Sequential restoration of external limiting membrane and ellipsoid zone after intravitreal anti-VEGF therapy in diabetic macular oedema

Dicer Loss in Müller Glia Leads to a Defined Sequence of Pathological Events Beginning With Cone Dysfunction

Purpose

The loss of Dicer in Müller glia (MG) results in severe photoreceptor degeneration, as it occurs in retinitis pigmentosa or age-related macular degeneration; however, the sequence of events leading to this severe degenerative state is unknown. The aim of this study was to conduct a chronological functional and structural characterization of the pathological events in MG-specific Dicer-conditional knockout (cKO) mice in vivo and histologically.

Methods

To delete Dicer and mature microRNAs (miRNAs) in MG, two conditional Dicer1 knockout mouse strains (Rlbp-CreER:tdTomato:Dicer-cKOMG and Glast-CreER:tdTomato:Dicer-cKOMG) were created. Optical coherence tomography (OCT), electroretinograms (ERGs), and histological analyses were conducted to investigate structural and functional changes up to 6 months after Dicer deletion.

Results

Dicer/miRNA loss in MG leads to (1) impairments of the area spanning from the external limiting membrane (ELM) to the retinal pigment epithelium (RPE), (2) cone photoreceptor dysfunction, and (3) retinal remodeling and functional loss of the inner retina at 1, 3, and 6 months after Dicer loss, respectively, in both of the knockout mouse strains. Furthermore, in the Rlbp-CreER:tdTomato:Dicer-cKOMG strain, rod photoreceptor impairment was found 4 months after Dicer depletion (4) accompanied by alteration of RPE integrity (5).

Conclusions

MG Dicer loss in the adult mouse retina impacts cone function prior to any measurable changes in rod function, suggesting a pivotal role for MG Dicer and miRNAs in supporting cone health. A partially impaired RPE, however, seems to accelerate rod degeneration and overall degenerative events.

Photoreceptor layer elevation due to subretinal fluid: Impact on visual acuity measurements and simulation from biometrics

PURPOSE

Visual acuity (VA) is a primary outcome measure that defines the success of clinical interventions for retinal diseases such as age-related macular degeneration (AMD) or diabetic macular oedema (DME). These conditions can lead to the presence of subretinal fluid, causing substantial photoreceptor layer elevation. Hyperopic defocus then occurs, affecting the VA measurements. In this study, we simulated the induced hyperopic shift for real-world values of photoreceptor layer elevation and measured the effect on VA measurements.

METHODS

To simulate the hyperopic shift, we used a four-surface eye model. To measure the effect of defocus on VA, normally sighted adults (N = 44, mean [SD] age = 32 [13.0] year, range: 21-71 year) performed four test conditions, that is, defocus of 0.00, +0.75, +1.50 and +2.25 D. For each subject, mean VA and SD obtained from a cumulative normal fit to the VA data provided the coefficient of variation (CV) and 95% confidence interval (CI).

RESULTS

Refractive error induced by photoreceptor layer elevation was maximum for hyperopic error conditions, followed by emmetropic and myopic refractive error conditions. The 76% threshold VA worsened with increasing defocus conditions. The 95% CI was significantly larger for +0.75, +1.50 and +2.25 D defocus compared to no defocus (p = 0.04, 0.02 and 0.01, respectively). The CI for the +2.25 D defocus condition was larger (3-10 letters) compared with no defocus (3-6 letters).

CONCLUSIONS

Photoreceptor layer elevation causes a hyperopic shift sufficient for clinically meaningful changes: worse VA and more variable measurements.

Dicer loss in Müller glia leads to a defined sequence of pathological events beginning with cone dysfunction

Purpose

The loss of Dicer in Müller glia (MG) results in severe photoreceptor degeneration as it occurs in retinitis pigmentosa or AMD. However, the sequence of events leading to this severe degenerative state is unknown. The aim of this study was to conduct a chronological functional and structural characterization of the pathological events in MG-specific Dicer-cKO mice in vivo and histologically.

Methods

To delete Dicer and mature microRNAs (miRNAs) in MG, two conditional Dicer1 knock-out mouse strains namely RlbpCre:Dicer-cKO MG and GlastCre:Dicer-cKO MG, were created. Optical coherence tomography (OCT), electroretinograms (ERGs) as well as histological analyses were conducted to investigate structural and functional changes up to six months after Dicer deletion.

