Disorganization of Retinal Inner Layers (DRIL) and Neuroretinal Dysfunction in Early Diabetic Retinopathy

Diabetic Disease of the Eye in Canada: Consensus Statements from a Retina Specialist Working Group

Despite advances in systemic care, diabetic disease of the eye (DDE) remains the leading cause of blindness worldwide. There is a critical gap of up-to-date, evidence-based guidance for ophthalmologists in Canada that includes evidence from recent randomized controlled trials. Previous guidance has not always given special consideration to applying treatments and managing DDE in the context of the healthcare system. This consensus statement aims to assist practitioners in the field by providing a spectrum of acceptable opinions on DDE treatment and management from recognized experts in the field. In compiling evidence and generating consensus, a working group of retinal specialists in Canada addressed clinical questions surrounding the four themes of disease, patient, management, and collaboration. The working group reviewed literature representing the highest level of evidence on DDE and shared their opinions on topics surrounding the epidemiology and pathophysiology of diabetic retinopathy and diabetic macular edema; diagnosis and monitoring; considerations around diabetes medication use; strategic considerations for management given systemic comorbidities, ocular comorbidities, and pregnancy; treatment goals and modalities for diabetic macular edema, non-proliferative and proliferative diabetic retinopathy, and retinal detachment; and interdisciplinary collaboration. Ultimately, this work highlighted that the retinal examination in DDE not only informs the treating ophthalmologist but can serve as a global index for disease progression across many tissues of the body. It highlighted further that DDE can be treated regardless of diabetic control, that a systemic approach to patient care will result in the best health outcomes, and prevention of visual complications requires a multidisciplinary management approach. Ophthalmologists must tailor their clinical approach to the needs and circumstances of individual patients and work within the realities of their healthcare setting.

Correlation of contrast sensitivity with ganglion cell/inner plexiform layer thickness and damage location in glaucoma with varying severity

OBJECTIVES

To investigate the correlation of contrast sensitivity with macular region ganglion cell/inner plexiform layer (GC/IPL) thickness and damage location in open-angle glaucoma (OAG) of varying severity.

METHODS

Cross-sectional study with 106 patients (203 eyes) who had OAG. Contrast sensitivity of each eye evaluated by quick contrast sensitivity function test based on intelligent algorithm. The GC/IPL thickness measured with optical coherence tomography; six sectors were delineated for localization of damage area. All eyes were grouped by the healthy macular sector and divided into pre-perimetric, early, moderate, and advanced stages, according to severity of visual field impairment.

RESULTS

Mean GC/IPL thickness in the entire macular region and each sector were correlated with parameters that reflected contrast sensitivity (p < 0.01). The structure-function correlations were stronger nasally compared with temporally, and superiorly compared with inferiorly. Eyes with normal structure in inferior temporal sector had less visual field (p' = 0.024) and macular damage (p' = 0.034) compared with eyes that had healthy superior nasal sector; there was no difference in contrast sensitivity (p = 0.898). The structure-function correlations were significant in early, moderate, and advanced glaucoma (p < 0.05) but not in pre-perimetric glaucoma (p = 0.116).

CONCLUSIONS

GC/IPL thinning in all sectors of the macular region in OAG was correlated with contrast sensitivity impairment, whereas the inferior temporal sector was least affected. Contrast sensitivity was supported as a severity evaluation indicator of early, moderate, and advanced glaucoma, but not of pre-perimetric glaucoma.

A New Approach to Staging Diabetic Eye Disease: Staging of Diabetic Retinal Neurodegeneration and Diabetic Macular Edema

Topic

The goal of this review was to summarize the current level of evidence on biomarkers to quantify diabetic retinal neurodegeneration (DRN) and diabetic macular edema (DME).

Clinical relevance

With advances in retinal diagnostics, we have more data on patients with diabetes than ever before. However, the staging system for diabetic retinal disease is still based only on color fundus photographs and we do not have clear guidelines on how to incorporate data from the relatively newer modalities into clinical practice.

Methods

In this review, we use a Delphi process with experts to identify the most promising modalities to identify DRN and DME. These included microperimetry, full-field flash electroretinogram, spectral-domain OCT, adaptive optics, and OCT angiography. We then used a previously published method of determining the evidence level to complete detailed evidence grids for each modality.

Results

Our results showed that among the modalities evaluated, the level of evidence to quantify DRN and DME was highest for OCT (level 1) and lowest for adaptive optics (level 4).

Conclusion

For most of the modalities evaluated, prospective studies are needed to elucidate their role in the management and outcomes of diabetic retinal diseases.

Financial Disclosures

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

Retinal OCT biomarkers associated with reading performance in patients with persistent vs. resolved diabetic macular edema

BACKGROUND

Recent advancements in imaging technologies, particularly structural optical coherence tomography (OCT), have improved the understanding of diabetic macular edema (DME) pathophysiology and provided valuable biomarkers for disease progression and visual outcomes. This prospective study aimed to investigate the association between specific retinal biomarkers identified through OCT imaging and reading performance metrics in patients with previously treated persistent versus resolved DME and good visual acuity.

METHODS

Forty-nine eyes from 35 patients with a history of DME were enrolled. Reading performance was assessed using the Radner reading charts, which include standardized sentences with geometrically progressing print sizes. Structural alterations in the inner and outer retina, as well as the retinal pigment epithelium (RPE), were graded based on OCT images.

RESULTS

Reading performance, measured as maximum reading speed, was associated with specific retinal biomarkers. The disruption of the ellipsoid zone (EZ) in the parafoveal region and the presence of disorganization of the inner retinal layers (DRIL) in the parafovea were correlated with reduced reading speed. These associations were independent of the presence of intraretinal or subretinal fluid.

CONCLUSIONS

Understanding the relationship between retinal biomarkers and reading performance could contribute to a comprehensive evaluation of visual function and quality of life in patients with DME, leading to better management strategies and treatment outcomes.

OCT outcomes as biomarkers for disease status, visual function, and prognosis in diabetic macular edema

OBJECTIVE

To evaluate disorganization of retinal inner layers (DRIL), as detected on spectral-domain optical coherence tomography (OCT) images, as a biomarker for diabetic macular edema (DME) activity, visual function, and prognosis in eyes with DME.

DESIGN

Longitudinal prospective.

METHODS

Post hoc correlation analyses were performed on data from a phase 2 clinical trial. Seventy-one eyes of 71 patients with treatment-naive DME received either suprachoroidally administered CLS-TA (proprietary formulation of a triamcinolone acetonide injectable suspension) combined with intravitreal aflibercept or intravitreal aflibercept with a sham suprachoroidal injection procedure. DRIL area, maximum horizontal extent of DRIL, ellipsoid zone (EZ) integrity, and the presence and location of subretinal (SRF) and intraretinal fluid (IRF) were evaluated at baseline and week 24 by certified reading centre graders.

RESULTS

At baseline, the area and maximum horizontal extent of DRIL were negatively correlated with best-corrected visual acuity (BCVA; r = -0.25, p = 0.05 and r = -0.32, p =0.01, respectively). Mean baseline BCVA progressively worsened with each ordinal drop in EZ integrity, improved with the presence of SRF, and was invariant to the presence of IRF. DRIL area and maximum extent were significantly decreased at week 24 (-3.0 mm2 [p < 0.001] and -775.8 mm [p < 0.001], respectively. At week 24, decreases in the area and maximum horizontal extent of DRIL were positively correlated with increases in BCVA (r = -0.40, p = 0.003 and r = -0.30, p = 0.04). Improvements in BCVA at week 24 were no different between patients showing improvement in EZ, SRF, or IRF and those showing no improvement or worsening from baseline.

CONCLUSIONS

DRIL area and DRIL maximum horizontal extent were demonstrated to be novel biomarkers for macular edema status, visual function, and prognosis in eyes with treatment-naive DME.

Optical coherence tomography biomarkers indicating visual enhancement in diabetic macular edema resolved through anti-VEGF therapy: OCT biomarkers in resolved DME

PURPOSE

to investigate the structural features and extended visual results in eyes affected by diabetic retinopathy (DR) and diabetic macular edema (DME) that have been successfully treated with anti-vascular endothelial growth factor (VEGF) therapy.

