e33
CORRESPONDENCE
Iatrogenic retinal breaks were seen in 12 eyes and were lasered intraoperatively. We prefer the laser indirect ophthalmoscope to treat retinal breaks during surgery, but understand that endophotocoagulation is an equally good alternative for treating retinal breaks. We do not believe that tamponade is necessary to successfully treat a retinal break, as long as all vitreous is removed from the break and the break is lasered appropriately. We did not encounter postoperative hypotony in our study, as we typically adhere to meticulous wound construction and use beveled trocars at a 30° angle to the sclera. We believe that excellent wound construction in addition to short and limited vitrectomy contributes to minimal postoperative hypotony. Although we did not encounter a case of retinal detachment in our mean 18 months of follow-up, we certainly agree that with longer follow-up, complications such as retinal detachment can occur. We believe that our extremely low rate of retinal detachment is due to meticulous examination of the peripheral retina and the laser treatment of any suspicious retinal pathology before concluding the surgery. Our study was a consecutive case series and therefore was not intended to have a control group. The patients obviously realized that they had surgery, and therefore the placebo effect, first attributed to Henry Beecher, cannot be avoided in this particular study. We are currently enrolling patients in a prospective controlled study evaluating reading speed before and after vitrectomy for symptomatic vitreous debris. This will provide additional answers and objective measurements regarding the efficacy of surgery. We thank Modi et al for their interest in our study. John O. Mason, III, MD* Michael G. Neimkin, MD† John V. Mason, IV‡ Duncan A. Friedman, MD* Richard M. Feist, MD* Martin L. Thomley, MD* Michael A. Albert, Jr., MD* Lauren Mason‡ *Department of Ophthalmology, Retina Consultants of Alabama, University of Alabama at Birmingham School of Medicine, Birmingham, Alabama †Department of Ophthalmology, University of Alabama at Birmingham School of Medicine, Birmingham, Alabama ‡Retina Consultants of Alabama, Birmingham, Alabama None of the authors have any financial/conflicting interests to disclose.
References 1. Mason JO III, Neimkin MG, Mason JO IV, et al. Safety, efficacy and quality of life following sutureless vitrectomy for symptomatic vitreous floaters. Retina 2014;34:1055– 1061. 2. Tan HS, Mura M, Lesnik Oberstein SY, Bijl HM. Safety of vitrectomy for floaters. Am J Ophthalmol 2011;151:995–998.
Correspondence To the Editor: In the recent article titled “Pars plana vitrectomy compared with pars plana vitrectomy combined with scleral buckle in the primary management of noncomplex rhegmatogenous retinal detachment,” Orlin et al1 have concluded that pars plana vitrectomy (PPV) and PPV combined with scleral buckle (PPV/SB) are comparable in the management of primary noncomplex rhegmatogenous retinal detachment. However, this has significant limitations, some of which have been aptly highlighted by the authors themselves. From the available data, we know that the percentage of resurgeries in pars plana vitrectomy (PPV) and PPV combined with sclera buckle (PPV/SB) group were 25% (13 out of 52) and 13.6% (3 out of 22) respectively. Hence, the absolute risk reduction (ARR) was 11.4%. The number needed to treat is approximately one in nine (100/11.4). It means that if all the patients are treated with PPV/SB then one resurgery can be prevented in nine cases. This is clinically significant. In our opinion, the sample size in this study was small. The sample size required finding out whether the difference between the proportion of resurgeries in PPV and PPV/SB groups is statistically significant assuming the power of study to be 80%, and the alpha as 0.05 is 376. We also calculated the power of this particular study from the given data to be 16.8%, which in our opinion is inadequate to draw any conclusion. The author has not mentioned standard deviation wherever the data are expressed in mean. A small sample size with a large standard deviation may suggest that the data are nonparametric, and in such a scenario, the use of a parametric test like independent sample t-test might not be appropriate. The percentage of inferior breaks was more in the PPV/SB group that is likely to have a confounding effect on the results. The outcome measures were well defined by the authors, but the causes and extent of redetachments and the exact surgical intervention that has been carried out during resurgery have not been mentioned. It would have been interesting to see
e34
RETINA, THE JOURNAL OF RETINAL AND VITREOUS DISEASES 2014 VOLUME 34 NUMBER 10
whether scleral buckle was used as an adjunct in managing redetachments. However, I agree with the authors that a longer follow-up period in both groups could bring more differences. Therefore, it will be prudent if we do not infer on the basis of the available data that the two surgical techniques described here are comparable in treating primary noncomplex rhegmatogenous retinal detachment, and look forward to future studies with similar objective but with a larger sample size. Anuria De, DO Rohit R. Modi, MS Umesh C. Behera, MS Retina-Vitreous Service, L. V. Prasad Eye Institute, Bhubaneswar, India None of the authors have any financial/conflicting interests to disclose. Reference 1. Orlin A, Hewing NJ, Nissen M, et al. Pars plana vitrectomy compared with pars plana vitrectomy combined with scleral buckle in the primary management of noncomplex rhegmatogenous retinal detachment. Retina 2014;34:1069–1075.