Results

Dicer/miRNA loss in MG leads to 1) impairments of the external limiting membrane (ELM) - retinal pigment epithelium (RPE), 2) cone photoreceptor dysfunction and 3) retinal remodeling and functional loss of the inner retina, 1, 3 and 6 months after Dicer loss, respectively, in both strains. Furthermore, in the Rlbp:Dicer-cKO MG strain, rod photoreceptor impairment was found 4 months after Dicer depletion (4) accompanied by alteration of RPE integrity (5).

Conclusions

MG Dicer loss in the adult mouse retina impacts cone function prior to any measurable changes in rod function, suggesting a pivotal role for MG Dicer and miRNAs in supporting cone health. A partially impaired RPE however seems to accelerate rod degeneration and overall degenerative events.

The Ellipsoid Zone Is a Structural Biomarker for Visual Outcomes in Diabetic Macular Edema and Macular Hole Management

OBJECTIVES

The goal was to study the ellipsoid zone (EZ) as a structural biomarker for final visual outcomes after pharmacological intervention in center-involving diabetic macular edema (DME) and surgical intervention for full-thickness macular holes (FTMHs).

METHODS

This was a tertiary care center-based retrospective study. After sample size calculations, data from 64 consecutive cases were collected, with subjects aged between 40 and 60 years. Thirty-two cases of DME with anti-vascular endothelial growth factor (VEGF) therapy and 32 cases of FTMHs with successful macular hole surgery (MHS) were studied. Spectral-domain optical coherence tomography (SD-OCT) data were collected. Measurements of EZ defects documented at the time of presentation and 12 weeks after intervention were analyzed using the caliper function of the machine. EZ restoration was graded, and a Pearson correlation analysis was performed.

RESULTS

Mean logMAR VA decreased after intravitreal therapy (IVT) from 1.12 ± 0.22 pre-intervention to 0.81 ± 0.41 post-intervention and after MHS, from 1.05 + 0.25 to 0.62 + 0.11 (p < 0.001). EZ disruption reduced from 73.4% to 19.4% after IVT and from 67% to 19.3% after MHS. DME and MHS postoperative visual acuity and residual EZ defect were observed to have a statistically significant linear correlation (r = 0.794, p < 0.001 and r = 0.894, p < 0.001, respectively). The EZ was found to be an excellent structural biomarker for final BCVA (area under curve = 0.95 for DME and 1.00 for MHS).

CONCLUSION

Notable EZ restoration results were obtained from pharmacological and surgical interventions. The EZ proves to be a critical structural biomarker for predicting visual outcomes in center-involving DME and MHS.

Retinal photoreceptor ellipsoid zone is a structural biomarker for visual outcome after successful macular hole surgery: A novel grading system-based study

PURPOSE

To develop a novel external limiting membrane (ELM) and ellipsoid zone (EZ) restoration-based grading system after successful macular hole surgery (MHS) and to evaluate EZ as a structural biomarker for the final visual outcome.

METHODS

In a tertiary care center-based retrospective study, 34 consecutive cases of successful MHS for full-thickness macular holes (FTMHs) were included. Spectral domain optical coherence tomography (SD-OCT) cross-sectional analysis was performed on preoperative and postoperative data of weeks 1, 4, 12, and 24, respectively. Sequential measurements of FTMH size, ELM and EZ defect were performed using the caliper function of SD-OCT. MHS was uniquely graded as grade 0: persistence of ELM and EZ defect; grade 1: partial or complete restoration of ELM with shortening of EZ defect; and grade 2: complete restoration of ELM and EZ. Data were statistically analyzed on Statistical Package for the Social Sciences software-version 24.

RESULTS

MHS was graded as grade 0 ( n = 8), grade 1 ( n = 15), and grade 2 ( n = 11). Best corrected visual activity (BCVA) was found to be 1.13 ± 0.19 in grade 0, 0.59 ± 0.09 in grade 1, and 0.26 ± 0.06 in grade 2. One-way analysis of variance showed improvement in final BCVA among the three grades ( P < 0.001) Postoperative visual acuity and residual EZ defect had a statistically significant linear correlation ( r = 0.899, P < 0.001). EZ was found to be an excellent structural biomarker for final BCVA (area under the curve = 0.99).

CONCLUSION

Successful MHS is associated with better visual outcomes in eyes with restored EZ. ELM restoration preceded EZ regeneration. MHS novel grading system is physician friendly, incorporates pathoanatomic aspects, and correlates well with visual outcomes.