METHODS

Individuals (39 eyes of 39 patients) who had undergone long-term follow-up and demonstrated evidence of resolved DME after at least 2 years of follow-up following the initiation of anti-VEGF therapy were included. During the ""study visit"", structural OCT scans were examined to assess qualitative features indicative of neuroretina or retinal pigment epithelium distress. Additionally, a quantitative assessment of the inner and outer retinal thicknesses was conducted for topographical analysis.

RESULTS

The most robust qualitative association observed with BCVA at the "study visit" was linked to the presence of DRIL (p = 0.043) and the appearance of the ELM. (p = 0.045). Regarding quantitative parameters, a strong correlation was noted between the visual acuity during the "study visit" and the foveal and parafoveal thicknesses of both the inner and outer retina (p < 0.001).

CONCLUSIONS

Changes in the status of ELM, the presence of DRIL, and the thicknesses of the foveal and parafoveal regions can act as OCT biomarkers, signifying prolonged visual improvements in eyes that have experienced resolved DME after undergoing anti-VEGF therapy.

Analysis of OCT Scanning Parameters in AMD and RVO

Optical coherence tomography (OCT) is an extensively used imaging tool for disease monitoring in both age-related macular degeneration (AMD) and retinal vein occlusion (RVO). However, there is limited literature on minimum requirements of OCT settings for reliable biomarker detection. This study systematically investigates both the influence of scan size and interscan distance (ISD) on disease activity detection. We analyzed 80 OCT volumes of AMD patients and 12 OCT volumes of RVO patients for the presence of subretinal fluid (SRF), intraretinal fluid (IRF), and pigment epithelium detachment (PED). All volume scans had a scan size of 6 × 6 mm and an ISD of 125 µm. We analyzed both general fluid distribution and how biomarker detection sensitivity decreases when reducing scan size or density. We found that in AMD patients, all fluids were nearly normally distributed, with most occurrences in the foveal center and concentric decrease towards the periphery. When reducing the scan size to 3 × 3 and 2 × 2 mm, disease activity detection was still high (0.98 and 0.96). Increasing ISD only slightly can already compromise biomarker detection sensitivity (0.9 for 250 µm ISD against 125 µm ISD).

Impact of Pachychoroid and DRIL on the Treatment of Diabetic Macular Oedema with Intravitreal Bevacizumab

PURPOSE

To evaluate the long-term outcome of intravitreal bevacizumab in eyes with diabetic macular oedema (DME) following a PRN (pro re nata) regimen. Additionally, we investigated the effect of the presence of disorganisation of the retinal inner layers (DRILs) and pachychoroid (PC) at baseline on clinical outcome.

METHODS

This retrospective study included 112 naïve eyes with DME that were followed up for 2 years. All eyes were treated with six initial bevacizumab injections at monthly intervals and then received treatment according to a PRN regimen. In case of poor response to bevacizumab, therapy was switched to other agents. Main outcome measures included: best-corrected visual acuity (BCVA), central macular thickness (CMT), and number of intravitreal injections (IVI s). In addition, we examined the effect of the presence of DRILs and PC at baseline on clinical outcome.

RESULTS

BVCA improved significantly and CMT decreased significantly during the first 2 years of treatment. The number of IVI s per eye was 11.1 ± 4.8 at the end of the second year. Treatment had to be switched to other agents in 47 eyes (42%). The timing of switching was 12.4 ± 6.1 months after a mean of 9.2 ± 3.3 IVI s. Patients with DRILs at baseline (29.5%) had significantly worse BCVA at all time points before and after treatment, although CMT was significantly lower before treatment and comparable to patients without DRILs during treatment. Patients with PC at baseline (35.7%) had no significant differences in BVCA and CMT at all time points compared with patients without PC.

CONCLUSIONS

This study demonstrates statistically significant functional and anatomical improvement in patients with DME treated with intravitreal bevacizumab after 2 years. However, more than 40% of eyes required a switch in therapy. The presence of DRILs at baseline had a negative effect whereas the presence of PC at baseline had no effect on clinical outcome.

Discriminating early-stage diabetic retinopathy with subjective and objective perimetry

Introduction

To prevent progression of early-stage diabetic retinopathy, we need functional tests that can distinguish multiple levels of neural damage before classical vasculopathy. To that end, we compared multifocal pupillographic objective perimetry (mfPOP), and two types of subjective automated perimetry (SAP), in persons with type 2 diabetes (PwT2D) with either no retinopathy (noDR) or mild to-moderate non-proliferative retinopathy (mmDR).

Methods

Both eyes were assessed by two mfPOP test methods that present stimuli within either the central ±15° (OFA15) or ±30° (OFA30), each producing per-region sensitivities and response delays. The SAP tests were 24-2 Short Wavelength Automated Perimetry and 24-2 Matrix perimetry.

Results

Five of eight mfPOP global indices were significantly different between noDR and mmDR eyes, but none of the equivalent measures differed for SAP. Per-region mfPOP identified significant hypersensitivity and longer delays in the peripheral visual field, verifying earlier findings. Diagnostic power for discrimination of noDR vs. mmDR, and normal controls vs. PwT2D, was much higher for mfPOP than SAP. The mfPOP per-region delays provided the best discrimination. The presence of localized rather than global changes in delay ruled out iris neuropathy as a major factor.

Discussion

mfPOP response delays may provide new surrogate endpoints for studies of interventions for early-stage diabetic eye damage.

The endoplasmic reticulum: Homeostasis and crosstalk in retinal health and disease

The endoplasmic reticulum (ER) is the largest intracellular organelle carrying out a broad range of important cellular functions including protein biosynthesis, folding, and trafficking, lipid and sterol biosynthesis, carbohydrate metabolism, and calcium storage and gated release. In addition, the ER makes close contact with multiple intracellular organelles such as mitochondria and the plasma membrane to actively regulate the biogenesis, remodeling, and function of these organelles. Therefore, maintaining a homeostatic and functional ER is critical for the survival and function of cells. This vital process is implemented through well-orchestrated signaling pathways of the unfolded protein response (UPR). The UPR is activated when misfolded or unfolded proteins accumulate in the ER, a condition known as ER stress, and functions to restore ER homeostasis thus promoting cell survival. However, prolonged activation or dysregulation of the UPR can lead to cell death and other detrimental events such as inflammation and oxidative stress; these processes are implicated in the pathogenesis of many human diseases including retinal disorders. In this review manuscript, we discuss the unique features of the ER and ER stress signaling in the retina and retinal neurons and describe recent advances in the research to uncover the role of ER stress signaling in neurodegenerative retinal diseases including age-related macular degeneration, inherited retinal degeneration, achromatopsia and cone diseases, and diabetic retinopathy. In some chapters, we highlight the complex interactions between the ER and other intracellular organelles focusing on mitochondria and illustrate how ER stress signaling regulates common cellular stress pathways such as autophagy. We also touch upon the integrated stress response in retinal degeneration and diabetic retinopathy. Finally, we provide an update on the current development of pharmacological agents targeting the UPR response and discuss some unresolved questions and knowledge gaps to be addressed by future research.

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.

Retinal changes after fluocinolone acetonide implant (ILUVIEN®) for DME: SD-OCT imaging assessment using ESASO classification

INTRODUCTION

A detailed understanding of the anatomical and structural changes occurring in the retina following intravitreal fluocinolone acetonide implantation may help improve the management and prognosis of persistent or recurrent diabetic macular edema (DME).

METHODS

Overall, 45 eyes (from 35 patients) with refractory center-involved DME received an intravitreal fluocinolone acetonide implant. They were monitored at baseline and at 6, 12, 24, and 36 months for best-corrected visual acuity (BCVA), central foveal thickness (CFT), and the seven retinal parameters used in the classification of diabetic maculopathy recently developed at the European School for Advanced Studies in Ophthalmology (ESASO).

RESULTS

Within 6 months of implantation, significant improvements were evident in BCVA, CFT, maculopathy stage, and the percentage of eyes with: intraretinal cysts; CFT > 30% above the upper normal value; and disrupted or absent ellipsoid zone (EZ) and/or external limiting membrane (ELM). Significant improvements were still maintained at 36 months post-implantation. At month 36, early treatment with the implant (i.e., after < 6 previous intravitreal injections for DME) trended toward being more effective than later treatment in improving BCVA, CFT, maculopathy stage, and the percentage of eyes with CFT > 30% above the upper normal value. However, statistical significance was not achieved.

