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Clinical and Experimental Ophthalmology 2015; 43: 815–819 doi: 10.1111/ceo.12580
Original Article Comparison of swept source optical coherence tomography and spectral domain optical coherence tomography in polypoidal choroidal vasculopathy Daniel SW Ting MBBS(Hons) MMed(Ophth), Gemmy CM Cheung FRCOphth(London), Laurence S Lim FRCS(Ed) and Ian YS Yeo FRCS(Ed) Singapore National Eye Center, Singapore Health Service (SingHealth), Singapore, Singapore
ABSTRACT Background: Swept source optical coherence tomography (SS-OCT, Topcon Medical System, Japan) is known to have longer wavelength than spectral domain OCT (SD-OCT, Spectralis, Heidelberg Engineering, Germany), allowing a deeper penetration into retina and choroidal layers. This objective of this study was to compare the visibility of retinal and choroidal features in polypoidal choroidal vasculopathy (PCV) using SS-OCT and SD-OCT. Design: This study employs prospective comparative observational case series in Singapore National Eye Center. Participants: There were 20 eyes (20 patients) with PCV confirmed with indocyanine green angiogram. Methods: Six pre-specified OCT parameters (presence of polyps, sharp pigment epithelial detachment [PED] peak, notched PED and visibility of full maximum height of PED, inner segment/outer segment [IS/OS] line and choroid-scleral interface [CSI]) were graded using SS-OCT and SD-OCT. Main Outcome Measures: The Kappa statistics between the two imaging modalities were calculated. Results: Both SS-OCT and SD-OCT were able to detect polypoidal lesions in the majority of eyes (90% and 85%, respectively). However, SS-OCT had
better detection for CSI and IS/OS lines (CSI: 80% vs 45%, P = 0.05; IS/OS line: 65% vs 45%, P = 0.34). For sharp PED peak, notched PED, ability to visualize the full PED height and retinal pigment epithelial line, both OCT machines were able to detect in ≥80% of the eyes. Conclusion: In conclusion, SS-OCT and SD-OCT appeared to be similarly effective at detecting most features associated with PCV. However, SS-OCT is more superior in detecting the CSI. Key words: polypoidal choroidal vasculopathy, swept source optical coherence tomography, polyp.
INTRODUCTION Polypoidal choroidal vasculopathy (PCV) is a disorder involving inner choroidal circulation characterized by the presence of polypoidal, subretinal branching vascular network with aneurysmal terminals.1 It appears as polyp-like orange nodules on fundoscopy. It often presents as multiple, recurrent serosanguineous retinal pigment epithelial (RPE) and neurosensory detachment due to the leakage or bleeding from the lesions.1 Traditionally, the diagnosis of PCV has been made on the basis of clinical examination (subretinal orange nodules, haemorrhagic pigment epithelial detachment) and indocyanine green angiography (ICGA).1,2 More recently, optical coherence tomography (OCT) has also been described as a useful tool.
■ Correspondence: Dr Daniel Shu Wei Ting, Singapore National Eye Centre, Ophthalmology, 11 Third Hospital Avenue, Singapore 168751, Singapore. Email: [email protected] Received 6 February 2015; accepted 14 June 2015. Conflicts of interest: None. Funding sources: None. © 2015 Royal Australian and New Zealand College of Ophthalmologists
816
Ting et al.
Reported OCT-based features often associated with PCV include ‘double layer sign’ in branching vascular network; notched pigment epithelial detachment (PED) representing polyp adherent to the undersurface of RPE within a PED; and the actual polyp characterized by a rounded hypo-reflective lumen surrounded by hyper-reflective wall adherent to the underside of RPE.3–8 Abnormalities in the choroid have also been suggested to be an important contributing factor in the pathogenesis of PCV.2 The advance of enhanced depth imaging OCT (EDI-OCT) and swept source OCT (SS-OCT) have enabled researchers to image the choroid with improved resolution. SS-OCT has a wavelength of 1050 nm with a scanning speed of 100 000 A-scans/sec, allowing a rapid penetration of vitreous, retina, choroid and sclera within a short time. Compared to spectral-domain OCD (SD-OCT), swept source OCT (SS-OCT) has greater sensitivity and lower signal-to-noise ratios (SNR) at greater scanning depths. In addition, while the enhanced depth imaging (EDI) mode, SD-OCT provides clearer images of sub-RPE structures, clarity of structures above the RPE in the EDI mode may deteriorate, as the signals above the RPE are scattered in the inverted image and the image quality decreases during averaging in eyes with poor fixation.9 One may hypothesize that SS-OCT would be more sensitive than SD-OCT in non-invasively detecting features suggestive of PCV. However, to date, only limited studies have evaluated the use of SS-OCT for in eyes with PCV.10,11 In the current study, we aim to investigate whether the SS-OCT provides significant advantages over SD-OCT in imaging several important retina and choroidal features in the setting of PCV.
