Three-dimensional automated choroidal volume assessment on standard spectral-domain optical coherence tomography and correlation with the level of diabetic macular edema

Brolucizumab for the Treatment of Diabetic Macular Edema: An Optical Coherence Tomography-Based Analysis

Objectives: The objectives of this study were to evaluate the structural and functional outcomes after the loading phase with brolucizumab in switched patients with diabetic macular edema (DME) and to identify potential predictive biomarkers of treatment response. Methods: A total of 28 eyes with DME, switched to brolucizumab, were retrospectively reviewed. Main outcomes during the follow-up period, up to 6 weeks after the fifth injection, included changes in best-corrected visual acuity (BCVA), central subfield thickness (CST), macular volume, subfoveal choroidal thickness, intraretinal and subretinal fluid (IRF and SRF), cyst dimension including maximal horizontal cyst diameter (MHCD), maximal vertical cyst diameter (MVCD), width-to-height ratio (WHR), foveal avascular zone (FAZ) dimension, and vessel density (VD). Results: At the last follow-up, BCVA was significantly improved (p = 0.003). Significant reduction of CST was demonstrated after each injection time point (p < 0.05), and a dry macula was detected in 64.3% of patients at the last follow-up. The WHR was 1.23 ± 0.46, and a negative correlation to final CST (p < 0.0001) was found. In FAZ and VD analysis, no significant variation was detected. At the last disease activity assessment, the treatment regimen was q12 in 64% of patients. Conclusions: Brolucizumab leads to anatomical and functional improvements in switched eyes affected by DME. WHR may represent a predictive biomarker of treatment response.

Segmentation of choroidal area in optical coherence tomography images using a transfer learning-based conventional neural network: a focus on diabetic retinopathy and a literature review

BACKGROUND

This study aimed to evaluate the effectiveness of DeepLabv3+with Squeeze-and-Excitation (DeepLabv3+SE) architectures for segmenting the choroid in optical coherence tomography (OCT) images of patients with diabetic retinopathy.

METHODS

A total of 300 B-scans were selected from 21 patients with mild to moderate diabetic retinopathy. Six DeepLabv3+SE variants, each utilizing a different pre-trained convolutional neural network (CNN) for feature extraction, were compared. Segmentation performance was assessed using the Jaccard index, Dice score (DSC), precision, recall, and F1-score. Binarization and Bland-Altman analysis were employed to evaluate the agreement between automated and manual measurements of choroidal area, luminal area (LA), and Choroidal Vascularity Index (CVI).

RESULTS

DeepLabv3+SE with EfficientNetB0 achieved the highest segmentation performance, with a Jaccard index of 95.47, DSC of 98.29, precision of 98.80, recall of 97.41, and F1-score of 98.10 on the validation set. Bland-Altman analysis indicated good agreement between automated and manual measurements of LA and CVI.

CONCLUSIONS

DeepLabv3+SE with EfficientNetB0 demonstrates promise for accurate choroid segmentation in OCT images. This approach offers a potential solution for automated CVI calculation in diabetic retinopathy patients. Further evaluation of the proposed method on a larger and more diverse dataset can strengthen its generalizability and clinical applicability.

Association of SDF-1-3' Gene A Variant with Diabetic Retinopathy in the Hungarian Population

We investigated the association between the SDF-1-3' (c801G > A) variant and the development of diabetic macular edema (DME) or proliferative diabetic retinopathy (PDR) in a Hungarian cohort. SDF-1-3' (c801G > A) was genotyped in 103 patients with diabetic retinopathy and 31 age- and sex-matched non-diabetic controls. Central retinal and choroidal thickness was measured by swept-source optical coherence tomography. The distribution of heterozygous and homozygous SDF-1-3' (c801G > A) genotypes was similar in diabetic and control subjects. The SDF-3'(c801AA) genotype was associated with DME (n = 94 eyes, allele distribution p = 0.006, genotype distribution p = 0.01 OR: 2.48, 95% CL: 1.21-5.08) in both univariable and multivariable modelling, independent of duration and type of diabetes, HbA1C, hypertension and microalbuminuria (p = 0.03). DME occurred earlier in patients carrying the SDF-1 (c801A) allele (Kaplan-Meier analysis, log-rank test p = 0.02). A marginally significant association was found between the presence of the SDF-1 (c801A) allele and the development of PDR (n = 89 eyes, p = 0.06). The SDF-1-3' (c801A) allele also showed a correlation with central retinal (p = 0.006) and choroidal (p = 0.08) thickness. SDF-1-3' (c801G > A) is involved in the development of macular complications in DM independent of critical clinical factors, suggesting that SDF-1 may be a future therapeutic target for high-risk patients, especially those carrying the SDF-1 (c801A) allele.

The Anatomic and Functional Outcomes of Ozurdex-Aided Vitrectomy in Proliferative Diabetic Retinopathy

Purpose

To investigate the 3-months outcomes of patients who underwent intraoperative intravitreal injection of Ozurdex for proliferative diabetic retinopathy (PDR).

Methods

This is a prospective randomized controlled clinical trial (ChiCTR2100043399). Seventy-one patients with PDR who had indications for surgery without intravitreal injection history within 3 months preoperatively were enrolled. Patients were randomly divided into three groups based on the medicine injected intraoperatively: Ozurdex, Conbercept, and Control group. The primary outcome is the best-corrected visual acuity (BCVA) within 3 months postoperatively. The secondary outcomes include the intraocular pressure (IOP), mean sensitivity, central retinal thickness and vessels perfusion.

Results

The BCVA and the mean sensitivity improved in the three groups (F = 130.8, P < 0.0001; F = 34.18, P < 0.0001), but there was no statistical difference among the three groups (F = 0.858, P = 0.552; F = 0.964, P = 0.452). The IOP was no significant differences among the three groups within 3 months postoperatively (F = 0.881, P = 0.533). Compared with the other two groups, central retinal thickness (CRT) and outer retinal layer (ORL) thickness decreased significantly in patients of the Ozurdex group (F = 3.037, P = 0.008; F = 2.626, P = 0.018), especially in the diabetic macular edema (DME) patients (F = 2.761, P = 0.0164; F = 2.572, P = 0.0240). In macular region, superficial vascular plexus (SVP), intermediate capillary plexus (ICP) and deep capillary plexus (DCP) perfusion were not shown statistical difference at 3 months postoperatively in the all three groups compared with 1 day postoperatively (P > 0.05).

Conclusion

Compared with the other two groups, anatomical outcomes was improved significantly in Ozurdex group for DR patients. Ozurdex may help to improve the visual acuity and visual sensitivity, and there is no significant difference in the change of IOP and microvascular improvement.

Clinical Trial Registration

This trial is registered with the Chinese Clinical Trial Registry (http://www.chictr.org.cn, registration number ChiCTR2100043399).

Interocular Symmetry of Choroidal Parameters in Patients with Diabetic Retinopathy with and without Diabetic Macular Edema

This study focuses on the interocular comparison of choroidal parameters in diabetic patients with diabetic retinopathy (DR) with and without diabetic macular edema (DME), as well as in patients with unilateral DME (present in only one eye). The aim of this study was to determine the symmetry in order to obtain better insights into the pathophysiology of diabetic choroidopathy. This retrospective single-center cross-sectional study included 170 eyes from 85 patients (61 with DR and 24 controls), divided into subgroups depending on the presence of DME. The patients underwent fluorescein angiography and spectral domain optical coherence tomography examination, and the analysis included various choroidal parameters: choroidal thickness, volume, and the choroidal vascularity index (CVI). In terms of the choroidal thickness, one eye of a patient with DR, regardless of the presence, absence, or unilaterality of DME, may be treated as representative for that patient. CVI proved symmetrical for controls and patients with DR without DME. However, there was some asymmetry of CVI in patients with bilateral or unilateral DME. There was no straightforward relationship between choroidopathy and DME. Other mechanisms were also involved in the pathogenesis.

Short-term Effects of Intravitreal Dexamethasone Implant on Choroidal Structure in Eyes with Refractory Diabetic Macular Edema

Objectives

The objective of the study was to evaluate choroidal structural changes after intravitreal dexamethasone implant (IDI) in eyes with diabetic macular edema (DME) refractory to antivascular endothelial growth factor (VEGF) therapy.

Methods

Twenty-three eyes of 14 patients with DME refractory to anti-VEGF therapy were included in this retrospective study. Detailed ophthalmological examinations were recorded, and optical coherence tomography images were obtained before and 3 months after IDI. Choroidal images were binarized into the luminal area and total choroidal area. Subfoveal choroidal thickness and choroidal vascularity index (CVI) were calculated.

Results

The mean best-corrected visual acuity (BCVA) and central macular thickness (CMT) were improved significantly (from 0.94 to 0.81 LogMAR, p=0.02, and from 464 to 371 μ, p=0.01, respectively) after IDI. There were no significant changes in both SCFT and CVI at the end of the follow-up period (from 446.3 to 428.8 μ, p=0.51 and from 63.1 to 63.7 p=0.35, respectively).

Conclusion

IDI in eyes with DME refractory to anti-VEGF therapy improves BCVA and CMT but has no significant effect on SCFT and CVI in the short term.