CONCLUSION

In persistent or recurrent DME, fluocinolone acetonide implantation can be effective in improving maculopathy stage and reducing the percentage of eyes with: intraretinal cysts; CFT > 30% above the upper normal value; and disrupted or absent EZ and/or ELM. It can also increase BCVA and reduce CFT.

Fractal Phototherapy in Maximizing Retina and Brain Plasticity

The neuroplasticity potential is reduced with aging and impairs during neurodegenerative diseases and brain and visual system injuries. This limits the brain's capacity to repair the structure and dynamics of its activity after lesions. Maximization of neuroplasticity is necessary to provide the maximal CNS response to therapeutic intervention and adaptive reorganization of neuronal networks in patients with degenerative pathology and traumatic injury to restore the functional activity of the brain and retina.Considering the fractal geometry and dynamics of the healthy brain and the loss of fractality in neurodegenerative pathology, we suggest that the application of self-similar visual signals with a fractal temporal structure in the stimulation therapy can reactivate the adaptive neuroplasticity and enhance the effectiveness of neurorehabilitation. This proposition was tested in the recent studies. Patients with glaucoma had a statistically significant positive effect of fractal photic therapy on light sensitivity and the perimetric MD index, which shows that methods of fractal stimulation can be a novel nonpharmacological approach to neuroprotective therapy and neurorehabilitation. In healthy rabbits, it was demonstrated that a long-term course of photostimulation with fractal signals does not harm the electroretinogram (ERG) and retina structure. Rabbits with modeled retinal atrophy showed better dynamics of the ERG restoration during daily stimulation therapy for a week in comparison with the controls. Positive changes in the retinal function can indirectly suggest the activation of its adaptive plasticity and the high potential of stimulation therapy with fractal visual stimuli in a nonpharmacological neurorehabilitation, which requires further study.

Clinical Utility of Spectral-Domain Optical Coherence Tomography Marker Disorganization of Retinal Inner Layers in Diabetic Retinopathy

BACKGROUND AND OBJECTIVE

Disorganization of retinal inner layers (DRIL) is a potential spectral-domain optical coherence tomography (SD-OCT) imaging biomarker with clinical utility in diabetic retinopathy (DR).

PATIENTS AND METHODS

A cross-sectional study was conducted at a large academic center. The cohort was composed of 1,175 patients with type 2 diabetes with and without retinopathy on initial examination between September 2009 and January 2019 (n = 2,083 eyes). DR risk and progression factors were obtained from the medical record. Trained graders masked to patients' clinical histories evaluated SD-OCT scans for DRIL.

RESULTS

Of 2,083 eyes, 28.1% (n = 585) demonstrated presence of DRIL with high interrater reliability (K = 0.88, 95% CI 0.86-0.90). DRIL was associated with worse visual acuity (VA) (P < 0.001) and DR severity (P < 0.0001). Insulin users had more severe DR (P < 0.0001). DR-related factors, race (Black, White) and sex (male) were significantly associated with DRIL (P < 0.05).

CONCLUSIONS

DRIL was strongly associated with DR severity and worse VA, supporting its utility as an unfavorable prognostic indicator. [Ophthalmic Surg Lasers Imaging Retina 2023;54:692-700.].

Structure-function associations between contrast sensitivity and widefield swept-source optical coherence tomography angiography in diabetic macular edema

PURPOSE

To evaluate the relationship between contrast sensitivity (CS) and widefield swept-source optical coherence tomography angiography (WF SS-OCTA) vascular metrics in diabetic macular edema (DME) was the purpose.

METHODS

This prospectively enrolled cross-sectional observational study included 61 eyes of 48 patients that were tested with the quantitative CS function (qCSF) test on the same day as imaging with WF SS-OCTA (PLEX® Elite 9000, Carl Zeiss Meditec) 3 × 3, 6 × 6, and 12 × 12 mm scans. Outcomes included visual acuity (VA) and multiple qCSF metrics. Vascular metrics included vessel density (VD) and vessel skeletonized density (VSD) in the superficial (SCP) and deep capillary plexus (DCP) and whole retina (WR) and foveal avascular zone (FAZ) parameters. Mixed effects multivariable linear regression models controlling for age, lens status, and diabetic retinopathy stage were performed. Standardized beta coefficients were calculated by refitting the standardized data.

RESULTS

SS-OCTA metrics had a significant association with CS and VA. The effect size of OCTA metrics was larger on CS compared to VA. For example, the standardized beta coefficients for VSD and CS at 3 cpd (βSCP = 0.76, βDCP = 0.71, βWR = 0.72, p < 0.001) were larger than those for VA (βSCP =  - 0.55, p < 0.001; βDCP =  - 0.43, p = 0.004; βWR =  - 0.50, p < 0.001). On 6 × 6 mm images, AULCSF, CS at 3 cpd, and CS at 6 cpd were significantly associated with VD and VSD in all three slab types (SCP, DCP, and WR), while VA was not.

CONCLUSION

Structure-function associations in patients with DME leveraging the qCSF device suggest microvascular changes on WF SS-OCTA are associated with larger changes in contrast sensitivity than VA.

Deep Learning Algorithm Detects Presence of Disorganization of Retinal Inner Layers (DRIL)-An Early Imaging Biomarker in Diabetic Retinopathy

Purpose

To develop and train a deep learning-based algorithm for detecting disorganization of retinal inner layers (DRIL) on optical coherence tomography (OCT) to screen a cohort of patients with diabetic retinopathy (DR).

Methods

In this cross-sectional study, subjects over age 18, with ICD-9/10 diagnoses of type 2 diabetes with and without retinopathy and Cirrus HD-OCT imaging performed between January 2009 to September 2019 were included in this study. After inclusion and exclusion criteria were applied, a final total of 664 patients (5992 B-scans from 1201 eyes) were included for analysis. Five-line horizontal raster scans from Cirrus HD-OCT were obtained from the shared electronic health record. Two trained graders evaluated scans for presence of DRIL. A third physician grader arbitrated any disagreements. Of 5992 B-scans analyzed, 1397 scans (∼30%) demonstrated presence of DRIL. Graded scans were used to label training data for the convolution neural network (CNN) development and training.

Results

On a single CPU system, the best performing CNN training took ∼35 mins. Labeled data were divided 90:10 for internal training/validation and external testing purpose. With this training, our deep learning network was able to predict the presence of DRIL in new OCT scans with a high accuracy of 88.3%, specificity of 90.0%, sensitivity of 82.9%, and Matthews correlation coefficient of 0.7.

Conclusions

The present study demonstrates that a deep learning-based OCT classification algorithm can be used for rapid automated identification of DRIL. This developed tool can assist in screening for DRIL in both research and clinical decision-making settings.

Translational Relevance

A deep learning algorithm can detect disorganization of retinal inner layers in OCT scans.

The Disorganization of Retinal Inner Layers Is Correlated to Müller Cells Impairment in Diabetic Macular Edema: An Imaging and Omics Study

The disorganization of retinal inner layers (DRIL) is an optical coherence tomography (OCT) biomarker strictly associated with visual outcomes in patients with diabetic macular edema (DME) whose pathophysiology is still unclear. The aim of this study was to characterize in vivo, using retinal imaging and liquid biopsy, DRIL in eyes with DME. This was an observational cross-sectional study. Patients affected by center-involved DME were enrolled. All patients underwent spectral domain optical coherence tomography (SD-OCT) and proteomic analysis of aqueous humor (AH). The presence of DRIL at OCT was analyzed by two masked retinal experts. Fifty-seven biochemical biomarkers were analyzed from AH samples. Nineteen eyes of nineteen DME patients were enrolled. DRIL was present in 10 patients (52.63%). No statistically significant difference was found between DME eyes with and without DRIL, considering the AH concentration of all the analyzed biomarkers except for glial fibrillary acidic protein (GFAP), a biomarker of Müller cells dysfunction (p = 0.02). In conclusion, DRIL, in DME eyes, seems to strictly depend on a major dysfunction of Müller cells, explaining its role not only as imaging biomarker, but also as visual function Müller cells-related parameter.

Characteristics and Related Parameters of Quick Contrast Sensitivity Function in Chinese Ametropia Children

PURPOSE

To investigate the characteristics of quick contrast sensitivity function (qCSF) and its related parameters in Chinese ametropia children.