Ultrastructural imaging biomarkers in diabetic macular edema: A major review

Diabetic macular edema (DME) is a vision-threatening complication of diabetic retinopathy and causes significant morbidity in patients. Anti-vascular endothelial growth factor (VEGF) agents are the mainstay of treatment for DME, with steroid implants being used for the treatment of anti-VEGF resistant eyes. Over the years, several classification systems have been devised to describe the patterns of DME using optical coherence tomography (OCT). With the advent of effective treatments, it has become imperative that imaging cues are not merely used for classifying the disease but also as biomarkers for prognostication of disease activity and treatment response. In this aspect, newer imaging findings such as hyperreflective dots, photoreceptor integrity, and disorganization of retinal inner layers have been characterized in detail by several authors. Macular perfusion analysis using OCT angiography is the latest in the armamentarium for imaging DME. In this narrative review, we have summarized all relevant literature related to the ultrastructural imaging-based biomarkers of DME and their correlation to treatment.

COMPARISON OF SURGICAL OUTCOMES OF MACULAR TELANGIECTASIA TYPE 2-ASSOCIATED MACULAR HOLE WITH IDIOPATHIC MACULAR HOLE: A Tertiary Center Review

PURPOSE

To assess the longitudinal surgical outcomes of macular telangiectasia Type 2 macular hole (MacTel-MH) and compare them with those of idiopathic MH.

METHODS

This retrospective, single-tertiary center study included patients who underwent MH surgery between January 2015 and September 2023. Patients with characteristic optical coherence tomography findings of MacTel in both eyes or those who underwent fluorescence angiography were classified as having MacTel MH. Baseline and postoperative best-corrected visual acuity and optical coherence tomography parameters were reviewed.

RESULTS

Totally, 27 and 243 eyes with MacTel and idiopathic MH, respectively, were included. Macular hole closure rate was better achieved in idiopathic than in MacTel MH group at two years postoperatively. Temporal recovery of ellipsoid zone and external limiting membrane was more prominent in MacTel than in idiopathic MH group. Statistically significant visual acuity improvement was seen between three months and two years postoperatively in MacTel MH group.

CONCLUSION

To the best of our knowledge, this is the first study to analyze the surgical outcomes of MacTel MH in both anatomical and functional aspects and compare them with patients with idiopathic MH. Postoperative microglia change would have affected the restoration of outer retinal layer of patients; however, further studies are needed for clarification.

Evaluation of Anatomical and Tomographic Biomarkers as Predictive Visual Acuity Factors in Eyes with Retinal Vein Occlusion Treated with Dexamethasone Implant

Background: This prospective study evaluated the impact of anatomical and tomographic biomarkers on clinical outcomes of intravitreal dexamethasone implants in patients with macular edema secondary to retinal vein occlusion (RVO). Methods: The study included 46 patients (28 with branch RVO (BRVO) and 18 with central RVO (CRVO)). Best corrected visual acuity (BCVA) significantly improved from a mean baseline of 0.817 ± 0.220 logMAR to 0.663 ± 0.267 logMAR at six months and 0.639 ± 0.321 logMAR at twelve months (p < 0.05). Central retinal thickness (CRT) showed a significant reduction from 666.2 ± 212.2 µm to 471.1 ± 215.6 µm at six months and 467 ± 175.7 µm at twelve months (p < 0.05). No significant differences were found in OCT biomarkers between baseline and follow-ups. Results: The study analysed improvements in visual acuity relative to baseline biomarkers. At six months, ellipsoid zone disruption (EZD) was significant for all subgroups. Disorganization of retinal inner layers (DRIL), external limiting membrane (ELM) disruption, macular ischemia (MI), CRT, and BRVO showed significance for any improvement, while DRIL and ELM were significant for changes greater than 0.3 logMAR (p < 0.05). At twelve months, EZD remained significant for all subgroups. ELM, MI, CRT, and BRVO were significant for any improvement, while MI and BRVO were significant for changes greater than 0.3 logMAR (p < 0.05). Hyperreflective foci were not statistically significant at either time point (p > 0.05). Conclusions: The regression model suggested that MI and CRVO could be negative predictive factors for visual outcomes, while ELM and EZD were associated with BCVA improvement one-year post-treatment.

OCT Prognostic Biomarkers for Progression to Late Age-related Macular Degeneration: A Systematic Review and Meta-analysis

TOPIC

To evaluate which OCT prognostic biomarkers best predict the risk of progression from early/intermediate to late age-related macular degeneration (AMD).

CLINICAL RELEVANCE

Among > 100 OCT prognostic biomarkers for AMD, it is unclear which are the most relevant for clinicians and researchers to focus on. This review evaluated which OCT biomarkers confer the greatest magnitude of prediction for progression to late AMD.