Pathological Neurovascular Unit Mapping onto Multimodal Imaging in Diabetic Macular Edema

Diabetic retinopathy is a form of diabetic microangiopathy, and vascular hyperpermeability in the macula leads to retinal thickening and concomitant reduction of visual acuity in diabetic macular edema (DME). In this review, we discuss multimodal fundus imaging, comparing the pathogenesis and interventions. Clinicians diagnose DME using two major criteria, clinically significant macular edema by fundus examination and center-involving diabetic macular edema using optical coherence tomography (OCT), to determine the appropriate treatment. In addition to fundus photography, fluorescein angiography (FA) is a classical modality to evaluate morphological and functional changes in retinal capillaries, e.g., microaneurysms, capillary nonperfusion, and fluorescein leakage. Recently, optical coherence tomography angiography (OCTA) has allowed us to evaluate the three-dimensional structure of the retinal vasculature and newly demonstrated that lamellar capillary nonperfusion in the deep layer is associated with retinal edema. The clinical application of OCT has accelerated our understanding of various neuronal damages in DME. Retinal thickness measured by OCT enables us to quantitatively assess therapeutic effects. Sectional OCT images depict the deformation of neural tissues, e.g., cystoid macular edema, serous retinal detachment, and sponge-like retinal swelling. The disorganization of retinal inner layers (DRIL) and foveal photoreceptor damage, biomarkers of neurodegeneration, are associated with visual impairment. Fundus autofluorescence derives from the retinal pigment epithelium (RPE) and its qualitative and quantitative changes suggest that the RPE damage contributes to the neuronal changes in DME. These clinical findings on multimodal imaging help to elucidate the pathology in the neurovascular units and lead to the next generation of clinical and translational research in DME.

Automatic Choroidal Segmentation in Optical Coherence Tomography Images Based on Curvelet Transform and Graph Theory

Background

Automatic segmentation of the choroid on optical coherence tomography (OCT) images helps ophthalmologists in diagnosing eye pathologies. Compared to manual segmentations, it is faster and is not affected by human errors. The presence of the large speckle noise in the OCT images limits the automatic segmentation and interpretation of them. To solve this problem, a new curvelet transform-based K-SVD method is proposed in this study. Furthermore, the dataset was manually segmented by a retinal ophthalmologist to draw a comparison with the proposed automatic segmentation technique.

Methods

In this study, curvelet transform-based K-SVD dictionary learning and Lucy-Richardson algorithm were used to remove the speckle noise from OCT images. The Outer/Inner Choroidal Boundaries (O/ICB) were determined utilizing graph theory. The area between ICB and outer choroidal boundary was considered as the choroidal region.

Results

The proposed method was evaluated on our dataset and the average dice similarity coefficient (DSC) was calculated to be 92.14% ± 3.30% between automatic and manual segmented regions. Moreover, by applying the latest presented open-source algorithm by Mazzaferri et al. on our dataset, the mean DSC was calculated to be 55.75% ± 14.54%.

Conclusions

A significant similarity was observed between automatic and manual segmentations. Automatic segmentation of the choroidal layer could be also utilized in large-scale quantitative studies of the choroid.

Association between Aqueous Humor Cytokines and Structural Characteristics Based on Optical Coherence Tomography in Patients with Diabetic Macular Edema

Purpose

To investigate the relationship between aqueous humor cytokines and structural characteristics based on optical coherence tomography (OCT) in patients with diabetic macular edema (DME).

Methods

Forty eyes of 28 patients with DME diagnosed in the Affiliated Eye Hospital of Wenzhou Medical University at Hangzhou were included. All patients collected aqueous humor during anti-VEGF treatment, and the IL-6, IL-8, IL-10, VEGF, VCAM-1, ICAM-1, TGF-β1, FGF, and MCP-1 concentrations were detected. OCT examination was performed before anti-VEGF treatment and 1 month after anti-VEGF operation. Central macular thickness (CMT), macular volume (MV), choroidal thickness (CT), and the number of hyperreflective foci (HRF) were obtained for analysis. Each eye was determined whether there is subretinal effusion (SRD), cystoid macular edema (CME), and diffuse retinal thickening (DRT).

Results

The levels of IL-6 and FGF in DME patients with SRD were significantly higher than those without SRD (all P < 0.05). The level of VEGF in DME patients with CME was significantly higher than that in DME patients without CME (P = 0.005); IL-6, TGF-β1, and MCP-1 were significantly higher in DME patients with DRT than that without DRT (all P < 0.05). There was no significant correlation between aqueous humor cytokines and retinal thickness and retinal volume. However, the thinner the CT, the higher the level of aqueous humor cytokines IL-6 (r = -0.313, P = 0.049) and FGF (r = -0.361, P = 0.022). A multivariate linear regression analysis showed that IL-6 was significantly correlated with CT (P = 0.002) and SRD (P = 0.017), FGF was also significantly correlated with CT (P = 0.002) and SRD (P = 0.005), and TGF-β1 was correlated with triglycerides (P = 0.030) and HRF (P = 0.021).

Conclusion

DME patients with significant macular cystoid edema changes may be related to high VEGF concentrations and thin CT; meanwhile, the presence of SRD or a high number of HRF on OCT macular scans in DME patients may indicate high levels of intraocular inflammatory factors. Thus, OCT morphology characteristics to some extent reflect intraocular inflammatory factors and VEGF levels and may guide treatment alternatives.

Influence of Intravitreal Therapy on Choroidal Thickness in Patients with Diabetic Macular Edema

OBJECTIVE

This study aimed to analyze the variation in subfoveal choroidal thickness (SFCT) and its relationship with the variation in central macular thickness (CME) in response to intravitreal therapy with an antiangiogenic (anti-VEGF) drug or corticosteroid in type 2 diabetic patients with diabetic macular edema (DME).

MATERIAL AND METHODS

This retrospective study included 70 eyes of 35 patients: 26 eyes received 4-5 intravitreal injections of aflibercept, 26 eyes were treated with a single intravitreal implant injection of dexamethasone, and 18 eyes without DME did not receive intravitreal therapy. SPECTRALIS® optical coherence tomography (OCT) (Heidelberg Engineering, Heidelberg, Germany) was used to measure the SFCT and CME before and at the end of the follow-up period.

RESULTS

The mean reductions in CME were 18.8 +/- 14.7% (aflibercept) and 29.7 +/- 16.9% (dexamethasone). The mean reductions in SFCT were 13.8 +/- 13.1% (aflibercept) and 19.5 +/- 9.6% (dexamethasone). The lowering effects of both parameters were significantly greater in the group treated with the dexamethasone implant (p = 0.022 and p = 0.046 for CMT and SFCT, respectively). Both therapies significantly decreased both CME and SFCT, independent of factors such as age, sex, previous intravitreal therapy, antidiabetic treatment, and the time of diabetes progression. There were no changes in the mean values of CME and SFCT in the untreated eyes.

CONCLUSIONS

SFCT significantly decreased in response to intravitreal therapy with anti-VEGF or corticosteroids, irrespective of age, sex, previous intravitreal therapy, antidiabetic treatment, and the time of diabetes progression. There was a correlation between the changes in CME and SFCT after intravitreal therapy with aflibercept or dexamethasone implantation. SFCT was not a good predictor of the CME response but could be used to monitor the response to treatment. Local intravitreal therapy only affected the treated eye.

Correlation between Choroidal Vascularity Index and Outer Retina in Patients with Diabetic Retinopathy

The choroid supplies blood to the outer retina. We quantified outer retinal and choroidal parameters to understand better the pathogenesis of diabetic retinopathy (DR) and diabetic macular edema (DME). The retrospective cross-sectional single-center study included 210 eyes from 139 diabetic patients and 76 eyes from 52 healthy controls. Spectral-domain optical coherence tomography (OCT) was carried out with a Spectralis HRA + OCT imaging device. The outer retinal layer (ORL), outer nuclear layer (ONL), and choroidal thicknesses were assessed along with the choroidal vascularity index (CVI). The presence of DR, whether with DME or without, was associated with choroidal thinning (p < 0.001). Compared with the controls, patients with DR without DME presented with lower ORL and ONL thickness (p < 0.001), whereas those with DR and DME had higher values of both parameters (p < 0.001). Significant correlations between outer retinal and choroidal parameters were found only in patients with DR without DME (ORL with choroidal thickness: p = 0.003, rho = 0.34; ORL with CVI: p < 0.001, rho = 0.49, ONL with CVI: p < 0.027, rho = 0.25). No correlations between choroidal and outer retinal parameters were observed in the controls and patients with DR and concomitant DME. Aside from diabetic choroidopathy, other pathogenic mechanisms seem to predominate in the latter group.

