Spectral-domain optical coherence tomography for macular edema

Methods of ex vivo analysis of tissue status in vascularized composite allografts

Vascularized composite allotransplantation can improve quality of life and restore functionality. However, the complex tissue composition of vascularized composite allografts (VCAs) presents unique clinical challenges that increase the likelihood of transplant rejection. Under prolonged static cold storage, highly damage-susceptible tissues such as muscle and nerve undergo irreversible degradation that may render allografts non-functional. Skin-containing VCA elicits an immunogenic response that increases the risk of recipient allograft rejection. The development of quantitative metrics to evaluate VCAs prior to and following transplantation are key to mitigating allograft rejection. Correspondingly, a broad range of bioanalytical methods have emerged to assess the progression of VCA rejection and characterize transplantation outcomes. To consolidate the current range of relevant technologies and expand on potential for development, methods to evaluate ex vivo VCA status are herein reviewed and comparatively assessed. The use of implantable physiological status monitoring biochips, non-invasive bioimpedance monitoring to assess edema, and deep learning algorithms to fuse disparate inputs to stratify VCAs are identified.

Oct biomarkers of treatment-naive diabetic macular edema in patients with non-proliferative and proliferative diabetic retinopathy

PURPOSE

To evaluate and compare the retinal and choroidal spectral-domain optic coherence tomography (SD-OCT) findings of treatment-naïve diabetic macular edema (DME) secondary to non-proliferative and proliferative diabetic retinopathy (NPDR-PDR).

MATERIAL AND METHODS

A hundred and thirty-eight eyes of 138 patients with DME were evaluated. Best-corrected visual acuity was recorded, biomicroscopic anterior and posterior segment examination, SD-OCT imaging, and fundus fluorescein angiography (FFA) were performed. Demographic features, OCT characteristics, FFA, and visual acuity measurements were evaluated and compared between the two groups.

RESULTS

Sixteen eyes were excluded from the study due to the lack of FFA images. Data of 122 eyes were analyzed for the study. Sixty-five eyes with NPDR (Group 1) and 57 eyes with PDR (Group 2) were enrolled in the study. There was no significant difference in central macular thicknesses (CMT) between the two groups. The eyes with DME + PDR showed a higher rate of the diffuse type of macular edema with more para and peri-foveal extension accompanied by larger cysts than the eyes with DME + NPDR. Disorganization of retinal inner layers, disrupted ellipsoid zone, and the epiretinal membrane were more prominent in the eyes with PDR. Also, there were more prominent macular ischemia on FFA and worse initial visual acuity measurements in the eyes with PDR than those with NPDR. Choroidal thickness (CT) was significantly reduced in the PDR group.

CONCLUSION

SD-OCT features of treatment-naïve DME in patients with NPDR and PDR presented some differences. These variations may be related to diabetic retinopathy severity and may provide information about prognosis.

Differentiation of Underlying Pathologies of Macular Edema Using Spectral Domain Optical Coherence Tomography (SD-OCT)

Purpose: To describe the morphological characteristics of macular edema (ME) of different origins using spectral domain optical coherence tomography (SD-OCT). Methods: This article summarizes and highlights key morphologic findings, based on published articles, describing the characteristic presentations of ME of different origins using SD-OCT. The following pathologies were included: uveitic macular edema, pseudophakic cystoid macular edema (PCME), diabetic macular edema (DME), macular edema secondary to central or branch retinal vein occlusion (CRVO/BRVO), microcystic macular edema (MME), ME associated with epiretinal membrane (ERM), and retinitis pigmentosa (RP). Conclusions: Macular edema of different origins show characteristic patterns that are often indicative of the underlying cause and pathology. Thus, trained algorithms may in the future be able to automatically differentiate underlying causes and support clinical diagnosis. Knowledge of different appearances support the clinical diagnosis and can lead to improved and more targeted treatment of ME.

Multimodal OCT Reflectivity Analysis of the Cystoid Spaces in Cystoid Macular Edema

Purpose

To compare and evaluate images of macular cysts with different degrees of reflectivity (from gray to black signal) as observed in B scan spectral domain OCT (SDOCT) and EnFace OCT with decorrelation signal obtained with OCT-angiography (OCTA) in eyes with cystoid macular edema (CME) secondary to diabetic retinopathy (DR) and retinal vein occlusion (RVO).