METHODS Patients’ recruitment This was a single-centre prospective observational case series. Twenty eyes from 20 consecutive patients with treatment naïve PCV confirmed on ICGA were included. This study was approved by the Centralized Institutional Review Board of SingHealth, Singapore and conducted in accordance with the Declaration of Helsinki. All participants provided a signed informed consent for their participation. All patients underwent a comprehensive ocular examination and imaging which included SD-OCT (Spectralis, Heidelberg Engineering, Germany), fundus fluorescein and indocyanine green angiogram (Spectralis, Heidelberg Engineering, Germany) and SS-OCT (Topcon Atlantis DRI OCT-1; Topcon Medical Systems, Paramus, NJ, USA).
PCV diagnosis Diagnosis of PCV was made based on ICGA findings graded by two retina specialists using the EVEREST criteria,12 which requires presence of typical hyperfluorescent nodules in the early phase ICGA, and at least one of the following criteria must be fulfilled: (i) presence of hypofluorescent halo around the lesion; (ii) presence of pulsations; and (iii) association with a branching vascular network (BVN); (iv) correspondence with an orange-red nodule in fundus photographs; (v) a nodular appearance rather than a flat lesion, when viewed in stereo pairs; (vi) associated with massive submacular haemorrhage.
SS-OCT and SD-OCT imaging protocol SS-OCT images were captured using the automated averaging system in three modes – radial (12 mm), five lines and three-dimensional, centered at the macula. For SD-OCT, a minimum of 25 B-scans per volume scan of 20° × 20° was used. Each scan was averaged with nine frames per B-scan with a distance of 240 μm between each B-scan.
Grading of the PCV features in SS-OCT and SD-OCT For SS-OCT and SD-OCT, the following prespecified OCT features were graded by two retinal specialists: Presence of (i) polyp, (characterized by a rounded hypo-reflective lumen surrounded by hyper-reflective wall adherent to the underside of RPE); (ii) sharp and peaked pigment epithelial detachment (PED) and (iii) notched PED; (iv) ability to visualize full height of the PED; ability to clearly identify (v) the inner segment/outer segment (IS/ OS) line; (vi) the RPE line and; (vii) choroid-scleral interface (CSI). Detection rate and agreement between the two OCTs were compared. For statistical analysis, we used Chi-square with Yates’ correction with two-tailed P value. In addition, Kappa’s statistics between SS-OCT and SD-OCT were calculated using SPSS version 21 (SPSS, Chicago, IL, USA). The inter-observer variation is graded as: (i) < 0 – less than chance agreement; (ii) 0.01 – 0.20 – slight agreement; (iii) 0.21–0.40 – fair agreement; (iv) 0.41 – 0.60 – moderate agreement; (v) 0.61–0.80 – substantial agreement and; (vi) 0.81–0.99 – almost perfect agreement (Fig. 1).13
RESULTS A total of 20 eyes from 20 patients (10 males, 10 females) were recruited in our studies. The mean age was 63 years (standard deviation 9.4). At least one polypoidal lesion was detected in 17 eyes using
© 2015 Royal Australian and New Zealand College of Ophthalmologists
Swept-source OCT for PCV
817
Figure 1. Optical coherence tomography features associated with polypoidal choroidal vasculopathy. Swept source optical coherence tomography shows presence of sharp, peaked pigment epithelial detachment (asterisk), inner segment/outer segment (IS/OS) line, retina pigment epithelial (RPE) line, sclera-choroidal interface (CSI) and a polyp in a patient with polypoidal choroidal vasculopathy.
