Duke University residents’ review of “Impact of failure of...
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EW RESIDENTS 116 March 2012 by Peter C. Nicholas, M.D., Ph.D., Michael J. Allingham, M.D., Ph.D., Mark Hansen, M.D., Laura Vickers, M.D., and Pratap Challa, M.D. Duke University residents’ review of “Impact of tations. As noted by the authors, the retrospective design introduces sus- ceptibility to bias from patient selec- tion and other factors. Another limitation is sample size: 37 patients underwent phacoemulsification, and only 10 underwent phacoemulsifica- tion within 1 year post-trabeculec- tomy. The data show that these 10 patients had a much lower probabil- ity of good long-term IOP control. However, given the small sample size, an analysis of baseline charac- teristics of this group compared to the other patients could have been informative. In addition, the article would benefit from an analysis of whether these patients’ IOP control might have fared better had they been randomized to wait longer for their cataract surgery. It may have also been informative to provide an analysis of average IOP change after cataract surgery in these patients since cataract surgery itself can affect IOP. No patient details are presented to address the question of whether patients who underwent pha- coemulsification soon after tra- beculectomy might have had a more complex post-op course (e.g., flat an- terior chamber) contributing to sur- gical failure, or whether patients having phacoemulsification earlier within 1 year fared worse than those having it 12 months post-trabeculec- tomy. Another limitation is the use of multiple similar endpoints. The dis- tinguishing factor between condi- tion A and condition B is the IOP limit of 21 versus 18. This 3 mm Hg difference does not seem clinically significant given that target pres- sures for patients undergoing tra- beculectomy are usually much lower depending on the degree of glau- coma severity. However, including both of these endpoints doubles the number of statistical comparisons and could decrease the strength of the study’s conclusions due to multi- ple comparisons. Another important issue is the post-phacoemulsification treatment regimen, which in this study in- cluded fluorometholone and lev- ofloxacin for 1 month. It is typical practice in the United States to use more potent topical steroids follow- ing phacoemulsification, especially for eyes that might be susceptible to inflammation, e.g., those with thick irides or those who have recently This month, I asked the residents at Duke to review this Japanese paper looking at whether phaco adversely affects the function of a prior trabeculectomy. —David F. Chang, M.D., chief medical editor I n the article published this month in JCRS, “Impact of pha- coemulsification on failure of trabeculectomy with mito- mycin-C,” Nanako Awai- Kasoaka et al. attempted to further elucidate the effect of phacoemulsifi- cation on IOP control after tra- beculectomy. To date, published studies report conflicting answers to this question. This retrospective study evaluated phacoemulsification after trabeculectomy with mito- mycin-C (MMC) as a risk factor for subsequent failure of trabeculectomy surgery. The study included 178 pa- tients who had undergone tra- beculectomy with MMC for either primary open-angle glaucoma (POAG) or pseudoexfoliation glau- coma (PXG). Thirty-seven of these patients subsequently underwent phacoemulsification. The primary endpoints were failure of the tra- beculectomy as defined by either: condition A (persistent intraocular pressure [IOP] greater than 21 mm Hg or additional glaucoma proce- dures) or condition B (persistent IOP greater than 18 mm Hg or additional glaucoma procedures). The authors used the Cox proportional hazard model to identify the relative risk of trabeculectomy failure following phacoemulsification cataract surgery. The authors found the 3-year probability of treatment success for all patients who underwent tra- beculectomy with MMC to be 92.7% for condition A and 81.8% for con- dition B. Of those patients who un- derwent phacoemulsification after trabeculectomy with MMC, the probability of treatment success at 5 years for patients who underwent phacoemulsification more than 1 year after trabeculectomy with MMC was 92.6%, whereas for patients who underwent phacoemulsification within 1 year of trabeculectomy with MMC, the corresponding prob- ability of success was 48.0%. Using the Cox proportional hazard model, the authors found that for condition A, higher IOP prior to trabeculec- tomy was a risk factor for surgical failure (p=0.01). For condition B, significant risk factors included higher IOP prior to trabeculectomy (p=0.0006), as well as phacoemulsifi- cation within 1 year after trabeculec- tomy (p=0.04). The relative risk for surgical failure as defined by condi- tion B for patients undergoing pha- coemulsification within 1 year of trabeculectomy was 2.87, while the relative risk of surgical failure in- creased by 1.09 for each mm Hg ad- ditional pre-trabeculectomy IOP. Considering