PHOTORECEPTOR DAMAGE IN DIABETIC CHOROIDOPATHY

Photobiomodulation-induced choriocapillaris perfusion enhancement and outer retinal remodelling in intermediate age-related macular degeneration: a promising therapeutic approach with short-term results

PURPOSE

To evaluate the effects of photobiomodulation (PBM) on choriocapillaris (CC) perfusion and drusen volume in patients with intermediate age-related macular degeneration (AMD).

METHODS

In this retrospective pilot study, 30 patients receiving PBM therapy and 30 age-matched controls were analysed. Treatment consisted of 8 sessions over 4 weeks using the EYE-LIGHT® device. Best-corrected visual acuity (BCVA), low luminance visual acuity (LLVA), mean drusen volume (MDV), and CC flow deficit percentage (FD%) were evaluated at baseline and 2-month follow-up.

RESULTS

The PBM group showed significant improvements in BCVA (Δ +3.2 ± 1.4 letters, p = 0.042), reduction in drusen volume (Δ -0.003 ± 0.001 mm³, p = 0.028), and decrease in choriocapillaris FD% (Δ -3.1 ± 1.4%, p = 0.024), while no significant changes were observed in the control group. Changes in choriocapillaris FD% correlated with BCVA improvement (r = -0.54, p = 0.002) and drusen volume reduction (r = 0.35, p = 0.042).

CONCLUSIONS

PBM therapy induces significant choriocapillaris remodelling in intermediate AMD, associated with functional improvement and drusen volume reduction. These findings suggest a potential therapeutic role of PBM in modulating choroidal perfusion in AMD.

Impact of diabetes and diabetic retinopathy on neovascular exudative age-related macular degeneration

BACKGROUND

To evaluate the functional and morphological changes in patients with nAMD undergoing anti-VEGF therapy, focusing on the impact of concomitant diabetes with or without diabetic retinopathy.

METHODS

This retrospective cohort study included 1096 eyes from 916 patients with nAMD treated at the retina department of the University of Bari between August 2017 and May 2023. Patients were divided into two groups: 892 eyes without diabetes and 204 eyes with diabetes. Best-corrected visual acuity (BCVA), central retinal thickness (CRT) and presence of intraretinal fluid (IRF), subretinal fluid (SRF), subretinal hyperreflective material (SHRM) and atrophy were assessed at baseline, post-loading phase and at 12-month follow-up.

RESULTS

At baseline, no significant differences were observed between groups. Post-loading phase, both groups showed significant improvements in BCVA and reductions in CRT. However, SRF persistence was notably more frequent in the diabetic group (64.2% vs. 27.2%, p < 0.001). At 12 months, SRF was present in 53.7% of the diabetic group compared to 34.9% of the non-diabetic group (p < 0.001). Diabetic patients with moderate diabetic retinopathy (DR) exhibited significantly higher SRF persistence compared to those with mild DR or no DR.

CONCLUSIONS

While anti-VEGF therapy improves visual and anatomical outcomes in both diabetic and non-diabetic patients with nAMD, diabetic patients, particularly those with more severe DR, experience a higher rate of persistence of SRF. This suggests a less than optimal anatomic treatment response and the potential need for more tailored management strategies in this patient population.

PRECIS

This retrospective cohort study investigated the impact of diabetes mellitus and diabetic retinopathy on neovascular age-related macular degeneration treatment outcomes. The study analysed 1096 eyes from 916 patients undergoing anti-VEGF therapy over 12 months.

DECREASING OUTER RETINA TRAUMATISM OF INTERNAL LIMITING MEMBRANE PEELING IN DIABETIC EYES WITH FOVEAL SPARING TECHNIQUE

PURPOSE

To evaluate the effect on outer retina integrity of foveal sparing (FS) internal limiting membrane peeling compared with standard internal limiting membrane peeling on proliferative diabetic retinopathy eyes affected by diabetic macular edema and epiretinal membrane.

METHODS

Eyes diagnosed with proliferative diabetic retinopathy, diabetic macular edema, and epiretinal membrane eligible for vitrectomy were prospectively recruited and randomly assigned to either FS group or no foveal sparing group. Ellipsoid zone (EZ) lesion size, EZ reflectivity, and external limiting membrane integrity and angular sign of Henle fiber layer hyperreflectivity were assessed preoperatively and 1 year postoperatively.

RESULTS

Twelve (12) eyes and fifteen (15) eyes were included in FS and no foveal sparing group, respectively. The two groups showed no differences in terms of EZ lesion size ( P = 0.549), EZ reflectivity ( P = 0.657), and external limiting membrane integrity (0.999) at preoperative examination. A significant increase in EZ lesion size was noted in the no foveal sparing group between preoperative and postoperative examination ( P = 0.040), which was not present in FS group ( P = 0.862). Moreover, the no foveal sparing group showed a higher prevalence of angular sign of Henle fiber layer hyperreflectivity and a lower EZ reflectivity at follow-up compared with FS group ( P = 0.047 and P = 0.041, respectively).

CONCLUSION

Vitrectomy with FS internal limiting membrane peeling may result in a better preservation of the Muller-photoreceptors complex in proliferative diabetic retinopathy complicated with diabetic macular edema and epiretinal membrane.

En face OCT: Breakthroughs in understanding the pathoanatomy of retinal disease and clinical applications

En face optical coherence tomography (OCT) is a practical and informative imaging modality to noninvasively visualize distinct retinal and choroidal layers by providing coronal images using boundary-specific segmentation. Ongoing research with this method is generating breakthroughs in the illustration of new perspectives of retinal disease. The clinical value of en face OCT as an advanced retinal imaging tool is growing steadily and it has unveiled many new insights into the pathoanatomy of retinal disorders. Moreover, this modality can capture various en face OCT biomarkers that correspond to different cell or tissue subtypes, which were previously only identified through histological or electron microscopy methods, underscoring the significance of this technique in providing valuable pathoanatomical information. In this comprehensive review, we will systematically summarize the en face OCT findings across a broad spectrum of retinal diseases, including disorders of the vitreoretinal interface and retinal vascular system (e.g. paracentral acute middle maculopathy or PAMM and diabetic retinopathy), in addition to the en face OCT features of other conditions such as age-related macular degeneration, pachychoroid disease spectrum, myopic degeneration, uveitis and inflammatory disorders, inherited retinal dystrophies, and drug toxicity. We will discuss and highlight the unique clinical and pathoanatomical findings uncovered with en face OCT of each these diseases mentioned above.

Correlation Between Photoreceptor and Vascular Parameters in Diabetic Retinopathy Using Adaptive Optics

BACKGROUND AND OBJECTIVE

This study aimed to investigate correlations between photoreceptor and vascular parameters in varying stages of diabetic retinopathy (DR) using adaptive optics (AO) imaging.

PATIENTS AND METHODS

In this single-center, prospective cohort study, 29 participants (46 eyes) were classified into control/mild non-proliferative DR (NPDR), moderate/severe NPDR, and proliferative DR. AO images of photoreceptors and retinal vasculature were analyzed, and Spearman's correlation (ρ) was used to assess relationships between photoreceptor density and vascular parameters.

RESULTS

Higher cone density was inversely associated with total vessel (ρ = 0.22, P = 0.03) and lumen diameters (ρ = -0.24, P = 0.01), while higher dispersion was associated with total vessel (ρ = 0.19, P = 0.06) and lumen diameters (ρ = 0.21, P = 0.04). These associations were primarily significant in mild NPDR. No significant correlations were found in advanced DR stages.

CONCLUSION

This study underscores intricate neurovascular correlations in early-stage DR, suggesting these parameters may aid in early disease detection. Further research is needed to understand whether similar correlations exist in advanced DR. [Ophthalmic Surg Lasers Imaging Retina 2025;56:150-158.].

The role of optical coherence tomography angiography in assessing diabetic choroidopathy: a systematic review

BACKGROUND

Diabetic retinopathy (DR) is a leading cause of vision impairment worldwide, affecting both retinal and choroidal vasculature. While advances in imaging technology, particularly optical coherence tomography angiography (OCTA), provide new opportunities to assess choroidal changes in diabetic patients, the role of OCTA in early diagnosis and monitoring of diabetic choroidopathy remains unclear.

OBJECTIVE

This review aims to evaluate the potential role of OCTA in diagnosing and monitoring diabetic choroidopathy.

METHODS

A systematic review was conducted following Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) 2020 guidelines. Databases including PubMed, Embase, Cochrane Library, Google Scholar, ISI, and Scopus were searched for studies on diabetic choroidopathy assessed by OCTA. Studies included were peer-reviewed, published in English, and excluded case reports, conference proceedings, and studies on treated DR patients. Two independent reviewers screened articles for eligibility based on predefined criteria.

RESULTS

OCTA allows for non-invasive, high-resolution visualization of retinal and choroidal microvasculature, providing both qualitative and quantitative data. The majority of studies indicate a significant decrease in choroidal perfusion parameters in diabetic patients without DR compared to healthy controls. Conflicting evidence exists regarding the correlation between choriocapillaris flow reduction and DR severity. OCTA may also predict changes in visual function related to choroidal perfusion, though it cannot fully replace clinical examinations.

CONCLUSIONS

OCTA is a valuable tool for early detection and monitoring of diabetic choroidopathy. However, its role is limited by variability in findings and its inability to detect certain features of diabetic microangiopathy. Further studies are needed to clarify its clinical utility and standardize assessment methods.