Table 1. Comparison of SS-OCT versus SD-OCT in detecting different structures in patients with polypoidal choroidal vasculopathy (PCV)
Polyp Sharp PED peak PED notch Full PED height IS/OS line RPE line Choroidal scleral interface
SS-OCT % (eyes)
SD-OCT % (eyes)
P-value
Kappa’s statistics
90% (18) 90% (18) 90% (18) 90% (18) 65% (13) 95% (19) 80% (16)
85% (17) 85% (17) 85% (17) 80% (16) 45% (9) 90% (18) 45% (9)
0.63 0.63 0.63 0.66 0.34 0.55 0.05
0.78 0.78 0.77 0.62 0.42 0.64 0.34
IS/OS, inner segment/outer segment; PED, pigment epithelial detachment; RPE, recurrent pigment epithelial; SD-OCT, spectral domain optical coherence tomography; SS-OCT, swept source optical coherence tomography.
SD-OCT and in 18 eyes using SS-OCT. (Table 1) Similarly, sharp, peaked PED and notched PED were also detected on both SD-OCT and SS-OCT in the majority of eyes. However, IS/OS line and CSI were only clearly visible in 9 of 20 eyes using SD-OCT. Using SS-OCT however, IS/OS line was visible in 13 eyes and CSI was visible in 16 eyes (Fig. 1 and Fig. 2). SS-OCT was able to detect more polyps as compared to SD-OCT (18 eyes vs 16 eyes) (Fig. 3). The Kappa statistics show that agreement between the two OCT systems was in the substantial
range (Kappa = 0.61–0.80) for detection of polyps, sharp PED peak, notched PED and visibility of full height of PED and RPE line. However, agreement was only moderate (Kappa = 0.41–0.60) for visibility of IS/OS line, and fair (Kappa = 0.21–0.40) for visibility of CSI.
DISCUSSION SS-OCT has been found to be superior to SD-OCT in the imaging of choroidoscleral interface in normal patients14 and posterior staphyloma in pathological myopia15 due to the higher resolution resulting from higher signal-to-noise ratio, and ability to penetrate to deeper retinal and choroidal structures. These properties may be particularly important in eyes with large serosanguineous PED. We perform a pilot study to evaluate the feasibility of SS-OCT in detecting various retina and choroidal structures in PCV patients, with comparison to the SD-OCT. In our study, both OCTs were able to detect ‘polypoidal lesions’ in the majority of eyes. SS-OCT was able to detect one more patient with a polyp due to its wider scanning width (Fig. 3). The detection rate for most of the other PCV features above RPE was similar between the two imaging modalities. One notable difference between the SS-OCT and SD-OCT from our results is the superior ability to visualize the choroidal scleral interfact (CSI) (SS-
© 2015 Royal Australian and New Zealand College of Ophthalmologists
818
Ting et al. Figure 2. Comparison of swept source optical coherence tomography (SS-OCT) and spectral domain (SD)-OCT features in polypoidal choroidal vasculopathy. Neurosensory retina detachment (asterisk) and notched pigment epithelial detachment are clearly seen on both SS-OCT and SD-OCT. However, the choroid-slceral interface and segment/outer segment (IS-OS) line are clearly visible on SS-OCT but not on SD-OCT.
Figure 3. Comparison of swept source optical coherence tomography (SS-OCT) (Fig. 3a) and spectral domain (SD)-OCT (Fig. 3b) features in polypoidal choroidal vasculopathy (PCV). SS-OCT was able to detect a polyp due to a wider scanning width, compared to SD-OCT.
(a)
(b)
OCT: 80%; SD-OCT: 45%, P = 0.05). CSI is increasingly recognized as an important landmark in retinal disease. Identification of the CSI allows assessment of choroidal thickness, which may help to differentiate between PCV and neovascular age-related macular degeneration (AMD)16 as eyes with PCV
have been reported to have thicker choroid compared to AMD patients,16 possibly due to the dilation of middle or large choroidal vessels17 or choroidal vascular hyperpermeability.18 Future research with a larger sample size will be of great value to evaluate the diagnostic sensitivity and specificity of SS-OCT
© 2015 Royal Australian and New Zealand College of Ophthalmologists
Swept-source OCT for PCV in detecting PCV as compared to SD-OCT, with reference to ICGA. Our study is limited by the small sample size. However, it provides us with a good overview on the image quality and the differences in structure visibility between the two imaging modalities. In conclusion, SS-OCT is more superior in detecting the CSI but has comparable visibility for the other retina features in PCV patients as compared to SD-OCT. Further research will be of great value to determine the sensitivity and specificity of SS-OCT versus SD-OCT in diagnosing PCV without the use of FFA/ICG.
