Ophthalmic Surgery, Lasers and Imaging Retina

Instruments/Devices/Technology 

Imaging of Epiretinal Membranes Using En Face Widefield Swept-Source Optical Coherence Tomography

Elie Motulsky, MD, PhD; Fang Zheng, MD; Yingying Shi, MD; José M. B. Garcia, MD; Giovanni Gregori, PhD; Philip J. Rosenfeld, MD, PhD

Abstract

BACKGROUND AND OBJECTIVE:

Swept-source optical coherence tomography (SS-OCT) imaging was performed on eyes with epiretinal membranes (ERMs), and the extent of the ERMs were compared between the 12 mm × 12 mm scans and the more routine 6 mm × 6 mm field of view (FOV).

PATIENTS AND METHODS:

Eyes containing ERMs were imaged using a 12 mm × 12 mm SS-OCT scan. En face images derived from vitreoretinal interface (VRI) slabs were reviewed to assess the full extent of the ERM.

RESULTS:

En face VRI slab images from 12 mm × 12 mm scans could visualize the full extent in eyes with ERMs.

CONCLUSIONS:

The use of 12 mm × 12 mm SS-OCT scans and en face VRI slabs provided better visualization of large ERMs compared with a 6 mm × 6 mm FOV. This strategy can be useful in identifying the full extent of tractional forces and may help with preoperative surgical planning in selected cases.

[Ophthalmic Surg Lasers Imaging Retina. 2019;50:106–112.]

Abstract

BACKGROUND AND OBJECTIVE:

Swept-source optical coherence tomography (SS-OCT) imaging was performed on eyes with epiretinal membranes (ERMs), and the extent of the ERMs were compared between the 12 mm × 12 mm scans and the more routine 6 mm × 6 mm field of view (FOV).

PATIENTS AND METHODS:

Eyes containing ERMs were imaged using a 12 mm × 12 mm SS-OCT scan. En face images derived from vitreoretinal interface (VRI) slabs were reviewed to assess the full extent of the ERM.

RESULTS:

En face VRI slab images from 12 mm × 12 mm scans could visualize the full extent in eyes with ERMs.

CONCLUSIONS:

The use of 12 mm × 12 mm SS-OCT scans and en face VRI slabs provided better visualization of large ERMs compared with a 6 mm × 6 mm FOV. This strategy can be useful in identifying the full extent of tractional forces and may help with preoperative surgical planning in selected cases.

[Ophthalmic Surg Lasers Imaging Retina. 2019;50:106–112.]

Introduction

Epiretinal membranes (ERMs) are a common vitreoretinal interface disorder.1 Around 10% of patients older than 60 years of age may experience an idiopathic ERM.2 ERMs can be asymptomatic, but their progression may result in macular distortions and abnormal central visual function. Routinely, pars plana vitrectomy and membrane peeling are performed on symptomatic ERMs to relieve the patient's visual complaints.3 Although imaging and operative techniques have improved over the years, about 10% of idiopathic ERMs recur and approximately 3% require a second surgery.4,5 The preoperative use of optical coherence tomography (OCT) imaging can allow physicians to better judge the full extent of a central macular disturbance and can help planning the surgery.6 However, the 6 mm × 6 mm field of view (FOV) available on most clinical spectral-domain OCT (SD-OCT) instruments may not be large enough to image the full extent of the ERM with a single scan. A wider FOV, like the FOV currently available on swept-source OCT (SS-OCT) instruments, may be useful to assess the full extent of ERMs and any associated vitreomacular adhesions or traction. The purpose of this study was to determine whether a 12 mm × 12 mm SS-OCT scan provided additional information about the full extent of large ERMs that could be clinically relevant in either explaining symptoms or planning surgery.

Patients and Methods

This case series is part of a prospective OCT imaging study at the Bascom Palmer Eye Institute. The institutional review board (IRB) of the University of Miami Miller School of Medicine approved the study. All patients signed an IRB-approved consent before OCT imaging was performed. The study complied with the tenets of the Declaration of Helsinki and with the Health Insurance Portability and Accountability Act of 1996.