Colocalization of Ellipsoid Zone Disruption With Capillary Nonperfusion in Different Retinal Vascular Layers and Choriocapillaris on En Face OCT of Diabetic Patients

PURPOSE

To assess the colocalization of ellipsoid zone (EZ) disruption with nonperfusion in choriocapillaris (CC), retinal superficial capillary plexus (SCP), and deep capillary plexus (DCP) in diabetic patients using en face optical coherence tomography (OCT) and OCT angiography (OCTA).

METHODS

Macular OCT and OCTA scans (3 × 3 mm) of 41 patients with diabetic retinopathy were obtained using an RTVue XR Avanti instrument. After correcting the shadow artifacts, EZ integrity was assessed in the en face OCT slab using the Gaussian mixture model clustering method compared with the corresponding EZ en face OCT of 11 age-matched normal patients. A similar technique was used for detecting capillary nonperfusion using CC en face OCTA. Geometric perfusion density (GPD) maps were also generated for the SCP and DCP. Maps of capillary nonperfusion in the CC, SCP, and DCP were compared pixel by pixel with the map generated from EZ disruption.

RESULTS

Twenty-one patients with diabetic macular edema (DME) and 20 patients with diabetic retinopathy without macular edema were included in this study. In both groups, the overlap of EZ disruption was significantly greater with choriocapillaris nonperfusion than with nonperfusion in the SCP and DCP (dry macular group: 33.15% with CC vs. 0.46% with SCP vs. 1.70% with DCP, p < 0.001; DME group: 29.81% with CC vs. 1.22% with SCP vs. 6.25% with DCP, p < 0.001). In multivariate analysis, after adjusting for stage of diabetic retinopathy and DME, EZ disruption was only associated with nonperfusion in CC (p value = 0.03). According to the linear regression model, there was a statistically significant correlation between logMAR visual acuity and EZ disruption in the dry macular group (p = 0.041).

CONCLUSION

In patients with diabetic retinopathy, choriocapillaris nonperfusion may play a more significant role in photoreceptor loss than retinal nonperfusion.

Metabolic, Microvascular, and Structural Predictors of Long-Term Functional Changes Evaluated by Multifocal Electroretinogram in Type 1 Diabetes

BACKGROUND

This study aimed to analyze the potential pathogenic connection between metabolic factors, photoreceptor cell rearrangements, retinal microvascular perfusion, and functional parameters through multifocal electroretinography (mfERG) in type 1 diabetes mellitus (DM1).

METHODS

This prospective observational cohort study enrolled DM1 patients (40.5 ± 9.1 years) with mild nonproliferative diabetic retinopathy followed for 4 years. Patients were subjected to multimodal imaging, which included color fundus photography, optical coherence tomography (OCT), OCT angiography, adaptive optics (AO), and mfERG. OCTA slabs were analyzed using ImageJ software (software version 2.3.0/1.53f) to calculate perfusion density (PD) at both superficial (SCP) and deep (DCP) capillary plexuses, as well as flow deficit percentage (FD%) at the choriocapillaris (CC). To calculate cone metrics on AO at the parafovea, including cone density (CD), linear dispersion index (LDi), and heterogeneity packing index (Hpi%) in the parafovea, the images were post-processed using a MATLAB algorithm. The mfERG P1 implicit time (IT) and N1-P1 response amplitude density (RAD) from R1 (foveal area), R2 (parafoveal area), and the unified rings R1 + R2 were evaluated.

RESULTS

A total of 22 patients (22 eyes) were enrolled. No significant differences were noted in central mfERG amplitude and implicit time-averaged values (p > 0.05, all). The main factor influencing R1 IT was HbA1c, while R1 RAD was affected by Hpi and CC FD%. R1 + R2 IT was influenced by Hpi, LDi (p > 0.001, all), and modifications in the perfusion density in the SCP (p < 0.001) and DCP (p = 0.03) at the parafovea. In contrast, R1 + R2 RAD were associated with HbA1c (p = 0.02) and Hpi (p < 0.001).

CONCLUSIONS

Microvascular changes and glucometabolic factors are key elements influencing the long-term morphofunctional alterations at the photoreceptor level in DM1.

Associations of Retinal Vessel Geometry and Optical Coherence Tomography Angiography Metrics With Choroidal Metrics in Diabetic Retinopathy

Purpose

To elucidate the mechanism underlying changes in choroidal metrics (choroidal thickness [CT], choroidal vascularity index [CVI], and choriocapillaris [CC] flow deficit [FD]) observed in diabetic retinopathy (DR) and examine the association of choroidal metrics with both retinal vessel geometry and optical coherence tomography angiography (OCTA) metrics.

Methods

Overall, 133 eyes of 133 patients were analyzed retrospectively. Retinal vessel geometry parameters were assessed using semiautomated software. The OCTA metrics and CT were calculated using automated algorithms provided by the manufacturer, whereas the CVI and CC-FD were calculated using ImageJ software from the binarized choroid B-scan image and the CC slab provided by the manufacturer, respectively. To assess the associations among choroidal metrics, retinal vessel geometry, and OCTA metrics, multivariable regression analyses were performed while controlling for clinical features and DR severity.

Results

In the multivariable linear regression analysis, CT (β = -399.84; P = 0.014) and CVI (β = -2.34; P = 0.021) showed significant associations with the arteriole-venule ratio, which is a ratio of central retinal arteriolar equivalent caliber with respect to central retinal venular equivalent caliber. The CC-FD showed a significant association with the fractal dimension of retinal arteriolar network (β = -2.90; P = 0.040). In contrast, the OCTA metrics showed no significant association with the choroidal metrics.

Conclusions

The CT, CVI, and CC-FD in patients with DR were associated with retinal arteriolar geometry parameters rather than OCTA metrics, which indicates an association between choroidal changes and hemodynamic alterations in retinal arterioles and venules.

Severity of Disorganization of Retinal Layers and Visual Function Impairment in Diabetic Retinopathy

PURPOSE

To evaluate best-corrected visual acuity (BCVA), retina sensitivity (RS), and fixation impairment by microperimetry (MP) due to the presence and severity of disorganization of retinal inner and outer layers (DRIL/DROL) and ischemia in OCT/OCT angiography (OCTA) in diabetic retinopathy (DR).

DESIGN

Retrospective case-control study.

SUBJECTS

Seventy-six eyes (65 patients) with DR were analyzed. Major exclusion criteria were: center-involving diabetic macular edema (DME), significant media opacity, nondiabetic macular pathology, and active proliferative DR. Patients with DRIL and DROL within central 3 mm were enrolled as cases. Patients with DR and no retina disorganization were considered as controls.

METHODS

A detailed grading of MP and OCT/OCTA images using Image J software, and specific Image Manipulation Program was applied to colocalize the presence of retina disorganization and RS. Best-corrected visual acuity and RS were correlated with the disorganization of retina layers' characteristics and grading (grade 1-DRIL; grade 2-DROL; grade 3-DROL plus, with involvement of the ellipsoid zone). The same procedure of colocalization was applied to the vascular layers on OCTA using MATLAB.

MAIN OUTCOME MEASURES

Correlation between BCVA and MP parameters with disorganization of retina layers grading and OCTA parameters.

RESULTS

Best-corrected visual acuity, mean RS within 1 mm and central 3 mm (overall RS [oRS]), perfusion density, vessel density, and geometric perfusion deficit in intermediate and deep capillary plexuses were lower in cases versus controls (P < 0.001). Mean RS within 1 mm (21.4 decibels [dB] ± 2.4 vs. 13.8 dB ± 5.4, P = 0.002), oRS (22.0 dB ± 2.1 vs. 14.4 dB ± 4.6, P < 0.001), and BCVA (76.1 ± 7.4 vs. 61.2 ± 20.4 ETDRS letters; P = 0.02), had a significant decrease from grade 1 to grade 3 retina disorganization. Choriocapillaris flow voids (CC-FVs) increased from grade 1 to grade 3 (DROL plus) (P = 0.004). Overall retina sensitivity and CC-FV were identified as significant predictors of retina disorganization grade with an adjusted coefficient of determination, R2 = 0.45. Cases had more dense scotomas (P = 0.03) than controls with a positive correlation between the worsening of fixation stability and the severity of DRIL/DROL (P = 0.04).

CONCLUSIONS

Microperimetry and BCVA documented a reduction in visual function in patients with DR and disorganization of retina layers at different grades, with greater functional impairment when outer retina layers and photoreceptors are involved. The severity of retina disorganization and the presence of ischemia could serve as a potential biomarker of functional impairment.

FINANCIAL DISCLOSURES

Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.

Detection of choroidal vascular features in diabetic patients without clinically visible diabetic retinopathy by optical coherence tomography angiography: A systemic review and meta-analysis

Researchers have explored choroidal features in the eyes of diabetic patients without clinically visible diabetic retinopathy (DM-NoDR) employing optical coherence tomography angiography (OCTA); however, the results are controversial. We systematically searched PubMed, Embase, and Ovid databases for OCTA studies comparing choroidal parameters between DM-NoDR eyes and healthy controls or nonproliferative diabetic retinopathy (NPDR) eyes. Outcomes included choriocapillaris (CC) perfusion density (PD), flow area (FA), and flow deficits (FD). 36 studies were finally included in the quantitative meta-analysis, involving 1908 DM-NoDR eyes, 792 NPDR eyes, and 1391 healthy control eyes. DM-NoDR eyes had significantly lower CC PD in the foveal region (P = 0.0005) and superior parafoveal region (P = 0.003) than healthy control eyes, but no significant difference was found in other parafoveal subregions (P > 0.05). DM-NoDR eyes were also associated with increased CC FD (P < 0.00001) and decreased CC FA (P < 0.0001) in whole OCTA images with a 3 × 3 mm2 field of view (FOV). Compared with all-stage NPDR eyes, DM-NoDR eyes had higher CC PD in the foveal region (P < 0.0001), parafoveal region (P < 0.00001), and the whole OCTA images with a 6 × 6 mm2 FOV (P < 0.00001). Early choroidal microvascular changes may precede clinically visible DR and can be detected early using OCTA in DM-NoDR eyes.

