order should rely on surgeon preference. J Cataract Refract Surg 2019; 45:615–619 Q 2019 ASCRS and ESCRS
safety profile and a rapid postoperative recovery due to smaller incisions and quicker operative times.4 Most of these procedures also spare the conjunctiva and facilitate aqueous outflow through physiologic outflow pathways. These include devices that bypass the juxtacanalicular trabecular meshwork to increase trabecular outflow.5 These techniques are a suitable option for patients who have difficulty with medication adherence or tolerance, a concern for disease progression, or uncontrolled IOP despite medical therapy alone. Most of these procedures target outflow pathways residing in the anterior chamber angle and must be performed through direct gonioscopic visualization of angle
Submitted: November 28, 2018 | Final revision submitted: January 4, 2019 | Accepted: January 4, 2019 From the Department of Ophthalmology, University of Colorado School of Medicine, Aurora, USA. Presented at the annual meeting of the American Glaucoma Society, San Diego, California, USA, March 2017. Corresponding author: Leonard K. Seibold, MD, University of Colorado Health Eye Center, 1675 Aurora Court, Aurora, CO 80045, USA. Email: leonard.seibold@ ucdenver.edu. Q 2019 ASCRS and ESCRS Published by Elsevier Inc.
0886-3350/$ - see frontmatter https://doi.org/10.1016/j.jcrs.2019.01.012
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ANGLE VISUALIZATION DURING AB INTERNO GLAUCOMA SURGERY BEFORE OR AFTER PHACOEMULSIFICATION
structures. Optimum visualization of these structures is paramount to accurate tissue targeting and precise placement of devices. In recent years, there has been much debate on whether it is advantageous to perform ab interno angle-based procedures before or after phacoemulsification when the 2 procedures are combined. Although to our knowledge no previous studies have examined angle visualization at different times of a combined procedure, several potential advantages to each approach have been proposed. Performing the angle procedure first might cause less corneal edema secondary to phacoemulsification; such edema can cloud the view of the angle. Performing the angle surgery before phacoemulsification also guarantees that the glaucoma procedure will be completed, regardless of any surgical complications that might occur with cataract surgery. Alternatively, completing an angle-based procedure after cataract surgery achieves a deeper angle, potentially improving the surgeon’s view of the angle anatomy as well as providing a greater anterior chamber depth (ACD) within which to work. In addition, reflux of blood into the canal of Schlemm might further delineate the location of the trabecular meshwork in eyes with little to no pigmentation. Despite the growing availability and utilization of anglebased glaucoma procedures, to our knowledge, no study has addressed this issue to date. In this study, we sought to determine whether there is an optimum sequence for a combined cataract surgery and angle-based glaucoma procedure in terms of angle visualization. PATIENTS AND METHODS This retrospective single-center study included intraoperative video recordings of eyes that had cataract surgery with or without angle-based surgery between September 2016 and May 2017 at the University of Colorado Health Eye Center, Aurora. The study was approved by the Colorado Multiple Institutional Review Board. Three fellowship-trained glaucoma surgeons experienced in intraoperative gonioscopy and angle-based procedures performed the surgical cases used in the recordings. All patients had routine phacoemulsification and intraocular lens (IOL) implantation in the capsular bag. Before surgery, patients were given 3 doses each of flurbiprofen, moxifloxacin, and a mixture of phenylephrine 10.0%, cyclopentolate 1.0%, and tropicamide 1.0% spaced 10 minutes apart in the preoperative holding suite. Immediately before surgery in the operating room, topical anesthesia was administered as follows: tetracaine drops given 3 times 1 minute
apart followed by lidocaine gel 1.0%. The eye was then sterilely prepped in the usual ophthalmic fashion using povidone–iodine 5.0% (Betadine). All surgeries were performed using an OPMI Lumera T ophthalmic microscope (Carl Zeiss Meditec AG). During surgery, a 2.4 mm temporal clear corneal incision was made and the anterior chamber was adequately deepened with a dispersive ophthalmic viscosurgical device (OVD) (sodium hyaluronate 3.0%–chondroitin sulfate 4.0% [Viscoat]). The microscope was tilted approximately 45 degrees toward the surgeon, and the patient’s head was turned approximately 45 degrees away from the surgeon. Using the OVD as a coupling agent, a Swan Jacob direct gonioprism (Ocular Instruments) was placed on the corneal surface so the surgeon could view the anterior chamber angle. Care was taken to achieve the best view of the angle by manipulating the gonioprism and