The Role of Different Retinal Imaging Modalities in Predicting Progression of Diabetic Retinopathy: A Survey

Diabetic retinopathy (DR) is a devastating condition caused by progressive changes in the retinal microvasculature. It is a leading cause of retinal blindness in people with diabetes. Long periods of uncontrolled blood sugar levels result in endothelial damage, leading to macular edema, altered retinal permeability, retinal ischemia, and neovascularization. In order to facilitate rapid screening and diagnosing, as well as grading of DR, different retinal modalities are utilized. Typically, a computer-aided diagnostic system (CAD) uses retinal images to aid the ophthalmologists in the diagnosis process. These CAD systems use a combination of machine learning (ML) models (e.g., deep learning (DL) approaches) to speed up the diagnosis and grading of DR. In this way, this survey provides a comprehensive overview of different imaging modalities used with ML/DL approaches in the DR diagnosis process. The four imaging modalities that we focused on are fluorescein angiography, fundus photographs, optical coherence tomography (OCT), and OCT angiography (OCTA). In addition, we discuss limitations of the literature that utilizes such modalities for DR diagnosis. In addition, we introduce research gaps and provide suggested solutions for the researchers to resolve. Lastly, we provide a thorough discussion about the challenges and future directions of the current state-of-the-art DL/ML approaches. We also elaborate on how integrating different imaging modalities with the clinical information and demographic data will lead to promising results for the scientists when diagnosing and grading DR. As a result of this article's comparative analysis and discussion, it remains necessary to use DL methods over existing ML models to detect DR in multiple modalities.

Comparison of choroidal thickness in eyes of diabetic patients with eyes of healthy individuals using optical coherence tomography in a tertiary care hospital

Objectives:

To compare the choroidal thickness in eyes of diabetic patients with eyes of age matched controls using optical coherence tomography in a tertiary care hospital.

Methods:

This Cross sectional study was conducted at the Department of Ophthalmology, Jinnah Postgraduate Medical Centre Karachi, for six months from13^thJanuary 2020 to13^thJuly 2020. The study group comprised of 44 patients with 88 eyes. Patients who fulfill the inclusion criteria that is age ranging from 35 to 80years, either gender, known case of diabetes mellitus and having any type of diabetic retinopathy (HbA1c >7), non-diabetic healthy individuals (HbA1c < 7) and those giving informed consent were included in the study. However, patients having active ocular infections, history of myocardial infarction, stroke, uveitis, any ocular surgery, lasers, intravitreal injections, poor fundus view and not giving consent were excluded. A pre-designed proforma was filled. A baseline ocular examination was performed and choroidal thickness was assessed from retinal pigment epithelium to choroid sclera junction in diabetic and healthy participants of the study group using high resolution Swept source OCT (DRI-OCT-2 Triton; Topcon).

Results:

The average age of the patients was 39.41±15.95 years. According to our study mean central subfoveal choroidal thickness in diabetic eyes was 268.5 ± 66.22 (95% CI 240 – 297) and in non-diabetic healthy participants it was 339.3 ± 71.49 (95% CI 308 – 369) with a p-value of 0.001. However, average choroidal thickness was 261.8 ± 61.93 (95% CI 235 – 288) and 336.0 ± 74.35 (95% CI 304 – 367) in diabetic and non-diabetic healthy population with a p-value of 0.001. Choroidal thickness comparison between gender in diabetic and non-diabetic population also showed similar trend.

Conclusion:

In this study, mean central choroidal thickness as well as average choroidal thickness was significantly reduced in eyes having diabetic retinopathy as compared to participants with non-diabetic healthy eyes. These findings indicate that changes in choroid may be a probable route in the pathogenesis of diabetic retinopathy.

Intravitreal Ozurdex has no short term influence on choroidal thickness and vascularity index in eyes with diabetic macular edema: A pilot study

AIM:

To analyze choroidal parameters in eyes with diabetic macular edema (DME) treated with intravitreal Ozurdex.

PATIENTS AND METHODS:

Twenty eyes of 14 patients were included in this prospective study. Optical coherence tomography images were obtained before and 8–10 weeks after intravitreal Ozurdex injection; binarized and subfoveal choroidal thickness (SFCT) and choroidal vascularity index (CVI) were calculated.

RESULTS:

Mean SFCT (treatment naïve; 242.22 ± 32.87 reduced to 218.10 ± 22.10, P = 0.158 and previously treated; 330.4 ± 56.72 reduced to 328.93 ± 50.55, P = 0.833) and mean CVI (treatment naïve; 0.64 ± 0.03 changed to 0.65 ± 0.04, P = 0.583 and previously treated; 0.65 ± 0.05 reduced to 0.64 ± 0.03, P = 0.208) showed no significant change.

CONCLUSION:

Intravitreal Ozurdex showed no significant effects on SFCT and CVI in eyes with DME over short term. Larger studies with longer follow-up may allow a better understanding.

Quantitative Assessment of Choroidal Parameters in Patients with Various Types of Diabetic Macular Oedema: A Single-Centre Cross-Sectional Analysis

Simple Summary

Choroidopathy is one of the components in the pathogenesis of diabetic macular oedema (DME). This study investigated the optical coherence tomography-based choroidal parameters: thickness, volume, choroidal vascularity index (CVI), luminal area (LA), stromal area (SA), and total choroidal area (TCA) in relation to the presence and type of DME (cystoid, diffuse, and with subretinal fluid). Diabetic choroidopathy seems to play a role in the development of DME but is less likely involved in the pathogenesis of specific types thereof.

Abstract

Diabetic macular oedema (DME) is an outcome of multiple, complex and not fully understood mechanisms. The aim of this study was to define the role of choroidopathy in the pathogenesis of various DME types. The retrospective cross-sectional single-centre study included 140 eyes from 105 patients with DME and 76 eyes from 52 non-diabetic controls. The eyes were stratified according to the type of DME: cystoid, diffuse, and with subretinal fluid. Optical coherence tomography-based choroidal parameters: thickness, volume, choroidal vascularity index (CVI), luminal area (LA), stromal area (SA), and total choroidal area (TCA) were compared. Eyes with DME, regardless of the type thereof, had lower choroidal thickness, volume, and CVI values than the controls. Further, the eyes with some specific DME types differed significantly from the controls in terms of LA and SA. While the eyes with various DME types did not differ significantly in terms of their choroidal thickness, volume and CVI, some between-group differences were found in LA, SA and TCA. Diabetic choroidopathy seems to play a role in the development of DME but is less likely involved in the pathogenesis of specific types thereof.

Malfunction of outer retinal barrier and choroid in the occurrence and progression of diabetic macular edema

Diabetic macular edema (DME) is the most common cause of vision loss in diabetic retinopathy, affecting 1 in 15 patients with diabetes mellitus (DM). The disruption of the inner blood-retina barrier (BRB) has been largely investigated and attributed the primary role in the pathogenesis and progression in DME, but there is increasing evidence regarding the role of outer BRB, separating the RPE from the underlying choriocapillaris, in the occurrence and evolution of DME. The development of novel imaging technologies has led to major improvement in the field of in vivo structural analysis of the macula allowing us to delve deeper into the pathogenesis of DME and expanding our vision regarding this condition. In this review we gathered the results of studies that investigated specific outer BRB optical coherence tomography parameters in patients with DM with the aim to outline the current status of its role in the pathogenesis and progression of DME and identify new research pathways contributing to the advancement of knowledge in the understanding of this condition.

Foveal Avascular Zone Does Not Correspond to Choroidal Characteristics in Patients with Diabetic Retinopathy: A Single-Center Cross-Sectional Analysis

PURPOSE

The aim of the study was to compare two non-overlapping blood supply systems of the retina to obtain a better insight into the relation between diabetic macular retinopathy and choroidopathy. Specifically, the study focused on the relationships between (1) retinal vascular changes around the fovea in fluorescein angiography (FA) and (2) choroidal thickness, volume and other parameters assessed by optical coherence tomography (OCT).

PATIENTS AND METHODS

The retrospective cross-sectional single-center study included 210 eyes from 152 patients with diabetic retinopathy (mean age 60.7±12.4 years, 49.3% of women; foveal avascular zone [FAZ] outline: 44.3% grade ≤2, 55.7% grade ≥3). The outline of FAZ, a measure of capillary loss due to ischemic processes, was analyzed on FA according to the Early Treatment Diabetic Retinopathy Study Research Group (ETDRS) standards. The eyes were stratified according to the FAZ outline and size and the presence of clinically significant diabetic macular edema (CSME). Then, resultant groups were compared in terms of the spectral domain OCT parameters: choroidal thickness and volume (within ETDRS subfields), luminal, stromal and total choroidal areas and choroidal vascularity index (based on the foveal scan). Statistical analysis was based on univariate models with the choroidal parameters as independent variables, and age, sex, panretinal photocoagulation, the severity of diabetic retinopathy and CSME as covariates.

RESULTS

No significant relationships were found between the FAZ outline and area and choroidal characteristics of patients with diabetic retinopathy. In patients without CSME, no correlation was observed between the FAZ area and choroidal characteristics. In patients with CSME, no correlation was found between the FAZ area and choroidal characteristics other than the choroidal vascularity index.

CONCLUSION

In patients with diabetic retinopathy, damage to the macular retinal vasculature (FAZ) does not seem to be associated with changes in the choroidal vasculature, and these two processes appear to occur independently.