Choriocapillaris in Age-Related Macular Degeneration

Age-related macular degeneration (AMD) is a multifactorial disease characterized by progressive alterations of different retinal structures ultimately leading to vision loss. Among these, the choriocapillaris (CC) has been found to be affected in different stages of AMD. In this review we provide a discussion on the different stages of AMD, focusing particularly on the alterations involving the CC. This has been possible thanks to the introduction of optical coherence tomography-angiography, a recently developed imaging technique which allows the detection of blood flow in choroidal vessels. Therefore, the aim of this review is to provide a description of the various alterations involving the CC in the different stages of AMD.

Long-Term Impact of Diabetic Retinopathy on Response to Anti-VEGF Treatment in Neovascular AMD

Purpose

To explore the long-term effect of diabetic retinopathy on response to anti-vascular endothelial growth factor (VEGF) treatment in age-related macular degeneration-associated type 1 macular neovascularization (MNV) using optical coherence tomography angiography (OCTA).

Methods

A total of 45 eyes with exudative neovascular age-related macular degeneration (nAMD) with type 1 MNV were included in the analysis. Among them, 24 eyes of 24 patients had no history of diabetes mellitus (DM) in their anamnesis and were assigned to the Not Diabetic group; 21 eyes of 21 patients had mild diabetic retinopathy and were included in the Diabetic group. We considered the following outcome measures: (1) best-corrected visual acuity changes; (2) central macular thickness; (3) MNV lesion area; and (4) MNV flow area. The OCTA acquisitions were performed at the following time points: (1) baseline visit, which corresponded to the day before the first injection; (2) post-loading phase (LP), which was scheduled at 1 month after the last LP injection; and (3) 12-month follow-up visit.

Results

All morphofunctional parameters showed a significant improvement after the LP and at the 12-month follow-up visit. Specifically, both the Diabetic group and the Not Diabetic group displayed a significant reduction of MNV lesion areas at both the post-LP assessment (P = 0.026 and P = 0.016, respectively) and the 12-month follow-up (P = 0.039 and P = 0.025, respectively). Similarly, the MNV flow area was significantly decreased in both the Diabetic group and the Not Diabetic group at the post-LP assessment (P < 0.001 and P = 0.012, respectively) and at the 12-month follow-up (P = 0.01 and P = 0.035, respectively) compared to baseline. A smaller reduction in the MNV lesion area was observed in the Diabetic group at both the post-LP evaluation (P = 0.015) and the 12-month follow-up (P = 0.032). No other significant differences were found between the groups for the other parameters (P > 0.05).

Conclusions

Our results indicated that the Diabetic group exhibited a smaller reduction in MNV lesion area after 12 months of anti-VEGF treatment. This highlights the importance of considering diabetic retinopathy as a potential modifier of treatment outcomes in nAMD management, with DM serving as a crucial risk factor during anti-angiogenic treatment.

Mitochondrial retinopathies and optic neuropathies: The impact of retinal imaging on modern understanding of pathogenesis, diagnosis, and management

Advancements in ocular imaging have significantly broadened our comprehension of mitochondrial retinopathies and optic neuropathies by examining the structural and pathological aspects of the retina and optic nerve in these conditions. This article aims to review the prominent imaging characteristics associated with mitochondrial retinopathies and optic neuropathies, aiming to deepen our insight into their pathogenesis and clinical features. Preceding this exploration, the article provides a detailed overview of the crucial genetic and clinical features, which is essential for the proper interpretation of in vivo imaging. More importantly, we will provide a critical analysis on how these imaging modalities could serve as biomarkers for characterization and monitoring, as well as in guiding treatment decisions. However, these imaging methods have limitations, which will be discussed along with potential strategies to mitigate them. Lastly, the article will emphasize the potential advantages and future integration of imaging techniques in evaluating patients with mitochondrial eye disorders, considering the prospects of emerging gene therapies.

Quantitative Analysis of the Vasculature and Cone Photoreceptors in Subjects With Diabetes Without Diabetic Retinopathy

PURPOSE

To characterize any differences in the vasculature and cone photoreceptor packing geometry (CPG) between subjects with diabetes without/no diabetic retinopathy (NDR) and healthy controls.

METHODS

Eight NDR and five controls were enrolled. Optical coherence tomography angiography (OCTA) taken at the macula was used to measure vessel density, vessel length density, and vessel density index (VDI) in three vascular plexuses, namely, the superficial vascular plexus, intermediate capillary plexus, and deep capillary plexus (DCP). The choriocapillaris (CC) flow deficit (FD) was also measured. OCTA images were binarized and processed to extrapolate the parafovea and parafoveal quadrants and the OCTA indices mentioned above. The CC was processed with six different radii to quantify FD. Adaptive optics - scanning laser ophthalmoscopy images were acquired and processed to extract CPG indices, i.e., cone density (CD), cone-to-cone spacing (CS), linear dispersion index, heterogeneity packing index and percent of cells with six neighbors at 3.6° in the temporal retina.

RESULTS

In all eyes, statistically significant differences were found (i) in parafoveal FD across the six radii (p < 0.001) and (ii) in the correlation between the parafoveal temporal quadrant (PTQ) DCP VDI and CS (r = 0.606, p = 0.048). No other significant correlations were found. For OCTA or CPG indices, no significant differences were found between the cohorts in the parafovea or parafoveal quadrants.

CONCLUSIONS

CS is the most sensitive CPG index for detecting alterations in the cone mosaic. The DCP and the cone photoreceptors are significantly correlated, indicating that alterations in the DCP can affect the cones. Future work elucidating the vascular alterations and neurodegeneration present in diabetic eyes should focus on the DCP and multiple CPG indices, not solely CD. Moreover, such alterations are highly localized, hence using larger regions e.g. parafovea versus smaller areas, such as the PTQ, will potentially mask significant correlations.

Retinal neurodegeneration in age-related macular degeneration

Age-related macular degeneration (AMD) is a complex and multifactorial disease characterized by the damage of the unit comprised of the photoreceptors, retinal pigment epithelium (RPE), Bruch's membrane, and choriocapillaris. Although the outer retina appears to be mainly affected in this disorder, several evidences exhibit that also the inner retina may be impaired. In this review we will provide a description of the prominent histologic and imaging findings suggesting an inner retinal loss in these eyes. In details, structural optical coherence tomography (OCT) technology proved either the inner and outer retina is impacted by AMD and that these two impairments are associated. Therefore, the purpose of this review is to provide a description of the role of neurodegeneration in AMD in order to better understand the relationship between neuronal loss and the outer retinal damage in this disease.

An OCT-A Analysis of the Importance of Intermediate Capillary Plexus in Diabetic Retinopathy: A Brief Review

Optical coherence tomography-angiography is a technique that allows us to non-invasively study in vivo the different retinal vascular networks. This allows a deeper understanding of retinal capillary anatomy and function, in addition to the pathophysiologic changes encountered in diverse diseases. The four retinal capillary layers have different anatomies and functions, implying distinct adaptation and roles in the course of the diseases. Diabetic retinopathy is the leading cause of blindness in working-age adults. Several studies have evaluated how each retinal capillary layer is specifically affected according to the stage of the disease. Unfortunately, too few studies have considered the intermediate capillary plexus as a separate layer, as it has often been incorporated in another layer. In this review, we shed light on the potential role the intermediate capillary plexus plays in the physiopathology of diabetic retinal disease as well as its potential use in grading diabetic retinopathy and its clinical added value in estimating the disease prognosis.

Correlation between ellipsoid zone thickness and the presence of subretinal drusenoid deposits in age-related macular degeneration

PURPOSE

Subretinal drusenoid deposits (SDDs) in age-related macular degeneration (AMD) are associated with systemic vascular diseases that compromise ocular perfusion. We demonstrate that SDDs are associated with decreased ellipsoid zone (EZ) thickness, further evidence of hypoxic damage.

METHODS

Post hoc analysis of a cross-sectional study. 165 AMD subjects (aged 51-100; 61% women). Spectral-domain optical coherence tomography was obtained in both eyes. Masked readers assigned subjects to three groups: drusen only, SDD+drusen (SDD+D) and SDD only. EZ thickness was measured subfoveally and 2000 µm nasally, temporally, superiorly and inferiorly from the fovea. Univariate testing was performed using two-tailed t-tests with Bonferroni correction.

RESULTS

The mean EZ thickness differences between the SDD+D and drusen-only groups were (in μm) 1.10, 0.67, 1.21, 1.10 and 0.50 at the foveal, nasal, temporal, superior and inferior locations, respectively (p=0.08 inferiorly, otherwise p≤0.01); between the SDD-only and drusen-only groups, the differences were 3.48, 2.48, 2.42, 2.08 and 1.42 (p≤0.0002). Differences in EZ thicknesses across all subjects and between groups were not significantly different based on gender, race or age.

CONCLUSION

Subjects with SDDs (±drusen) had thinner EZs than those with drusen only, and the inferior EZ was least affected. EZs were thinnest in SDD-only subjects. This thinning gradation is consistent with progressive destruction of highly oxygen-sensitive mitochondria in the EZ from hypoxia. These findings support the reduced ophthalmic perfusion hypothesis for the formation of SDDs secondary to high-risk systemic vasculopathy.

