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Metamorphopsia and Optical Coherence Tomography Findings After Rhegmatogenous Retinal Detachment Surgery
CORRESPONDENCE Metamorphopsia and Optical Coherence Tomography Findings After Rhegmatogenous Retinal Detachment Surgery EDITOR: WE WOULD LIKE TO COMMENT SOME ASPECTS OF THE
manuscript by Okamoto and associates1 regarding the relationship between metamorphopsia and macular morphologic changes in patients who have undergone surgery for rhegmatogenous retinal detachment (RRD). Interestingly, the authors report that 64% of the metamorphopsic eyes exhibited normal-appearing spectraldomain optical coherence tomography (OCT) findings. However, OCT images and metamorphopsia scores were obtained at variable intervals (6-12 months) after operation, so it is possible that substantial retinal morphologic abnormalities were already resolved by the time the images were taken.2,3 The chance of missing subtle abnormalities might have been further enhanced by the use of an OCT protocol consisting of only 5 horizontal and 5 vertical raster scans. Another limitation of the study is that the authors do not clarify if special attention was paid to check whether the central scan was centered on the fovea and whether the retinal abnormalities involving the central scan were considered more relevant than those observed elsewhere. This is important because alterations occurring at the fovea may have repercussions on the quality of vision, including metamorphopsia, more conspicuous than alterations involving other macular areas. The authors speculate, but do not prove, that metamorphopsia in eyes with ‘‘normal-appearing OCT’’ might be related to unintentional retinal displacement, a complication clearly visualized using fundus autofluorescence (FAF) imaging4 (not recorded in this study). According to our experience,5 the rate of unintentional displacement, originally reported as high as 62% in association to cystic RRD managed with pars plana vitrectomy (PPV) and gas,4 is reduced by postoperative face-down posturing. In the present study, patients injected with gas were instructed to maintain a facedown position during the first postoperative week. Therefore, it is possible that at least some cases of unexplained metamorphopsia were actually related to subtle abnormalities that remained undetected on OCT rather than to retinal displacement. Recently, we described that hyperreflective lesions formed by the folded hyperreflective bands constituted by the photoreceptor inner segment/outer segment (IS/OS) 1322
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2014 BY
and by the external limiting membrane (ELM) lines, the so-called ‘‘outer retinal folds’’ (ORFs), are common findings after RRD repair with PPV and gas and relate to metamorphopsia evaluated by Amsler grid.5 ORFs tend to resolve spontaneously within 6 months or less from the operation,6 leaving behind sharply demarcated skip changes in reflectivity of the IS/OS line, the so-called ‘‘IS/OS skip reflectivity abnormalities’’ (RAs). There is no true loss or irregularity but rather skip reflectivity attenuation of the IS/OS line in the context of IS/OS skip RAs. These abnormalities probably reflect morphologic changes and/or very subtle misalignment of the distal end of photoreceptors, are noticed in areas previously occupied by ORFs or pockets of subretinal fluid (both of which may cause metamorphopsia), and may be associated with metamorphopsia themselves.5 IS/OS skip RAs may still be visible in a substantial proportion of eyes 6 months after operation.6 We believe that becoming familiar with these subtle abnormalities might be useful to explain at least some cases of ‘‘unexplained’’ metamorphopsia occurring in eyes not showing gross OCT abnormalities in the macula after successfully repaired RRD. ROBERTO DELL’OMO
Campobasso, Italy MARCO MURA
Amsterdam, The Netherlands BOTH AUTHORS HAVE COMPLETED AND SUBMITTED THE ICMJE Form for Disclosure of Potential Conflicts of Interest and none were reported. The authors indicate no funding support.