Reply To the Editor: We thank De et al for their interest in our recent article “Pars plana vitrectomy compared with pars plana vitrectomy combined with scleral buckle in the primary management of noncomplex rhegmatogenous retinal detachment.”1 Although their points regarding absolute risk reduction and alternate outcomes are interesting, our conclusions regarding the study endpoints including single surgery anatomical success remain unchanged. In our study, the mean follow-up was 406.73 days in the PPV group and 502.14 days in the PPB/SB group with minimum inclusion criteria of 2 months. We believe that the majority of redetachments should have occurred within our follow-up period. Mansouri et al2 required a minimum follow-up of 1 month and found that the average time to redetachment was 35 days in the PPV
group, whereas Kinori et al3 defined primary failure as redetachment within 8 weeks. Our minimum follow-up coincides with other studies, and our mean follow-up is comparable with other studies. We do, however, agree that our study has limitations including sample size and others intrinsic to a retrospective review. We attempted to detail these limitations in our discussion section and the impact they may have on our surgical outcomes. Careful interpretation of our results is therefore necessary. The risks and benefits of an encircling element should be weighed for each individual case by the surgeon based on his or her own experience and the detachment’s characteristics. We agree that larger and prospective future studies will be helpful. Anton Orlin, MD* Nina J. Hewing, MD† Michael Nissen, MD* Sangwoo Lee, MD* Szilard Kiss, MD* Donald J. D’Amico, MD* Ya-Lin Chiu, MSc‡ R. V. Paul Chan, MD* *Department of Ophthalmology, Weill Cornell Medical College, New York, New York †Department of Ophthalmology, Campus Benjamin Franklin, Charite - Universitatsmedizin Berlin, Berlin, Germany ‡Everest Clinical Research, Little Falls, New Jersey None of the authors have any financial/conflicting interests to disclose. References 1. Orlin A, Hewing NJ, Nissen M, et al. Pars plana vitrectomy compared with pars plana vitrectomy combined with scleral buckle in the primary management of noncomplex rhegmatogenous retinal detachment. Retina 2014;34:1069–1075. 2. Mansouri A, Almony A, Shah GK, et al. Recurrent retinal detachment: does initial treatment matter? Br J Ophthalmol 2010;94:1344–1347. 3. Kinori M, Moisseiev E, Shoshany N, et al. Comparison of pars plana vitrectomy with and without scleral buckle for the repair of primary rhegmatogenous retinal detachment. Am J Ophthalmol 2011;152:291–297.e2.
CORRESPONDENCE
Iatrogenic retinal breaks were seen in 12 eyes and were lasered intraoperatively. We prefer the laser indirect ophthalmoscope to treat retinal breaks during surgery, but understand that endophotocoagulation is an equally good alternative for treating retinal breaks. We do not believe that tamponade is necessary to successfully treat a retinal break, as long as all vitreous is removed from the break and the break is lasered appropriately. We did not encounter postoperative hypotony in our study, as we typically adhere to meticulous wound construction and use beveled trocars at a 30° angle to the sclera. We believe that excellent wound construction in addition to short and limited vitrectomy contributes to minimal postoperative hypotony. Although we did not encounter a case of retinal detachment in our mean 18 months of follow-up, we certainly agree that with longer follow-up, complications such as retinal detachment can occur. We believe that our extremely low rate of retinal detachment is due to meticulous examination of the peripheral retina and the laser treatment of any suspicious retinal pathology before concluding the surgery. Our study was a consecutive case series and therefore was not intended to have a control group. The patients obviously realized that they had surgery, and therefore the placebo effect, first attributed to Henry Beecher, cannot be avoided in this particular study. We are currently enrolling patients in a prospective controlled study evaluating reading speed before and after vitrectomy for symptomatic vitreous debris. This will provide additional answers and objective measurements regarding the efficacy of surgery. We thank Modi et al for their interest in our study. John O. Mason, III, MD* Michael G. Neimkin, MD† John V. Mason, IV‡ Duncan A. Friedman, MD* Richard M. Feist, MD* Martin L. Thomley, MD* Michael A. Albert, Jr., MD* Lauren Mason‡ *Department of Ophthalmology, Retina Consultants of Alabama, University of Alabama at Birmingham School of Medicine, Birmingham, Alabama †Department of Ophthalmology, University of Alabama at Birmingham School of Medicine, Birmingham, Alabama ‡Retina Consultants of Alabama, Birmingham, Alabama None of the authors have any financial/conflicting interests to disclose.
References 1. Mason JO III, Neimkin MG, Mason JO IV, et al. Safety, efficacy and quality of life following sutureless vitrectomy for symptomatic vitreous floaters. Retina 2014;34:1055– 1061. 2. Tan HS, Mura M, Lesnik Oberstein SY, Bijl HM. Safety of vitrectomy for floaters. Am J Ophthalmol 2011;151:995–998.