The images were acquired using a SS-OCT instrument (PLEX Elite 9000; Carl Zeiss Meditec, Dublin, CA) operating at 100-kHz with a central wavelength of 1,050 nm. A cube scan pattern covering a 12 mm × 12 mm FOV (approximately 40°) centered on the fovea was used. This scan consists of 512 A-scans per each horizontal B-scan and 512 B-scans. The OCT fundus images (OFI) and retinal thickness maps (RTMs) were generated from the scans using the software available on the instrument.

Scans from eyes with the diagnosis of ERM were reviewed. En face structure OCT images were generated using a vitreoretinal interface (VRI) slab. This slab had a thickness of 210 μm with the upper boundary located 190 μm above the inner limiting membrane (ILM) and lower boundary located 20 μm below the ILM. Small adjustments involving the contrast and brightness settings were performed on each scan to optimize image quality.

Results

Six representative eyes with large ERMs that extended outside a 6 mm × 6 mm FOV (approximately 20°) are shown in Figures 1 to 6. In these figures, Panel A shows the OFI, Panel B shows the RTM, Panel C shows the en face image from the VRI slab, Panels D and E contain a B-scan located outside the central 6 mm × 6 mm FOV corresponding to the yellow line in Panel C, Panel F shows an overlay of the RTM with 60% transparency overlaid on the VRI en face image, and Panels G and H show foveal B-scans corresponding to the yellow line in Panel F. In the panels showing the OFI, RTM, and VRI slab images, the white square boxes centered on the fovea represent the area covered by a conventional 6 mm × 6 mm scan.

Case No. 1: Multi-segmented images from a single 12 mm × 12 mm swept-source optical coherence tomography (SS-OCT) scan of an epiretinal membrane (ERM) in the right eye of a 65-year-old woman. The white square boxes centered on the fovea in panels A, B, C, and F represent a 6 mm × 6 mm field of view (FOV). (A) OCT fundus image. Notice some vessels converging to the ERM superotemporally. (B) Retinal thickness map (RTM). Note the superotemporal thickening of the retina corresponding to the ERM traction. (C) Vitreoretinal interface (VRI) en face image. The image shows a hyperreflective ERM extending from the parafoveolar to the superotemporal region. Yellow arrows in images C, D, and E are pointing to the edge of the ERM and emphasize potential traction and adherence of the ERM outside the 6 mm × 6 mm FOV. (D) B-scan corresponding to the yellow line of C outside the 6 mm × 6 mm white square. Dashed lines define the upper and lower boundaries of the VRI en face slab. (E) Magnification of the white rectangle of the image D. This demonstrates the extent of the ERM outside the 6 mm × 6 mm FOV. (F) Overlay of Panel B (60% transparency) on top of Panel C. Yellow horizontal line represents the foveal B-scan. Yellow vertical arrow highlights the extent of the ERM outside 6 mm × 6 mm FOV, whereas the yellow arrowhead indicate the presence of the ERM within the 6 mm × 6 mm FOV. (G) Foveal B-scan. Dashed lines define the upper and lower boundaries of the VRI en face slab. (H) Magnified B-scan of the white square shown in Panel G. The ERM extends from inside the 6 mm × 6 mm FOV (yellow arrowhead) to the outside 6 mm × 6 mm FOV (yellow vertical arrow).

Figure 1.

Case No. 1: Multi-segmented images from a single 12 mm × 12 mm swept-source optical coherence tomography (SS-OCT) scan of an epiretinal membrane (ERM) in the right eye of a 65-year-old woman. The white square boxes centered on the fovea in panels A, B, C, and F represent a 6 mm × 6 mm field of view (FOV). (A) OCT fundus image. Notice some vessels converging to the ERM superotemporally. (B) Retinal thickness map (RTM). Note the superotemporal thickening of the retina corresponding to the ERM traction. (C) Vitreoretinal interface (VRI) en face image. The image shows a hyperreflective ERM extending from the parafoveolar to the superotemporal region. Yellow arrows in images C, D, and E are pointing to the edge of the ERM and emphasize potential traction and adherence of the ERM outside the 6 mm × 6 mm FOV. (D) B-scan corresponding to the yellow line of C outside the 6 mm × 6 mm white square. Dashed lines define the upper and lower boundaries of the VRI en face slab. (E) Magnification of the white rectangle of the image D. This demonstrates the extent of the ERM outside the 6 mm × 6 mm FOV. (F) Overlay of Panel B (60% transparency) on top of Panel C. Yellow horizontal line represents the foveal B-scan. Yellow vertical arrow highlights the extent of the ERM outside 6 mm × 6 mm FOV, whereas the yellow arrowhead indicate the presence of the ERM within the 6 mm × 6 mm FOV. (G) Foveal B-scan. Dashed lines define the upper and lower boundaries of the VRI en face slab. (H) Magnified B-scan of the white square shown in Panel G. The ERM extends from inside the 6 mm × 6 mm FOV (yellow arrowhead) to the outside 6 mm × 6 mm FOV (yellow vertical arrow).