Automatic Segmentation and Visualization of Choroid in OCT with Knowledge Infused Deep Learning

The choroid provides oxygen and nourishment to the outer retina thus is related to the pathology of various ocular diseases. Optical coherence tomography (OCT) is advantageous in visualizing and quantifying the choroid in vivo. However, its application in the study of the choroid is still limited for two reasons. (1) The lower boundary of the choroid (choroid-sclera interface) in OCT is fuzzy, which makes the automatic segmentation difficult and inaccurate. (2) The visualization of the choroid is hindered by the vessel shadows from the superficial layers of the inner retina. In this paper, we propose to incorporate medical and imaging prior knowledge with deep learning to address these two problems. We propose a biomarker-infused global-to-local network (Bio-Net) for the choroid segmentation, which not only regularizes the segmentation via predicted choroid thickness, but also leverages a global-to-local segmentation strategy to provide global structure information and suppress overfitting. For eliminating the retinal vessel shadows, we propose a deep-learning pipeline, which firstly locate the shadows using their projection on the retinal pigment epithelium layer, then the contents of the choroidal vasculature at the shadow locations are predicted with an edge-to-texture generative adversarial inpainting network. The results show our method outperforms the existing methods on both tasks. We further apply the proposed method in a clinical prospective study for understanding the pathology of glaucoma, which demonstrates its capacity in detecting the structure and vascular changes of the choroid related to the elevation of intra-ocular pressure.

Increased choroidal thickness: a new indicator for monitoring diabetic macular oedema recurrence

PURPOSE

The aim of this study was to determine whether choroidal thickness (CT) increases at the time of exudative recurrence in diabetic patients with unilateral diabetic macular oedema (DME) treated with intravitreal injections of anti-VEGF or dexamethasone.

METHODS

A real-life, prospective, two-centre study was conducted over a 9-month period investigating diabetic patients presenting with unilateral DME treated with anti-VEGF or dexamethasone intravitreal injections, and CT was measured manually, using the enhanced depth imaging module of the spectral domain optical coherence tomography. Choroidal thickness (CT) was measured in the morning, in both the affected and healthy eye of each patient at two timepoints: when the macula was 'dry' (T0) and at the time of exudative recurrence (T1).

RESULTS

A total of 51 patients with unilateral DME were included. Mean CT in the affected eye was significantly thicker at the time of exudative recurrence (210.8 ± 44.1 μm at T0 versus 238.0 ± 49.0 μm at T1, p < 0.001). There was no significant variation in CT in the fellow eye (214.4 ± 52.3 µm at T0 versus 218.9 ± 53.4 µm at T1, p = 0.53). The type of intravitreal injection, the number of injections and the CT at T0 had no influence on the change in CT.

CONCLUSION

This study found that CT increased significantly in the affected eye at the time of recurrence of DME treated with anti-VEGF or dexamethasone injections. Choroidal thickness (CT) could constitute an interesting new indicator for monitoring patients with DME.

Choroidal Changes in Diabetic Patients With Different Stages of Diabetic Retinopathy

Diabetic retinopathy (DR) is one of the long-term microvascular complications of diabetes mellitus (DM) and is considered a leading cause of vision loss worldwide. Chronic hyperglycemia can cause microvascular abnormalities to the retina and the choroid as well. The vascular tissue of the choroid supplies blood to the outer retina, photoreceptors, and retinal pigment epithelium. It plays an important role in the metabolic exchange of the retina. Many experimental studies reported that choroidal pathology in diabetic patients might play a role in developing DR. Choroidal thickness (CT) can reflect changes in the vasculature of the choroid and can be used to assess the vascularity of the choroid itself. CT differs between healthy and diseased states of the eye as well as with the aging process. This means that thinner or thicker choroid may indicate an ocular disease. Choroidal vascularity index (CVI) is also used as a marker for choroidal vascularity assessment and indirectly measures choroidal vascularity quantitatively. Many studies have been conducted to evaluate the choroid in many different ocular diseases. However, the results regarding CT in DM, especially in patients with DR, are various as thickened, thinned, or no changes. Thus, the status of the choroid in patients with DM with or without DR remains controversial between researchers. In this systematic review, we reviewed 18 articles that were done to investigate the relationship between structural choroidal changes in diabetic patients with different stages of DR, focusing on CT, CVI, and some other parameters evaluating choroidal changes.

Inflammatory cytokines, oxidative and antioxidative stress levels in patients with diabetic macular edema and hyperreflective spots

PURPOSE

To determine the levels of serum oxidative, antioxidative markers and inflammatory cytokines in patients diagnosed with diabetic macular edema (DME) whose hyperreflective spots (HRS) were detected by optical coherence tomography (OCT).

METHODS

In this prospective cross-sectional clinical study included a total of 88 patients; 31 patients (group-1) with DME and HRS detected by OCT, 29 patients (group-2) with DME without HRS, and 28 patients (group-3) diagnosed with diabetes mellitus (DM) without any diabetic retinopathy findings. The main outcomes were best-corrected visual acuity (BCVA), CMT (central macular thickness), CMV (central macular volume), TMV (total macular volume), CT (choroidal thickness), serum TAS (total antioxidant status), TOS (total oxidant status), VEGF (vascular endothelial growth factor), FGF (fibroblast growth factor) and IL-1b levels. OCT parameters and biochemical measurements were compared statistically between the three groups.

RESULTS

A total of 88 patients (43 females (48.9%) and 45 males (51.1%)) were included in the study. The mean age was 56.29 ± 9.23 years. There was no difference between the three groups in age-and-sex. In group-1 and 2, BCVA(LogMAR) was statistically higher than group 3. CMT, CMV, TMV, TAS, TOS, VEGF and FGF were significantly higher in group-1 than in group-3. CMT, CMV, TMV, VEGF and FGF were significantly higher in group-2 than group 3. TOS and VEGF were significantly higher in group-1 than group-2.

CONCLUSIONS

This study demonstrates that in patients with DME and HRS, TOS and VEGF levels were higher than those without HRS. Hence, hyperreflective spots may be an inflammatory biomarker.

Choroid structure analysis following initiation of hemodialysis by using swept-source optical coherence tomography in patients with and without diabetes

We aimed to evaluate choroid structural changes using swept-source optical coherence tomography (SS-OCT) following hemodialysis initiation in diabetic and nondiabetic patients with end-stage kidney disease (ESKD). In this multicenter, prospective, cross-sectional study, diabetic (DM group; 30 eyes; 16 patients) and nondiabetic patients (NDM group; 30 eyes; 15 patients) with ESKD were evaluated after hemodialysis initiation. SS-OCT findings were analyzed using a manual delineation technique and binarization method before the first and last hemodialysis sessions, conducted approximately 2 weeks apart. Subfoveal choroidal thickness changes and mean large choroidal vessel layer thickness were significantly greater in the DM group (−13.3% ± 2.5% and −14.5% ± 5.2%, respectively) than the NDM group (−9.5% ± 3.1% and −9.2% ± 3.4%, respectively; p = 0.049 and p = 0.02, respectively). Binarized SS-OCT analysis revealed that the mean subfoveal choroidal area was significantly larger in the DM group (−21.9% ± 6.5%) than the NDM group (−17.2% ± 5.9%; p = 0.032). The change ratio in mean luminal area values was significantly greater in the DM group (−27.7% ± 8.7%) than the NDM group (−17.7% ± 5.8%; p = 0.007). The DM group exhibited substantial changes in the choroidal layer, possibly reflecting choroidal vascular disorders caused by diabetes.

Effects of Systemic Profiles on Choroidal Thickness in Treatment-Naïve Eyes With Diabetic Retinopathy

Purpose

The purpose of this study was to analyze the effects of systemic and ocular profiles on subfoveal choroidal thickness (SFChT) in treatment-naïve eyes with diabetic retinopathy (DR).

Methods

This study included patients with treatment-naïve DR. They underwent routine laboratory evaluations, including complete blood cell count, liver function tests, kidney function tests, and urinalysis for macroalbuminuria. The systemic and ocular factors associated with the change in SFChT in DR were analyzed.

Results

A total of 136 eyes from 136 patients with diabetes and 30 eyes from 30 age-matched healthy controls were recruited. Generalized linear model analyses showed that the SFChT in treatment-naïve eyes with DR was positively associated with the DR grade and estimated glomerular filtration rate (eGFR; P = 0.001) and negatively associated with age (P < 0.001) and serum phosphorus levels (P = 0.001). Treatment-naïve eyes with proliferative DR (PDR; 313.4 ± 9.0 µm) or severe nonproliferative DR (NPDR; 299.7 ± 9.7 µm) had thicker choroid than eyes with mild to moderate NPDR (251.7 ± 11.1 µm) or no DR (231.2 ± 14.5 µm) after adjusting for age, eGFR, and phosphorus levels.

Conclusions

Choroid is affected by renal function and the grade of DR in patients with diabetes. Advanced retinopathy is associated with choroidal thickening, and the severity of concomitant renal disease is associated with choroidal thinning.

Choroidal Thickness in Diabetes and Diabetic Retinopathy: A Swept Source OCT Study

Purpose

Previous studies on the association between choroidal thickness (CT) and severity of diabetic retinopathy (DR) gave conflicting results. The aim of this study was to evaluate the CT changes in diabetic patients and associated factors in a large sample of Chinese patients with diabetes.