METHODS

This case series study enrolled 106 eyes of 53 children (male/female=29/24, age: 9.04±2.06 years). Examinations included manifest refraction, axial length, corneal curvature, and monocular and binocular qCSF readings without refractive correction (area under log CSF [AULCSF], CSF acuity, and contrast sensitivity [CS] at 1.0 to 18.0 cpd). The subjects were divided into groups according to age and refractive parameters for analysis.

RESULTS

The mean spherical equivalent (SE), AULCSF, and CSF acuity of the test eyes were -0.94±1.53 D, 0.44±0.33, and 8.50±5.97 cpd, respectively. In the monocular qCSF comparison, the refraction sphere (RS) was the major factor correlated with qCSF readings (B=0.186, P =0.009 for AULCSF; B=0.543, P =0.019 for CSF acuity; generalized linear model). The three groups stratified by RS/SE (<-1.00D, -1.00D to 0D, and >0D) showed significant differences in CS at medium spatial frequencies (3.0 and 6.0 cpd; all P <0.05). In the low RS/SE group (within -1 to 0 D), the CS at 12.0 cpd was significantly lower than that in the hyperopia group (all P <0.05). Binocular qCSF readings were significantly correlated with those of the eyes with lower RS (all P <0.05).

CONCLUSION

RS and SE are the major contributing factors of qCSF without refractive correction in children. The CS at medium spatial frequencies decrease significantly as the RS/SE increase. In low myopia children, the CS at medium and high spatial frequencies are significantly decreased, providing practical value in visual function screening in children.

Association Between Contrast Sensitivity and Central Subfield Thickness in Center-Involving Diabetic Macular Edema

Purpose: To evaluate the association between contrast sensitivity (CS) and central subfield thickness (CST) in diabetic macular edema (DME). Methods: This prospectively recruited, cross-sectional study included eyes with DME evaluated from November 2018 to March 2021. CST was measured using spectral-domain optical coherence tomography on the same day as CS testing. Only eyes with center-involving DME (CST >305 µm for women; >320 µm for men) were included. CS was evaluated using the quantitative CS function (qCSF) test. Outcomes included visual acuity (VA) and the following qCSF metrics: area under the log CS function, contrast acuity (CA), and CS thresholds at 1 to 18 cycles per degree (cpd). Pearson correlation and mixed-effects regression analyses were performed. Results: The cohort included 52 eyes of 43 patients. Pearson correlation analysis showed a stronger association between CST and CS thresholds at 6 cpd (r = -0.422, P = 0.002) than CST and VA (r = 0.293, P = 0.035). Mixed-effects univariate and multivariate regression analyses showed significant associations between CST and CA (β = -0.001, P = .030), CS at 6 cpd (β = -0.002, P = .008), and CS at 12 cpd (β = -0.001, P = .049) but no significant associations between CST and VA. Among the visual function metrics, the effect size of CST was largest on CS at 6 cpd (βStandardized = -0.37, P = .008). Conclusions: In patients with DME, CS may be more strongly associated with CST than VA. Including CS as an adjunct visual function outcome measure in eyes with DME may prove clinically valuable.

Optical Coherence Tomography Angiographic Evaluation of Macular Vessel Density in Diabetic Macular Edema After Intravitreal Dexamethasone Implants: A Prospective Interventional Trial

BACKGROUND AND OBJECTIVE

The goal of this study was to assess macular vascular density evolution, macular thickness, and functional outcomes after intravitreal dexamethasone implants for diabetic macular edema.

PATIENTS AND METHODS

Vascular density was evaluated with optical coherence tomography (OCT) angiography in 21 eyes. Macular thickness was evaluated with structural OCT. Visual acuity and contrast sensitivity were evaluated before and after treatment, and these functional outcomes were analyzed for association with anatomic outcomes. Macular vessel density in the superficial capillary plexus was evaluated with OCT angiography and quantified in areas with no fluid, allowing a more accurate measurement and eliminating the segmentation bias in areas with intra-retinal fluid. Such a methodology was possible by positioning the scans only in areas with no fluid before and after the implant. The absence of fluid in these areas was confirmed by three experienced evaluators using both the B-scan and the en face. Visual acuity and contrast sensitivity were evaluated before and after treatment, and these functional outcomes were analyzed for association with anatomic outcomes.

RESULTS

At 30, 60, and 90 days after implantation, there was improvement in macular perfusion in areas without fluid after intravitreal dexamethasone implantation, accompanied by reduced macular thickness and improved visual acuity (P < .001). However, there was no improvement in contrast sensitivity after treatment.

CONCLUSIONS

Improved macular perfusion after treatment with intravitreal dexamethasone implantation may be associated with modulation of leukostasis, when the release of cytokines leads to capillary endothelial damage and obstruction of the micro-vasculature, leading to impaired capillary perfusion and ischemic damage. Despite the anatomical and functional findings demonstrated, further studies are needed to prove the relationship between the inflammatory mechanisms of diabetic macular edema and its relationship with macular perfusion and functional aspects. [Ophthalmic Surg Lasers Imaging Retina 2023;54(3):174-182.].

Imaging biomarkers and clinical factors associated with the rate of progressive inner and outer retinal thinning in patients with diabetic macular edema

The aim of this study was to assess the relationship of clinical characteristics to the rate of retinal thinning in eyes with diabetic macular edema (DME) treated with anti-vascular endothelial growth factor (VEGF) therapy. We analyzed subjects with a long-term follow-up (≥ 3 years) and evidence of resolved DME after the initiation of anti-VEGF therapy (baseline visit). To measure the long-term rate of retinal thinning during treatment, a second visit (first visit with evidence of resolved DME after 3 years) was also considered. A longitudinal quantitative topographical assessment of the inner and outer retinal thicknesses was provided. Clinical characteristics were associated with the rate of longitudinal retinal thinning. We included 56 eyes (50 patients) in the analysis. A significant longitudinal thinning in the inner and outer retina was detected in all the analyzed regions (p values between 0.027 and < 0.0001). In the multivariable analysis, type of diabetes (type 2 vs. type 1) was associated with increased foveal inner retinal thinning (p = 0.019). A higher number of subfoveal neuroretinal detachment during follow-up (p = 0.006) was associated with faster rates of foveal outer retinal thinning. Type of diabetes (p < 0.0001), higher age (p = 0.033) and cystoid macular edema phenotype (p = 0.040) were associated with increased parafoveal inner retinal thinning. Gender (p = 0.003) and diabetic retinopathy stage (p = 0.013) were associated with faster rates of perifoveal inner retinal thinning, while diabetic retinopathy stage (p = 0.036) was associated with increased perifoveal outer retinal thinning. In conclusion, clinical factors, including DME phenotypes, were associated with the rates of retinal thinning in patients undergoing anti-VEGF treatment.

Automated assessment of the smoothness of retinal layers in optical coherence tomography images using a machine learning algorithm

Quantifying the smoothness of different layers of the retina can potentially be an important and practical biomarker in various pathologic conditions like diabetic retinopathy. The purpose of this study is to develop an automated machine learning algorithm which uses support vector regression method with wavelet kernel and automatically segments two hyperreflective retinal layers (inner plexiform layer (IPL) and outer plexiform layer (OPL)) in 50 optical coherence tomography (OCT) slabs and calculates the smoothness index (SI). The Bland-Altman plots, mean absolute error, root mean square error and signed error calculations revealed a modest discrepancy between the manual approach, used as the ground truth, and the corresponding automated segmentation of IPL/ OPL, as well as SI measurements in OCT slabs. It was concluded that the constructed algorithm may be employed as a reliable, rapid and convenient approach for segmenting IPL/OPL and calculating SI in the appropriate layers.

Diabetic Retinopathy: Soluble and Imaging Ocular Biomarkers

Diabetic retinopathy (DR), the most common microvascular complication of diabetes mellitus, represents the leading cause of acquired blindness in the working-age population. Due to the potential absence of symptoms in the early stages of the disease, the identification of clinical biomarkers can have a crucial role in the early diagnosis of DR as well as for the detection of prognostic factors. In particular, imaging techniques are fundamental tools for screening, diagnosis, classification, monitoring, treatment planning and prognostic assessment in DR. In this context, the identification of ocular and systemic biomarkers is crucial to facilitate the risk stratification of diabetic patients; moreover, reliable biomarkers could provide prognostic information on disease progression as well as assist in predicting a patient's response to therapy. In this context, this review aimed to provide an updated and comprehensive overview of the soluble and anatomical biomarkers associated with DR.