METHODS

Study protocol was registered on PROSPERO (CRD42023400166). PubMed and Embase were searched from inception to March 2, 2023, and eligible studies assessed following the Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) approach. The primary outcome was any quantified risk of progression from treatment-naive early/intermediate AMD to late AMD, including hazard ratios (HRs), odds ratios (ORs), and standardized mean differences (at baseline, between eyes with versus without progression), subgrouped by each OCT biomarker. Further meta-analyses were subgrouped by progression to geographic atrophy or neovascularization.

RESULTS

A total of 114 quantified OCT prognostic biomarkers were identified. With high GRADE certainty of evidence, the greatest magnitudes of prediction to late AMD belonged to: external limiting membrane abnormality (OR, 15.42 [7.63, 31.17]), ellipsoid zone abnormality (OR, 10.8 [4.58, 25.46]), interdigitation zone abnormality (OR, 7.68 [2.57, 23]), concurrent large drusen and reticular pseudodrusen (HR, 6.73 [1.35, 33.65], hyporeflective drusen cores (HR, 2.48 [1.8, 3.4]; OR 1.85 [1.29, 2.66]), intraretinal hyperreflective foci (IHRF; HR, 2.16 [0.92, 5.07]; OR 5.08 [3.26, 7.92]), and large drusen (HR, 2.01 [1.35, 2.99]); OR, 1.98 [1.27, 3.08]). There was greater risk of geographic atrophy for IHRF and hyporeflective drusen cores (P < 0.05), and neovascularization for ellipsoid zone abnormality (P < 0.05). Other OCT biomarkers such as drusenoid pigment epithelium detachment, shallow irregular retinal pigment epithelium elevations, and nascent geographic atrophy exhibited large magnitudes of risk but required further studies for validation.

CONCLUSION

This review synthesizes the 6 most relevant OCT prognostic biomarkers for AMD with greater predictive ability than large drusen alone, for clinicians and researchers to focus on. Further study is required to validate other biomarkers with less than high certainty of evidence, and assess how the copresence of biomarkers may affect risks.

FINANCIAL DISCLOSURE(S)

The author(s) have no proprietary or commercial interest in any materials discussed in this article.

Optical coherence tomography biomarkers DROL, PROS, SND, hyperreflective walls of foveal cystoid spaces as predictors of central macular thickness and visual acuity in diabetic macular edema treated with intravitreal ranibizumab

PURPOSE

This study aims to establish DROL (disruption of retinal outer layers), PROS (photoreceptor outer segment length), SND (subfoveal neuroretinal detachment), and hyperreflective walls of foveal cystoid spaces (HRW) as optical coherence tomography (OCT) biomarkers and predictors of central macular thickness (CMT) and visual acuity in diabetic macular edema (DME) treated with intravitreal ranibizumab (IVR).

METHODS

In this prospective, interventional study performed at a tertiary care center over a span of 1 year from December 2021 to December 2022, 50 eyes of 46 patients of DME were included. Visual acuity and spectral domain OCT imaging were performed at baseline. Using inbuilt calipers on SD-OCT, the horizontal extent of DROL and the vertical extent of PROS were measured manually. SND and HRW were assessed qualitatively. IVR was administered and patients were followed up at 4, 8, and 12 weeks.

RESULTS

The eyes without DROL had statistically significant (P < 0.05) lesser CMT and better BCVA (best-corrected visual acuity) (P < 0.05) after pro re nata injection of IVR. There was a positive correlation between the extent of baseline DROL with final CMT (P < 0.05) and final logMAR BCVA (P > 0.05), whereas negative correlation with the extent of baseline PROS with final CMT (P < 0.05) and final logMAR BCVA (P > 0.05). The presence of HRW and SND predicted non-resolution of CMT and worse visual acuity after treatment with IVR in DME.

CONCLUSION

DROL, PROS, SND, and hyperreflective walls of foveal cystoid spaces may be utilized as qualitative as well as quantitative biomarkers to predict the post-treatment CMT and visual acuity in DME.

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.

Classification of diabetic maculopathy based on optical coherence tomography images using a Vision Transformer model

PURPOSE

To develop a Vision Transformer model to detect different stages of diabetic maculopathy (DM) based on optical coherence tomography (OCT) images.

METHODS

After removing images with poor quality, a total of 3319 OCT images were extracted from the Eye Center of the Renmin Hospital of Wuhan University and randomly split the images into training and validation sets in a 7:3 ratio. All macular cross-sectional scan OCT images were collected retrospectively from the eyes of DM patients from 2016 to 2022. One of the OCT stages of DM, including early diabetic macular oedema (DME), advanced DME, severe DME and atrophic maculopathy, was labelled on the collected images, respectively. A deep learning (DL) model based on Vision Transformer was trained to detect four OCT grading of DM.