REFERENCES 1. Yannuzzi LA, Sorenson J, Spaide RF, Lipson B. Idiopathic polypoidal choroidal vasculopathy (IPCV). Retina 1990; 10: 1–8. 2. Spaide RF, Yannuzzi LA, Slakter JS, Sorenson J, Orlach DA. Indocyanine green videoangiography of idiopathic polypoidal choroidal vasculopathy. Retina 1995; 15: 100–10. 3. Ojima Y, Hangai M, Sakamoto A et al. Improved visualization of polypoidal choroidal vasculopathy lesions using spectral-domain optical coherence tomography. Retina 2009; 29: 52–9. 4. De Salvo G, Vaz-Pereira S, Keane PA, Tufail A, Liew G. Sensitivity and specificity of spectral-domain optical coherence tomography in detecting idiopathic polypoidal choroidal vasculopathy. Am J Ophthalmol 2014; 158: 1228–38. 5. Abe S, Yamamoto T, Haneda S et al. Three-dimensional features of polypoidal choroidal vasculopathy observed by spectral-domain OCT. Ophthalmic Surg Lasers Imaging 2010; 9: 1–6. 6. Saito M, Iida T, Nagayama D. Cross-sectional and en face optical coherence tomographic features of polypoidal choroidal vasculopathy. Retina 2008; 28: 459–64. 7. Yang LH, Jonas JB, Wei WB. Optical coherence tomographic enhanced depth imaging of polypoidal choroidal vasculopathy. Retina 2013; 33: 1584–9. 8. Sato T, Kishi S, Watanabe G, Matsumoto H, Mukai R. Tomographic features of branching vascular networks
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9.
10.
11.
12.
13.
14.
15.
16.
17.
18.
© 2015 Royal Australian and New Zealand College of Ophthalmologists
in polypoidal choroidal vasculopathy. Retina 2007; 27: 589–94. Sayanagi K, Gomi F, Ikuno Y, Akiba M, Nishida K. Comparison of spectral-domain and high-penetration OCT for observing morphologic changes in age-related macular degeneration and polypoidal choroidal vasculopathy. Graefes Arch Clin Exp Ophthalmol 2014; 252: 3–9. Alasil T, Ferrara D, Adhi M et al. En face imaging of the choroid in polypoidal choroidal vasculopathy using swept-source optical coherence tomography. Am J Ophthalmol 2014; 634–43. Sayanagi K, Gomi F, Akiba M, Sawa M, Hara C, Nishida K. En-face high-penetration optical coherence tomography imaging in polypoidal choroidal vasculopathy. Br J Ophthalmol 2015; 99: 29–35. Koh A, Lee WK, Chen LJ et al. EVEREST study: efficacy and safety of verteporfin photodynamic therapy in combination with ranibizumab or alone versus ranibizumab monotherapy in patients with symptomatic macular polypoidal choroidal vasculopathy. Retina 2012; 32: 1453–64. Viera AJ, Garrett JM. Understanding interobserver agreement: the kappa statistic. Fam Med 2005; 37: 360–3. Adhi M, Liu JJ, Qavi AH et al. Choroidal analysis in healthy eyes using swept-source optical coherence tomography compared to spectral domain optical coherence tomography. Am J Ophthalmol 2014; 157: 1272–81. Lim LS, Cheung G, Lee SY. Comparison of spectral domain and swept-source optical coherence tomography in pathological myopia. Eye (Lond) 2014; 28: 488– 91. Koizumi H, Yamagishi T, Yamazaki T, Kawasaki R, Kinoshita S. Subfoveal choroidal thickness in typical age-related macular degeneration and polypoidal choroidal vasculopathy. Graefes Arch Clin Exp Ophthalmol 2011; 249: 1123–8. Yuzawa M, Mori R, Kawamura A. The origins of polypoidal choroidal vasculopathy. Br J Ophthalmol 2005; 89: 602–7. Sasahara M, Tsujikawa A, Musashi K et al. Polypoidal choroidal vasculopathy with choroidal vascular hyperpermeability. Am J Ophthalmol 2006; 142: 601– 7.