REFERENCES
1. Okamoto F, Sugiura Y, Okamoto Y, Hiraoka T, Oshika T. Metamorphopsia and optical coherence tomography findings after rhegmatogenous retinal detachment surgery. Am J Ophthalmol 2014;157(1):214–220. 2. Wakabayashi T, Oshima Y, Fujimoto H, et al. Foveal microstructure and visual acuity after retinal detachment repair: imaging analysis by Fourier-domain optical coherence tomography. Ophthalmology 2009;116(3):519–528. 3. Shimoda Y, Sano M, Hashimoto H, Yokota Y, Kishi S. Restoration of photoreceptor outer segment after vitrectomy for retinal detachment. Am J Ophthalmol 2010;149(2): 284–290. 4. Shiragami C, Shiraga F, Yamaji H, et al. Unintentional displacement of the retina after standard vitrectomy for rhegmatogenous retinal detachment. Ophthalmology 2010;117(1): 86–92.
ELSEVIER INC. ALL
RIGHTS RESERVED.
0002-9394/$36.00 http://dx.doi.org/10.1016/j.ajo.2014.02.024
5. dell’Omo R, Mura M, Lesnik Oberstein SY, Bijl HM, Tan HS. Early simultaneous fundus autofluorescence and optical coherence tomography features after pars plana vitrectomy for primary rhegmatogenous retinal detachment. Retina 2012;32(4):719–728. 6. dell’Omo R, Tan HS, Schlingemann RO, et al. Evolution of outer retinal folds occurring after vitrectomy for retinal detachment repair. Invest Ophthalmol Vis Sci 2012;53(13):7928–7935.
However, some other cases demonstrated metamorphopsia that was unexplainable by a transient retinal morphologic change. One patient exhibited normal-appearing OCT findings and severe metamorphopsia even 10 days after surgery. Future studies involving more evaluation points with shorter intervals may further facilitate our understanding about metamorphopsia after RD surgery. FUMIKI OKAMOTO
REPLY
YOSHIMI SUGIURA YOSHIFUMI OKAMOTO
WE THANK DRS DELL’OMO AND MURA FOR THEIR COM-
TAKAHIRO HIRAOKA
ments regarding our article. In almost all of our cases, we performed 5 horizontal and 5 vertical raster scans at least 3 times using spectral-domain optical coherence tomography (OCT), and selected a representative image centered on the fovea. In our results, 32 of the 50 metamorphopsic eyes (64%) after rhegmatogenous retinal detachment (RD) surgery exhibited normal-appearing OCT findings without any disruption of inner/outer segment (IS/OS), external limiting membrane (ELM), or abnormal macular contour.1 As Drs dell’Omo and Mura pointed out, outer retinal folds (ORFs) and IS/OS skip reflectivity abnormalities (RAs)2,3 might have been included in these 32 cases with normalappearing OCT. ORFs tend to resolve spontaneously within 6 months or less following vitrectomy. However, we evaluated the patients at 6-12 months postoperatively. Thus, it is difficult to detect transient retinal morphologic abnormalities occurring in the 6-month period after surgery. From the total of 32 cases with metamorphopsia and normal-appearing OCT, therefore, we extracted some cases whose OCT images were obtained within 6 months postoperatively. As a result, we were able to investigate OCT images within 1 month postoperatively in 5 of the 32 cases, and within 3 months postoperatively in 20 of the 32 cases. The results showed that 2 of the 32 cases had ORFs at the fovea at 3 months postoperatively. The ORFs resolved, but IS/OS skip RAs remained at 6 months postoperatively. Seven of the 32 cases had hyperreflective IS/OS line at the foveal region at 3 months postoperatively, of which the hyperreflective IS/OS line resolved at 6 months postoperatively in 5 cases and no change was observed in the other 2 cases. We are not sure whether the hyperreflective IS/OS line in these 7 cases had ORFs within 3 months postoperatively. Nine of the 20 cases whose OCT images were obtained at 3 months postoperatively had neither ORFs nor IS/OS skip RAs. It could be considered that certain retinal morphologic abnormalities existed in these cases within 3 months following surgery. dell’Omo and associates found that the presence of ORFs was associated with metamorphopsia.2 In consideration of our results and those of the previous report, our findings suggested that transient retinal morphologic abnormalities such as ORFs and IS/OS skip RAs occurred within 6 months after operation and caused metamorphopsia in some of the cases with ‘‘normal-appearing OCT.’’