Optical coherence tomography in the management of diabetic macular oedema

Diabetic macular oedema (DMO) is the major cause of visual impairment in people with diabetes. Optical coherence tomography (OCT) is now the most widely used modality to assess presence and severity of DMO. DMO is currently broadly classified based on the involvement to the central 1 mm of the macula into non-centre or centre involved DMO (CI-DMO) and DMO can occur with or without visual acuity (VA) loss. This classification forms the basis of management strategies of DMO. Despite years of research on quantitative and qualitative DMO related features assessed by OCT, these do not fully inform physicians of the prognosis and severity of DMO relative to visual function. Having said that, recent research on novel OCT biomarkers development and re-defined classification of DMO show better correlation with visual function and treatment response. This review summarises the current evidence of the association of OCT biomarkers in DMO management and its potential clinical importance in predicting VA and anatomical treatment response. The review also discusses some future directions in this field, such as the use of artificial intelligence to quantify and monitor OCT biomarkers and retinal fluid and identify phenotypes of DMO, and the need for standardisation and classification of OCT biomarkers to use in future clinical trials and clinical practice settings as prognostic markers and secondary treatment outcome measures in the management of DMO.

Alterations of outer retinal reflectivity in diabetic patients without clinically detectable retinopathy

PURPOSE

This study aimed to investigate alterations of outer retinal reflectivity on spectral-domain optical coherence tomography (OCT) in diabetic patients without clinically detectable retinopathy (NDR).

METHODS

In this retrospective study, 64 NDR patients and 71 controls were included. Relative reflectivity (RR) of the ellipsoid zone (EZ), photoreceptor outer segment (OS) and inner segment (IS), and outer nuclear layer (ONL) at the foveola and at 500 μm, 1000 μm, and 2000 μm nasal (N), temporal (T), superior (S), and inferior (I) to the foveola was measured by cross-line OCT and ImageJ. Retinal vessel densities (VD) in fovea, parafovea, and perifovea areas were detected by OCT angiography (OCTA).

RESULTS

EZ RR in most retinal locations was significantly lower in NDR eyes compared to controls (all P < 0.05), except the foveola. Compared with controls, NDR eyes also displayed lower RR at N2000, T2000, S1000, and I1000 of OS, at S500 and I500 of IS, and at I500 of ONL (all P < 0.05). Negative correlations could be observed between retinal RR and diabetes duration, HbA1c, and best-corrected visual acuity (BCVA) (r =  - 0.303 to - 0.452). Compared to controls, EZ, OS, and IS RR of the NDR eyes showed lower correlation coefficients with whole image SCP and DCP VD of parafovea and perifovea regions.

CONCLUSION

Outer retinal reflectivity, along with the coefficients between retinal reflectivity and VD, is reduced in NDR patients and is correlated with diabetes duration, HbA1c, and BCVA. The reduction of outer retinal reflectivity may be a potential biomarker of early retinal alterations in diabetic patients.

Outer Retinal and Choroidal Changes in Adolescents with Long-Lasting Type 1 Diabetes

This study aimed to assess outer retinal layer (ORL), retinal pigment epithelium (RPE), choroid (Ch) and choriocapillaris (CC) modifications in adolescents with long-lasting (>10 years) type 1 diabetes (T1D) without (noDR) or with diabetic retinopathy (DR). ORL and RPE thickness were measured at optical coherence tomography (OCT) macular scans. Vascular parameters of Ch and CC were quantified after elaboration of macular OCT-angiography (OCTA) images. Insulin dose and auxological and metabolic parameters were correlated with OCT and OCTA findings in patients. ORL thickness was higher in DR eyes than in noDR and healthy controls (HC), and RPE thickness was higher in noDR and DR eyes than in HC, with statistical significance for some sectors in noDR versus HC. No OCTA parameters of CC and Ch differed among groups, and no significant correlation was observed with auxological and metabolic parameters. In conclusion, ORL and RPE were both increased in adolescents with long-lasting T1D. Such changes were not associated with insulin dose and glycemia control, nor to any choroid or choriocapillaris flow change clinically detectable at OCTA, and they could be potential imaging biomarkers of disease progression.

In vivo assessment of associations between photoreceptors structure and macular perfusion in type 1 diabetes

PURPOSE

To explore the potential relationships between macular vascular network and different adaptive optics (AO) metrics in patients with type 1 diabetes mellitus (DM1) with no signs (NoDR) or mild non-proliferative diabetic retinopathy (NPDR).

DESIGN

Observational cross-sectional study.

METHODS

Forty eyes of consecutive patients with DM1 (12 NoDR and 28 NPDR) and 10 healthy age-matched control subjects were included. All patients and controls were imaged using AO retinal camera and PLEX Elite 9000 optical coherence tomography (OCT) angiography (OCTA). The AO outcome measures to evaluate the cone photoreceptor mosaic characteristics were as follows: (1) Cone density (CD); (2) Linear Dispersion Index (LDi) and (3) Heterogeneity Packing Index (HPi). The OCTA outcome measures included: (1) superficial capillary plexus (SCP) perfusion density (PD); (2) deep capillary plexus (DCP) PD and (3) the choriocapillaris (CC) flow deficit percentage (FD%).

RESULTS

NPDR group exhibited a close relationship between cone metrics and CC FD. Notably, CC FD% increase along with LDi (p=0.035), while the increasing CC FD% were associated with reducing CD (p=0.042) and the HPi (p=0.017). Furthermore, the OCTA parameters, including PD SCP and DCP, showed a significant negative correlation with CD.

CONCLUSIONS

Our results demonstrated the relationship between macular perfusion at both retinal and choroidal levels and the cone mosaic in patients with DM1 interpolating swept-source-OCTA and AO metrics. In NPDR eyes, the photoreceptor damage was accompanied by CC insufficiency since the early stages of the disease.

Short-term peripapillary structural and vascular changes following anti-VEGF vs. Dexamethasone intravitreal therapy in patients with DME

PURPOSE

To evaluate short-term peripapillary structural and vascular changes in DME after treatment with dexamethasone implant (DEX-I) and anti-VEGFs using OCT-A.

METHODS

Sixty-five patients with naïve center-involving DME were enrolled. 33 of sixty five patients (group 1) underwent with single DEX-I 0.7 mg (Ozurdex, Allergan, Inc., USA), 32 of sixty-five (group 2) underwent with intravitreal injection of aflibercept 0.5 mg (Eylea, Bayer, Genentech, San Francisco, USA). The OCT acquisition was completed at the following visits: (i) "T1 visit" corresponding to the intravitreal injection of DEX-I or aflibercept in patients with naïve center-involving DME (ii) "T2 visit" corresponding to the examination performed 2 weeks after intravitreal injection of aflibercept and 1 month after DEX-I. The parameters analyzed were: (i) RPC vasculature density (VD); (ii) peripapillary retinal nerve fiber layer (pRNFL) thickness, and (iii) intraocular pressure (IOP).

RESULTS

The RPC analysis showed a VD increase at T2 in both groups, although values did not reach statistical significance (48.12± 4.17 and 49.04 ± 4.23; P = 0.081 in Group 1 and 46.93± 3.16 and 47.17 ± 3.70; P = 0.087 in Group 2). Likewise, the pRNFL thickness and IOP fluctuations did not show statistically significant changes in in both groups among the different study visits.

CONCLUSIONS

After intravitreal injection (anti-VEGF or DEX-I), no significant short-term changes were found in peripapillary microvasculature, IOP and pRNFL thickness in diabetic eyes treated with anti-VEGF or DEX-I.

Development of diabetic macular oedema shows associations with systemic medication - An epidemiological study

PURPOSE

To identify associations between systemic drugs and the incidence of diabetic macular oedema (DME). Of interest was to find beneficial and/or deleterious associations of used drugs.

METHODS

A historic cohort design based on administrative data. Study population consisted of 150 353 individuals with diabetes. Endpoint event was the development of DME (ICD-10 H36.01), censoring events were death or study end December 2017. The follow-up started between 1997 and 2010. The systemic medication consisted of 95 substances. We constructed a nested case-control study design comparing 2630 cases with DME to 13 144 age- and sex-matched controls without DME. Results are reported as odds ratios (ORs) with 95% confidence intervals (CIs) based on conditional logistic regression models.

RESULTS

Incidence rate for DME was 1.80 per 1000 person-years (95% CI 1.73-1.87). In all, we observed a lower incidence rate of DME in females (IRR 0.57; 95% CI 0.52-0.62) compared to males. Exposure to hormone replacement therapy estradiol (OR 0.42; 0.25-0.68), temazepam (0.23; 0.08-0.62) and allopurinol (0.61; 0.43-0.86) were associated with lower risk of DME, while use of insulin or insulin analogue (3.30; 2.99-3.64), sulfonylureas (1.21; 1.05-1.40), diuretic furosemide (1.90; 1.61-2.24), calcium channel blocker amlodipine (1.53; 1.34-1.75), ACE inhibitors ramipril (1.66; 1.46-1.89) and enalapril (1.38; 1.16-1.64) were associated with an increased risk of DME.

CONCLUSIONS

Large-scale studies examining the incidence of DME are lacking. Our findings suggest that associations of systemic medications with the incidence of DME may shed light on the pathogenesis of complex DME, encouraging further studies.