Methods

Type 2 diabetes mellitus patients without history of ocular treatment were recruited from the community health system in Guangzhou, China. The swept source OCT instrument was used to obtain high-definition retina and choroid images. The diabetic retinopathy (DR) status was graded based on the guidelines of the United Kingdom National Diabetic Eye Screening Programme. Univariate and multivariate linear regression analyses was used to explore the association of CT with DR severity, diabetic macular edema (DME), hemoglobin A1c, and vision function.

Results

A total of 1347 patients were included in the final analysis. After adjusting for other factors, the patients with stage R3 DR had significantly thinner CT (β = –29.1 µm, 95% CI –53.8 to –4.4, P = 0.021) in comparison in those with R0. After adjusting for other factors, the CTs were thicker than those in R0 patients with difference of 15.6 µm (95% CI 4.3-26.9, P = 0.007) for outer nasal sector, 15.7 µm (95% CI 3.8-25.5, P = 0.008) for outer inferior, and 12.2 µm (95% CI 0.4-24.0, P = 0.042) for inner inferior sector. The presence of DME and hemoglobin A1c levels did not significantly affect average CT. Higher average CT was significantly associated with better best corrected visual acuity, with a –0.02 LogMAR unit per 100 µm increase in average CT (95% CI –0.03 to –0.01, P < 0.001).

Conclusions

CT increased in the early stage of DR, and further decreased with DR progression. DME was not significantly associated with CT. These findings provide more clues to suggest that choroid alterations play a role in the pathogenesis of DR.

Changes in choroidal thickness in advanced diabetic retinopathy treated with pan-retinal photocoagulation using a pattern scanning laser versus a conventional laser

Background

To compare the effect of pan-retinal photocoagulation (PRP) using pattern scanning or conventional laser on subfoveal choroidal thickness (SFChT).

Methods

Thirty-eight patients (64 eyes) with advanced diabetic retinopathy (DR) who underwent PRP using pattern scanning or conventional laser were included. Changes in SFChT were compared with baseline values at 1, 3, 6, and 12 months after PRP using swept-source optical coherence tomography.

Results

The conventional laser group showed a statistically significant decrease in SFChT at 1, 3, 6, and 12 months after PRP (P < 0.001). SFChT was significantly decreased at 3 (P = 0.025), 6 (P = 0.004), and 12 (P < 0.001) months after treatment in the pattern laser group.

Conclusion

Eyes with advanced DR showed a significant reduction in SFChT over 12 months regardless of the type of laser used; however, the reduction was sooner after conventional laser than after pattern laser.

Evaluation of choroidal thickness, macular thickness, and aqueous flare after cataract surgery in patients with and without diabetes: a prospective randomized study

BACKGROUND

In diabetic eyes, various choroidal abnormalities are noted in addition to changes in the retinal circulation, and the risk of increased aqueous flare and retinal thickening after cataract surgery is higher in diabetic eyes. Inflammation caused by surgery induces breakdown of the blood-retinal barrier and affects the retina, although the influence on the choroid is unknown. Several researchers have evaluated the choroidal thickness (CT) after cataract surgery in patients with diabetes; however, the results are inconsistent. The purpose of this study was to evaluate the influence of uneventful small-incision phacoemulsification cataract surgery on the subfoveal choroidal thickness (SCT), the central macular thickness (CMT), and aqueous flare in patients with diabetes.

METHODS

This study included 59 randomly selected eyes (33 eyes of patients with diabetes and 26 eyes of control patients without diabetes) undergoing small-incision cataract surgery. Among the diabetic eyes, 26 were without diabetic retinopathy, and the remaining eyes had non-proliferative diabetic retinopathy. Aqueous flare, CMT, and SCT measurements were performed before and at 1 week, 1 month, and 3 months after surgery.

RESULTS

The postoperative CMT continued to increase significantly until 3 months in both groups. Although the CMT was more in patients with diabetes than in patients without diabetes during the follow-up period, there was no significant difference between the two groups. The aqueous flare value increased until 3 months after surgery in both groups. Although the increase was significant at 3 months after surgery in patients with diabetes, the increase in controls was not significant. The aqueous flare values differed significantly between the two groups before and at 3 months after surgery. There was no significant within-group or between-group difference in pre- and postoperative SCT values.

CONCLUSION

In diabetic eyes with early stage of retinopathy, even small-incision cataract surgery can induce increased aqueous flare and macular thickening until 3 months, although there is no significant change in the choroidal thickness. Further studies are essential to evaluate choroidal changes after the cataract surgery in diabetic eyes.

Diabetic Macular Edema: State of Art and Intraocular Pharmacological Approaches

Diabetic macular edema (DME) is the main cause of vision loss in diabetic retinopathy (DR). Although it is one of the main complications of diabetes, the pathogenesis of DME is not completely understood. The hyperglycemic state promotes the activation of multiple interlinked pathways leading to DME. Different classifications have been proposed: based on clinical features, on pathogenesis or on diagnostic tests (optical coherence tomography - OCT and fluorescin angiography - FA). The multimodal imaging allows a better analysis of the morphological features of the DME. Indeed, new inflammatory biomarkers have been identified on OCT. Also, several studies are evaluating the role of the morphological features, identified on multimodal imaging, to find new prognostic factors. Over the past decade, great progresses have been made in the management of DME. Therapeutic alternatives include intraocular injection of anti-vascular endothelial grow factor agents (anti-VEGF) and steroid molecules, focal/grid laser photocoagulation and vitreo-retinal surgery. This review is focused on the description and analysis of the current intravitreal therapeutic pharmacological strategies. Current guidelines recommend anti-VEGF as first line therapy in DME. Corticosteroids are becoming increasingly relevant blocking the inflammatory cascade and indirectly reducing VEGF synthesis.

Longitudinal analysis of subfoveal choroidal thickness after panretinal laser photocoagulation in diabetic retinopathy using swept-source optical coherence tomography

Purpose: To describe the central three-dimensional (3D) thickness profile of the macula (CMT) and the subfoveal choroidal region (SFCT) in diabetic retinopathy (DR) following panretinal laser photocoagulation (PRP) using swept-source optical coherence tomography (SS-OCT). Methods: A prospective observational study including 17 eyes with proliferative DR (PDR) and 27 eyes with severe nonproliferative DR (sNPDR)] for whom PRP was done. All subjects received SS-OCT imaging before and 3 months after PRP (POM#3). SFCT and CMT changes were analysed at both visits. Intraclass Correlation Coefficients (ICC) and Coefficients of Variation (COV) were used to test the accuracy of thickness data. Results: SFCT has thinned from 233 ± 54 µm before PRP treatment to 216 ± 51 µm 3 months later (p < 0.001). Likewise, CMT declined at POM#3 as compared to pre-PRP status (p<0.001). SFCT was thinner in PDR before and at POM#3 (p<0.05) than sNPDR; whereas, no significant difference was observed in CMT between both groups in the two visits. No significant changes were found between groups in SFCT and CMT at POM#3. Regarding reliability, ICCSFCT=0.98 and ICCCMT=0.99. The COVs for CMT and SFCT were 5.03% and 5.91%, respectively. Conclusion: The mean SFCT and CMT decreased 3 months after PRP. We also reported reliability of SFCT measurements in DR using SS-OCT. Abbreviations: SS = Swept-Source, TD = time domain, SD = spectral domain, FD = Fourier-domain, 3D = three-dimensional, 2D = two-dimensional.

[Clinical Decision Making for Treatment of Diabetic Macular Oedema with DEX Implant: a Consensus Paper]

BACKGROUND

Currently two intravitreally applied corticosteroids (dexamethasone and fluocinolone) are licensed in Germany for treatment of diabetic macular oedema (DME). The use of DEX implant for DME in daily clinical practice has not been defined in detail. Following a Delphi panel survey, a group of retina experts set out to come up with a consensus for use of the DEX implant in DME.

MATERIAL AND METHODS

International and national treatment recommendations were identified from the literature. A steering group generated a catalogue of 72 statements on the aetiology and pathogenesis of DME, therapy with DEX implant, use of DEX implant in patients previously treated with VEGF-inhibitors, use of DEX implant in combination therapy, safety of DME therapies as well as patients' burden of treatment. Twenty-two ophthalmologists from private practice and 6 hospital ophthalmologists participated in the Delphi panel via Survey Monkey. Consensus was reached if at least 75% of participants agreed or disagreed with a statement. Statements for which consensus was not reached were discussed once more during the expert consensus meeting and a vote was taken. Based on these results a treatment algorithm for foveal DME was proposed.

RESULTS

If a patient does not show sufficient response after 3 - 6 months of anti-VEGF treatment (visual acuity gain of < 5 ETDRS letters or reduction of central retinal thickness ≤ 20%), a switch to DEX implant should take place. DEX implant is also suitable in eyes with longer presentation of DME, showing e.g. massive lipid exudates. DEX implant is suitable as first-line therapy especially in pseudophakic patients, patients unwilling or able to comply with tight anti-VEGF injection intervals or patients with known vascular diseases. With fixed control visits every 4 - 8 weeks, use of DEX implant is flexible and individual. Decision parameters for repeated use should be visual acuity, retinal thickness and intraocular pressure. Treatment of both eyes on the same day should not take place.