Proteomic Analysis of Retinal Mitochondria-Associated ER Membranes Identified Novel Proteins of Retinal Degeneration in Long-Term Diabetes

The mitochondria-associated endoplasmic reticulum (ER) membrane (MAM) is the physical contact site between the ER and the mitochondria and plays a vital role in the regulation of calcium signaling, bioenergetics, and inflammation. Disturbances in these processes and dysregulation of the ER and mitochondrial homeostasis contribute to the pathogenesis of diabetic retinopathy (DR). However, few studies have examined the impact of diabetes on the retinal MAM and its implication in DR pathogenesis. In the present study, we investigated the proteomic changes in retinal MAM from Long Evans rats with streptozotocin-induced long-term Type 1 diabetes. Furthermore, we performed in-depth bioinformatic analysis to identify key MAM proteins and pathways that are potentially implicated in retinal inflammation, angiogenesis, and neurodegeneration. A total of 2664 unique proteins were quantified using IonStar proteomics-pipeline in rat retinal MAM, among which 179 proteins showed significant changes in diabetes. Functional annotation revealed that the 179 proteins are involved in important biological processes such as cell survival, inflammatory response, and cellular maintenance, as well as multiple disease-relevant signaling pathways, e.g., integrin signaling, leukocyte extravasation, PPAR, PTEN, and RhoGDI signaling. Our study provides comprehensive information on MAM protein changes in diabetic retinas, which is helpful for understanding the mechanisms of metabolic dysfunction and retinal cell injury in DR.

Advances in cell therapies using stem cells/progenitors as a novel approach for neurovascular repair of the diabetic retina

BACKGROUND

Diabetic retinopathy, a major complication of diabetes mellitus, is a leading cause of sigh-loss in working age adults. Progressive loss of integrity of the retinal neurovascular unit is a central element in the disease pathogenesis. Retinal ischemia and inflammatory processes drive interrelated pathologies such as blood retinal barrier disruption, fluid accumulation, gliosis, neuronal loss and/or aberrant neovascularisation. Current treatment options are somewhat limited to late-stages of the disease where there is already significant damage to the retinal architecture arising from degenerative, edematous and proliferative pathology. New preventive and interventional treatments to target early vasodegenerative and neurodegenerative stages of the disease are needed to ensure avoidance of sight-loss.

MAIN BODY

Historically, diabetic retinopathy has been considered a primarily microvascular disease of the retina and clinically it is classified based on the presence and severity of vascular lesions. It is now known that neurodegeneration plays a significant role during the pathogenesis. Loss of neurons has been documented at early stages in pre-clinical models as well as in individuals with diabetes and, in some, even prior to the onset of clinically overt diabetic retinopathy. Recent studies suggest that some patients have a primarily neurodegenerative phenotype. Retinal pigment epithelial cells and the choroid are also affected during the disease pathogenesis and these tissues may also need to be addressed by new regenerative treatments. Most stem cell research for diabetic retinopathy to date has focused on addressing vasculopathy. Pre-clinical and clinical studies aiming to restore damaged vasculature using vasoactive progenitors including mesenchymal stromal/stem cells, adipose stem cells, CD34+ cells, endothelial colony forming cells and induced pluripotent stem cell derived endothelial cells are discussed in this review. Stem cells that could replace dying neurons such as retinal progenitor cells, pluripotent stem cell derived photoreceptors and ganglion cells as well as Müller stem cells are also discussed. Finally, challenges of stem cell therapies relevant to diabetic retinopathy are considered.

CONCLUSION

Stem cell therapies hold great potential to replace dying cells during early and even late stages of diabetic retinopathy. However, due to the presence of different phenotypes, selecting the most suitable stem cell product for individual patients will be crucial for successful treatment.

Disorganization of retinal inner layers: diagnostic and clinical characteristics

This review describes the current state of knowledge oт the phenomenon of disorganization of retinal inner layers. DRIL is characterized by alteration of microcirculation in retinal capillary plexuses detected with optical coherence tomography angiography, alteration of several inner layers of the retina with the inability to differentiate them on optical coherence tomography, and by an impact on the quality of vision. Disorganization of retinal inner layers occurs in a number of different vascular retinal disorders, which indicates its importance as a clinical biomarker and clinical significance. However, the literature data on disorganization of retinal inner layers are still limited, and questions about the pathogenesis of this disease warrant further investigations.

Association of inner retinal reflectivity with qualitative and quantitative changes in retinal layers over time in diabetic eyes without retinopathy

OBJECTIVE

To assess the course of neurodegeneration based on retinal layer thickness and integrity analysis in diabetic patients without retinopathy and to evaluate its association with inner retinal reflectivity.

METHODS

This retrospective case-control study included 80 eyes of 80 patients with DM without retinopathy and 40 eyes of 40 healthy subjects with a follow-up of ≥1 year. SD-OCT was used for assessment of retinal reflectivity and macular layer thicknesses. Optical intensity ratios (OIRs) were defined as the mean OCT reflectivity of ganglion cell and inner nuclear layer to the mean reflectivity of RPE.

RESULTS

After Bonferroni correction, thinning in pericentral, superior and nasal sectors in total retina, superior ganglion cell, pericentral and nasal inner plexiform, and superior inner retinal layers, as well as thickening in inferior and pericentral outer plexiform layer remained significant in the study group (p < 0.0125). Ganglion cell layer OIR significantly correlated with the changes in superior retina (r = 0.278, p = 0.013), central inner retina (r = 0.247, p = 0.027), and pericentral retinal thickness (r = 0.240, p = 0.032), and no eyes had disruption of retinal layers in the study group initially or finally.

CONCLUSION

Ganglion cell layer reflectivity significantly correlated with the amount of pericentral retinal thinning during the time course in the diabetic group, which was more prominent in the inner retinal layers.

Excessive dietary salt promotes neuroinflammation to worsen retinopathy in mice with streptozotocin-induced diabetes

OBJECTIVE

Diabetic retinopathy (DR) includes vascular and neural tissue injury. Persistent low-grade inflammation may contribute to DR. Increased salt intake has been shown to promote autoimmunity in the brain. This study determined the role of salt intake in DR development.

METHODS

Eight-week-old C57BL/6 J male mice received streptozotocin to induce diabetes. Diabetic or non-diabetic mice were fed a diet containing normal, low and high amounts of salt. The retinal function, structure and inflammatory response were determined 8 weeks after the establishment of diabetes. Interleukin (IL)-1β or a NLR family pyrin domain containing 3 (NLRP3) inhibitor was injected intravitreally and the retinal changes were evaluated.

RESULTS

A high salt diet worsened the functional and structural damage of retinal cells and increased IL-1β in the retina of diabetic mice. IL-1β injection impaired the function of photoreceptors and retinal structure in the diabetic mice. Blocking NLRP3 inhibited IL-1β increase in the mouse bone marrow macrophages cultured in high sodium medium. NLRP3 inhibition attenuated retinal injury of diabetic mice on high salt diet. A low-salt diet also triggered inflammation and cell damage in the retina of diabetic mice but at a lower grade than those induced by high salt diet. A low or high salt diet for 8 weeks did not induce inflammation or cell injury in the retina of mice without diabetes.

CONCLUSION

These results indicate that high salt intake has deleterious effects in DR development through NLRP3 inflammasome activation and the subsequent production of IL-1β. Limiting salt intake may not attenuate DR development.

Cellular stress signaling and the unfolded protein response in retinal degeneration: mechanisms and therapeutic implications

Background

The retina, as part of the central nervous system (CNS) with limited capacity for self-reparation and regeneration in mammals, is under cumulative environmental stress due to high-energy demands and rapid protein turnover. These stressors disrupt the cellular protein and metabolic homeostasis, which, if not alleviated, can lead to dysfunction and cell death of retinal neurons. One primary cellular stress response is the highly conserved unfolded protein response (UPR). The UPR acts through three main signaling pathways in an attempt to restore the protein homeostasis in the endoplasmic reticulum (ER) by various means, including but not limited to, reducing protein translation, increasing protein-folding capacity, and promoting misfolded protein degradation. Moreover, recent work has identified a novel function of the UPR in regulation of cellular metabolism and mitochondrial function, disturbance of which contributes to neuronal degeneration and dysfunction. The role of the UPR in retinal neurons during aging and under disease conditions in age-related macular degeneration (AMD), retinitis pigmentosa (RP), glaucoma, and diabetic retinopathy (DR) has been explored over the past two decades. Each of the disease conditions and their corresponding animal models provide distinct challenges and unique opportunities to gain a better understanding of the role of the UPR in the maintenance of retinal health and function.