Effects of diabetic retinopathy on longitudinal morphological changes in AMD-associated type 1 macular neovascularization

The purpose of this study was to investigate the effect of diabetic retinopathy (DR) on longitudinal morphological changes in AMD-associated type 1 macular neovascularization using optical coherence tomography angiography (OCTA). We enrolled fifty treatment-naïve eyes with a diagnosis of exudative AMD and type 1 MNV. Twenty of 50 eyes were affected by mild DR. En face OCT angiography were examined for the MNV lesion area (mm2), the MNV flow area (mm2), the central macular thickness (CMT) and the BCVA. The OCTA acquisition was performed at the following visits: (i) before the loading phase (LP) of intravitreal injection of aflibercept (T1), and (ii) 1 month after the last intravitreal injection of loading phase comprising 3 monthly injections (T2). All morpho-functional parameters showed a significantly change at T2 compared to T1 values in both groups. Furthermore, we found a greater MNV area reduction after LP in eyes without DR (P = 0.023). With regard to the remaining parameters, no significant changes were found between two groups (P > 0.05). Our analysis revealed a less MNV area reduction after loading dose of anti-VEGF therapy in eyes affected by diabetic retinopathy.

Pushing Retinal Imaging Forward: Innovations and Their Clinical Meaning - The 2022 Ophthalmologica Lecture

Retinal imaging has greatly expanded our understanding of various pathological conditions. This article presents a summary of the key points covered during the 2022 Ophthalmologica Lecture held at the Euretina Congress in Hamburg. The first part of the article focuses on the use of optical coherence tomography angiography to examine and comprehend the choroid in age-related macular degeneration (AMD). Subsequently, we delve into the discussion of the "postreceptor neuronal loss" theory in AMD, which was studied using en face structural optical coherence tomography (OCT). Following that, we explore pertinent findings obtained through cross-sectional OCT in retinal and optic nerve diseases, such as AMD, diabetic macular edema, pathologic myopia, central serous chorioretinopathy, and Leber's hereditary optic neuropathy.

Risk Factors for Diabetic Retinopathy in Chinese Patients with Different Diabetes Duration: Association of C-Peptide and BUN/Cr Ratio with Type 2 Diabetic Retinopathy

Background and Aim

Controlling the risk factors was the most effective strategy to prevent diabetic retinopathy (DR). This study aimed to recognize the risk factors of DR, and explores whether the effect of those factors is modified by diabetes mellitus (DM) duration.

Methods

A total of 1058 DM patients with information about DR assessment were included. DR was measured by a complete ophthalmic examination and was classified as having one or more distinct microaneurysms in the eyes. Data from the lab and clinical factors were gathered. Multivariate logistic analysis was used to examine the risk factors, and the best-fitting model was selected by a backward stepwise based on A1C.

Results

In the current study, 274 (25.9%) patients developed DR. In the entire subjects, baseline age, the level of C-peptide, and urinary creatinine were all presented as protective effects of DR, whose odds ratios (ORs) and 95% confidence intervals (CIs) were 0.79 (0.62, 0.99), 0.75 (0.61, 0.91), and 0.70 (0.52, 0.93), respectively. Conversely, systolic pressure (SBP), urinary albumin, and BUN/Cr ratio were the important risk factors for DR with ORs (95% CIs) 1.21 (1.01, 1.46), 1.55 (1.30, 1.84), and 1.33 (1.11, 1.59), respectively. In stratification analysis, females with higher SBP would be more likely to develop DR in the short-duration group, while C-peptide and urinary creatinine showed protective effects in the long-duration group. BUN/Cr ratio all presented as a risk factor, with ORs 1.38 (p = 0.041) and 1.33 (p = 0.014) in short- and long-duration groups, respectively.

Conclusion

Although renal functions presented a significant association with DR in all DM patients, the risk factors of DR varied widely in different disease-duration subjects. Target strategies to prevent DR should be put forward individually, considering the patient's DM duration. Improving the BUN/Cr ratio may be beneficial to delaying DR.

Imaging Biomarkers of Mesopic and Dark-Adapted Macular Functions in Eyes With Treatment-Naïve Mild Diabetic Retinopathy

PURPOSE

To investigate the relationship between imaging biomarkers and mesopic and dark-adapted (ie, scotopic) functions in patients with treatment-naïve mild diabetic retinopathy (DR) and normal visual acuity.

DESIGN

Prospective cross-sectional study.

METHODS

In this study, 60 patients with treatment-naïve mild DR (Early Treatment of Diabetic Retinopathy Study levels 20-35) and 30 healthy control subjects underwent microperimetry, structural optical coherence tomography (OCT), and OCT angiography (OCTA).

RESULTS

The foveal mesopic (22.4 ± 4.5 dB and 25.8 ± 2.0 dB, P = .005), parafoveal mesopic (23.2 ± 3.8 and 25.8 ± 1.9, P < .0001), and parafoveal dark-adapted (21.1 ± 2.8 dB and 23.2 ± 1.9 dB, P = .003) sensitivities were reduced in DR eyes. For foveal mesopic sensitivity, the regression analysis showed a significant topographic association with choriocapillaris flow deficits percentage (CC FD%; β = -0.234, P = .046) and ellipsoid zone (EZ) normalized reflectivity (β = 0.282, P = .048). Parafoveal mesopic sensitivity was significantly topographically associated with inner retinal thickness (β = 0.253, P = .035), deep capillary plexus (DCP) vessel length density (VLD; β = 0.542, P = .016), CC FD% (β = -0.312, P = .032), and EZ normalized reflectivity (β = 0.328, P = .031). Similarly, parafoveal dark-adapted sensitivity was topographically associated with inner retinal thickness (β = 0.453, P = .021), DCP VLD (β = 0.370, P = .030), CC FD% (β = -0.282, P = .048), and EZ normalized reflectivity (β = 0.295, P = .042).

CONCLUSIONS

In treatment-naïve mild DR eyes, both rod and cone functions are affected and they are associated with both DCP and CC flow impairment, which suggests that a macular hypoperfusion at these levels might implicate a reduction in photoreceptor function. Normalized EZ reflectivity may be a valuable structural biomarker for assessing photoreceptor function in DR. NOTE: Publication of this article is sponsored by the American Ophthalmological Society.

The Role of Diabetic Choroidopathy in the Pathogenesis and Progression of Diabetic Retinopathy

Diabetic choroidopathy was first described on histopathological specimens of diabetic eyes. This alteration was characterized by the accumulation of PAS-positive material within the intracapillary stroma. Inflammation and polymorphonuclear neutrophils (PMNs) activation are crucial elements in choriocapillaris impairment. The evidence of diabetic choroidopathy in vivo was confirmed with multimodal imaging, which provides key quantitative and qualitative features to characterize the choroidal involvement. The choroid can be virtually affected in each vascular layer, from Haller's layer to the choriocapillaris. However, the damage on the outer retina and photoreceptor cells is essentially driven by a choriocapillaris deficiency, which can be assessed through optical coherence tomography angiography (OCTA). The identification of characteristic features of diabetic choroidopathy can be significant for understanding the potential pathogenic and prognostic implications in diabetic retinopathy.

Choriocapillaris Flow Deficit as a Biomarker for Diabetic Retinopathy and Diabetic Macular Edema: 3-Year Longitudinal Cohort

PURPOSE

To investigate the relationship between choriocapillaris flow deficit percentage (CC FD%) by swept-source optical coherence tomography angiography (SS-OCTA) and 3-year risk of diabetic retinopathy (DR) progression and diabetic macular edema (DME) development.

DESIGN

Prospective, observational cohort study.

METHODS

A total of 903 participants with type 2 diabetes mellitus (T2DM) without DR or with mild nonproliferative DR (NPDR) free of DME at baseline were followed up annually for 3 years. All participants underwent standard 7-field fundus photography and spectral-domain OCT. SS-OCTA was used for retinal and choriocapillaris imaging and 3 × 3-mm2 macular CC FD% was quantified. Univariate and multivariate logistic models were used to evaluate the association between CC FD% and 2 or more steps of DR progression and DME development. The additional predictive value of CC FD% for outcome events was assessed using C statistic, net reclassification index (NRI), and integrated discrimination improvement index (IDI).

RESULTS

Over 3 years, 295 of 1805 eyes (16.34%) developed DR progression, and 118 eyes (6.54%) developed DME. A higher average CC FD% was correlated with DR progression (odds ratio [OR], 3.41 per SD increase, 95% CI: 2.65-4.39, P < .001) and DME development (OR, 1.37 per SD increase, 95% CI: 1.06-1.77, P = .016) after adjusting for confounders. In the ETDRS regions, increased CC FD% in all fields was associated with DR progression; however, increased CC FD% in the inferior field was associated with DME development. Compared with the models based on established risk factors, the addition of average CC FD% significantly improved the C statistics for DR progression (0.712 to 0.777, P < .001) and DME occurrence (0.743 to 0.773, P = .044). The estimated NRIs and IDIs (all >0) indicated that the addition of CC FD% led to a significant improvement in the discriminative performance for end points.

CONCLUSION

CC FD% is independently associated with DR progression and DME development in the Chinese T2DM population and provides incremental predictive value beyond traditional risk factors and retinal microvascular parameters. Further inclusion of CC FD% in DR prediction models helps guide population-based screening and personalized management.

The Association between Decreased Choriocapillary Flow and Electroretinogram Impairments in Patients with Diabetes

PURPOSE

To evaluate the association between choriocapillary flow (CCF) and electroretinogram (ERG) in patients with diabetes.

METHOD

This was a cross-sectional study. Patients with type 2 diabetes and healthy controls who had undergone both flicker ERG and optical coherence tomography angiography (OCTA) were included, while patients with severe diabetic retinopathy (DR) and macular edema were excluded. Correlations among OCTA and ERG parameters were conducted by generalized linear mixed models (GLMM).