Case No. 2: Multi-segmented images from a single 12 mm × 12 mm swept-source optical coherence tomography (SS-OCT) scan of an epiretinal membrane (ERM) in the left eye of a 68-year-old woman. The white square boxes centered on the fovea in panels A, B, C, and F represent a 6 mm × 6 mm field of view (FOV). (A) OCT fundus image. Notice some vessel tortuosity in the macular area. (B) Retinal thickness map (RTM). Note the disappearing of the foveal contour. Radiation and ERM striae can be appreciated. (C) Vitreoretinal interface (VRI) en face image. The image shows a hyperreflective ERM, which correspond to ERM striae centrifugally spreading from the fovea beyond the 6 mm × 6 mm FOV. Yellow arrows in images C, D, and E emphasize potential traction and adherence of the ERM outside the 6 mm × 6 mm FOV. Note that the yellow arrow points to the edge of the ERM. (D) B-scan corresponding to the yellow line outside the 6 mm × 6 mm white square shown in image C. Dashed lines define the upper and lower boundaries of the VRI en face slab. (E) Magnification of the white rectangle of the image D. This demonstrates the extent of the ERM outside the 6 mm × 6 mm FOV. (F) Overlay of Panel B (60% transparency) on top of Panel C. Yellow horizontal line represents the foveal B-scan. Yellow vertical arrow in Panels F, G, and H highlight the extent of the ERM outside the 6 mm × 6 mm FOV, whereas the yellow arrowheads indicate the presence of the ERM within the 6 mm × 6 mm FOV. (G) Foveal B-scan. Dashed lines define the upper and lower boundaries of the VRI en face slab. (H) Magnified B-scan from within the white square shown in Panel G. Observe the massive extension of the ERM from inside the 6 mm × 6 mm FOV (yellow arrowhead) to outside the 6 mm × 6 mm FOV (yellow vertical arrow).

Figure 2.

Case No. 2: Multi-segmented images from a single 12 mm × 12 mm swept-source optical coherence tomography (SS-OCT) scan of an epiretinal membrane (ERM) in the left eye of a 68-year-old woman. The white square boxes centered on the fovea in panels A, B, C, and F represent a 6 mm × 6 mm field of view (FOV). (A) OCT fundus image. Notice some vessel tortuosity in the macular area. (B) Retinal thickness map (RTM). Note the disappearing of the foveal contour. Radiation and ERM striae can be appreciated. (C) Vitreoretinal interface (VRI) en face image. The image shows a hyperreflective ERM, which correspond to ERM striae centrifugally spreading from the fovea beyond the 6 mm × 6 mm FOV. Yellow arrows in images C, D, and E emphasize potential traction and adherence of the ERM outside the 6 mm × 6 mm FOV. Note that the yellow arrow points to the edge of the ERM. (D) B-scan corresponding to the yellow line outside the 6 mm × 6 mm white square shown in image C. Dashed lines define the upper and lower boundaries of the VRI en face slab. (E) Magnification of the white rectangle of the image D. This demonstrates the extent of the ERM outside the 6 mm × 6 mm FOV. (F) Overlay of Panel B (60% transparency) on top of Panel C. Yellow horizontal line represents the foveal B-scan. Yellow vertical arrow in Panels F, G, and H highlight the extent of the ERM outside the 6 mm × 6 mm FOV, whereas the yellow arrowheads indicate the presence of the ERM within the 6 mm × 6 mm FOV. (G) Foveal B-scan. Dashed lines define the upper and lower boundaries of the VRI en face slab. (H) Magnified B-scan from within the white square shown in Panel G. Observe the massive extension of the ERM from inside the 6 mm × 6 mm FOV (yellow arrowhead) to outside the 6 mm × 6 mm FOV (yellow vertical arrow).