CONCLUSION

The algorithm presented reflects survey as well as expert discussion results and may differ from recommendations issued by the German professional society. The consensus recommendations for the treatment of DME generated during the survey and meeting of retina experts are intended to guide use of DEX implant in daily practice.

Choroidal binarization analysis: clinical application

INTRODUCTION

Image processing of optical coherence tomography scans through binarization techniques represent a non-invasive way to separately asses and measure choroidal components, in vivo. In this review, we systematically search the scientific literature regarding binarization studies published so far.

METHODS

A systematic research was conducted at PubMed database, including English literature articles for all of the following terms in various combinations: binarization, choroid/al, enhanced depth spectral domain/swept source optic coherence tomography, and latest publications up to November 2018 were reviewed.

RESULTS

Thirty-seven articles were included and analyzed regarding studied disease, binarization method, studied variables, and outcomes. Most of the studies have focused on the more common retinal pathologies, such as age-related macular degeneration, central serous chorioretinopathy and diabetic retinopathy but binarization techniques have also been applied to the study of choroidal characteristics in ocular inflammatory diseases, corneal dystrophies and in postsurgical follow-up. Advantages and disadvantages of binarization techniques are also discussed.

CONCLUSION

Binarization of choroidal images seems to represent a promising approach to study choroid subcomponents in an increasingly detailed manner.

Choroidal structural analysis in eyes with diabetic retinopathy and diabetic macular edema-A novel OCT based imaging biomarker

PURPOSE

To evaluate structural changes in the choroid among patients with diabetic macular edema (DME), with varying grades of diabetic retinopathy (DR), using enhance depth imaging spectral domain optical coherence tomography (EDI SD-OCT) scans.

METHODS

A cross-sectional study was conducted on 82 eyes with DR and DME and 86 healthy control eyes. Eyes with DME were classified according to the severity of DR as per the international DR severity scale. Sub foveal choroidal thickness (SFCT)was obtained using EDI SD-OCT scans. These scans were binarized into luminal and stromal areas, to derive the choroidal vascularity index (CVI). CVI and SFCT were analyzed between the study and control group using paired-T test. Tukey's test was used to correlate the differences in CVI and SFCT between different grades of DR. Further analysis was done to look for the effect of DR severity and type of DME on CVI as well as SFCT using correlation coefficient and linear regression analysis.

RESULTS

SFCT was significantly increased in eyes with DME as compared to the controls (334.47±51.81μm vs 284.53±56.45μm, p<0.001), and showed an ascending trend with worsening of DR, though this difference was not statistically significant [mild non-proliferative diabetic retinopathy (NPDR) = 304.33±40.39μm, moderate NPDR = 327.81±47.39μm, severe NPDR = 357.72±62.65μm, proliferative DR (PDR) = 334.59±47.4μm, p-0.09]. CVI was significantly decreased in DME with DR eyes as compared to controls (63.89±1.89 vs 67.51±2.86, p<0.001). CVI was also significantly decreased with worsening DR (mild NPDR = 66.38±0.3, moderate NPDR = 65.28±0.37, severe NPDR = 63.50±0.47, PDR = 61.27±0.9, p<0.001).

CONCLUSION

SFCT and CVI are dynamic parameters that are affected by DME. Unlike CVI, SFCT is also affected by ocular and systemic factors like edema and hypertension. CVI may be a more accurate surrogate marker for DME and DR and can potentially be used to monitor the progression of DR.

Effects of intravitreal injection of ranibizumab on choroidal structure and blood flow in eyes with diabetic macular edema

PURPOSE

To determine the effects of an intravitreal injection of ranibizumab (IVR) on the choroidal structure and blood flow in eyes with diabetic macular edema (DME).

METHODS

Twenty-eight consecutive patients with DME who received an IVR and 20 non-diabetic, age-matched controls were followed for 1 month. The eyes with DME were divided into those with prior panretinal photocoagulation (PRP, n = 16) and those without prior PRP (no-PRP, n = 12). The enhanced depth imaging optical coherence tomography (EDI-OCT) scans and Niblack's image binarization were performed to determine the choroidal structure. The choroidal blood flow was determined by laser speckle flowgraphy.

RESULTS

The subfoveal choroidal thickness at the baseline was significantly thicker in the no-PRP group than in the PRP-treated group. After IVR, the best-corrected visual acuity (BCVA) and central retinal thickness in eyes with DME were significantly improved compared to the baseline values. There were significant differences in the choroidal thickness, total choroidal area, and choroidal vascularity index between the groups after IVR. Choroidal vascular index and choroidal blood flow were significantly reduced only in the no-PRP group and not in the PRP-treated group. In addition, the correlation between the central retinal thickness and the choroidal blood flow was significant in the no-PRP group (r = 0.47, P < 0.05).

CONCLUSIONS

A single IVR will reduce the central retinal thickness and improve the BCVA in eyes with DME in both the no-PRP and PRP-treated group. IVR affected the choroidal vasculature and blood flow significantly, and a significant correlation was found between the central retinal thickness and the choroidal blood flow in eyes without PRP.

CHOROIDAL THICKNESS IN DIABETIC RETINOPATHY ASSESSED WITH SWEPT-SOURCE OPTICAL COHERENCE TOMOGRAPHY

PURPOSE

To compare the choroidal thickness (CT) of diabetic eyes (different stages of disease) with controls, using swept-source optical coherence tomography.

METHODS

A multicenter, prospective, cross-sectional study of diabetic and nondiabetic subjects using swept-source optical coherence tomography imaging. Choroidal thickness maps, according to the nine Early Treatment Diabetic Retinopathy Study (ETDRS) subfields, were obtained using automated software. Mean CT was calculated as the mean value within the ETDRS grid, and central CT as the mean in the central 1 mm. Diabetic eyes were divided into four groups: no diabetic retinopathy (No DR), nonproliferative DR (NPDR), NPDR with diabetic macular edema (NPDR + DME), and proliferative DR (PDR). Multilevel mixed linear models were performed for analyses.

RESULTS

The authors included 50 control and 160 diabetic eyes (n = 27 No DR, n = 51 NPDR, n = 61 NPDR + DME, and n = 21 PDR). Mean CT (ß = -42.9, P = 0.022) and central CT (ß = -50.2, P = 0.013) were statistically significantly thinner in PDR eyes compared with controls, even after adjusting for confounding factors. Controlling for age, DR eyes presented a significantly decreased central CT than diabetic eyes without retinopathy (β = -36.2, P = 0.009).

CONCLUSION

Swept-source optical coherence tomography demonstrates a significant reduction of CT in PDR compared with controls. In the foveal region, the choroid appears to be thinner in DR eyes than in diabetic eyes without retinopathy.

Approach for a Clinically Useful Comprehensive Classification of Vascular and Neural Aspects of Diabetic Retinal Disease

The Early Treatment Diabetic Retinopathy Study (ETDRS) and other standardized classification schemes have laid a foundation for tremendous advances in the understanding and management of diabetic retinopathy (DR). However, technological advances in optics and image analysis, especially optical coherence tomography (OCT), OCT angiography (OCTa), and ultra-widefield imaging, as well as new discoveries in diabetic retinal neuropathy (DRN), are exposing the limitations of ETDRS and other classification systems to completely characterize retinal changes in diabetes, which we term diabetic retinal disease (DRD). While it may be most straightforward to add axes to existing classification schemes, as diabetic macular edema (DME) was added as an axis to earlier DR classifications, doing so may make these classifications increasingly complicated and thus clinically intractable. Therefore, we propose future research efforts to develop a new, comprehensive, and clinically useful classification system that will identify multimodal biomarkers to reflect the complex pathophysiology of DRD and accelerate the development of therapies to prevent vision-threatening DRD.

Diabetic Choroidopathy: Choroidal Vascular Density and Volume in Diabetic Retinopathy With Swept-Source Optical Coherence Tomography

PURPOSE

To compare choroidal vascular density (CVD) and volume (CVV) in diabetic eyes and controls, using en face swept-source optical coherence tomography (SS-OCT).

DESIGN

Prospective cross-sectional study.

METHODS

Setting: Multicenter.

PATIENT POPULATION

Total of 143 diabetic eyes-27 with no diabetic retinopathy (DR), 47 with nonproliferative DR (NPDR), 51 with NPDR and diabetic macular edema (DME), and 18 with proliferative DR (PDR)-and 64 age-matched nondiabetic control eyes.

OBSERVATION PROCEDURES

Complete ophthalmologic examination and SS-OCT imaging. En face SS-OCT images of the choroidal vasculature were binarized.

MAIN OUTCOME MEASURES

CVD, calculated as the percent area occupied by choroidal vessels in the central macular region (6-mm-diameter circle centered on the fovea), and throughout the posterior pole (12 × 9 mm). The central macular CVV was calculated by multiplying the average CVD by macular area and choroidal thickness (obtained with SS-OCT automated software). Multilevel mixed linear models were performed for analyses.