Methods

Images from 3033 patients affected by CME secondary to diabetes or RVO examined OCTA (Optovue XR Avanti, Optovue, USA) at the University Eye Clinic of Créteil, Hôpital Intercommunal, France, and at the University Eye Clinic of Cagliari, “San Giovanni di Dio” Hospital, Italy, were retrospectively examined. The deep capillary plexus OCTA images and the corresponding EnFace OCT images, both acquired with the same automatic segmentation, had been overlapped to compose RGB color images as red and green channels, respectively, using ImageJ software (National Institutes of Health, Bethesda, MD). Afterward, linear regions of interest were traced on the color images to obtain the profiles of OCTA and EnFace gray values. Number of pixels, mean gray value and standard deviation of the area traced in OCT-A, and EnFace image were analyzed and statistically correlated. Data were exported to Excel to create the plots.

Results

94 patients with DME and 27 patients with RVO showed intraretinal macular cystoid spaces with similar homogeneous, gray-looking content; 73 patients with DME and 113 patients with RVO showed macular cystoid spaces with homogeneous, black-looking content, as observed at SD-OCT, EnFace and OCTA scans. Interestingly, the limits of macular cystoid spaces were clearly detectable with OCTA. The analysis of red and green profiles demonstrated a clearly visible overlap between average OCTA and EnFace signal observed around cystoid spaces that could be attributed to a relationship between the dynamic vascularization and the structural density of the tissue.

Conclusions

This is the first investigation that characterizes and correlates OCTA and EnFace signals on images of macular cystoid spaces in DR and RVO. The low intensity OCTA signals observed inside cystoid spaces raise a relevant question about their nature, as to whether they are due to the presence of corpusculated material pouring out from bloodocular-barrier or they should be considered OCTA artifacts.

Multimodal imaging of diabetic retinopathy

PURPOSE OF REVIEW

Diabetic retinopathy is the most common microvascular complication of diabetes mellitus and a leading cause of blindness throughout the world. Ocular imaging continues to play a vital role in the diagnosis, management and monitoring of diabetic retinopathy. Major technological advancements in imaging over the past decade have improved our understanding and knowledge of diabetic retinopathy and therefore a multimodal approach to imaging has become the standard of care.

RECENT FINDINGS

Updates to traditional technologies such as digital fundus photography along with recent advancements in optical coherence tomography (OCT) and OCT angiography (OCTA) have provided clinicians with new information and improved efficiency.

SUMMARY

In this review, we describe the benefits and clinical applications of several imaging techniques in diabetic retinopathy including color photography, fluorescein angiography, OCT, OCTA and adaptive optics. Understanding the indications and limitations of each technology allows clinicians to gain the most information from each modality and thereby optimize patient care.

Age and myopia associated optical coherence tomography of retina and choroid in pediatric eyes

Purpose:

To evaluate the association between retinal and choroidal thickness and volume along with choroidal vessel volume in children using optical coherence tomography (OCT) images.

Methods:

113 normal eyes of children ranging from 5-17 years of age were imaged with a clinical OCT scanner (Optovue Inc., Fremont, USA). The retina, choroid and choroidal vessels were automatically segmented with algorithms. Parameters evaluated were thickness and volume. Location specific analyses of thickness were also performed at a distance of 2.5 mm from foveal center. Multivariate analyses of variance were used to analyze the effect of age and myopia. Manual segmentation of the fovea and subfoveal choroid thickness was also performed to compare with the algorithm segmentation.

Results:

There was excellent agreement between manual and automatic segmentation (intra-class correlation of 0.95). Within the same eye, total retinal and choroid thickness of nasal and temporal location were significantly lower than the superior and inferior thickness (P < 0.0001). With age (P = 0.026) and myopia (P < 0.001), foveal thickness increased. Choroid volume, vessel volume and temporal choroid thickness increased with increasing myopia (P < 0.05). There was significant positive correlation between choroid volume and retinal volume (r = 0.62, P < 0.0001), choroid volume and vessel volume (r = 0.48, P < 0.0001), and with foveal thickness (r = 0.31, P = 0.009). Choroid vessel volume also showed significant positive correlations with the other metrics (P < 0.05).

Conclusion:

Retinal and choroidal structural features were quantified simultaneously from OCT images. Magnitude of myopia had a greater effect on retino-choroid features than age in children.

Contemporary retinal imaging techniques in diabetic retinopathy: a review

Over the last decade, there has been an expansion of imaging modalities available to clinicians to diagnose and monitor the treatment and progression of diabetic retinopathy. Recently, advances in image technologies related to OCT and OCT angiography have enabled improved visualization and understanding of this disease. In this review, we will describe the use of imaging techniques such as colour fundus photography, fundus autofluorescence, fluorescein angiography, infrared reflectance imaging, OCT, OCT-Angiography and techniques in adaptive optics and hyperspectral imaging in the diagnosis and management of diabetic retinopathy.