Case No. 3: Multi-segmented images from a single 12 mm × 12 mm swept-source optical coherence tomography (SS-OCT) scan of an epiretinal membrane (ERM) in the right eye of an 85-year-old woman. The white square boxes centered on the fovea in panels A, B, C, and F represent a 6 mm × 6 mm field of view (FOV). (A) OCT fundus image. Superior arcade reveals asymmetrical vessel tortuosity. (B) Retinal thickness map (RTM). Observe the disturbances of macular thickness. (C) Vitreoretinal interface (VRI) en face image. The image shows a hyperreflective ERM, which is composed of two focal adherences. Both are present within and spread outside the 6 mm × 6 mm FOV. Yellow arrows in images C, D, and E designate a digit of the superior focal adherence stretching outside 6 mm × 6 mm. (D) B-scan corresponding to the yellow line outside the 6 mm × 6 mm white square shown in image C. Dashed lines define the upper and lower boundaries of the VRI en face slab. (E) Magnification of the white rectangle of the image D. This demonstrates the extent of the ERM outside the 6 mm × 6 mm FOV, as well as retinal folds. (F) Overlay of Panel B (60% transparency) on top of Panel C. Yellow horizontal line represents the foveal B-scan. Yellow vertical arrow in Panels F, G, and H highlight the extent of the ERM outside the 6 mm × 6 mm FOV, whereas the yellow arrowheads designate an isolated foci of the ERM within the 6 mm × 6 mm FOV. (G) Foveal B-scan. Dashed lines define the upper and lower boundaries of the VRI en face slab. (H) Magnified B-scan from within the white square shown in Panel G. The ERM extends from inside the 6 mm × 6 mm FOV (yellow arrowhead) to outside the 6 mm × 6 mm FOV (yellow vertical arrow). Observe the interruption of the ERM from inside (yellow arrowhead) to the outside (yellow vertical arrow) 6 mm × 6 mm FOV.

Figure 3.

Case No. 3: Multi-segmented images from a single 12 mm × 12 mm swept-source optical coherence tomography (SS-OCT) scan of an epiretinal membrane (ERM) in the right eye of an 85-year-old woman. The white square boxes centered on the fovea in panels A, B, C, and F represent a 6 mm × 6 mm field of view (FOV). (A) OCT fundus image. Superior arcade reveals asymmetrical vessel tortuosity. (B) Retinal thickness map (RTM). Observe the disturbances of macular thickness. (C) Vitreoretinal interface (VRI) en face image. The image shows a hyperreflective ERM, which is composed of two focal adherences. Both are present within and spread outside the 6 mm × 6 mm FOV. Yellow arrows in images C, D, and E designate a digit of the superior focal adherence stretching outside 6 mm × 6 mm. (D) B-scan corresponding to the yellow line outside the 6 mm × 6 mm white square shown in image C. Dashed lines define the upper and lower boundaries of the VRI en face slab. (E) Magnification of the white rectangle of the image D. This demonstrates the extent of the ERM outside the 6 mm × 6 mm FOV, as well as retinal folds. (F) Overlay of Panel B (60% transparency) on top of Panel C. Yellow horizontal line represents the foveal B-scan. Yellow vertical arrow in Panels F, G, and H highlight the extent of the ERM outside the 6 mm × 6 mm FOV, whereas the yellow arrowheads designate an isolated foci of the ERM within the 6 mm × 6 mm FOV. (G) Foveal B-scan. Dashed lines define the upper and lower boundaries of the VRI en face slab. (H) Magnified B-scan from within the white square shown in Panel G. The ERM extends from inside the 6 mm × 6 mm FOV (yellow arrowhead) to outside the 6 mm × 6 mm FOV (yellow vertical arrow). Observe the interruption of the ERM from inside (yellow arrowhead) to the outside (yellow vertical arrow) 6 mm × 6 mm FOV.