focusing the microscope. The cataract was removed by phacoemulsification performed using a combination of the divide-and-conquer technique and chopping technique per the surgeon’s preference. Irrigation/aspiration of the remaining cortical material was completed, and a 1-piece acrylic IOL was implanted in the capsular bag. After IOL insertion, the anterior chamber was deepened with a cohesive OVD. The microscope and patient’s head were again rotated in the same fashion as before cataract removal, and the angle was visualized using the same gonioprism coupled with OVD. Effort was again directed toward achieving the best view of the angle structures. The angle-based procedure was then performed as indicated for each patient. Some patients did not have glaucoma and therefore did not have a glaucoma procedure after the cataract was removed; however, the angle in these cases was visualized before and after cataract extraction, as in cases with glaucoma. Demographic data were gathered from the patients’ medical records and included age, sex, race, surgical eye, glaucoma type, and gonioscopic findings before surgery. Ocular biometry measurements, including ACD and axial length (AL), as well as the cumulative dissipated energy (CDE) data were collected to determine whether these measurements influenced the grader’s choice. Surgical video recordings were reviewed for each case, and the clearest still images before and after phacoemulsification were selected (Figure 1). The before and after phacoemulsification images were randomized and placed side by side. Four glaucoma surgeons were then asked to rate each set of images individually based on which image provided superior visualization of the angle. All image graders were masked to whether the images were obtained before or after phacoemulsification. A 5-point scale and comment section were used to rate reviewer preference for each set of images. The scale used was as follows: 1 Z the image on the left is significantly better, 2 Z the image on the left is somewhat better, 3 Z no difference, 4 Z the image on the right is somewhat better, and 5 Z the image on the right is significantly better. After completion of the survey, an independent masked reviewer decoded the image ratings according to the appropriate timing of each masked image. The same masked
Figure 1. Direct gonioscopic image of the angle before (left) and after (right) cataract surgery in a patient with marked pigmentation. Note the similar quality of the view in the 2 photographs.
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Table 1. Demographic and clinical factors by image rating. Parameter Patients, n Sex, n (%) Male Female Race/ethnicity, n (%) White Hispanic African-American Unknown Glaucoma type (n Z 14), n (%) CACG POAG PXF/pigmentary Mean age (y) G SD Mean ACD (mm) G SD Mean AL (mm) G SD Mean CDE† G SD Pigmentation grade, n (%) Absent to light Moderate to heavy
Mean Rating %2.75
Mean Rating >2.75 to <3.25
Mean Rating R3.25
8
5
7
2 (25.0) 6 (75.0)
2 (40.0) 3 (60.0)
5 (71.4) 2 (28.6)
6 (75.0) 1 (12.5) 0 1 (12.5)
2 (40.0) 2 (40.0) 1 (20.0) 0
5 (71.4) 1 (14.3) 1 (14.3) 0
0 2 (50.0) 2 (50.0) 72.2 (9.1) 3.3 (0.5) 24.3 (1.5) 2.1 (1.1)
1 (33.3) 2 (66.7) 0 70.8 (10.2) 2.8 (0.5) 23.3 (1.1) 3.4 (3.8)
1 (14.3) 6 (85.7) 0 69.0 (6.3) 3.3 (0.5) 24.7 (1.3) 4.6 (2.3)
2 (25.0) 6 (75.0)
3 (60.0) 2 (40.0)
2 (28.6) 5 (71.4)
P Value* d .27
.65
.20
.77 .22 .27 .17 .50
ACD Z anterior chamber depth; AL Z axial length; CACG Z chronic angle-closure glaucoma; CDE Z cumulative dissipated energy; POAG Z primary openangle glaucoma; PXF Z pseudoexfoliative *Fisher exact testing for categorical variables and analysis of variance for continuous variables † Cumulative dissipated energy was not normally distributed, and nonparametric tests were performed; the P value was not significant
reviewer graded angle pigmentation according to the Spaeth gonioscopic grading system.6 The mean image ratings were then calculated for each reviewer and the group as a whole. Descriptive statistics were used to analyze surgeon preferences for images before and after cataract surgery. The mean ratings for each image were grouped into the following 3 categories: preference for before phacoemulsification (mean rating %2.75), no difference (mean rating O2.75 and !3.25), or preference for after phacoemulsification (mean rating R3.25). Demographic and clinical characteristics were compared across these 3 categories with Fisher exact testing for categorical variables, analysis of variance testing for normally distributed continuous variables and the Wilcoxon-rank sum test for CDE as a nonparametric continuous variable. Interrater agreement among the 4 surgeons was assessed with the k statistic7 after ratings of 1 and 2 were combined and ratings of 4 and 5 together were combined, yielding the following 3 groups: preference for image before phacoemulsification, no difference, and preference for image after phacoemulsification.