Clinical and Experimental Ophthalmology 2015; 43: 815–819 doi: 10.1111/ceo.12580
Original Article Comparison of swept source optical coherence tomography and spectral domain optical coherence tomography in polypoidal choroidal vasculopathy Daniel SW Ting MBBS(Hons) MMed(Ophth), Gemmy CM Cheung FRCOphth(London), Laurence S Lim FRCS(Ed) and Ian YS Yeo FRCS(Ed) Singapore National Eye Center, Singapore Health Service (SingHealth), Singapore, Singapore
ABSTRACT Background: Swept source optical coherence tomography (SS-OCT, Topcon Medical System, Japan) is known to have longer wavelength than spectral domain OCT (SD-OCT, Spectralis, Heidelberg Engineering, Germany), allowing a deeper penetration into retina and choroidal layers. This objective of this study was to compare the visibility of retinal and choroidal features in polypoidal choroidal vasculopathy (PCV) using SS-OCT and SD-OCT. Design: This study employs prospective comparative observational case series in Singapore National Eye Center. Participants: There were 20 eyes (20 patients) with PCV confirmed with indocyanine green angiogram. Methods: Six pre-specified OCT parameters (presence of polyps, sharp pigment epithelial detachment [PED] peak, notched PED and visibility of full maximum height of PED, inner segment/outer segment [IS/OS] line and choroid-scleral interface [CSI]) were graded using SS-OCT and SD-OCT. Main Outcome Measures: The Kappa statistics between the two imaging modalities were calculated. Results: Both SS-OCT and SD-OCT were able to detect polypoidal lesions in the majority of eyes (90% and 85%, respectively). However, SS-OCT had
better detection for CSI and IS/OS lines (CSI: 80% vs 45%, P = 0.05; IS/OS line: 65% vs 45%, P = 0.34). For sharp PED peak, notched PED, ability to visualize the full PED height and retinal pigment epithelial line, both OCT machines were able to detect in ≥80% of the eyes. Conclusion: In conclusion, SS-OCT and SD-OCT appeared to be similarly effective at detecting most features associated with PCV. However, SS-OCT is more superior in detecting the CSI. Key words: polypoidal choroidal vasculopathy, swept source optical coherence tomography, polyp.
INTRODUCTION Polypoidal choroidal vasculopathy (PCV) is a disorder involving inner choroidal circulation characterized by the presence of polypoidal, subretinal branching vascular network with aneurysmal terminals.1 It appears as polyp-like orange nodules on fundoscopy. It often presents as multiple, recurrent serosanguineous retinal pigment epithelial (RPE) and neurosensory detachment due to the leakage or bleeding from the lesions.1 Traditionally, the diagnosis of PCV has been made on the basis of clinical examination (subretinal orange nodules, haemorrhagic pigment epithelial detachment) and indocyanine green angiography (ICGA).1,2 More recently, optical coherence tomography (OCT) has also been described as a useful tool.
■ Correspondence: Dr Daniel Shu Wei Ting, Singapore National Eye Centre, Ophthalmology, 11 Third Hospital Avenue, Singapore 168751, Singapore. Email: [email protected] Received 6 February 2015; accepted 14 June 2015. Conflicts of interest: None. Funding sources: None. © 2015 Royal Australian and New Zealand College of Ophthalmologists
816
Ting et al.
Reported OCT-based features often associated with PCV include ‘double layer sign’ in branching vascular network; notched pigment epithelial detachment (PED) representing polyp adherent to the undersurface of RPE within a PED; and the actual polyp characterized by a rounded hypo-reflective lumen surrounded by hyper-reflective wall adherent to the underside of RPE.3–8 Abnormalities in the choroid have also been suggested to be an important contributing factor in the pathogenesis of PCV.2 The advance of enhanced depth imaging OCT (EDI-OCT) and swept source OCT (SS-OCT) have enabled researchers to image the choroid with improved resolution. SS-OCT has a wavelength of 1050 nm with a scanning speed of 100 000 A-scans/sec, allowing a rapid penetration of vitreous, retina, choroid and sclera within a short time. Compared to spectral-domain OCD (SD-OCT), swept source OCT (SS-OCT) has greater sensitivity and lower signal-to-noise ratios (SNR) at greater scanning depths. In addition, while the enhanced depth imaging (EDI) mode, SD-OCT provides clearer images of sub-RPE structures, clarity of structures above the RPE in the EDI mode may deteriorate, as the signals above the RPE are scattered in the inverted image and the image quality decreases during averaging in eyes with poor fixation.9 One may hypothesize that SS-OCT would be more sensitive than SD-OCT in non-invasively detecting features suggestive of PCV. However, to date, only limited studies have evaluated the use of SS-OCT for in eyes with PCV.10,11 In the current study, we aim to investigate whether the SS-OCT provides significant advantages over SD-OCT in imaging several important retina and choroidal features in the setting of PCV.