Case No. 4: Multi-segmented images from a single 12 mm × 12 mm swept-source optical coherence tomography (SS-OCT) scan of an epiretinal membrane (ERM) associated with incomplete posterior vitreous detachment (PVD) in the left eye of a 62-year-old man. The white square boxes centered on the fovea in panels A, B, C, and F represent a 6 mm × 6 mm field of view (FOV). (A) OCT fundus image. Observe the asymmetrical vessel tortuosity predominant in the superior arcade. (B) Retinal thickness map (RTM). Inspect the disturbances of macular thickness. (C) Vitreoretinal interface (VRI) en face image. The image shows a hyperreflective ERM, whereas posterior hyaloid associated with ERM is well-lighted in white. Yellow arrows in images C, D, and E emphasize the traction component of the ERM that leads to retinal folds. (D) B-scan corresponding to the yellow line outside the 6 mm × 6 mm white square shown in image C. Dashed lines define the upper and lower boundaries of the VRI en face slab. (E) Magnification of the white rectangle of the image D. This demonstrates the extent of the ERM outside the 6 mm × 6 mm FOV as well as retinal folds. (F) Overlay of Panel B (60% transparency) on top of Panel C. Yellow horizontal line represents the foveal B-scan. Yellow vertical arrow in Panels F, G, and H highlight the extent of the ERM outside 6 mm × 6 mm FOV. The fusion of the posterior hyaloid and ERM unveils intense hyperreflectivity. (G) Foveal B-scan. Dashed lines define the upper and lower boundaries of the VRI en face slab. (H) Magnified B-scan from within the white square shown in Panel G. The ERM extends from inside the 6 mm × 6 mm FOV (yellow arrowhead) to outside the 6 mm × 6 mm FOV (yellow vertical arrow). Observe the inverted foveal depression associated with intraretinal cystic spaces, presence of ERM in the temporal side and in the nasal side posterior vitreous adherence associated with ERM enhancing hyperreflectivity and incomplete PVD.

Figure 4.

Case No. 4: Multi-segmented images from a single 12 mm × 12 mm swept-source optical coherence tomography (SS-OCT) scan of an epiretinal membrane (ERM) associated with incomplete posterior vitreous detachment (PVD) in the left eye of a 62-year-old man. The white square boxes centered on the fovea in panels A, B, C, and F represent a 6 mm × 6 mm field of view (FOV). (A) OCT fundus image. Observe the asymmetrical vessel tortuosity predominant in the superior arcade. (B) Retinal thickness map (RTM). Inspect the disturbances of macular thickness. (C) Vitreoretinal interface (VRI) en face image. The image shows a hyperreflective ERM, whereas posterior hyaloid associated with ERM is well-lighted in white. Yellow arrows in images C, D, and E emphasize the traction component of the ERM that leads to retinal folds. (D) B-scan corresponding to the yellow line outside the 6 mm × 6 mm white square shown in image C. Dashed lines define the upper and lower boundaries of the VRI en face slab. (E) Magnification of the white rectangle of the image D. This demonstrates the extent of the ERM outside the 6 mm × 6 mm FOV as well as retinal folds. (F) Overlay of Panel B (60% transparency) on top of Panel C. Yellow horizontal line represents the foveal B-scan. Yellow vertical arrow in Panels F, G, and H highlight the extent of the ERM outside 6 mm × 6 mm FOV. The fusion of the posterior hyaloid and ERM unveils intense hyperreflectivity. (G) Foveal B-scan. Dashed lines define the upper and lower boundaries of the VRI en face slab. (H) Magnified B-scan from within the white square shown in Panel G. The ERM extends from inside the 6 mm × 6 mm FOV (yellow arrowhead) to outside the 6 mm × 6 mm FOV (yellow vertical arrow). Observe the inverted foveal depression associated with intraretinal cystic spaces, presence of ERM in the temporal side and in the nasal side posterior vitreous adherence associated with ERM enhancing hyperreflectivity and incomplete PVD.