Method

We performed an extensive literature search on PubMed and Google Scholar using the following keywords: unfolded protein response, metabolism, ER stress, retinal degeneration, aging, age-related macular degeneration, retinitis pigmentosa, glaucoma, diabetic retinopathy.

Results and conclusion

We summarize recent advances in understanding cellular stress response, in particular the UPR, in retinal diseases, highlighting the potential roles of UPR pathways in regulation of cellular metabolism and mitochondrial function in retinal neurons. Further, we provide perspective on the promise and challenges for targeting the UPR pathways as a new therapeutic approach in age- and disease-related retinal degeneration.

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.

Treat-and-Extend vs. Pro Re Nata Regimen of Ranibizumab for Diabetic Macular Edema—A Two-Year Matched Comparative Study

Purpose

To compare 2-year treatment outcomes of ranibizumab using treat-and-extend (T&E) or pro re nata (PRN) regimens for diabetic macular edema (DME) in clinical settings.

Methods

We retrospectively enrolled 34 patients (34 eyes) with DME treated with ranibizumab using the T&E regimen, and 34 patients (34 eyes) treated with ranibizumab using the PRN regimen and matched to cases in the treat-and-extend group by baseline best-corrected visual acuity (BCVA) and central foveal thickness (CFT). BCVA and CFT changes, number of injections and recurrence of macular edema over 2 years were compared between the groups.

Results

The average BCVA gain in the T&E and PRN groups was 16.2 and 7.6 ETDRS letters at 2 years (p = 0.011), respectively. The mean CFT reduction was 145.5 ± 127.3 and 97.3 ± 152.5 μm in the T&E and PRN groups at 2 years (p = 0.035), respectively. The T&E group had a higher proportion of patients with BCVA gain ≥ 15 letters at months 18 (p = 0.015) and 24 (p = 0.029) than the PRN group. During the 2-year treatment periods, the T&E group received more injections than the PRN group (11.0 ± 3.2 vs. 6.2 ± 2.0; p < 0.001), while the PRN group had more recurrence of macular edema than the T&E group (71 vs. 41%; p = 0.015).

Conclusions

After 2-year ranibizumab treatment for DME, better visual and anatomical improvement and less recurrence of macular edema were achieved in the T&E group, with more injections administered.

Retinal Neurodegeneration in Diabetes: an Emerging Concept in Diabetic Retinopathy

PURPOSE OF REVIEW

Diabetic retinopathy (DR), the leading cause of blindness in working-aged adults, remains clinically defined and staged by its vascular manifestations. However, early retinal neurodegeneration may precede vascular pathology, suggesting that this neuronal damage may contribute to disease pathogenesis and represent an independent target for intervention. This review will discuss the evidence and implications for diabetic retinal neurodegeneration.

RECENT FINDINGS

A growing body of literature has identified progressive retinal thinning and visual dysfunction in patients with diabetes even prior to the onset of DR, though advances in retinal vascular imaging suggest that vascular remodeling and choroidal changes occur during these early stages as well. Animal models of diabetes and in vitro studies have also suggested that diabetes may directly affect the retinal neural and glial tissue, providing support to the concept that diabetic retinal neurodegeneration occurs early in the disease and suggesting potentially relevant molecular pathways. Diabetic retinal neurodegeneration may represent a "preclinical" manifestation of diabetic retinal disease and remains an active area of investigation. As the natural history and molecular mechanisms become increasingly understood, it may lead to upcoming developments in not only the treatment options but also the clinical definition of DR.

Quantitative Imaging Biomarkers in Age-Related Macular Degeneration and Diabetic Eye Disease: A Step Closer to Precision Medicine

The management of retinal diseases relies heavily on digital imaging data, including optical coherence tomography (OCT) and fluorescein angiography (FA). Targeted feature extraction and the objective quantification of features provide important opportunities in biomarker discovery, disease burden assessment, and predicting treatment response. Additional important advantages include increased objectivity in interpretation, longitudinal tracking, and ability to incorporate computational models to create automated diagnostic and clinical decision support systems. Advances in computational technology, including deep learning and radiomics, open new doors for developing an imaging phenotype that may provide in-depth personalized disease characterization and enhance opportunities in precision medicine. In this review, we summarize current quantitative and radiomic imaging biomarkers described in the literature for age-related macular degeneration and diabetic eye disease using imaging modalities such as OCT, FA, and OCT angiography (OCTA). Various approaches used to identify and extract these biomarkers that utilize artificial intelligence and deep learning are also summarized in this review. These quantifiable biomarkers and automated approaches have unleashed new frontiers of personalized medicine where treatments are tailored, based on patient-specific longitudinally trackable biomarkers, and response monitoring can be achieved with a high degree of accuracy.

Effect of optical coherence tomography and angiography sampling rate towards diabetic retinopathy severity classification

Optical coherence tomography (OCT) and OCT angiography (OCT-A) may benefit the screening of diabetic retinopathy (DR). This study investigated the effect of laterally subsampling OCT/OCT-A en face scans by up to a factor of 8 when using deep neural networks for automated referable DR classification. There was no significant difference in the classification performance across all evaluation metrics when subsampling up to a factor of 3, and only minimal differences up to a factor of 8. Our findings suggest that OCT/OCT-A can reduce the number of samples (and hence the acquisition time) for a volume for a given field of view on the retina that is acquired for rDR classification.

Ocular Neurodegenerative Diseases: Interconnection between Retina and Cortical Areas

The possible interconnection between the eye and central nervous system (CNS) has been a topic of discussion for several years just based on fact that the eye is properly considered an extension of the brain. Both organs consist of neurons and derived from a neural tube. The visual process involves photoreceptors that receive light stimulus from the external environment and send it to retinal ganglionic cells (RGC), one of the cell types of which the retina is composed. The retina, the internal visual membrane of the eye, processes the visual stimuli in electric stimuli to transfer it to the brain, through the optic nerve. Retinal chronic progressive neurodegeneration, which may occur among the elderly, can lead to different disorders of the eye such as glaucoma, age-related macular degeneration (AMD), and diabetic retinopathy (DR). Mainly in the elderly population, but also among younger people, such ocular pathologies are the cause of irreversible blindness or impaired, reduced vision. Typical neurodegenerative diseases of the CSN are a group of pathologies with common characteristics and etiology not fully understood; some risk factors have been identified, but they are not enough to justify all the cases observed. Furthermore, several studies have shown that also ocular disorders present characteristics of neurodegenerative diseases and, on the other hand, CNS pathologies, i.e., Alzheimer disease (AD) and Parkinson disease (PD), which are causes of morbidity and mortality worldwide, show peculiar alterations at the ocular level. The knowledge of possible correlations could help to understand the mechanisms of onset. Moreover, the underlying mechanisms of these heterogeneous disorders are still debated. This review discusses the characteristics of the ocular illnesses, focusing on the relationship between the eye and the brain. A better comprehension could help in future new therapies, thus reducing or avoiding loss of vision and improve quality of life.

Reliability of Subjective Assessment of Spectral-Domain OCT Pathologic Features by Multiple Raters in Retinal Vein Occlusion

Purpose

Design

Participants

Methods

Main Outcome Measures

Results

Conclusions

Indicators of Visual Prognosis in Diabetic Macular Oedema

Diabetic macular oedema (DMO) is an important cause of moderate vision loss in people with diabetes. Advances in imaging technology have shown that a significant proportion of patients with DMO respond sub-optimally to existing treatment options. Identifying associations and predictors of response before treatment is initiated may help in explaining visual prognosis to patients and aid the development of personalized treatment strategies. Imaging features, such as central subfoveal thickness, photoreceptor integrity, disorganization of retinal inner layers, choroidal changes, and macular perfusion, have been reported to be prognostic factors of visual acuity (VA) in DMO. In this review we evaluated each risk factor to understand their relative importance in visual prognostication of DMO eyes post-treatment. Although individually, some of these factors may not be significant predictors, in combination they may form phenotypes that can inform visual prognosis. Stratification based on these phenotypes needs to be developed to progress to personalized medicine for DMO.