METHODS Patients’ recruitment This was a single-centre prospective observational case series. Twenty eyes from 20 consecutive patients with treatment naïve PCV confirmed on ICGA were included. This study was approved by the Centralized Institutional Review Board of SingHealth, Singapore and conducted in accordance with the Declaration of Helsinki. All participants provided a signed informed consent for their participation. All patients underwent a comprehensive ocular examination and imaging which included SD-OCT (Spectralis, Heidelberg Engineering, Germany), fundus fluorescein and indocyanine green angiogram (Spectralis, Heidelberg Engineering, Germany) and SS-OCT (Topcon Atlantis DRI OCT-1; Topcon Medical Systems, Paramus, NJ, USA).
PCV diagnosis Diagnosis of PCV was made based on ICGA findings graded by two retina specialists using the EVEREST criteria,12 which requires presence of typical hyperfluorescent nodules in the early phase ICGA, and at least one of the following criteria must be fulfilled: (i) presence of hypofluorescent halo around the lesion; (ii) presence of pulsations; and (iii) association with a branching vascular network (BVN); (iv) correspondence with an orange-red nodule in fundus photographs; (v) a nodular appearance rather than a flat lesion, when viewed in stereo pairs; (vi) associated with massive submacular haemorrhage.
SS-OCT and SD-OCT imaging protocol SS-OCT images were captured using the automated averaging system in three modes – radial (12 mm), five lines and three-dimensional, centered at the macula. For SD-OCT, a minimum of 25 B-scans per volume scan of 20° × 20° was used. Each scan was averaged with nine frames per B-scan with a distance of 240 μm between each B-scan.
Grading of the PCV features in SS-OCT and SD-OCT For SS-OCT and SD-OCT, the following prespecified OCT features were graded by two retinal specialists: Presence of (i) polyp, (characterized by a rounded hypo-reflective lumen surrounded by hyper-reflective wall adherent to the underside of RPE); (ii) sharp and peaked pigment epithelial detachment (PED) and (iii) notched PED; (iv) ability to visualize full height of the PED; ability to clearly identify (v) the inner segment/outer segment (IS/ OS) line; (vi) the RPE line and; (vii) choroid-scleral interface (CSI). Detection rate and agreement between the two OCTs were compared. For statistical analysis, we used Chi-square with Yates’ correction with two-tailed P value. In addition, Kappa’s statistics between SS-OCT and SD-OCT were calculated using SPSS version 21 (SPSS, Chicago, IL, USA). The inter-observer variation is graded as: (i) < 0 – less than chance agreement; (ii) 0.01 – 0.20 – slight agreement; (iii) 0.21–0.40 – fair agreement; (iv) 0.41 – 0.60 – moderate agreement; (v) 0.61–0.80 – substantial agreement and; (vi) 0.81–0.99 – almost perfect agreement (Fig. 1).13
RESULTS A total of 20 eyes from 20 patients (10 males, 10 females) were recruited in our studies. The mean age was 63 years (standard deviation 9.4). At least one polypoidal lesion was detected in 17 eyes using
© 2015 Royal Australian and New Zealand College of Ophthalmologists
Swept-source OCT for PCV
817
Figure 1. Optical coherence tomography features associated with polypoidal choroidal vasculopathy. Swept source optical coherence tomography shows presence of sharp, peaked pigment epithelial detachment (asterisk), inner segment/outer segment (IS/OS) line, retina pigment epithelial (RPE) line, sclera-choroidal interface (CSI) and a polyp in a patient with polypoidal choroidal vasculopathy.
