Combined Depth Imaging Technique on Spectral-Domain Optical Coherence Tomography

Abstract

PURPOSE To describe a technique to obtain combined images of vitreo-retino-choroidal structures using spectral-domain (SD) optical coherence tomography (OCT) and to evaluate applicability in normal eyes and limitations in eyes with cataract. DESIGN Prospective, observational case series. METHODS Three different foveal scans including conventional SD-OCT, enhanced depth imaging (EDI)-OCT and the novel method called “combined depth imaging” (CDI)-OCT were obtained in 42 eyes of healthy volunteers and in 26 eyes with cataract using Heidelberg Spectralis HRA. The CDI-OCT was manually obtained using an image modification process that enhances the vitreo-retinal interface first and then the choroid while averaging 100 separate OCT scans. The visualization of the inner border of the preretinal pocket and the outer border of the choroid was graded by independent masked observers for each OCT scan modality. RESULTS The CDI technique was able to create a good quality combined image of the posterior structures in all the eyes including eyes with cataract. The agreement between the grading performed by the independent observers was high for both the inner border of the vitreal pocket (kappa=0.86; P<0.001) and the outer choroidal border (kappa=0.90; P<0.001). CDI-OCT was equivalent to conventional SD-OCT in visualizing the vitreal pocket (P=0.445 for normal eyes, P=0.162 for eyes with cataract) and was equivalent to EDI-OCT in visualizing the outer choroidal border (P=0.660 for normal eyes, P=0.329 for eyes with cataract). CDI-OCT was superior to conventional SD-OCT and EDI-OCT to visualize both the structures (P<0.001). CONCLUSIONS The manual technique of CDI-OCT is highly sensitive to visualize posterior vitreo-retino-choroidal structures into a single full-depth image, and is not affected by mild to moderate cataract.

Enhanced Vitreous Imaging in Healthy Eyes Using Swept Source Optical Coherence Tomography

“…The HDR display has the advantage that is preserves retinal contrast while enhancing visualization of the vitreous, which may be valuable in detecting interactions between the vitreous and the retina, such as at the attachment of the hyaloid to retinal vessels and fibrovascular vitreoretinal adhesions in diseases such as advanced diabetic retinopathy. In addition, the HDR display has the ability to visualize vitreous, retinal, and choroidal structures in a single image, similar to the combined depth imaging SD-OCT images shown by Barteselli et al [21] …”

An Assessment of Vitreous Degeneration in Eyes with Vitreomacular Traction and Macular Holes

“…Furthermore, manipulation of image capture using standard spectral-domain optical coherence tomography (SD-OCT) allows for improved visualization of structures within the posterior vitreous [5, 6]. We previously described the anatomical features seen within the posterior vitreous and proposed a grading scheme for vitreous degeneration based on the state of the premacular bursa and its relationship to the various lacunae and degenerative cleavage planes within the vitreous body [2].…”

Real-Time Full-Depth Visualization of Posterior Ocular Structures

“…The double-enhanced FDI SD-OCT image was obtained as previously described. 3, 4 After positioning the OCT B-scan in the middle of the screen, the operator shifted the focus of the instrument slightly toward plus values to highlight the posterior vitreous architecture. The averaging system of the device using the conventional OCT software was then activated; after reaching at least 80% of the averaging (at least 80 of 100 B-scans), the operator manually activated the EDI acquisition software.…”

“…Two independent masked physicians (J.T.N., N.C.) reviewed each image on the same monitor with same resolution at different time points and evaluated images using a previously used method. 4 First, they evaluated the ability to visualize a full-depth image of the vitreoretino-choroidal structure. Then, they evaluated visualization of single structures; in particular, they graded visualization of the inner border of the premacular bursa, visualization of the interdigitation zone line, and visualization of the chorio-scleral boundary separately.…”

“…3, 4 The “Full Depth Imaging” (FDI) technique, also called “Combined Depth Imaging” (CDI) technique, 3-5 involves a live process that first enhances the vitreo-retinal interface using the conventional SD-OCT modality and then the choroid using the EDI-OCT modality, while averaging multiple OCT scans using the active eye-tracking feature of the Spectralis. This allows for a single-image full-depth evaluation of the posterior structures (including vitreous, retina, and choroid) in real time while imaging patients and without using multiple OCT modalities or external software for image processing.…”