TETSURO OSHIKA
VOL. 157, NO. 6
Ibaraki, Japan CONFLICT OF INTEREST DISCLOSURES: SEE THE ORIGINAL article1 for any disclosures of the authors.
REFERENCES
1. Okamoto F, Sugiura Y, Okamoto Y, Hiraoka T, Oshika T. Metamorphopsia and optical coherence tomography findings after rhegmatogenous retinal detachment surgery. Am J Ophthalmol 2014;157(1):214–220. 2. dell’Omo R, Mura M, Lesnik Oberstein SY, Bijl HM, Tan HS. Early simultaneous fundus autofluorescence and optical coherence tomography features after pars plana vitrectomy for primary rhegmatogenous retinal detachment. Retina 2012; 32(4):719–728. 3. dell’Omo R, Tan HS, Schlingemann RO, et al. Evolution of outer retinal folds occurring after vitrectomy for retinal detachment repair. Invest Ophthalmol Vis Sci 2012;53(13):7928–7935.
Impact of Crystalline Lens Opacification on Effective Phacoemulsification Time in Femtosecond Laser–Assisted Cataract Surgery EDITOR: WE WOULD LIKE TO THANK MAYER AND ASSOCIATES1 FOR
describing reduction of ultrasound energy with femtosecond laser phacofragmentation. However, the authors’ methodology is ambiguous and may ignore the contribution of torsional power during phacoemulsification. Mayer and associates used the Infiniti Vision System (Alcon, Inc, Ft. Worth, Texas, USA). Ambiguity results because the Infiniti Metrics Display does not provide Effective Phaco Time (EPT). Rather, it provides Phaco Time, defined as the ‘‘total time phaco power was active,’’ and 2 metrics of phaco power, ‘‘Average Phaco Power’’ and ‘‘Average Phaco Power in Position 3.’’ Average Phaco Power is defined as ‘‘Average phaco power over time when
CORRESPONDENCE
1323
manuscript by Okamoto and associates1 regarding the relationship between metamorphopsia and macular morphologic changes in patients who have undergone surgery for rhegmatogenous retinal detachment (RRD). Interestingly, the authors report that 64% of the metamorphopsic eyes exhibited normal-appearing spectraldomain optical coherence tomography (OCT) findings. However, OCT images and metamorphopsia scores were obtained at variable intervals (6-12 months) after operation, so it is possible that substantial retinal morphologic abnormalities were already resolved by the time the images were taken.2,3 The chance of missing subtle abnormalities might have been further enhanced by the use of an OCT protocol consisting of only 5 horizontal and 5 vertical raster scans. Another limitation of the study is that the authors do not clarify if special attention was paid to check whether the central scan was centered on the fovea and whether the retinal abnormalities involving the central scan were considered more relevant than those observed elsewhere. This is important because alterations occurring at the fovea may have repercussions on the quality of vision, including metamorphopsia, more conspicuous than alterations involving other macular areas. The authors speculate, but do not prove, that metamorphopsia in eyes with ‘‘normal-appearing OCT’’ might be related to unintentional retinal displacement, a complication clearly visualized using fundus autofluorescence (FAF) imaging4 (not recorded in this study). According to our experience,5 the rate of unintentional displacement, originally reported as high as 62% in association to cystic RRD managed with pars plana vitrectomy (PPV) and