Table 1. Comparison of SS-OCT versus SD-OCT in detecting different structures in patients with polypoidal choroidal vasculopathy (PCV)
Polyp Sharp PED peak PED notch Full PED height IS/OS line RPE line Choroidal scleral interface
SS-OCT % (eyes)
SD-OCT % (eyes)
P-value
Kappa’s statistics
90% (18) 90% (18) 90% (18) 90% (18) 65% (13) 95% (19) 80% (16)
85% (17) 85% (17) 85% (17) 80% (16) 45% (9) 90% (18) 45% (9)
0.63 0.63 0.63 0.66 0.34 0.55 0.05
0.78 0.78 0.77 0.62 0.42 0.64 0.34
IS/OS, inner segment/outer segment; PED, pigment epithelial detachment; RPE, recurrent pigment epithelial; SD-OCT, spectral domain optical coherence tomography; SS-OCT, swept source optical coherence tomography.
SD-OCT and in 18 eyes using SS-OCT. (Table 1) Similarly, sharp, peaked PED and notched PED were also detected on both SD-OCT and SS-OCT in the majority of eyes. However, IS/OS line and CSI were only clearly visible in 9 of 20 eyes using SD-OCT. Using SS-OCT however, IS/OS line was visible in 13 eyes and CSI was visible in 16 eyes (Fig. 1 and Fig. 2). SS-OCT was able to detect more polyps as compared to SD-OCT (18 eyes vs 16 eyes) (Fig. 3). The Kappa statistics show that agreement between the two OCT systems was in the substantial
range (Kappa = 0.61–0.80) for detection of polyps, sharp PED peak, notched PED and visibility of full height of PED and RPE line. However, agreement was only moderate (Kappa = 0.41–0.60) for visibility of IS/OS line, and fair (Kappa = 0.21–0.40) for visibility of CSI.
DISCUSSION SS-OCT has been found to be superior to SD-OCT in the imaging of choroidoscleral interface in normal patients14 and posterior staphyloma in pathological myopia15 due to the higher resolution resulting from higher signal-to-noise ratio, and ability to penetrate to deeper retinal and choroidal structures. These properties may be particularly important in eyes with large serosanguineous PED. We perform a pilot study to evaluate the feasibility of SS-OCT in detecting various retina and choroidal structures in PCV patients, with comparison to the SD-OCT. In our study, both OCTs were able to detect ‘polypoidal lesions’ in the majority of eyes. SS-OCT was able to detect one more patient with a polyp due to its wider scanning width (Fig. 3). The detection rate for most of the other PCV features above RPE was similar between the two imaging modalities. One notable difference between the SS-OCT and SD-OCT from our results is the superior ability to visualize the choroidal scleral interfact (CSI) (SS-
© 2015 Royal Australian and New Zealand College of Ophthalmologists
818
Ting et al. Figure 2. Comparison of swept source optical coherence tomography (SS-OCT) and spectral domain (SD)-OCT features in polypoidal choroidal vasculopathy. Neurosensory retina detachment (asterisk) and notched pigment epithelial detachment are clearly seen on both SS-OCT and SD-OCT. However, the choroid-slceral interface and segment/outer segment (IS-OS) line are clearly visible on SS-OCT but not on SD-OCT.
Figure 3. Comparison of swept source optical coherence tomography (SS-OCT) (Fig. 3a) and spectral domain (SD)-OCT (Fig. 3b) features in polypoidal choroidal vasculopathy (PCV). SS-OCT was able to detect a polyp due to a wider scanning width, compared to SD-OCT.
(a)
(b)
OCT: 80%; SD-OCT: 45%, P = 0.05). CSI is increasingly recognized as an important landmark in retinal disease. Identification of the CSI allows assessment of choroidal thickness, which may help to differentiate between PCV and neovascular age-related macular degeneration (AMD)16 as eyes with PCV
have been reported to have thicker choroid compared to AMD patients,16 possibly due to the dilation of middle or large choroidal vessels17 or choroidal vascular hyperpermeability.18 Future research with a larger sample size will be of great value to evaluate the diagnostic sensitivity and specificity of SS-OCT
© 2015 Royal Australian and New Zealand College of Ophthalmologists
Swept-source OCT for PCV in detecting PCV as compared to SD-OCT, with reference to ICGA. Our study is limited by the small sample size. However, it provides us with a good overview on the image quality and the differences in structure visibility between the two imaging modalities. In conclusion, SS-OCT is more superior in detecting the CSI but has comparable visibility for the other retina features in PCV patients as compared to SD-OCT. Further research will be of great value to determine the sensitivity and specificity of SS-OCT versus SD-OCT in diagnosing PCV without the use of FFA/ICG.