Correspondence To the Editor: In the recent article titled “Pars plana vitrectomy compared with pars plana vitrectomy combined with scleral buckle in the primary management of noncomplex rhegmatogenous retinal detachment,” Orlin et al1 have concluded that pars plana vitrectomy (PPV) and PPV combined with scleral buckle (PPV/SB) are comparable in the management of primary noncomplex rhegmatogenous retinal detachment. However, this has significant limitations, some of which have been aptly highlighted by the authors themselves. From the available data, we know that the percentage of resurgeries in pars plana vitrectomy (PPV) and PPV combined with sclera buckle (PPV/SB) group were 25% (13 out of 52) and 13.6% (3 out of 22) respectively. Hence, the absolute risk reduction (ARR) was 11.4%. The number needed to treat is approximately one in nine (100/11.4). It means that if all the patients are treated with PPV/SB then one resurgery can be prevented in nine cases. This is clinically significant. In our opinion, the sample size in this study was small. The sample size required finding out whether the difference between the proportion of resurgeries in PPV and PPV/SB groups is statistically significant assuming the power of study to be 80%, and the alpha as 0.05 is 376. We also calculated the power of this particular study from the given data to be 16.8%, which in our opinion is inadequate to draw any conclusion. The author has not mentioned standard deviation wherever the data are expressed in mean. A small sample size with a large standard deviation may suggest that the data are nonparametric, and in such a scenario, the use of a parametric test like independent sample t-test might not be appropriate. The percentage of inferior breaks was more in the PPV/SB group that is likely to have a confounding effect on the results. The outcome measures were well defined by the authors, but the causes and extent of redetachments and the exact surgical intervention that has been carried out during resurgery have not been mentioned. It would have been interesting to see
e34
RETINA, THE JOURNAL OF RETINAL AND VITREOUS DISEASES 2014 VOLUME 34 NUMBER 10
whether scleral buckle was used as an adjunct in managing redetachments. However, I agree with the authors that a longer follow-up period in both groups could bring more differences. Therefore, it will be prudent if we do not infer on the basis of the available data that the two surgical techniques described here are comparable in treating primary noncomplex rhegmatogenous retinal detachment, and look forward to future studies with similar objective but with a larger sample size. Anuria De, DO Rohit R. Modi, MS Umesh C. Behera, MS Retina-Vitreous Service, L. V. Prasad Eye Institute, Bhubaneswar, India None of the authors have any financial/conflicting interests to disclose. Reference 1. Orlin A, Hewing NJ, Nissen M, et al. Pars plana vitrectomy compared with pars plana vitrectomy combined with scleral buckle in the primary management of noncomplex rhegmatogenous retinal detachment. Retina 2014;34:1069–1075.
Reply To the Editor: We thank De et al for their interest in our recent article “Pars plana vitrectomy compared with pars plana vitrectomy combined with scleral buckle in the primary management of noncomplex rhegmatogenous retinal detachment.”1 Although their points regarding absolute risk reduction and alternate outcomes are interesting, our conclusions regarding the study endpoints including single surgery anatomical success remain unchanged. In our study, the mean follow-up was 406.73 days in the PPV group and 502.14 days in the PPB/SB group with minimum inclusion criteria of 2 months. We believe that the majority of redetachments should have occurred within our follow-up period. Mansouri et al2 required a minimum follow-up of 1 month and found that the average time to redetachment was 35 days in the PPV
group, whereas Kinori et al3 defined primary failure as redetachment within 8 weeks. Our minimum follow-up coincides with other studies, and our mean follow-up is comparable with other studies. We do, however, agree that our study has limitations including sample size and others intrinsic to a retrospective review. We attempted to detail these limitations in our discussion section and the impact they may have on our surgical outcomes. Careful interpretation of our results is therefore necessary. The risks and benefits of an encircling element should be weighed for each individual case by the surgeon based on his or her own experience and the detachment’s characteristics. We agree that larger and prospective future studies will be helpful. Anton Orlin, MD* Nina J. Hewing, MD† Michael Nissen, MD* Sangwoo Lee, MD* Szilard Kiss, MD* Donald J. D’Amico, MD* Ya-Lin Chiu, MSc‡ R. V. Paul Chan, MD* *Department of Ophthalmology, Weill Cornell Medical College, New York, New York †Department of Ophthalmology, Campus Benjamin Franklin, Charite - Universitatsmedizin Berlin, Berlin, Germany ‡Everest Clinical Research, Little Falls, New Jersey None of the authors have any financial/conflicting interests to disclose. References 1. Orlin A, Hewing NJ, Nissen M, et al. Pars plana vitrectomy compared with pars plana vitrectomy combined with scleral buckle in the primary management of noncomplex rhegmatogenous retinal detachment. Retina 2014;34:1069–1075. 2. Mansouri A, Almony A, Shah GK, et al. Recurrent retinal detachment: does initial treatment matter? Br J Ophthalmol 2010;94:1344–1347. 3. Kinori M, Moisseiev E, Shoshany N, et al. Comparison of pars plana vitrectomy with and without scleral buckle for the repair of primary rhegmatogenous retinal detachment. Am J Ophthalmol 2011;152:291–297.e2.