RESULTS

Compared to controls (0.31 ± 0.07), central macular CVD was significantly decreased by 9% in eyes with NPDR + DME (0.28 ± 0.06; ß = -0.03, P = .02) and by 15% in PDR (0.26 ± 0.05; ß = -0.04, P = .01). The central macular CVV was significantly decreased by 19% in eyes with PDR (0.020 ± 0.005 mm3, ß = -0.01, P = .01) compared to controls (0.025 ± 0.01 mm3).

CONCLUSIONS

Choroidal vascular density and volume are significantly reduced in more advanced stages of diabetic retinopathy. New imaging modalities should allow further exploration of the contributions of choroidal vessel disease to diabetic eye disease pathogenesis, prognosis, and treatment response.

Influence of scanning area on choroidal vascularity index measurement using optical coherence tomography

PURPOSE

Recently, choroidal vascularity index (CVI) is proposed as a novel tool to evaluate the choroidal vasculature. In this study, we investigate the impact of scanning area on CVI measurement using spectral-domain optical coherence tomography (SD-OCT).

METHODS

Spectral-domain optical coherence tomography (SD-OCT) using enhanced depth imaging mode was performed in 30 eyes from 15 normal subjects. Three scanning areas were compared: dingle foveal scan; central macular scans [scan passing through central 1000 microns circle on Early Treatment Diabetic Retinopathy Study (ETDRS) grid, inner circle]; and total macular cube scans. Binarization of OCT B-scans and segmentation of the binarized choroid layer were achieved using a previously reported validated automated software. Choroidal vascularity index (CVI) percentage was calculated. Degree of agreement among foveal, central macular and total macular CVI was assessed using intraclass correlation coefficient (ICC) and was plotted using Bland-Altman plot.

RESULTS

The mean CVI in subfoveal, central macular and total macular scans was 49.95 ± 4.84%, 50.00 ± 4.68% and 51.10 ± 4.63%, respectively. Intraclass correlation coefficient (ICC) was more than 0.8 for all three comparisons [subfoveal versus central macular CVI, ICC = 0.92 (95% CI: 0.84-0.96); central macular versus total macular CVI, ICC = 0.90 (95% CI: 0.82-0.96); subfoveal versus total macular CVI, ICC = 0.92 (95% CI: 0.85-0.95)]. No significant differences in variance (all p > 0.05) were noted among CVI measured from the three scanning areas.

CONCLUSION

Choroidal vascularity index (CVI) measurements were highly reproducible using subfoveal, central and total macular scans in healthy individuals. Single foveal scan choroidal vascularity represents total macular choroidal vascularity in healthy population.

Macular Fluid Reduces Reproducibility of Choroidal Thickness Measurements on Enhanced Depth Optical Coherence Tomography

PURPOSE

To determine if different types of retinal fluid in the central macula affect the reproducibility of choroidal thickness (CT) measurements on enhanced depth imaging optical coherence tomography (EDI-OCT).

DESIGN

Retrospective reliability analysis.

METHODS

EDI-OCT images were obtained and the choroidal-scleral junction was analyzed through semiautomated segmentation. CT was measured at the fovea and averaged across the central 3-mm horizontal segment. Demographic data, central macular thickness, and type of fluid present were recorded. Intragrader and intergrader repeatability were assessed using the intraclass correlation coefficient (ICC) and coefficient of repeatability (CR).

RESULTS

Of 124 eyes analyzed, 60 (48.4%) had diabetic macular edema, 32 (25.8%) had neovascular age-related macular degeneration, and 32 (25.8%) had other causes of fluid. Intergrader ICC (CR) was 0.95 (74.1 μm) and 0.96 (63.9 μm) for subfoveal and average CT, respectively. CR was similar across various causes of retinal fluid, but was worst for subretinal fluid compared to intraretinal or sub-retinal pigment epithelial fluid. CR also worsened with increasing choroidal thickness, but was not affected by retinal thickness. Intragrader repeatability was generally greater than intergrader values, and followed the same trend.

CONCLUSIONS

The presence of macular fluid reduces CT measurement reproducibility, particularly in eyes with subretinal fluid and greater choroidal thickness. A difference of 74.1 μm in subfoveal CT or 63.9 μm in average CT may be necessary to detect true clinical change in eyes with macular fluid.

Diabetic choroidopathy

Early histopathological studies of diabetic choroids demonstrated loss of choriocapillaris (CC), tortuous blood vessels, microaneurysms, drusenoid deposits on Bruchs membrane, and choroidal neovascularization. The preponderance of histopathological changes were at and beyond equator. Studies from my lab suggest that diabetic choroidopathy is an inflammatory disease in that leukocyte adhesion molecules are elevated in the choroidal vasculature and polymorphonuclear neutrophils are often associated with sites of vascular loss. Modern imaging techniques demonstrate that blood flow is reduced in subfoveal choroidal vasculature. Angiography has shown areas of hypofluorescence and late filling that probably represent areas of vascular loss and/or compromise. Perhaps, as a result of vascular insufficiency, the choroid appears to thin in DC unless macular edema is present. Enhanced depth imaging (EDI-SD) OCT and swept source (SS) OCT have documented the tortuosity and loss in intermediate and large blood vessels in Sattler's and Haller's layer seen previously with histological techniques. The risk factors for DC include diabetic retinopathy, degree of diabetic control, and the treatment regimen. In the future, OCT angiography could be used to document loss of CC. Because most of the measurement and imaging are in the posterior pole, the severity of DC may be underappreciated in the published accounts of DC assessed with imaging techniques. However, it is now possible to document DC and quantify these changes clinically. This suggests that DC should be evaluated in future clinical trials of drugs targeting DR because vascular changes similar to those in DR are occurring in DC.

Clinical relevance of reduced decorrelation signals in the diabetic inner choroid on optical coherence tomography angiography

Diabetes induces lesions of the retinal and choroidal capillaries, which promote the pathogenesis of diabetic retinopathy (DR). The decorrelation signals in optical coherence tomography angiography (OCTA) represent the blood flow and vascular structure, and three-dimensional OCTA images enable individual capillary layers to be evaluated separately. The current study documented that en-face OCTA images revealed spots of flow void in the choriocapillaris layer in eyes with DR. Quantitative investigation demonstrated that non-flow areas within the central subfield (CSF) increased in eyes with more severe DR grades. The non-flow areas in the choriocapillaris layer were also associated with poorer visual acuity (VA) in all 108 eyes. A modest correlation was noted between the areas of flow void and poorer VA in 69 eyes without DME, whereas the non-flow areas were not related to VA or to CSF thickness measured by OCT in 39 eyes with DME. In 12 eyes with ischemic maculopathy, the choriocapillaris layer beneath the disrupted ellipsoid zone of the photoreceptor (EZ) had greater areas of flow void than did the area beneath an intact EZ. These data suggested that disrupted choroidal circulation has clinical relevance and contributes to the pathogenesis of DR.

Choroidal Thickness and Choroidal Vessel Density in Nonexudative Age-Related Macular Degeneration Using Swept-Source Optical Coherence Tomography Imaging

Purpose

To analyze the relationship between choroidal thickness and the distribution of choroidal blood vessels in eyes with nonexudative AMD.

Methods

Eyes with a diagnosis of nonexudative AMD were imaged using a prototype 100-kHz swept-source (SS) optical coherence tomography (OCT) instrument (Carl Zeiss Meditec, Dublin, CA, USA) with a central wavelength of 1050 nm. We used an OCT cube scan pattern consisting of 512 × 512 A-scans over a 12 × 12 mm retinal area. The eyes were partitioned into two groups based on the presence or absence of reticular pseudodrusen (RPD). All scans were segmented using an automated algorithm. In addition, five eyes from each of the two groups were randomly chosen for manual segmentation. Binary choroidal vessels maps were generated from suitable OCT choroidal slabs, and the relationship between the density of large choroidal vessels and choroidal thickness was analyzed using an Early Treatment Diabetic Retinopathy Study–like target centered on the fovea.

Results

Twenty-five eyes were enrolled in each group. The automated algorithm produced accurate choroidal thickness maps with an average difference between the manual and automated segmentations of 13.7 μm. There was a significant and stable correlation between choroidal thickness and choroidal vessel density across the two groups. Both average choroidal thickness and vessel density were significantly lower in eyes with RPD.

Conclusions

Our fully automated choroidal segmentation algorithm was able to capture the different patterns of choroidal thickness over a wide area. Choroidal thickness has a clear relationship with the density of large choroid vessels in our sample, irrespective of the presence or absence of RPD.

Open-source algorithm for automatic choroid segmentation of OCT volume reconstructions

The use of optical coherence tomography (OCT) to study ocular diseases associated with choroidal physiology is sharply limited by the lack of available automated segmentation tools. Current research largely relies on hand-traced, single B-Scan segmentations because commercially available programs require high quality images, and the existing implementations are closed, scarce and not freely available. We developed and implemented a robust algorithm for segmenting and quantifying the choroidal layer from 3-dimensional OCT reconstructions. Here, we describe the algorithm, validate and benchmark the results, and provide an open-source implementation under the General Public License for any researcher to use (https://www.mathworks.com/matlabcentral/fileexchange/61275-choroidsegmentation).

CHOROIDAL THICKNESS IN INFANTS WITH RETINOPATHY OF PREMATURITY

PURPOSE

To evaluate choroidal thickness in premature infants and its relationship with stage of retinopathy of prematurity (ROP) using spectral domain optical coherence tomography (SD-OCT).