RESULTS The study comprised 20 eyes of 20 patients. Table 1 shows the patients’ demographic data by image rating. The mean age of all patients was 70.75 years, and 11 (55%) were women. The majority of patients (13 [65%]) identified as white followed by Hispanic (4 [20%]) and AfricanAmerican (2 [10%]). One patient’s race was unidentified. Ten images were of the right eye and 10 of the left eye. Most patients in the study had been previously diagnosed with primary open-angle glaucoma (10 [50%]); however, 6 patients (30%) had no history of glaucoma. The remaining patients had pigmentary glaucoma (1 [5%]),
pseudoexfoliative glaucoma (1 [5%]), or chronic angleclosure glaucoma (2 [10%]) without significant peripheral anterior synechiae formation. Figure 2 shows the frequency of each reviewer rating option. The most common response was “no difference” between each before phacoemulsification image and after phacoemulsification image (26/80 [32.5%]). This was followed in frequency by “after phacoemulsification
Figure 2. Frequency of masked surgeon image preference ratings (1 Z the pre-phacoemulsification image is significantly better; 2 Z the pre-phacoemulsification image is somewhat better; 3 Z no difference; 4 Z the post-phacoemulsification image is somewhat better; 5 Z the post-phacoemulsification image is significantly better).
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Figure 3. Direct gonioscopic image of the angle before (left) and after (right) cataract surgery in a patient with light trabecular pigmentation. The image after phacoemulsification shows blood in the canal of Schlemm, which gives better visualization of the trabecular meshwork.
image somewhat better” (24/80 [30.0%]) and “before phacoemulsification image somewhat better” (22/80 [27.5%]). Only 7.5% (6/80) of ratings showed a strong preference for before phacoemulsification images, and 2.5% (2/80) of ratings showed a strong preference for after phacoemulsification images. After combining “somewhat better” and “strong preference” ratings so that physicians each fell into one of the 3 groups, the k was 0.11 (standard error 0.06), indicating only slight agreement across physicians. The ACD, AL, angle pigmentation, and CDE were similar between the 3 groups. No other clinical or demographic parameter was found to be a significant predictor of image preference. DISCUSSION Minimally invasive glaucoma surgery continues to grow in popularity because of its enhanced safety profile compared with traditional filtration surgery. Although some anglebased procedures can be performed as standalone operations, they are most commonly combined with cataract surgery. Surgical preferences regarding the order of these 2 procedures (ie, whether phacoemulsification should precede or follow an angle-based procedure) largely revolve around anecdotal experiences alone. We believe that our study is the first to objectively grade gonioscopic angle visualization intraoperatively before and after cataract surgery. Several ocular and surgical parameters have the potential to influence surgeon preference for angle surgery before or after phacoemulsification. In eyes with a shorter AL or ACD, surgeons might prefer to wait until after cataract removal to create a deeper anterior chamber within which
to work. Eyes with dense nuclear cataract that require greater amounts of phacoemulsification energy or CDE might be more ideal for angle surgery first to avoid corneal edema and haze after cataract removal. Angle pigmentation might also influence preference because angles with lightly pigmented trabecular meshwork might be better visualized after cataract removal when blood reflux occurs in the canal of Schlemm. In our study, statistical comparisons between groups of eyes with a mean preference for before phacoemulsification image, after phacoemulsification image, or no preference found no significant difference in AL, ACD, or CDE. Despite individual opinions, our masked surgeon observers most often found no difference between before images and after images. The mean rating for all surgeons combined across all patients was 2.93, very near the rating of no difference (3). When observers detected differences, the differences were rated as “slight,” with an even distribution between the before phacoemulsification preference and after phacoemulsification preference. In fact, only 10% of all ratings showed a strong preference for either preference. These results suggest that in the vast majority of cases, there is little to no true visualization advantage in performing an angle procedure before or after phacoemulsification cataract surgery. However, some preliminary conclusions may be drawn from a qualitative analysis of the images from 5 eyes in which surgeons uniformly favored either the before or after phacoemulsification image. Images from 2 patients had an average rating of 4.0 and 3.75, significantly favoring the after-phacoemulsification image. The raters’ rationale for these scores stemmed from blood in the canal of Schlemm,
Figure 4. Direct gonioscopic image of the angle before (left) and after (right) cataract surgery. Viewers favored the pre-phacoemulsification image.