Case No. 5: Multi-segmented images from a single 12 mm × 12 mm swept-source optical coherence tomography (SS-OCT) scan of an epiretinal membrane (ERM) associated with incomplete posterior vitreous detachment (PVD) in the right eye of a 95-year-old woman. The white square boxes centered on the fovea in panels A, B, C, and F represent a 6 mm × 6 mm field of view (FOV). (A) OCT fundus image. Note preponderant vessel tortuosity in the posterior pole emerging from the inferior arcade. (B) Retinal thickness map (RTM) depicts a diffuse retinal thinning probably related to the patient age and myopia. (C) Vitreoretinal interface (VRI) en face image. The image shows a hyperreflective ERM. Some parts of the retinal surface present a fusion of both ERM and posterior hyaloid and highly reflect the light beam giving rise to well-lighted white signal. Yellow arrows in images C, D, and E emphasize the fusion between the ERM and the posterior hyaloid. (D) B-scan corresponding to the yellow line outside the 6 mm × 6 mm white square shown in image C. Dashed lines define the upper and lower boundaries of the VRI en face slab. (E) Magnification of the white rectangle of the image D. Yellow arrow points the zone of fusion between the posterior hyaloid and the ERM that is hyperreflective in the VRI slab. (F) Overlay of Panel B (60% transparency) on top of Panel C. Yellow horizontal line represents the foveal B-scan. Yellow vertical arrow in Panels F, G, and H highlight the extent of the ERM outside the 6 mm × 6 mm FOV. Yellow arrowheads point the intense hyperreflectivity of the complex made of the posterior hyaloid and the ERM. (G) Foveal B-scan. Dashed lines define the upper and lower boundaries of the VRI en face slab. (H) Magnified B-scan from within the white square shown in Panel G. The ERM extends from inside the 6 mm × 6 mm FOV (yellow arrowhead) to outside the 6 mm × 6 mm FOV (yellow vertical arrow). Yellow vertical arrow specifies the extent of the ERM that stretches outside the 6 mm × 6 mm FOV in the temporal area.

Figure 5.

Case No. 5: Multi-segmented images from a single 12 mm × 12 mm swept-source optical coherence tomography (SS-OCT) scan of an epiretinal membrane (ERM) associated with incomplete posterior vitreous detachment (PVD) in the right eye of a 95-year-old woman. The white square boxes centered on the fovea in panels A, B, C, and F represent a 6 mm × 6 mm field of view (FOV). (A) OCT fundus image. Note preponderant vessel tortuosity in the posterior pole emerging from the inferior arcade. (B) Retinal thickness map (RTM) depicts a diffuse retinal thinning probably related to the patient age and myopia. (C) Vitreoretinal interface (VRI) en face image. The image shows a hyperreflective ERM. Some parts of the retinal surface present a fusion of both ERM and posterior hyaloid and highly reflect the light beam giving rise to well-lighted white signal. Yellow arrows in images C, D, and E emphasize the fusion between the ERM and the posterior hyaloid. (D) B-scan corresponding to the yellow line outside the 6 mm × 6 mm white square shown in image C. Dashed lines define the upper and lower boundaries of the VRI en face slab. (E) Magnification of the white rectangle of the image D. Yellow arrow points the zone of fusion between the posterior hyaloid and the ERM that is hyperreflective in the VRI slab. (F) Overlay of Panel B (60% transparency) on top of Panel C. Yellow horizontal line represents the foveal B-scan. Yellow vertical arrow in Panels F, G, and H highlight the extent of the ERM outside the 6 mm × 6 mm FOV. Yellow arrowheads point the intense hyperreflectivity of the complex made of the posterior hyaloid and the ERM. (G) Foveal B-scan. Dashed lines define the upper and lower boundaries of the VRI en face slab. (H) Magnified B-scan from within the white square shown in Panel G. The ERM extends from inside the 6 mm × 6 mm FOV (yellow arrowhead) to outside the 6 mm × 6 mm FOV (yellow vertical arrow). Yellow vertical arrow specifies the extent of the ERM that stretches outside the 6 mm × 6 mm FOV in the temporal area.