gas,4 is reduced by postoperative face-down posturing. In the present study, patients injected with gas were instructed to maintain a facedown position during the first postoperative week. Therefore, it is possible that at least some cases of unexplained metamorphopsia were actually related to subtle abnormalities that remained undetected on OCT rather than to retinal displacement. Recently, we described that hyperreflective lesions formed by the folded hyperreflective bands constituted by the photoreceptor inner segment/outer segment (IS/OS) 1322
Ó
2014 BY
and by the external limiting membrane (ELM) lines, the so-called ‘‘outer retinal folds’’ (ORFs), are common findings after RRD repair with PPV and gas and relate to metamorphopsia evaluated by Amsler grid.5 ORFs tend to resolve spontaneously within 6 months or less from the operation,6 leaving behind sharply demarcated skip changes in reflectivity of the IS/OS line, the so-called ‘‘IS/OS skip reflectivity abnormalities’’ (RAs). There is no true loss or irregularity but rather skip reflectivity attenuation of the IS/OS line in the context of IS/OS skip RAs. These abnormalities probably reflect morphologic changes and/or very subtle misalignment of the distal end of photoreceptors, are noticed in areas previously occupied by ORFs or pockets of subretinal fluid (both of which may cause metamorphopsia), and may be associated with metamorphopsia themselves.5 IS/OS skip RAs may still be visible in a substantial proportion of eyes 6 months after operation.6 We believe that becoming familiar with these subtle abnormalities might be useful to explain at least some cases of ‘‘unexplained’’ metamorphopsia occurring in eyes not showing gross OCT abnormalities in the macula after successfully repaired RRD. ROBERTO DELL’OMO
Campobasso, Italy MARCO MURA
Amsterdam, The Netherlands BOTH AUTHORS HAVE COMPLETED AND SUBMITTED THE ICMJE Form for Disclosure of Potential Conflicts of Interest and none were reported. The authors indicate no funding support.
REFERENCES
1. Okamoto F, Sugiura Y, Okamoto Y, Hiraoka T, Oshika T. Metamorphopsia and optical coherence tomography findings after rhegmatogenous retinal detachment surgery. Am J Ophthalmol 2014;157(1):214–220. 2. Wakabayashi T, Oshima Y, Fujimoto H, et al. Foveal microstructure and visual acuity after retinal detachment repair: imaging analysis by Fourier-domain optical coherence tomography. Ophthalmology 2009;116(3):519–528. 3. Shimoda Y, Sano M, Hashimoto H, Yokota Y, Kishi S. Restoration of photoreceptor outer segment after vitrectomy for retinal detachment. Am J Ophthalmol 2010;149(2): 284–290. 4. Shiragami C, Shiraga F, Yamaji H, et al. Unintentional displacement of the retina after standard vitrectomy for rhegmatogenous retinal detachment. Ophthalmology 2010;117(1): 86–92.
ELSEVIER INC. ALL
RIGHTS RESERVED.
0002-9394/$36.00 http://dx.doi.org/10.1016/j.ajo.2014.02.024
5. dell’Omo R, Mura M, Lesnik Oberstein SY, Bijl HM, Tan HS. Early simultaneous fundus autofluorescence and optical coherence tomography features after pars plana vitrectomy for primary rhegmatogenous retinal detachment. Retina 2012;32(4):719–728. 6. dell’Omo R, Tan HS, Schlingemann RO, et al. Evolution of outer retinal folds occurring after vitrectomy for retinal detachment repair. Invest Ophthalmol Vis Sci 2012;53(13):7928–7935.