the complexities and risks associated with trabeculec- tomy surgery, it is vital to identify and understand risk factors for surgi- cal failure. This study suggests that phacoemulsification within 1 year of trabeculectomy is a risk factor for surgical failure. The authors suggest that this may occur via scarring of the bleb by post-phacoemulsifica- tion inflammation. While it has been attempted to address this question in prior studies, the present investigation uses the Cox propor- tional hazard model (a time-to-event analysis estimating the relative risk of surgical failure based on multiple patient characteristics) to estimate the relative contribution of individ- ual risk factors to trabeculectomy failure. However, with a borderline p-value and lack of an adjustment for multiple comparisons, further studies are warranted to support the authors’ conclusion. While the statistical analysis is unique for this specific question, the study design introduces several limi- Impact of phacoemulsification on failure of trabeculectomy with mitomycin-C Nanako Awai-Kasaoka, M.D., Toshihiro Inoue, M.D., Ph.D., Yuji Takihara, M.D., Ph.D., Atsushi Kawaguchi, Ph.D., Masaru Inatani, M.D., Ph.D., Minako Ogata-Iwao, M.D., Hidenobu Tanihara, M.D., Ph.D. J Cataract Refract Surg (March) 2012; 38:419-424 Purpose: To evaluate whether phacoemulsification after trabeculectomy affects post-op IOP Setting: Kumamoto University, Kumamoto, Japan Design: Cohort study Methods: The medical records of patients with primary open-angle glaucoma or pseudoexfoliation glaucoma who had trabeculectomy with mitomycin-C were reviewed. The primary endpoints were con- dition A (persistent post-op IOP 21 mm Hg or higher or additional glaucoma procedures with or without medications) and condition B (post-op IOP 18 mm Hg or higher or additional glaucoma procedures with or without medications). Multivariable analysis was performed using the Cox proportional hazards model. Results: The records of 178 patients (178 eyes) were reviewed. The mean follow-up was 37.0 months. For condition A, the probability of treatment success at 1 year, 2 years, and 3 years was 97.9%, 95.0%, and 92.7%, respectively. For condition B, the corresponding probabilities of success were 92.3%, 84.1%, and 81.8%. Thirty-seven patients (37 eyes) had phacoemulsification after trabeculectomy; 10 of those patients had phacoemulsification within 1 year after tra- beculectomy. Multivariate analysis showed that a higher IOP before trabeculectomy was a significant risk factor for condition A and condition B (P=.01 and P=.0006, respectively); phacoemulsification within 1 year after trabeculectomy was significantly associated with trabeculectomy failure for condition B (P=.04). Conclusion: Post-op IOP in eyes with previous trabeculectomy may be affected by the IOP before trabeculectomy and phacoemulsifica- tion within 1 year after trabeculectomy. EyeWorld journal club Pratap Challa, M.D. Residency program director, Duke University failure of trabeculectomy with mitomycin-C”
Transcript of Duke University residents’ review of “Impact of failure of...
EW RESIDENTS116 March 2012
by Peter C. Nicholas, M.D., Ph.D., Michael J. Allingham, M.D., Ph.D., Mark Hansen, M.D., Laura Vickers, M.D., and Pratap Challa, M.D.
Duke University residents’ review of “Impact of
tations. As noted by the authors, theretrospective design introduces sus-ceptibility to bias from patient selec-tion and other factors. Anotherlimitation is sample size: 37 patientsunderwent phacoemulsification, andonly 10 underwent phacoemulsifica-tion within 1 year post-trabeculec-tomy. The data show that these 10patients had a much lower probabil-ity of good long-term IOP control.However, given the small samplesize, an analysis of baseline charac-teristics of this group compared tothe other patients could have beeninformative. In addition, the articlewould benefit from an analysis ofwhether these patients’ IOP controlmight have fared better had theybeen randomized to wait longer fortheir cataract surgery. It may havealso been informative to provide ananalysis of average IOP change aftercataract surgery in these patientssince cataract surgery itself can affectIOP. No patient details are presentedto address the question of whetherpatients who underwent pha-coemulsification soon after tra-beculectomy might have had a morecomplex post-op course (e.g., flat an-terior chamber) contributing to sur-gical failure, or whether patientshaving phacoemulsification earlierwithin 1 year fared worse than thosehaving it 12 months post-trabeculec-tomy.
Another limitation is the use ofmultiple similar endpoints. The dis-tinguishing factor between condi-tion A and condition B is the IOPlimit of 21 versus 18. This 3 mm Hgdifference does not seem clinicallysignificant given that target pres-sures for patients undergoing tra-beculectomy are usually much lowerdepending on the degree of glau-coma severity. However, includingboth of these endpoints doubles thenumber of statistical comparisonsand could decrease the strength ofthe study’s conclusions due to multi-ple comparisons.