Case No. 6: Multi-segmented images from a single 12 mm × 12 mm swept-source optical coherence tomography (SS-OCT) scan of an epiretinal membrane (ERM) in the left eye of a 66-year-old woman. The white square boxes centered on the fovea in panels A, B, C, and F represent a 6 mm × 6 mm field of view (FOV). (A) OCT fundus image. Note that the superior arcade is displaced inferiorly and that the inferior vessels exhibit some tortuosity. (B) Retinal thickness map (RTM). Note the abnormal thickening of the macular thickness. (C) Vitreoretinal interface (VRI) en face image. The image shows a hyperreflective ERM, which pulls both superior and inferior arcades vessels and spreads outside the 6 mm × 6 mm FOV. Yellow arrows in images C, D, and E emphasize the traction component of the ERM that leads to retinal folds. (D) B-scan corresponding to the yellow line outside the 6 mm × 6 mm white square shown in image C. Dashed lines define the upper and lower boundaries of the VRI en face slab. (E) Magnification of the white rectangle of the image D. Note the retinal folds representing all the digits of the ERM. (F) Overlay of Panel B (60% transparency) on top of Panel C. Yellow horizontal line represents the foveal B-scan. Yellow vertical arrow in Panels F, G, and H highlight the extent of the ERM outside 6 mm × 6 mm FOV, whereas the yellow arrowheads indicate element of the ERM close to the foveal area within the 6 mm × 6 mm FOV. (G) Foveal B-scan. Dashed lines define the upper and lower boundaries of the VRI en face slab. (H) Magnified B-scan from within the white square shown in Panel G. The ERM extends from inside the 6 mm × 6 mm FOV (yellow arrowhead) to outside the 6 mm × 6 mm FOV (yellow vertical arrow). Observe the presence of the ERM within the 6 mm × 6 mm FOV (yellow arrowhead) and the extent of the ERM outside the 6 mm × 6 mm FOV highlighted by the yellow arrows.

Figure 6.

Case No. 6: Multi-segmented images from a single 12 mm × 12 mm swept-source optical coherence tomography (SS-OCT) scan of an epiretinal membrane (ERM) in the left eye of a 66-year-old woman. The white square boxes centered on the fovea in panels A, B, C, and F represent a 6 mm × 6 mm field of view (FOV). (A) OCT fundus image. Note that the superior arcade is displaced inferiorly and that the inferior vessels exhibit some tortuosity. (B) Retinal thickness map (RTM). Note the abnormal thickening of the macular thickness. (C) Vitreoretinal interface (VRI) en face image. The image shows a hyperreflective ERM, which pulls both superior and inferior arcades vessels and spreads outside the 6 mm × 6 mm FOV. Yellow arrows in images C, D, and E emphasize the traction component of the ERM that leads to retinal folds. (D) B-scan corresponding to the yellow line outside the 6 mm × 6 mm white square shown in image C. Dashed lines define the upper and lower boundaries of the VRI en face slab. (E) Magnification of the white rectangle of the image D. Note the retinal folds representing all the digits of the ERM. (F) Overlay of Panel B (60% transparency) on top of Panel C. Yellow horizontal line represents the foveal B-scan. Yellow vertical arrow in Panels F, G, and H highlight the extent of the ERM outside 6 mm × 6 mm FOV, whereas the yellow arrowheads indicate element of the ERM close to the foveal area within the 6 mm × 6 mm FOV. (G) Foveal B-scan. Dashed lines define the upper and lower boundaries of the VRI en face slab. (H) Magnified B-scan from within the white square shown in Panel G. The ERM extends from inside the 6 mm × 6 mm FOV (yellow arrowhead) to outside the 6 mm × 6 mm FOV (yellow vertical arrow). Observe the presence of the ERM within the 6 mm × 6 mm FOV (yellow arrowhead) and the extent of the ERM outside the 6 mm × 6 mm FOV highlighted by the yellow arrows.

The full extent of the ERMs are clearly visualized on the VRI en face images (panel C). The ERMs appear as hyperreflective structures and their reflectivity depends on their thickness. The overlay of the RTM with 60% transparency on top of the VRI en face structure image highlights the areas with both traction and increased retinal thickness. Moreover, the VRI en face images can show evidence of traction and retinal striae even in the absence of retinal thickening. The composite images display the retinal thickening related to the traction forces associated with the ERMs. The horizontal lines on the en face images mark the position of the B-scans shown in the adjacent panels. The dashed yellow lines on the B-scans correspond to the boundary layers for the en face VRI slabs. The magnified B-scans emphasize the presence of the ERM. These six representative cases are intended to demonstrate how the 12 mm × 12 mm scan might be helpful to clinicians.