REFERENCES 1. Yannuzzi LA, Sorenson J, Spaide RF, Lipson B. Idiopathic polypoidal choroidal vasculopathy (IPCV). Retina 1990; 10: 1–8. 2. Spaide RF, Yannuzzi LA, Slakter JS, Sorenson J, Orlach DA. Indocyanine green videoangiography of idiopathic polypoidal choroidal vasculopathy. Retina 1995; 15: 100–10. 3. Ojima Y, Hangai M, Sakamoto A et al. Improved visualization of polypoidal choroidal vasculopathy lesions using spectral-domain optical coherence tomography. Retina 2009; 29: 52–9. 4. De Salvo G, Vaz-Pereira S, Keane PA, Tufail A, Liew G. Sensitivity and specificity of spectral-domain optical coherence tomography in detecting idiopathic polypoidal choroidal vasculopathy. Am J Ophthalmol 2014; 158: 1228–38. 5. Abe S, Yamamoto T, Haneda S et al. Three-dimensional features of polypoidal choroidal vasculopathy observed by spectral-domain OCT. Ophthalmic Surg Lasers Imaging 2010; 9: 1–6. 6. Saito M, Iida T, Nagayama D. Cross-sectional and en face optical coherence tomographic features of polypoidal choroidal vasculopathy. Retina 2008; 28: 459–64. 7. Yang LH, Jonas JB, Wei WB. Optical coherence tomographic enhanced depth imaging of polypoidal choroidal vasculopathy. Retina 2013; 33: 1584–9. 8. Sato T, Kishi S, Watanabe G, Matsumoto H, Mukai R. Tomographic features of branching vascular networks
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10.
11.
12.
13.
14.
15.
16.
17.
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© 2015 Royal Australian and New Zealand College of Ophthalmologists
in polypoidal choroidal vasculopathy. Retina 2007; 27: 589–94. Sayanagi K, Gomi F, Ikuno Y, Akiba M, Nishida K. Comparison of spectral-domain and high-penetration OCT for observing morphologic changes in age-related macular degeneration and polypoidal choroidal vasculopathy. Graefes Arch Clin Exp Ophthalmol 2014; 252: 3–9. Alasil T, Ferrara D, Adhi M et al. En face imaging of the choroid in polypoidal choroidal vasculopathy using swept-source optical coherence tomography. Am J Ophthalmol 2014; 634–43. Sayanagi K, Gomi F, Akiba M, Sawa M, Hara C, Nishida K. En-face high-penetration optical coherence tomography imaging in polypoidal choroidal vasculopathy. Br J Ophthalmol 2015; 99: 29–35. Koh A, Lee WK, Chen LJ et al. EVEREST study: efficacy and safety of verteporfin photodynamic therapy in combination with ranibizumab or alone versus ranibizumab monotherapy in patients with symptomatic macular polypoidal choroidal vasculopathy. Retina 2012; 32: 1453–64. Viera AJ, Garrett JM. Understanding interobserver agreement: the kappa statistic. Fam Med 2005; 37: 360–3. Adhi M, Liu JJ, Qavi AH et al. Choroidal analysis in healthy eyes using swept-source optical coherence tomography compared to spectral domain optical coherence tomography. Am J Ophthalmol 2014; 157: 1272–81. Lim LS, Cheung G, Lee SY. Comparison of spectral domain and swept-source optical coherence tomography in pathological myopia. Eye (Lond) 2014; 28: 488– 91. Koizumi H, Yamagishi T, Yamazaki T, Kawasaki R, Kinoshita S. Subfoveal choroidal thickness in typical age-related macular degeneration and polypoidal choroidal vasculopathy. Graefes Arch Clin Exp Ophthalmol 2011; 249: 1123–8. Yuzawa M, Mori R, Kawamura A. The origins of polypoidal choroidal vasculopathy. Br J Ophthalmol 2005; 89: 602–7. Sasahara M, Tsujikawa A, Musashi K et al. Polypoidal choroidal vasculopathy with choroidal vascular hyperpermeability. Am J Ophthalmol 2006; 142: 601– 7.