Quantitative assessment of vascular density in diabetic retinopathy subtypes with optical coherence tomography angiography

Background

Quantitative assessment of vascular density (VD) of retinal and choriocapillaris (CC) in various stages of diabetic retinopathy (DR) using spectral domain optical coherence tomography angiography (SD OCTA).

Methods

188 eyes of 97 participants were recruited in this cross-sectional study. The macular OCTA (3x3mm) scan was performed and the computer algorithm assessed VD at the level of superficial capillary plexus (SCP), deep capillary plexus (DCP) and CC.

Results

All measured parameters were decreased in retinal VD at the more extreme stages of DR, with the exception of SCP foveal VD. There was a constant pattern of decrease in VD of CC from normal cases to cases of NDR and NPDR and then a slight increase occurred in the PDR stage but never touching the normal quantities. Age, fasting blood sugar, and years of diabetes mellitus were correlated with reduced VD in different segments. Multivariate linear regression analysis showed that best-corrected visual acuity (BCVA) was positively correlated with parafoveal VD at SCP and VD of foveal area at CC. VD of all subfields of macular area except foveal DCP VD showed reduced levels in diabetic macular edema (DME) patients compared to those without DME.

Conclusions

The findings of the study endorse retina VD changes as a potential biomarker for DR development before retinopathy becomes clinically evident. It seems that parafoveal VD of SCP and foveal VD of CC are good biomarkers to predict VA in the diabetic patients.

SHORT-WAVELENGTH AUTOMATED PERIMETRY IN DIABETIC PATIENTS WITHOUT RETINOPATHY

AIM

To compare the results of short-wavelength automated perimetry (SWAP) in diabetic patients without retinopathy and healthy subjects and show if it is possible to detect an abnormal function of the retina in diabetic patients before vascular changes on the retina develop. Further, the effect of diabetes duration and long-term glycaemic control on the visual field was examined.

METHODS

The study group included 22 patients with diabetes type 1 or 2, without any signs of retinopathy. The control group consisted of 21 healthy subjects. Short-wavelength automated perimetry was performed on the Humphrey Field Analyzer (HFA 860, Carl Zeiss Meditec), SITA SWAP, 24-2 test. In diabetic patients, the duration of diabetes and the level of glycohemoglobin (HbA1c) was registered. The visual field indices MD (mean deviation) and PSD (pattern standard deviation) were compared between both groups by the Mann-Whitney test. The correlation between the visual field indices, HbA1c and duration of diabetes was assessed by the Spearman correlation coefficient.

RESULTS

The mean value of MD in the study and control group was -3.64±3.66 dB and -1.48±2.12 dB respectively, the values in the study group were significantly lower (p &lt; 0.05). Mean PSD in the study group was 2.92±1.04 dB and 2.23±0.33 dB in the control group, again the difference was statistically significant (p &lt; 0.05). Patients in the study group suffered from diabetes for 17±9.4 years in average. The mean value of HbA1c in the study group was 60.64±16.63 mmol/mol. A significant correlation was found only for PSD and HbA1c (p &gt; 0.05). The duration of diabetes had no effect on either of the visual field indices.

CONCLUSION

Short-wavelength sensitivity of retina seems to be affected in diabetic patients without clinically significant retinopathy suggesting a neuroretinal impairment at early stages of the retinopathy. We found no association between the visual field and the control or duration of diabetes.

Short wavelength automated perimetry and standard automated perimetry in central serous chorioretinopathy

Short wavelength automated perimetry (SWAP) is known for detecting the early reduction of retinal sensitivity (RS) in glaucoma. It’s application in retinal diseases have also been discussed previously. We investigated the difference in RS measured between standard white-on-white automated perimetry (WW) and blue-on-yellow SWAP in central serous chorioretinopathy (CSC). The overall RS (W-RS, S-RS) as well as the RS inside and outside of the serous retinal detachment (SRD) region were investigated in 26 eyes of 26 CSC patients using WW and SWAP. The central retinal thickness, central choroidal thickness, SRD area (SRDa), and SRD height at the fovea were measured using optic coherence tomography. RS inside the SRD region was lower than that of outside for both perimetries (both p < 0.001). The difference between RS inside and outside of the SRD region was greater in SWAP compared to WW (p < 0.001). Univariate analysis revealed significant correlations between SRDa and both W-RS and S-RS (both p < 0.001); moreover, multivariate analysis indicated that only S-RS was selected as the optimal model for SRDa. Our study demonstrated that SWAP was detected the decrease in RS more accurately than WW in CSC. These results may suggest the usefulness of SWAP for detecting change of retinal function in CSC.

Disorganisation of retinal inner layers is associated with reduced contrast sensitivity in retinal vein occlusion

BACKGROUND/AIMS

To determine if disorganisation of retinal inner layers (DRIL) is associated with reduced contrast sensitivity (CS) in patients with retinal vein occlusion (RVO) with a history of macular oedema (ME).

METHODS

Prospective, observational cohort study. Patients with a history of ME secondary to central retinal vein occlusion (CRVO) or branch retinal vein occlusion (BRVO) from October 2017 to July 2019 at a single institution were included. Patients underwent complete ophthalmic examination, spectral domain optical coherence tomography (SD-OCT) and CS testing using the quick contrast sensitivity function (qCSF) method. Eyes with coexisting macular disease were excluded. SD-OCT images were analysed for presence and extent of DRIL, intraretinal fluid (IRF), subretinal fluid (SRF), hyperreflective foci, epiretinal membrane (ERM), external limiting membrane (ELM) disruption, ellipsoid zone (EZ) disruption, central macular thickness (CMT) and central foveal thickness (CFT). Multivariable mixed-effect linear regressions were performed for the area under the log contrast sensitivity function (AULCSF) using Stata (StataCorp). P values <0.05 were considered significant.

RESULTS

58 visits from 31 patients were included (1.9±1.2 visits per patient). 29 (50%) were for CRVO. The average age was 63.9±10.5 years. On multivariable analysis, DRIL extent (p<0.001), CMT (p=0.007), CFT (p=0.024) and moderate cataract (p=0.001) were significantly associated with worse AULCSF.

CONCLUSIONS

DRIL extent is associated with reduced CS in eyes with ME secondary to RVO. DRIL is an imaging feature that has important implications for visual function.

Visual contrast sensitivity could be an early marker of diabetic retinopathy

The present study aimed to explore the early predictive marker of diabetic retinopathy (DR) and to elucidate the associated demographic, metabolic, and ocular factors. We enrolled 43 type 2 diabetic subjects with mild non-proliferative retinopathy (MNPDR), 30 diabetic subjects with no retinopathy (DNR), and 35 healthy controls (HC). The study groups showed no significant alteration in central macular thickness (CMT) and visual acuity (VA). The contrast sensitivity (CS) score was found to be significantly lower among DNR and MNPDR subjects compared to HCs (p < 0.0001). Between MNPDR and DNR subjects, the CS score was significantly lower in the former (p = 0.0036). CS score discriminated DNR subjects from HC, with 74% accuracy for the optimal threshold 0.71. The associated area under the ROC curve (AUC) is 0.82 (p < 0.0001) while the discrimination rule has 66% sensitivity and 80% specificity. The CS score also discriminated MNPDR subjects from DNR with 64% accuracy for the optimal threshold 0.53. The associated AUC is 0.65 (p < 0.023) and the rule has 86% sensitivity and 33% specificity. According to best subset regression analysis, not only glycaemic parameters but also lipid parameters [low-density lipoprotein cholesterol (LDL-C) (p = 0.045) and triglycerides (TG) (p = 0.0005)] were found to be significant predictors of CS. CMT (p = 0.058) was another marginally significant predictor of CS. CS may be used as an early predictive marker for DR. So, not only hyperglycemia, but also hyperlipidemia seems to significantly affect retinal CS function in diabetes.

Baseline predictors for visual acuity loss during observation in diabetic macular oedema with good baseline visual acuity

PURPOSE

To investigate clinical baseline characteristics and optical coherence tomography biomarkers predicting visual loss during observation in eyes with diabetic macular oedema (DMO) and good baseline visual acuity (VA).