Discussion

In this report, we highlight cases in which the 12 mm × 12 mm SS-OCT scan can identify the full extent of ERMs outside the boundaries of a typical 6 mm × 6 mm SD-OCT scan. As shown in this paper, the SS-OCT can give us many different images using a single instrument and a single scan pattern. A single 12 mm × 12 mm scan provides an OCT fundus image that includes the macula, vessels, and optic nerve. Moreover, a RTM can also be generated and identifies any areas of abnormal thickening or thinning in the entire macula. In addition, the VRI slab image provides a widefield view of the ERM so that the clinician can appreciate the correlation between the ERMs and any thickening or distortions of the retina. Furthermore, traditional B-scans are also available from the same widefield raster scan so that any structural abnormality above, under, or in the retina can be appreciated. One concern might be the lower image quality due to the decreased density of A-scans and B-scans in the 12 mm × 12 mm scan pattern compared with the denser scans patterns used in the more traditional 6 mm × 6 mm scans, but the image quality of the 12 mm × 12 mm scan appears to be more than adequate to diagnose an ERM. The cases demonstrate how a single 12 mm × 12 mm scan can easily demonstrate the presence and the extent of the ERM, the traction component of the ERM that leads to retinal folds, the abnormal foveal contour associated with the traction, and the adherence and incomplete detachment of the posterior vitreous. This widefield imaging strategy might be an excellent screening tool in detecting asymptomatic or mildly symptomatic ERMs. In addition, it can identify vitreomacular adhesions and retinal traction, which should also help in explaining visual symptoms.

The en face VRI slab images clearly show the full extent of the ERMs. This slab image allows the clinician to correlate the visual complaints with the full extent of ERM. Moreover, VRI slab images can give a better perspective for the clinician when planning surgery. The en face VRI slab images can help clinicians fully appreciate the extent and three-dimensional (3-D) configuration of the ERM. In addition, this imaging strategy may assist in the training of residents and fellows, and 3-D printing of the ERM may aid in planning the surgical intervention.7 Currently, after an idiopathic ERM peeling, about 10% of them will recur and approximately 3% will require another surgery.4,5 In the future, pre- and post-surgical studies with widefield SS-OCT imaging might help us better understand these recurrences. Re-proliferation could start from unpeeled parts of the ERM located outside the central macula since the surgeon couldn't fully appreciated the extent of the ERM. Moreover, it might be useful to compare the widefield images with intraoperative OCT images during live surgeries, and as we enter an era where surgeries may be robotically assisted, the SS-OCT images could be used to assist with the surgeries.

In summary, the 12 mm × 12 mm SS-OCT en face VRI slab images can be useful in assessing the full extent and progression of large ERMs extending outside the standard 6 mm × 6 mm FOV. Moreover, the combined 12 mm × 12 mm RTM and VRI slab en face images can provide a better understanding of the traction forces on the retina, which may help explaining symptoms and aid in surgical planning.

References

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Authors

From the Department of Ophthalmology, Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami.

This research was supported by grants from Carl Zeiss Meditec (Dublin, CA) and the Salah Foundation to the Department of Ophthalmology, University of Miami Miller School of Medicine.

Dr. Gregori and Dr. Rosenfeld received research support from Carl Zeiss Meditec. Dr. Gregori and the University of Miami co-own a patent that is licensed to Carl Zeiss Meditec. Dr. Rosenfeld has received additional research support from Genentech and Tyrogenex; he is a consultant for Achillion Pharmaceuticals, Acucela, Boehringer-Ingelheim, Carl Zeiss Meditec, Cell Cure Neurosciences, Chengdu Kanghong Biotech, Ocunexus Therapeutics, Genentech, Healios K.K, Hemera Biosciences, F. Hoffmann-La Roche Ltd., Isarna Pharmaceuticals, Lin Bioscience, MacRegen, NGM Biopharmaceuticals, Ocunexus, Ocudyne, Tyrogenex, and Unity Biotechnology; and he has equity interest in Apellis, Digisight, and Ocudyne. The remaining authors report no relevant financial disclosures.

Address correspondence to Philip J. Rosenfeld, MD, PhD, Bascom Palmer Eye Institute, 900 NW 17th Street, Miami, FL, 33136; email: prosenfeld@miami.edu.

Received: May 25, 2018
Accepted: November 07, 2018

10.3928/23258160-20190129-07

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