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ANGLE VISUALIZATION DURING AB INTERNO GLAUCOMA SURGERY BEFORE OR AFTER PHACOEMULSIFICATION
which emphasized the trabecular meshwork as a key visual landmark that is often the target in angle-based surgeries (Figure 3). In 2 eyes with a uniform preference for the before phacoemulsification image (mean rating 2), surgeons explained their choice by the clarity of the angle structures compared with that after cataract removal. Lack of clarity in the post-phacoemulsification image might have been the result of corneal edema or to a recording error leading to poor image quality (Figure 4). Images from another eye showed a strong preference for the prephacoemulsification image (mean rating 1.75); however, this appeared to be caused by poor position of the direct gonioprism, leading to poor visualization of angle structures. We acknowledge limitations in the current study. First, the modest sample size might have precluded more subtle trends or significant predictors of better visualization from being recognized. Second, images were extracted from video recordings and do not represent the dynamic visualization experienced in live surgery. Third, visual clues, such as blood reflux into Schlemm canal, might have revealed the timing of images to the masked reviewers, presenting a source of bias. However, this occurred in 8 eyes with a mean reviewer rating of 3.15 (range 2 to 4), suggesting it did not significantly influence overall results. Finally, no complex or dense cataract cases with very high CDE times were included in this sample; their inclusion might have led to more preference for before phacoemulsification images because of the corneal edema that can occur after phacoemulsification. In conclusion, our findings suggest that there is no significant difference between gonioscopic visualization of angle structures before or after routine cataract surgery. Corneal edema and blood reflux in the canal of Schlemm were the 2 main factors leading to a preference in cases in which there was a preference. Therefore, the timing of angle surgery in combination with cataract surgery should be based on surgeon preference and the clinical case scenario.
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WHAT WAS KNOWN Several ab interno angle-based glaucoma procedures have become commercially available in recent years. These procedures are becoming more prevalent because of their efficacy, excellent safety profile, and rapid recovery. Although these procedures are commonly combined with cataract surgery, it is not known whether it is more advantageous to perform angle-based surgery before or after phacoemulsification.
WHAT THIS PAPER ADDS In most cases, gonioscopic angle visualization was similar before and after phacoemulsification. When combining angle surgery with phacoemulsification cataract removal, the optimum sequence should be determined by surgeon preference and the clinical case scenario.
REFERENCES 1. Tham Y-C, Li X, Wong TY, Quigley HA, Aung T, Cheng C-Y. Global prevalence of glaucoma and projections of glaucoma burden through 2040; a systematic review and meta-analysis. Ophthalmology 2014; 121:2081–2090 2. Watson PG, Jakeman C, Ozturk M, Barnett MF, Barnett F, Khaw KT. The complications of trabeculectomy (a 20-year follow-up). Eye 1990; 4:425–438 3. Gedde SJ, Herndon LW, Brandt JD, Budenz DL, Feuer WJ, Schiffman JC, on behalf of the Tube Versus Trabeculectomy Study Group. Postoperative complications in the Tube Versus Trabeculectomy (TVT) Study during five years of follow-up. Am J Ophthalmol 2012; 153:804–814 4. Saheb H, Ahmed IIK. Micro-invasive glaucoma surgery: Current perspectives and future directions. Curr Opin Ophthalmol 2012; 23:96–104 5. SooHoo JR, Seibold LK, Radcliffe NM, Kahook MY. Minimally invasive glaucoma surgery: current implants and future innovations. Can J Ophthalmol 2014; 49:528–533 6. Spaeth GL, Araujo SV, Azuara-Blanco A. Comparison of the configuration of the human anterior chamber angle, as determined by the Spaeth gonioscopic grading system and ultrasound biomicroscopy. Trans Am Ophthalmol Soc 1995; 93:337–347; discussion, 347–351 7. Fleiss JL. Measuring nominal scale agreement among many raters. Psychol Bull 1971; 76:378–382
Disclosures: None of the authors has a financial or proprietary interest in any material or method mentioned.
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