METHODS

A sub-analysis of a 12-month, retrospective study, including patients with baseline VA ≤0.1 logMAR (≥20/25 Snellen) and centre-involving DMO. The primary outcome measure was the correlation between baseline characteristics and VA loss ≥10 letters during follow-up.

RESULTS

A total of 249 eyes were included in the initial study, of which 147 eyes were observed and 80 eyes received anti-vascular endothelial growth factor (VEGF) treatment at baseline. Visual acuity (VA) loss ≥10 letters occurred in 21.8% (observed cohort) and in 24.3% (treated cohort), respectively. Within observed eyes, presence of hyperreflective foci [HRF; odds ratio (OR): 3.18, p = 0.046], and disorganization of inner retina layers (DRIL; OR: 2.71, p = 0.026) were associated with a higher risk of VA loss ≥10 letters. In observed eyes with a combined presence of HRF, DRIL and ellipsoid zone (EZ) disruption, the risk of VA loss was further increased (OR: 3.86, p = 0.034). In eyes with combined presence of DRIL, HRF and EZ disruption, risk of VA loss was 46.7% (7/15 eyes) in the observed cohort, and 26.3% (5/19 eyes) in the treated cohort (p = 0.26).

CONCLUSION

Patients with DMO and good baseline VA, managed by observation, are of increased risk for VA loss if DRIL, HRF and EZ disruption are present at baseline. Earlier treatment with anti-VEGF in these patients may potentially decrease the risk of VA loss at 12 months.

Density-based classification in diabetic retinopathy through thickness of retinal layers from optical coherence tomography

Diabetic retinopathy (DR) is a severe retinal disorder that can lead to vision loss, however, its underlying mechanism has not been fully understood. Previous studies have taken advantage of Optical Coherence Tomography (OCT) and shown that the thickness of individual retinal layers are affected in patients with DR. However, most studies analyzed the thickness by calculating summary statistics from retinal thickness maps of the macula region. This study aims to apply a density function-based statistical framework to the thickness data obtained through OCT, and to compare the predictive power of various retinal layers to assess the severity of DR. We used a prototype data set of 107 subjects which are comprised of 38 non-proliferative DR (NPDR), 28 without DR (NoDR), and 41 controls. Based on the thickness profiles, we constructed novel features which capture the variation in the distribution of the pixel-wise retinal layer thicknesses from OCT. We quantified the predictive power of each of the retinal layers to distinguish between all three pairwise comparisons of the severity in DR (NoDR vs NPDR, controls vs NPDR, and controls vs NoDR). When applied to this preliminary DR data set, our density-based method demonstrated better predictive results compared with simple summary statistics. Furthermore, our results indicate considerable differences in retinal layer structuring based on the severity of DR. We found that: (a) the outer plexiform layer is the most discriminative layer for classifying NoDR vs NPDR; (b) the outer plexiform, inner nuclear and ganglion cell layers are the strongest biomarkers for discriminating controls from NPDR; and (c) the inner nuclear layer distinguishes best between controls and NoDR.

Novel imaging biomarkers in diabetic retinopathy and diabetic macular edema

Diabetic retinopathy is one of the major microvascular complications of diabetes mellitus. The most common causes of vision loss in diabetic retinopathy are diabetic macular edema and proliferative diabetic retinopathy. Recent developments in ocular imaging have played a significant role in early diagnosis and management of these complications. Color fundus photography is an imaging modality, which is helpful for screening patients with diabetic eye disease and monitoring its progression as well as response to treatment. Fundus fluorescein angiography (FFA) is a dye-based invasive test to detect subtle neovascularization, look for areas of capillary non-perfusion, diagnose macular ischemia, and differentiate between focal and diffuse capillary bed leak in cases of macular edema. Recent advances in retinal imaging like the introduction of spectral-domain and swept source-based optical coherence tomography (OCT), fundus autofluorescence (FAF), OCT angiography, and ultrawide field imaging and FFA have helped clinicians in the detection of certain biomarkers that can identify disease at an early stage and predict response to treatment in diabetic macular edema. This article will summarize the role of different imaging biomarkers in characterizing diabetic retinopathy and their potential contribution in its management.

A critical review: Psychophysical assessments of diabetic retinopathy

Diabetic retinal disease remains a leading cause of vision loss despite currently available screening methods, ocular treatments, and efforts to control metabolic dysfunction. It is now understood that diabetes damages the entire retina and the cellular components of the neurovascular unit. Multiple studies have demonstrated impairment of various aspects of retinal function across the spectrum of retinopathy severity. Here we review these tests, the principles underlying their use, clinical data from multiple publications, the strengths and limitations of the studies, and prospects for their application to understand the pathophysiology of diabetic retinal disease and monitor its response to therapy. We focus on visual acuity, contrast sensitivity, color vision, visual field, and dark adaptation and their use to understand the pathophysiology of diabetic retinopathy and as potential endpoints for clinical trials.

Comparison of SDOCT Scan Types for Grading Disorganization of Retinal Inner Layers and Other Morphologic Features of Diabetic Macular Edema

Purpose

To assess grading reproducibility of disorganization of the retinal inner layers (DRIL) and other morphologic features of diabetic macular edema (DME) across spectral domain optical coherence tomography (SDOCT) instruments and scan types.

Methods

A cross-sectional study enrolled participants with current or recent center-involved DME. In group A (27 eyes), we obtained two Cirrus scans (512 × 128 macular cube [Cube] and high-definition five-line raster [HD 5-Line]) and two Spectralis scans (high-resolution [HR] and high-speed [HS]). In group B, 26 eyes underwent HR scans and Optovue AngioVue (OP) 3 × 3-mm scans. All scans were graded for type and extent of DRIL, intraretinal cysts, cone outer segment tip visibility, and subretinal fluid (SRF).

Results

In the total cohort, mean central subfield thickness was 342.9 ± 83.4 µm. Intraclass correlations were high for DRIL extent across the four different imaging settings (HR vs. HS, r = 0.93; HR vs. Cube, r = 0.84, HR vs. HD 5-Line, r = 0.76, HR vs. OP, r = 0.87) and ranged from good to excellent for intraretinal cyst and SRF area. There were significantly smaller mean normalized differences between HR/HS scans versus HR and all other scan modalities (HR/HS vs. HR/Cube, P = 0.02; HR/HD 5-Line, P = 0.0005; HR/OP, P < 0.0001).

Conclusions

Our data suggest that the reproducibility for SDOCT parameters of DRIL and intraretinal cysts was high across all five SDOCT scan types; thus, evaluation of DRIL is feasible using multiple SDOCT models in eyes with DME.

Translational Relevance

DME morphological changes can be evaluated on multiple SDOCT devices with good reproducibility, allowing clinicians and researchers flexibility in DME assessment for clinical care and research.

Clinical-Decision Criteria to Identify Recurrent Diabetic Macular Edema Patients Suitable for Fluocinolone Acetonide Implant Therapy (ILUVIEN®) and Follow-Up Considerations/Recommendations

Current management of diabetic macular edema (DME) predominantly involves treatment with short-acting intravitreal injections of anti-vascular endothelial growth factors (anti-VEGFs) and/or corticosteroids; however, short-acting therapies (lasting between 1 and 6 months) require frequent injections to maintain efficacy, meaning a considerable treatment burden for diabetic patients with multiple comorbidities. Continuous injections needed in some cases are an economic burden for patients/healthcare system, so real-life clinical practice tends to adopt a reactive approach, ie, watch and wait for worsening symptoms, which consequently increases the risk of undertreatment and edema recurrence. On March 7th 2019, a group of experts in retinal medicine and surgery held a roundtable meeting in Madrid, Spain to discuss how to (1) optimize clinical outcomes through earlier use of fluocinolone acetonide (FAc) implant (ILUVIEN^®) in patients with persistent or recurrent DME despite therapy; and, (2) to provide guidance to assist physicians in deciding which patients should be treated with ILUVIEN. In this regard, a 36-month follow-up consensus protocol is presented. In conclusion, patients that achieve a complete or partial anatomical, and preferably functional, response following one or two intravitreal dexamethasone implants, but with recurrence of edema after 3-4 months, are deemed by the authors most likely to benefit from ILUVIEN, and the switch to FAc implant should not be delayed more than 12 months after the initiation of at least the first dexamethasone implant.