METHODS

Spectral domain optical coherence tomography imaging for measuring subfoveal choroidal thickness was performed for 80 premature infants. Subfoveal choroidal thickness was defined as the distance from the hyperreflective line of the outermost retinal pigment epithelium (RPE) to the innermost hyperreflective line of the choroidoscleral junction. Each measurement was performed at the central fovea (CF) and 0.75 mm to 1.5 mm nasal (N1 and N2) and temporal (T1 and T2) to the fovea. Subfoveal choroidal thickness and grading of cystoid macular edema (CME) were analyzed statistically.

RESULTS

Choroidal thickness of CF was found to be significantly greater than nasal (N1 and N2) and temporal (T1 and T2) choroidal thickness (P < 0.05). There was no significant relationship between stage of ROP and nasal (N1 and N2) choroidal thickness (P = 0.057, P = 0.282, respectively). However, CF and temporal (T1 and T2) choroidal thickness was found to be significantly lower at a higher stage of ROP (P = 0.005, P = 0.01 and P = 0.001). No significant relationship was found between subfoveal choroidal thickness and the grades of cystoid macular edema (P > 0.05). The choroidal thickness of CF was found to be correlated with birth weight (r = 0.267, P = 0.017) but not birth week (r = 0.140, P = 0.217). Maximum stage of ROP was found to be negatively correlated with choroidal thickness, at N1, T1, and T2 (r < -0.250, P < 0.02).

CONCLUSION

The subfoveal choroid in premature infants can be effectively evaluated using a portable SD-OCT device. Choroidal thickness gets thinner with the severity of ROP and the decrease is more prominent at the central and temporal location. Cystoid macular edema is not correlated with choroidal thickness in premature infants.

Choroidal vascularity index - a novel optical coherence tomography parameter for disease monitoring in diabetes mellitus?

PURPOSE

To propose the use of choroidal vascularity index (CVI) as a novel tool to assess vascular status of the choroid using image binarization of enhanced depth imaging (EDI) optical coherence tomography (OCT) scans in diabetes mellitus (DM).

METHODS

A prospective cross-sectional study was performed at a tertiary referral eye care centre in Singapore. Age and gender matched EDI-OCT scans of 38 eyes of 19 patients with DM were compared with eyes of healthy controls (n = 19). The choroidal images were binarized into luminal areas (LA) and stromal areas (SA). Choroidal vascularity index (CVI) was defined as the proportion of LA to total circumscribed subfoveal choroid area (TCA). Mean choroidal thickness, mean retinal thickness and mean CVI between patients and controls were compared using student's t-test.

RESULTS

There were no significant differences in TCA (p = 0.78), LA (p = 0.90), SA (p = 0.33), average choroidal (p = 0.40) or retinal thickness (p = 0.70) between patients with DM and controls. However, there was a significantly lower CVI in patients with DM as compared to controls (65.10 ± 0.20 versus 67.20 ± 0.16, p < 0.0001).

CONCLUSION

Eyes of patients with DM showed decreased CVI with no corresponding change in choroidal thickness. Image binarization may be potentially useful as a tool to assess choroidal structures and vasculature.

Repeatability of Choroidal Thickness Measurements on Enhanced Depth Imaging Optical Coherence Tomography Using Different Posterior Boundaries

PURPOSE

To assess the reliability of manual choroidal thickness measurements by comparing different posterior boundary definitions of the choroidal-scleral junction on enhanced depth imaging optical coherence tomography (EDI-OCT).

DESIGN

Reliability analysis.

METHODS

Two graders marked the choroidal-scleral junction with segmentation software using different posterior boundaries: (1) the outer border of the choroidal vessel lumen, (2) the outer border of the choroid stroma, and (3) the inner border of the sclera, to measure the vascular choroidal thickness (VCT), stromal choroidal thickness (SCT), and total choroidal thickness (TCT), respectively. Measurements were taken at 0.5-mm intervals from 1.5 mm nasal to 1.5 mm temporal to the fovea, and averaged continuously across the central 3 mm of the macula. Intraclass correlation coefficient (ICC) and coefficient of reliability (CR) were compared to assess intergrader and intragrader reliability.

RESULTS

Choroidal thickness measurements varied significantly with different posterior boundaries (P < .001 for all). Intergrader ICCs were greater for SCT (0.959-0.980) than for TCT (0.928-0.963) and VCT (0.750-0.869), even in eyes where choroidal-scleral junction visibility was <75%. Intergrader CRs were lower for SCT (41.40-62.31) than for TCT (61.13-74.24) or VCT (72.44-115.11). ICCs and CRs showed greater reliability for averaged VCT, SCT, or TCT measurements than at individual locations. Intragrader ICCs and CRs were comparable to intergrader values.

CONCLUSIONS

Choroidal thickness measurements are more reproducible when measured to the border of the choroid stroma (SCT) than the vascular lumen (VCT) or sclera (TCT).

In Vivo Choroidal Vascular Lesions in Diabetes on Swept-Source Optical Coherence Tomography

Diabetes induces microvascular diseases including diabetic retinopathy and choroidopathy which reciprocally promote the pathogenesis, although optical coherence tomography images of diabetic choroidopathy remains to be documented. Here we evaluated the qualitative characteristics of choroidal vascular lesions in patients with diabetes and their association with diabetic retinopathy on swept-source optical coherence tomography (SS-OCT) images. We retrospectively reviewed 110 consecutive eyes of 110 patients with diabetes and 35 eyes of 35 healthy subjects for whom SS-OCT images (6x6-mm scans centered on the fovea) of sufficient quality were acquired. The curve of chorioretinal sections was flattened using Bruch’s membrane as a reference surface, followed by generation of en-face images. We characterized choroidal vascular lesions and evaluated their association with the logarithm of the minimum angle of resolution visual acuity (logMAR VA), retinal and choroidal thicknesses, and diabetic retinopathy severity. En-face SS-OCT images showed unvisualized vessels in Sattler’s layer in 33 eyes (30.0%). Focal narrowing was seen in choroidal vessels in Haller’s layer in 56 eyes (50.9%). The choroidal vessels ended in the superficial or middle portion of Haller’s layer, referred to as vascular stumps, in 20 eyes (18.2%). Diabetic eyes had these findings more frequently than nondiabetic eyes. The subfoveal choroid was thicker in eyes with focal vascular narrowing and vascular stumps than in eyes without such lesions. Vascular stumps in Haller’s layer were significantly related to diabetic retinopathy severity, logMAR VA, and central retinal and choroidal thicknesses. These novel findings on SS-OCT images would promote the better understanding of complicated pathogenesis in diabetic retinopathy and choroidopathy.

Predicting outcomes to anti-vascular endothelial growth factor (VEGF) therapy in diabetic macular oedema: a review of the literature

Diabetic macular oedema affects visual acuity to a varying degree. The current treatment of choice is intravitreal anti-vascular endothelial growth factor (VEGF) that has proven both its anatomical and visual efficacy in several large randomised clinical trials (RCTs). Although most patients respond well to anti-VEGF agents, some, however, show a moderate or even poor response. There is no clear consensus as to how to manage these patients, or define them. In addition, identifying early in the course of treatment which patients will respond and which patients will not is paramount to any personalised treatment regimen. Most large RCTs such as RESTORE and Protocol I have attempted post hoc analyses to identify demographic, clinical, optical coherence tomography (OCT) and fluorescein angiography findings that might predict patient response. Although some factors were found to be predictive, the lack of uniformity between the different RCTs means that no consensus exists as to which of these factors can be reliably used. This review looks at the large diabetic macular oedema RCTs such as RESTORE, Protocol I, READ-2 and BOLT in an attempt to identify common prognostic indicators between the various studies. We also attempted to look at several other OCT parameters such as the inner segment-outer segment (IS-OS) layer, the external limiting membrane layer, and choroidal thickness to help determine whether they can truly predict visual outcomes in patients being treated with anti-VEGF therapy. Finally, we provide a simplified summary about which factors might be relevant in clinical practice to help guide physicians in treatment decisions.

Diabetic choroidopathy: a review of the current literature

Diabetic retinopathy is an increasingly prevalent disease, and a leading contributor to the burden of all-cause blindness worldwide. In addition to retinal changes, choroidal abnormalities are common in patients with diabetes. The first studies concerning this vascular structure were based on histologic, indocyanine angiography and laser Doppler flowmetry techniques, but the development of new optical coherence tomography (OCT) technologies and imaging software for enhanced depth imaging (EDI)-OCT in recent years has made it possible to provide more detailed images of the choroidal anatomy and topography.In diabetic patients, several choroidal changes have been described in the literature throughout the years; the recent focus is choroidal thickness, which is significantly different from that in healthy patients. However, understanding choroidal manifestations of diabetic eye disease remains a real challenge, and this gap is hindering efforts towards better defining choroidal evaluation as a predictive factor for disease evolution and treatment response.This review aims to summarize the recent literature concerning changes in choroidal structure in diabetic patients, the relationship to diabetic retinal disease progression, and finally, the current and potential application of the measurement of variations in choroidal thickness for patient management.