Another important issue is thepost-phacoemulsification treatmentregimen, which in this study in-cluded fluorometholone and lev-ofloxacin for 1 month. It is typicalpractice in the United States to usemore potent topical steroids follow-ing phacoemulsification, especiallyfor eyes that might be susceptible toinflammation, e.g., those with thickirides or those who have recently
This month, I asked the residents atDuke to review this Japanese paperlooking at whether phaco adversely affects the function of a prior trabeculectomy.
—David F. Chang, M.D., chief medical editor
In the article published thismonth in JCRS, “Impact of pha-coemulsification on failure oftrabeculectomy with mito-mycin-C,” Nanako Awai-
Kasoaka et al. attempted to furtherelucidate the effect of phacoemulsifi-cation on IOP control after tra-beculectomy. To date, published
studies report conflicting answers tothis question. This retrospectivestudy evaluated phacoemulsificationafter trabeculectomy with mito-mycin-C (MMC) as a risk factor forsubsequent failure of trabeculectomysurgery. The study included 178 pa-tients who had undergone tra-beculectomy with MMC for eitherprimary open-angle glaucoma(POAG) or pseudoexfoliation glau-coma (PXG). Thirty-seven of thesepatients subsequently underwentphacoemulsification. The primaryendpoints were failure of the tra-beculectomy as defined by either:condition A (persistent intraocularpressure [IOP] greater than 21 mmHg or additional glaucoma proce-dures) or condition B (persistent IOPgreater than 18 mm Hg or additionalglaucoma procedures). The authorsused the Cox proportional hazardmodel to identify the relative risk of
trabeculectomy failure followingphacoemulsification cataract surgery.
The authors found the 3-yearprobability of treatment success forall patients who underwent tra-beculectomy with MMC to be 92.7%for condition A and 81.8% for con-dition B. Of those patients who un-derwent phacoemulsification aftertrabeculectomy with MMC, theprobability of treatment success at 5years for patients who underwentphacoemulsification more than 1year after trabeculectomy with MMCwas 92.6%, whereas for patients whounderwent phacoemulsificationwithin 1 year of trabeculectomywith MMC, the corresponding prob-ability of success was 48.0%. Usingthe Cox proportional hazard model,the authors found that for conditionA, higher IOP prior to trabeculec-tomy was a risk factor for surgicalfailure (p=0.01). For condition B, significant risk factors includedhigher IOP prior to trabeculectomy(p=0.0006), as well as phacoemulsifi-cation within 1 year after trabeculec-tomy (p=0.04). The relative risk forsurgical failure as defined by condi-tion B for patients undergoing pha-coemulsification within 1 year oftrabeculectomy was 2.87, while therelative risk of surgical failure in-creased by 1.09 for each mm Hg ad-ditional pre-trabeculectomy IOP.
Considering the complexitiesand risks associated with trabeculec-tomy surgery, it is vital to identifyand understand risk factors for surgi-cal failure. This study suggests thatphacoemulsification within 1 year oftrabeculectomy is a risk factor forsurgical failure. The authors suggestthat this may occur via scarring ofthe bleb by post-phacoemulsifica-tion inflammation. While it hasbeen attempted to address this question in prior studies, the presentinvestigation uses the Cox propor-tional hazard model (a time-to-eventanalysis estimating the relative riskof surgical failure based on multiplepatient characteristics) to estimatethe relative contribution of individ-ual risk factors to trabeculectomyfailure. However, with a borderlinep-value and lack of an adjustmentfor multiple comparisons, furtherstudies are warranted to support theauthors’ conclusion.
While the statistical analysis isunique for this specific question, thestudy design introduces several limi-
Impact of phacoemulsification on failureof trabeculectomy with mitomycin-CNanako Awai-Kasaoka, M.D., Toshihiro Inoue, M.D., Ph.D., Yuji Takihara, M.D., Ph.D., Atsushi Kawaguchi, Ph.D., Masaru Inatani, M.D., Ph.D., Minako Ogata-Iwao, M.D., Hidenobu Tanihara, M.D., Ph.D.