RESULT

One hundred ninety-four eyes of 102 patients with diabetes and fifty-six eyes of 28 controls were included. The implicit time of 30-Hz flicker ERG successively increased, while the amplitudes, inner-retina vessel density and CCF were decreased from the control to the nondiabetic retinopathy (NDR) to DR group. In patients with diabetes, all GLMM models of ERG parameters had statistically significance (P<0.05), and CCF was correlated with ERG parameters (coefficient index=-0.601, P< 0.001 with 16 Td-s implicit time; coefficient index=-0.687, P< 0.001 with 32 Td-s implicit time; coefficient index=0.933, P=0.035 with 32 Td-s amplitude) and the thickness of retinal pigment epithelium, while in the GLMM model of CCF, it was correlated with the thickness of retinal pigment epithelium and the level of glycosylated hemoglobin(both P= 0.001).

CONCLUSION

CCF decreased in patients with diabetes, and it was related with ERG. Choroidopathy and its functional impairment in the retina may occur very early in patients with diabetes by influencing the outer retina.

Qualitative and quantitative evaluation of diabetic choroidopathy using ultra-widefield indocyanine green angiography

To investigate angiographic characteristic features of diabetic choroidopathy, as well as choroidal vascular density (CVD) and fractal dimension (CFD) in diabetic eyes and controls using ultra-widefield (UWF) indocyanine green angiography (ICGA). All patients underwent UWF fluorescein angiography and ICGA. Using imageJ software, CVD and CFD was analyzed. SFCT was assessed using spectral-domain optical coherence tomography. The image parameters were compared based on the DR stage and the presence of diabetic macular edema (DME). One-hundred six eyes from 63 patients (59.11 ± 16.31 years; male [%]: 23 [36.5%]) were included in the DM group, and 40 eyes from 22 subjects were included in the control group. The DM group had a mean age of 59.11 ± 16.31 years and a mean HbA1c percentage of 7.72 ± 1.28%. The most common ICGA findings of DC were choroidal hyperpermeability (57.5%), hypofluorescent spots (48.1%). Salt and pepper pattern (19.8%), inverted inflow phenomenon (3.8%), choroidal arterial tortuosity (24.5%), and late choroidal non-perfusion (6.6%) were more common in advanced DR. The CVD, CFD, and SFCT increased as the DR severity progressed. The DME group had a significantly higher CFD and SFCT than the non-DME group (P < 0.001 and P = 0.019, respectively). The qualitative and quantitative UWF ICGA image analysis revealed that choroidal blood vessels became dilated, complex, and hyperpermeable as the DR progressed. These features of diabetic choroidopathy (DC) were more severe in eyes with DME than the non-DME eyes.

Early choroidal changes detected by swept-source OCT in type 2 diabetes and their association with diabetic kidney disease

INTRODUCTION

Microvascular changes in eye and kidney shares some common factors in diabetes mellitus (DM). The purpose was to evaluate choroidal thickness (CT) and choriocapillaris (CC) density in patients with type 2 diabetes (T2D) and their association with diabetic kidney disease (DKD) using swept-source optical coherence tomography (SS-OCT).

RESEARCH DESIGN AND METHODS

A cross-sectional study was conducted with patients with T2D with mild or no diabetic retinopathy (DR) and non-diabetic controls. CT was measured with SS-OCT, and CC vascular density was measured with OCT angiography. These parameters were compared with inner retinal layers thickness in patients with and without DKD and non-diabetic controls.

RESULTS

Ninety-three eyes from patients with T2D and 34 eyes from controls volunteers were included. Within the T2D group, 56 eyes with DKD and 37 eyes from patients with no diabetic kidney disease were examined. A statistically significant reduction of CT was observed in patients with DKD compared with controls, with no difference in CC density. There was an association between ganglion cell layer and central choroidal thickness reduction in the DKD group.

CONCLUSIONS

Patients with T2D with DKD showed a decrease in CT with no difference in CC density compared with non-diabetic controls. This thinning might be related to vascular changes of choroidal layers such as Haller's and Sattler's with preservation of CC density, which is crucial for outer retina and retinal pigment epithelium health. Longitudinal studies are warranted to determine the association of choroidal changes with the pathogenesis of diabetes, and its association with early DKD and progression to more severe DR.

Imaging-based Assessment of Choriocapillaris: A Comprehensive Review

PURPOSE

Over the past two decades, advancements in imaging modalities have significantly evolved the diagnosis and management of retinal diseases. Through these novel platforms, we have developed a deeper understanding of the anatomy of the choroidal vasculature and the choriocapillaris. The recently developed tools such as optical coherence tomography (OCT) and OCT angiography (OCTA) have helped elucidate the pathological mechanisms of several posterior segment diseases. In this review, we have explained the anatomy of the choriocapillaris and its close relationship to the outer retina and retinal pigment epithelium.

METHODS

A comprehensive search of medical literature was performed through the Medline/PubMed database using search terms: choriocapillaris, choroid, quantification, biomarkers, diabetic retinopathy, age-related macular degeneration, choroidal blood flow, mean blur rate, flow deficit, optical coherence tomography, optical coherence tomography angiography, fluorescein angiography, indocyanine green angiography, OCTA, Doppler imaging, uveitis, choroiditis, white dot syndrome, tubercular serpiginous-like choroiditis, choroidal granuloma, pachychoroid, toxoplasmosis, central serous chorioretinopathy, multifocal choroiditis, choroidal neovascularization, choroidal thickness, choroidal vascularity index, choroidal vascular density, and choroidal blood supply. The search terms were used either independently or combined with choriocapillaris/choroid.

RESULTS

The imaging techniques which are used to qualitatively and quantitatively analyze choriocapillaris are described. The pathological alterations in the choriocapillaris in an array of conditions such as diabetes mellitus, age-related macular degeneration, pachychoroid spectrum of diseases, and inflammatory disorders have been comprehensively reviewed. The future directions in the study of choriocapillaris have also been discussed.

CONCLUSION

The development of imaging tools such as OCT and OCTA has dramatically improved the assessment of choriocapillaris in health and disease. The choriocapillaris can be delineated from the stromal choroid using the OCT and quantified by manual or automated methods. However, these techniques have inherent limitations due to the lack of an anatomical distinction between the choriocapillaris and the stromal choroid, which can be overcome with the use of predefined segmentation slabs on OCT and OCTA. These segmentation slabs help in standardizing the choriocapillaris imaging and obtain repeatable measurements in various conditions such as diabetic retinopathy, age-related macular degeneration, pachychoroid spectrum, and ocular inflammations. Additionally, Doppler imaging has also been effectively used to evaluate the choroidal blood flow and quantifying the choriocapillaris and establishing its role in the pathogenesis of various retinochoroidal diseases. As tremendous technological advancements such as wide-field and ultra-wide field imaging take place, there will be a significant improvement in the ease and accuracy of quantifying the choriocapillaris.

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.

SPECTRAL DOMAIN OPTICAL COHERENCE TOMOGRAPHY BIOMARKERS OF RETINAL HYPERPERMEABILITY AND CHOROIDAL INFLAMMATION AS PREDICTORS OF SHORT-TERM FUNCTIONAL AND ANATOMICAL OUTCOMES IN EYES WITH DIABETIC MACULAR EDEMA TREATED WITH INTRAVITREAL BEVACIZUMAB

PURPOSE

To assess spectral domain optical coherence tomography biomarkers of short-term outcomes in eyes with diabetic macular edema treated with intravitreal bevacizumab.

METHODS

In a prospective interventional case series, 66 eyes with diabetic macular edema underwent 3 monthly intravitreal bevacizumab injections. Best-corrected visual acuity measurement and spectral domain optical coherence tomography were performed at baseline and at 3 months. Multivariate regression analysis was performed to investigate the baseline spectral domain optical coherence tomography parameters as predictors of functional and anatomical outcomes.

RESULTS

Patients with diabetic nephropathy had greater subfoveal choroidal thickness (300.8 ± 35.54 vs. 253.0 ± 50.07 µm, P < 0.01) and were more likely to have subretinal fluid (r = 0.26, P = 0.03) at baseline. Multivariate analysis showed that the extent of external limiting membrane disruption (P = 0.03) and the extent of disorganization of retinal inner layers (P = 0.03) at baseline were predictors of best-corrected visual acuity at 3 months, whereas the extent of disorganization of retinal inner layers (P = 0.04) and duration of diabetes mellitus (P = 0.03) were predictors of central subfield thickness at 3 months.

CONCLUSION

External limiting membrane disruption and disorganization of retinal inner layers, as the spectral domain optical coherence tomography biomarkers of retinal hyperpermeability, can predict short-term outcomes in diabetic macular edema eyes treated with intravitreal bevacizumab.

Changes in Macular Perfusion After ILUVIEN® Intravitreal Implant for Diabetic Macular Edema: An OCTA Study

INTRODUCTION

The aim of this study was to investigate changes in macular perfusion in patients affected by diabetic macular edema (DME) and treated with ILUVIEN® (fluocinolone acetonide intravitreal implant) 0.19 mg using optical coherence tomography angiography (OCTA).

METHODS

This was a retrospective cohort study that included patients aged > 18 years with type 2 non-proliferative diabetic retinopathy (DR) and DME at baseline. All patients were treated with the ILUVIEN® implant. A minimum of two 6 × 6-mm OCTA scans were required to ensure that all cases had a baseline OCTA and an OCTA performed at 4 months of follow-up. Qualitative and quantitative comparisons were performed.