However, some other cases demonstrated metamorphopsia that was unexplainable by a transient retinal morphologic change. One patient exhibited normal-appearing OCT findings and severe metamorphopsia even 10 days after surgery. Future studies involving more evaluation points with shorter intervals may further facilitate our understanding about metamorphopsia after RD surgery. FUMIKI OKAMOTO
REPLY
YOSHIMI SUGIURA YOSHIFUMI OKAMOTO
WE THANK DRS DELL’OMO AND MURA FOR THEIR COM-
TAKAHIRO HIRAOKA
ments regarding our article. In almost all of our cases, we performed 5 horizontal and 5 vertical raster scans at least 3 times using spectral-domain optical coherence tomography (OCT), and selected a representative image centered on the fovea. In our results, 32 of the 50 metamorphopsic eyes (64%) after rhegmatogenous retinal detachment (RD) surgery exhibited normal-appearing OCT findings without any disruption of inner/outer segment (IS/OS), external limiting membrane (ELM), or abnormal macular contour.1 As Drs dell’Omo and Mura pointed out, outer retinal folds (ORFs) and IS/OS skip reflectivity abnormalities (RAs)2,3 might have been included in these 32 cases with normalappearing OCT. ORFs tend to resolve spontaneously within 6 months or less following vitrectomy. However, we evaluated the patients at 6-12 months postoperatively. Thus, it is difficult to detect transient retinal morphologic abnormalities occurring in the 6-month period after surgery. From the total of 32 cases with metamorphopsia and normal-appearing OCT, therefore, we extracted some cases whose OCT images were obtained within 6 months postoperatively. As a result, we were able to investigate OCT images within 1 month postoperatively in 5 of the 32 cases, and within 3 months postoperatively in 20 of the 32 cases. The results showed that 2 of the 32 cases had ORFs at the fovea at 3 months postoperatively. The ORFs resolved, but IS/OS skip RAs remained at 6 months postoperatively. Seven of the 32 cases had hyperreflective IS/OS line at the foveal region at 3 months postoperatively, of which the hyperreflective IS/OS line resolved at 6 months postoperatively in 5 cases and no change was observed in the other 2 cases. We are not sure whether the hyperreflective IS/OS line in these 7 cases had ORFs within 3 months postoperatively. Nine of the 20 cases whose OCT images were obtained at 3 months postoperatively had neither ORFs nor IS/OS skip RAs. It could be considered that certain retinal morphologic abnormalities existed in these cases within 3 months following surgery. dell’Omo and associates found that the presence of ORFs was associated with metamorphopsia.2 In consideration of our results and those of the previous report, our findings suggested that transient retinal morphologic abnormalities such as ORFs and IS/OS skip RAs occurred within 6 months after operation and caused metamorphopsia in some of the cases with ‘‘normal-appearing OCT.’’
TETSURO OSHIKA
VOL. 157, NO. 6
Ibaraki, Japan CONFLICT OF INTEREST DISCLOSURES: SEE THE ORIGINAL article1 for any disclosures of the authors.
REFERENCES
1. Okamoto F, Sugiura Y, Okamoto Y, Hiraoka T, Oshika T. Metamorphopsia and optical coherence tomography findings after rhegmatogenous retinal detachment surgery. Am J Ophthalmol 2014;157(1):214–220. 2. dell’Omo R, Mura M, Lesnik Oberstein SY, Bijl HM, Tan HS. Early simultaneous fundus autofluorescence and optical coherence tomography features after pars plana vitrectomy for primary rhegmatogenous retinal detachment. Retina 2012; 32(4):719–728. 3. dell’Omo R, Tan HS, Schlingemann RO, et al. Evolution of outer retinal folds occurring after vitrectomy for retinal detachment repair. Invest Ophthalmol Vis Sci 2012;53(13):7928–7935.
Impact of Crystalline Lens Opacification on Effective Phacoemulsification Time in Femtosecond Laser–Assisted Cataract Surgery EDITOR: WE WOULD LIKE TO THANK MAYER AND ASSOCIATES1 FOR
describing reduction of ultrasound energy with femtosecond laser phacofragmentation. However, the authors’ methodology is ambiguous and may ignore the contribution of torsional power during phacoemulsification. Mayer and associates used the Infiniti Vision System (Alcon, Inc, Ft. Worth, Texas, USA). Ambiguity results because the Infiniti Metrics Display does not provide Effective Phaco Time (EPT). Rather, it provides Phaco Time, defined as the ‘‘total time phaco power was active,’’ and 2 metrics of phaco power, ‘‘Average Phaco Power’’ and ‘‘Average Phaco Power in Position 3.’’ Average Phaco Power is defined as ‘‘Average phaco power over time when
CORRESPONDENCE
1323