J Cataract Refract Surg (March) 2012; 38:419-424
Purpose: To evaluate whether phacoemulsification after trabeculectomy affects post-op IOPSetting: Kumamoto University, Kumamoto, JapanDesign: Cohort studyMethods: The medical records of patients with primary open-angleglaucoma or pseudoexfoliation glaucoma who had trabeculectomywith mitomycin-C were reviewed. The primary endpoints were con-dition A (persistent post-op IOP 21 mm Hg or higher or additionalglaucoma procedures with or without medications) and condition B(post-op IOP 18 mm Hg or higher or additional glaucoma procedureswith or without medications). Multivariable analysis was performedusing the Cox proportional hazards model.Results: The records of 178 patients (178 eyes) were reviewed. Themean follow-up was 37.0 months. For condition A, the probabilityof treatment success at 1 year, 2 years, and 3 years was 97.9%,95.0%, and 92.7%, respectively. For condition B, the correspondingprobabilities of success were 92.3%, 84.1%, and 81.8%. Thirty-sevenpatients (37 eyes) had phacoemulsification after trabeculectomy; 10of those patients had phacoemulsification within 1 year after tra-beculectomy. Multivariate analysis showed that a higher IOP beforetrabeculectomy was a significant risk factor for condition A and condition B (P=.01 and P=.0006, respectively); phacoemulsificationwithin 1 year after trabeculectomy was significantly associated withtrabeculectomy failure for condition B (P=.04).Conclusion: Post-op IOP in eyes with previous trabeculectomy maybe affected by the IOP before trabeculectomy and phacoemulsifica-tion within 1 year after trabeculectomy.
EyeWorld journal club
Pratap Challa, M.D.Residency program director, Duke University
failure of trabeculectomy with mitomycin-C”
undergone trabeculectomy. It is notpossible based on this study to deter-mine whether a more aggressiveanti-inflammatory post-op regimenwould have decreased the risk of sur-gical failure.
An additional limitation of thestudy is the inclusion of patientswith both POAG and PXG. It is notpossible to determine based on thedata presented whether the glau-coma diagnosis played any signifi-cant role in the patients’ post-opoutcomes. Although the univariableanalysis was not significant, it is notclear if the study was adequatelypowered to detect a difference. Fur-thermore, additional analyses wouldbe useful to address the impact ofother factors such as why differentMMC dosages were used in thestudy, the amount of phaco powerrequired during surgery (reflectsdensity of cataract), and whetherthere is a difference in failure ratesamong limbus or fornix-based inci-sions. Finally, the exclusion criteria,which include pre-trabeculectomyIOP less than 21 as well as any priorocular surgery, may limit the gener-
alizability of these conclusions toglaucoma patients that do not meetthese criteria.
In summary, this study providesimportant considerations prior toperforming phacoemulsification sur-gery in post-trabeculectomy pa-tients. The authors report thathigher pre-trabeculectomy IOP andphacoemulsification within 1 yearafter trabeculectomy are importantrisk factors for trabeculectomy fail-ure. Due to the limitations notedabove, the study cannot addresssome important clinical questionssuch as whether a more intensiveanti-inflammatory regimen afterphacoemulsification helps preventsurgical failure and whether it wouldbe beneficial for patients who de-velop cataracts soon after trabeculec-tomy to defer phacoemulsificationuntil 1 year post-trabeculectomy. Fu-ture prospective randomized trialswill be required in order to addressthese questions and provide impor-tant guidance for clinicians. EW
Contact informationChalla: [email protected]
March 2012
phacoemulsification on
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blocker. Propranolol 10 mg can helpthe hand tremor and tachycardiathat accompanies surgical anxiety. Adrop of sublingual timolol oph-thalmic solution can also work. Butdon’t try it the first time on themorning of your case. Test it a fewdays in advance to make sure thatyou can tolerate the medication.
Intraoperative: 1) Surgeon com-fort is key. Correct body and handposition is critical in controlling atremor. 2) Before the patient isprepped the resident should positionthe patient and microscope andmake sure the foot pedals of the mi-croscope and phaco machine are ina good position. 3) Wrist fatigue cancause a tremor. During the case thesurgeon’s wrist should be supportedeither on the patient’s cheek or browor on a wrist rest affixed to thestretcher. 4) Holding the instru-ments too tightly causes musclecramps, finger fatigue, and a tremor.Taking a break for a few relaxingbreaths and finger stretches help.Holding instruments too close to thetip decreases the range of motionand fluidity of movement with the
fingers, again leading to wrist andfinger fatigue. 5) Sometimes I justhold a resident’s hand to calm thetremor and guide the instrumentthrough a difficult step. Once I feelthe resident relax and take over themaneuver I let go—surgical trainingwheels. EW
References1. Elman MJ, Sugar J, Fiscella R, Deutsch TA,Noth J, Nyberg M, Packo K, Anderson RJ. Theeffect of propranolol versus placebo on resi-dent surgical performance. Trans Am Ophthal-mol Soc. 1998;96:283-91; discussion 291-4.
2. Humayun MU, Rader RS, Pieramici DJ, AwhCC, de Juan E Jr. Quantitative measurement ofthe effects of caffeine and propranolol on surgeon hand tremor. Arch Ophthalmol.1997Mar;115(3):371-4.
Editors’ note: The doctors mentionedhave no financial interests related tothis article.
Contact informationKarp: [email protected]: [email protected]: [email protected]