RESULTS

Ten eyes from ten subjects were included in the analysis. Mean (± standard deviation) age of the study cohort was 57.1 ± 8.3 years. Mean parafoveal perfusion density (PD) at baseline was 64.1 ± 1.8% at baseline, increasing to 66.1 ± 2.9% (p = 0.013) at the 4-month follow-up visit. Mean parafoveal PD at baseline was 64.4 ± 2.1%, increasing to 65.2 ± 2.6% (p = 0.024) after 4 months. In the qualitative assessment, 60 regions (10 areas for each subject) were graded to assess changes in retinal perfusion between the baseline and follow-up visits. This assessment revealed that 24 regions (40.0%) were characterized by a qualitative increase in perfusion after treatment, while 22 (36.7%) and 14 (23.3%) regions were featured by a stability and reduction in retinal perfusion, respectively.

CONCLUSION

OCTA analysis detects improvements in macular perfusion after treatment with ILUVIEN®. This improvement in macular perfusion may be associated with corticosteroid-related beneficial effects on leukostasis.

Long-Term Visual Outcomes and Morphologic Biomarkers of Vision Loss in Eyes With Diabetic Macular Edema Treated With Anti-VEGF Therapy

PURPOSE

To analyze the morphological characteristics and long-term visual outcomes in eyes with diabetic retinopathy (DR) and diabetic macular edema (DME) treated with anti-vascular endothelial growth factor (anti-VEGF) therapy.

DESIGN

Retrospective clinical cohort study.

METHODS

Patients with a long-term follow-up and evidence of resolved DME in at least 1 visit (study visit) after 5 years of follow-up after the initiation of anti-VEGF therapy were included. At the study visit, structural optical coherence tomography (OCT) scans were reviewed for qualitative features reflecting a distress of the neuroretina or retinal pigment epithelium (RPE). A quantitative topographical assessment of the inner and outer retinal thicknesses was also provided.

RESULTS

A total of 61 eyes (50 patients) were included and were divided into 2 subgroups according to visual acuity (VA) at the study visit, yielding a group of 24 eyes with a VA <20/40 ("poor/intermediate vision" group), and 37 eyes with a VA ≥20/40 ("good vision" group). The external limiting membrane (ELM) and RPE bands were more frequently disrupted or absent in the poor/intermediate vision group (P = .003 and P = .019). Similarly, disorganization of retinal inner layers was more prevalent in the poor/intermediate vision group (P = .013). The foveal and parafoveal outer retinal thicknesses were reduced in eyes with poor/intermediate vision (P = .022 and P = .044). Multivariate stepwise linear regression analysis demonstrated that VA was associated with appearances of the RPE and ELM (P < .0001 and P = .048), foveal and parafoveal outer retinal thicknesses (P = .046 and P = .035).

CONCLUSIONS

Modifications in the outer retina and RPE represent OCT biomarkers of long-term visual outcomes in eyes with DME treated with anti-VEGF.

Choriocapillaris perfusion assessed using swept source optical coherence tomographic angiography and the severity of diabetic retinopathy

AIMS

To investigate the relationship between choriocapillaris (CC) blood perfusion and the severity of diabetic retinopathy (DR) using swept-source optical coherence tomography angiography (SS-OCTA).

METHODS

Type 2 diabetes mellitus in the Guangzhou was recruited. DR was graded according to the standardised seven-field colour retinal images adhering to the ETDRS scale. CC perfusion was quantified by evaluating the flow deficit (FD) density, FD number and FD size using SS-OCTA. Multivariable linear regressions were used to evaluate the correlation between CC FD metrics and DR severity.

RESULTS

A total of 1692 patients (eyes) were included in the final analysis. Participants with DR had a significantly higher FD density than the NDR group, with the differences of 1.61% (95% CI 1.04 to 2.18; p<0.001) among mild non-proliferative DR (NPDR) patients, 2.23% (95% CI 1.76 to 2.70; p<0.001) among moderate NPDR patients and 3.31% (95% CI 2.27 to 4.36; p<0.001) among severe DR than NDR patients after adjusting for confounding factors. Similarly, the higher FD number and size were also correlated with severer degree of DR (all p<0.05). Furthermore, the addition of FD density to conventional risk factors significantly improved the performance for discriminating DR from NDR patients (AUC 0. 829, 95% CI 0. 804 to 0. 855; p<0.001).

CONCLUSION

Quantitative FD density, number and size assessed by using SS-OCTA were independently correlated with the severity of DR. The assessment of the CC perfusion metrics in the macula may be a sensitive biomarker of DR changes.

Correlation of Photoreceptor Integrity with Retinal Vessel Density and Choriocapillaris in Eyes with Diabetic Retinopathy

PURPOSE

To investigate the correlation of foveal photoreceptor integrity with the vessel density (VD) of the retina and choriocapillaris using swept-source optical coherence tomography (OCT) angiography (OCTA) in eyes with diabetic retinopathy (DR).

METHODS

We retrospectively reviewed subjects having eyes with DR, who underwent OCTA using swept-source OCT (DRI OCT Triton; Topcon). We analyzed the area of the foveal avascular zone (FAZ) and VDs of the superficial capillary plexus (SCP), deep capillary plexus (DCP), and choriocapillaris. The length of the lateral extent of ellipsoid zone (EZ) disruption, central subfield thickness, and subfoveal choroidal thickness were measured. Furthermore, we analyzed factors that were closely associated with the length of EZ disruption.

RESULTS

A total of 159 eyes with DR and 30 healthy control eyes were included in this study. In all eyes, the lengths of EZ disruption were positively correlated with the FAZ area (P=0.009). However, they were negatively correlated with the parafoveal VD of the SCP (P=0.049), the foveal VD of DCP (P=0.003), and that of the choriocapillaris (P=0.036).

CONCLUSIONS

The size of the FAZ and ischemia at the DCP may play an important role in maintaining foveal photoreceptor integrity in eyes with DR. Considering OCTA artifacts, such as projection and shadowing, future studies are required to reveal the correlation between EZ disruption and the VD of the choriocapillaris.

[The role of neurodegeneration biomarkers in the management of patients with diabetic retinopathy]

This literature review focuses on the role of disease biomarkers in the management of patients with diabetic retinopathy (DR) investigating in detail the problem of retinal neurodegeneration in such patients. Identification and assessment of the significance of qualitative and quantitative biomarkers of DR and neurodegeneration can complement screening examination, as well as help predict the course of the disease and the response to therapy. A comprehensive analysis of these factors allows for effective treatment and prevention of complications in patients with DR based on prognostic models and dynamic monitoring of these indicators.

Assessment of Detailed Photoreceptor Structure and Retinal Sensitivity in Diabetic Macular Ischemia Using Adaptive Optics-OCT and Microperimetry

Purpose

The purpose of this study was to assess density and morphology of cone photoreceptors (PRs) and corresponding retinal sensitivity in ischemic compared to nonischemic retinal capillary areas of diabetic eyes using adaptive optics optical coherence tomography (AO-OCT) and microperimetry (MP).

Methods

In this cross-sectional, observational study five eyes of four patients (2 eyes with proliferative diabetic retinopathy (DR) and 3 eyes moderate nonproliferative DR) were included. PR morphology and density was manually assessed in AO-OCT en face images both at the axial position of the inner-segment outer segment (IS/OS) and cone outer segment tips (COSTs). Retinal sensitivity was determined by fundus-controlled microperimetry in corresponding areas (MP-3, Nidek).

Results

In AO-OCT, areas affected by capillary nonperfusion showed severe alterations of cone PR morphology at IS/OS and COST compared to areas with intact capillary perfusion (84% and 87% vs. 9% and 8% of area affected for IS/OS and COST, respectively). Mean reduction of PR signal density in affected areas compared to those with intact superficial capillary plexus (SCP) and deep capillary plexus (DCP) perfusion of similar eccentricity was -38% at the level of IS/OS (P = 0.01) and -39% at the level of COST (P = 0.01). Mean retinal sensitivity was 10.8 ± 5.4 in areas affected by DCP nonperfusion and 28.2 ± 1.5 outside these areas (P < 0.001).

Conclusions

Cone PR morphology and signal density are severely altered in areas of capillary nonperfusion. These structural changes are accompanied by a severe reduction of retinal sensitivity, indicating the importance of preventing impaired capillary circulation in patients with DR.

Femto-assisted versus conventional phacoemulsification differently impact on choroid structure after surgery

PURPOSE

To report potential choroidal changes in eyes undergoing femtosecond laser cataract surgery (FLACS) and phacoemulsification surgery (PCS) by OCT.

METHODS

The patients were images by means Spectral Domain OCT imaging with EDI technology which may obtain OCT image. We exported a single EDI-OCT scan passing through the fovea and then it was imported into ImageJ program to perform a quantitative analysis.

MAIN OUTCOME MEASURES

The main outcome measures were: (i) sub foveal choroidal thickness (SFCT); (ii) the choroidal vascularity index (CVI); and (iii) central retinal thickness (CRT).

RESULTS

At postoperative 1 week, FLACS group showed an increased CRT (241.2 ± 31.6-245.5 ± 36.4 µm; p = 0.016). Likewise, CVI and SFCT exhibited a slight increase but no statistically differences were highlighted (p > 0.05). At the follow-up visit of 1 month, all OCT parameters did not display any significant difference (p > 0.05). At post-operative 1 week, the PCS group displayed a significant increase in CRT, SFCT, and CVI. On the contrary, at the follow-up visit of 1-month, all choroidal parameters were characterized by a no statistically significant reduction (p > 0.05).

CONCLUSIONS

Our study exhibited a significant increase in CT and CVI in eyes that underwent conventional cataract surgery. Femtosecond laser-assisted cataract extraction did not result in macular change due to less postoperative inflammation.

Outer retina dysfunction and choriocapillaris impairment in type 1 diabetes

To study the outer retina morpho-functional characteristics and the choriocapillaris (CC) features in type 1 diabetic (T1D) patients, with and without signs of diabetic retinopathy (NPDR and NoDR). Twenty-five NPDR and 18 NoDR eyes were imaged by Optical Coherence Tomography Angiography. Ellipsoid zone (EZ) “normalized” reflectivity and CC perfusion density parameters, as flow deficits number (FDn), flow deficit average area (FDa) and flow deficit percentage (FD%), were analysed. Multifocal electroretinogram (mfERG) response amplitude densities (RADs) were measured. Mean EZ “normalized” reflectivity, CC FDn and FD% values, were similar (p > 0.05) in both groups, FDa was significant greater (p > 0.05) in NPDR compared with NoDR eyes. MfERG-RADs were similar in both groups. NPDR eyes showed a significant (p < 0.05) linear correlation between RADs and both, CC FDa and FD%. The EZ “normalized” reflectivity was negatively correlated with CC FD% in NoDR eyes. In NPDR T1D eyes a significant relationship between abnormal outer retina functional responses and CC impairment was observed, while in NoDR eyes the photoreceptor reflectivity was correlated to CC abnormalities. The outer retina dysfunction in NPDR correlated to CC drop-out let hypothesize that the outer retinal elements are functionally impaired in proportion to the CC vascular supply deficit.

Higher choroidal thickness and lower choriocapillaris blood flow signal density based on optical coherence tomography angiography in diabetics

Diabetes mellitus (DM) is one of the fastest growing chronic diseases in the world and one of the main causes of vision loss. Whether or not diabetic choroidopathy (DC) is involved in the initiation and progression of diabetic ocular complications needs to be explored. We included 54 diabetic eyes from 36 diabetic patients, and 54 healthy eyes from 32 control subjects after propensity scores matching. All of the subjects were given pupil light and dark adaptation examination and optical coherence tomography angiography (OCTA). Scotopic pupil diameter (SPD), pupil contraction amplitude, and velocity of pupil contraction of the diabetic group were significantly lower than that of the healthy control group (P < 0.05).Choroidal thickness at temporal quadrant (at 750 μm) and superior quadrant (at 1500 μm and 2250 μm) increased in diabetic group compared to control group(P < 0.05).In the diabetic group, choriocapillaris blood flow signal density (CCBFSD) in the macular area (diameter = 2000 μm) were significantly decreased compared with the healthy control group (P < 0.05). Apparent changes in pupil and choroidal blood flow were observed in the diabetic patients.

Ellipsoid zone optical intensity reduction as an early biomarker for retinitis pigmentosa

PURPOSE

To investigate photoreceptor degeneration in retinitis pigmentosa (RP) by quantitatively analysing optical intensity of ellipsoid zone (EZ) on optical coherence tomography (OCT).

METHODS

We conducted OCT line scans of the horizontal meridian in 24 eyes of 24 RP patients and 30 eyes of 30 healthy controls and obtained longitudinal reflectance profiles using ImageJ at every 5 pixels. Relative optical intensity was calculated from dividing the peak of EZ by the mean of the whole retina.

RESULTS

The optical intensity of EZ variation followed a similar pattern in all patients. It decreased with eccentricity and then vanished, regardless whether it was normal or reduced at the fovea. The mean relative optical intensity of EZ in RP patients was 0.69 ± 0.13 to that of control subjects at the location just before it disappeared. The relative optical intensity of EZ at fovea was significantly correlated with the best-corrected visual acuity in patients (r = -0.617, p = 0.001).

CONCLUSION

The optical intensity of EZ detected by OCT can serve as a biomarker for early detection of photoreceptor degeneration in RP.

The Role of the Outer Lamellar Macular Hole in the Surgical Management of Myopic Traction Maculopathy

PURPOSE

To evaluate the anatomical and functional surgical outcomes of eyes affected by myopic traction maculopathy (MTM) with and without an outer lamellar macular hole (O-LMH).

METHODS

Forty-eight eyes affected by MTM were included: a study group of 24 eyes with an O-LMH and a control group of 24 eyes without an O-LMH. All patients underwent spectral-domain optical coherence tomography (SD-OCT) and were staged according to the MTM staging system. The surgical techniques applied were pars plana vitrectomy (PPV), macular buckle (MB), or combined surgery. The follow-up visit was 12 months after the latest intervention.

RESULTS

Best-corrected visual acuity (BCVA) improved significantly in both groups after surgery (p < 0.05). A successful surgical result was obtained in both groups at the final follow-up. In the study group, 3 eyes underwent PPV, 14 eyes underwent MB, and 7 underwent a combined surgery. Six patients developed an iatrogenic full-thickness macular hole (FTMH). In the control group, 5 eyes underwent PPV, 16 underwent MB, and 3 had combined surgery. Four patients developed a FTMH. In both groups, all the eyes with an iatrogenic FTMH received PPV as first surgery (alone or combined). A topographical correspondence between the interruption of the ellipsoid zone (EZ) and the backscattering phenomenon was found on OCT.

CONCLUSION

The O-LMH is an OCT sign that may occur in eyes affected by MTM. Its presence is correlated with a higher risk of developing an iatrogenic FTMH after PPV (alone or combined) probably due to the thinner residual retinal tissue. Postoperative BCVA is not limited in eyes with an O-LMH and this may be explained by the restoration of the EZ after surgery.

Dilated retinal large vessels and capillaries associated with diabetic macular edema and photoreceptor loss respectively

PURPOSE

Previously, we measured retinal large vessels and capillaries separately on optical coherence tomography angiography (OCTA). In the present study, we aim to evaluate the role of these parameters in association to diabetic macular edema (DME) and ellipsoid zone disruption (EZD).

METHODS

In this cross-sectional study, 54 eyes from 31 patients (10 females, 31 Asians) with severe non-proliferative diabetic retinopathy (25 eyes) or proliferative diabetic retinopathy (PDR, 29 eyes) were enrolled. All eyes underwent 3 × 3 mm OCTA scans centered on the fovea. Perfusion density (PD), vessel length density (VLD), and vessel diameter index (VDI) were calculated for retinal large vessels and superficial capillaries separately. Other OCTA findings included suspended scattering particles in motion (SSPiM), number of microaneurysms (MA) in all retinal layers, and the area of foveal avascular zone (FAZ) of superficial capillary plexus. DME and EZD were evaluated on B-scans. Both univariate and multivariate analysis were performed.

RESULTS

Of the 54 study eyes, 31 (57%) had DME and 21 (40%) had EZD. Multivariate regression model showed that PDR (β = 27.8, 95% confidence interval (CI): 2.7-282.8, p = 0.005), more MA (β = 2.5, 95% CI: 1.3-4.5, p = 0.003), and increased VDI of larger vessels (β = 1.9, 95% CI: 1.0-3.5, p = 0.047) were risk factors for DME. As for EZD, presence of SSPiM (β = 5.5, 95% CI: 1.2-26.1, p = 0.032) and increased VDI of capillaries (β = 3.9, 95% CI: 1.1-13.8, p = 0.034) were risk factors.

CONCLUSIONS

In eyes with diabetic retinopathy, dilation of retinal larger vessels was associated with macular edema, while dilation of retinal capillaries was associated with ellipsoid zone disruption.

Analysis of the Choroid and Its Relationship with the Outer Retina in Patients with Diabetes Mellitus Using Binarization Techniques Based on Spectral-Domain Optical Coherence Tomography

(1) Background: We aimed to reveal the relationship between the choroid and the outer retina with optical coherence tomography (OCT) in patients with diabetes mellitus (DM) with mild or no diabetic retinopathy (DR) in order to find early biomarkers for progressing retinopathy. (2) Methods: We performed a prospective study including 61 eyes of patients with type 1 or type 2 DM and 36 eyes of healthy controls. All subjects were imaged with Spectralis OCT. The choroid was assesseed using enhanced depth imaging OCT (EDI-OCT). Binarization of subfoveal choroidal images was done with public domain software, ImageJ (version 1.53a; National Institutes of Health, Bethesda, Maryland, USA). (3) Results: Luminal area, stromal area and total choroidal area were significantly decreased in diabetic patients compared to control: 0.23 ± 0.07 vs. 0.28 ± 0.08, p = 0.012; 0.08 ± 0.03 vs. 0.10 ± 0.04, p = 0.026; 0.31 ± 0.09 vs. 0.38 ± 0.11, p = 0.008. The thickness of retinal pigment epithelium (RPE) correlated positively with the choroidal vascularity index (CVI). The correlations between outer nuclear layer (ONL), photoreceptors (PR) and foveal choroidal thickness (FChT) were moderately negative. (4) Conclusion: Thicker RPE and a thinner PR layer may be assigned the role of early biomarkers signaling the conversion time to progressing retinopathy.

Optical Coherence Tomography Angiography in Diabetes

ABSTRACT

The introduction of optical coherence tomography angiography (OCTA) has significantly improved our knowledge on the ocular vascular alterations occurring in diabetes. In this article, we will provide a review of the prominent OCTA findings in diabetes. In details, OCTA demonstrated that both the retinal vessels and the choriocapillaris are affected in diabetic subjects. The recent employment of widefield technology and a 3-dimensional (3D) visualization in OCTA imaging are also discussed.