RESULTS

The model proposed in our paper can provide an impressive detection performance. We achieved an accuracy of 82.00%, an F1 score of 83.11%, an area under the receiver operating characteristic curve (AUC) of 0.96. The AUC for the detection of four OCT grading (ie, early DME, advanced DME, severe DME and atrophic maculopathy) was 0.96, 0.95, 0.87 and 0.98, respectively, with an accuracy of 90.87%, 89.96%, 94.42% and 95.13%, respectively, a precision of 88.46%, 80.31%, 89.42% and 87.74%, respectively, a sensitivity of 87.03%, 88.18%, 63.39% and 89.42%, respectively, a specificity of 93.02%, 90.72%, 98.40% and 96.66%, respectively and an F1 score of 87.74%, 84.06%, 88.18% and 88.57%, respectively.

CONCLUSION

Our DL model based on Vision Transformer demonstrated a relatively high accuracy in the detection of OCT grading of DM, which can help with patients in a preliminary screening to identify groups with serious conditions. These patients need a further test for an accurate diagnosis, and a timely treatment to obtain a good visual prognosis. These results emphasised the potential of artificial intelligence in assisting clinicians in developing therapeutic strategies with DM in the future.

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.].

Predictive effect of TCED-HFV grading and imaging biomarkers on anti-VEGF therapy in diabetic macular edema

BACKGROUND

To evaluate the predictive effect of TCED-HFV grading and imaging biomarkers on anti-vascular endothelial growth factor (anti-VEGF) treatment in diabetic macular edema (DME).

METHODS

81 eyes of 81 DME patients who were treated with anti-VEGF were included in this retrospective cohort study. All patients underwent a comprehensive ophthalmic examination at baseline and follow-up, including best-corrected visual acuity (BCVA), fundus photography, and spectral domain-optical coherence tomography (SD-OCT). Baseline imaging biomarkers were qualitatively and quantitatively graded according to the TCED-HFV classification protocol, and DME was divided into early stage, advanced stage, severe stage, and atrophy stage.

RESULTS

Six months post treatment, central subfield thickness (CST) in 49 eyes (60.5%) had decreased by 10% from baseline, 30 eyes (37.0%) had achieved CST < 300 μm, and 45 eyes (55.6%) had BCVA improved by more than five letters. Multivariate regression analysis revealed that eyes with baseline CST ≥ 390 μm had a higher probability of ≥ 10% reduction in CST from baseline, and eyes with abundant hyperreflective dots (HRD) had a lower probability of 10% reduction in CST (all P < 0.05). Eyes with vitreomacular traction (VMT) or epiretinal membrane (ERM) at baseline were less likely to reach the end point of CST < 300 μm (P < 0.05). BCVA increases of more than five letters were less likely in eyes with baseline BCVA ≥ 69 letters, complete or partial destruction of ellipsoid zone (EZ) at baseline (all P < 0.05). TCED-HFV staging was negatively correlated with BCVA at both baseline and 6 months (Kendall's tau-b=-0.39 and - 0.55, all P < 0.01). TCED-HFV staging was positively correlated with CST at 6 months (Kendall's tau-b = 0.19, P = 0.049) and negatively correlated with the reduction of CST (Kendall's tau-b=-0.32, P < 0.01).

CONCLUSION

The TCED-HFV grading protocol facilitates a comprehensive assessment of DME severity, standardizes the grading of multiple imaging biomarkers, and predicts the anatomical and functional outcomes of anti-VEGF treatment.

OCT-based biomarkers for predicting treatment response in eyes with centre-involved diabetic macular oedema treated with anti-VEGF injections: a real-life retina clinic-based study

BACKGROUND/AIMS

To determine whether a combination of baseline and change in spectral domain-optical coherence tomography (SD-OCT)-based biomarkers can predict visual outcomes in eyes with diabetic macular oedema (DMO) treated with antivascular endothelial growth factors (VEGF) injections.

METHODS

This is a retrospective cohort study conducted in Hong Kong, China. 196 eyes with centre-involving DMO, who received anti-VEGF injections between 1 January 2011 and 30 June 2018 were recruited. Medical records of the participants were retrieved retrospectively, visual acuity (VA) at baseline, 6, 12 and 24 months and SD-OCT before initiation and after completion of anti-VEGF treatment were obtained. The SD-OCT images were evaluated for the morphology of DMO, vitreomacular status, presence of disorganisation of retinal inner layers (DRIL), sizes of intraretinal cysts, visibility of external limiting membrane (ELM), ellipsoid zone (EZ) and cone outer segment tip (COST) and the presence of hyper-reflective foci in retina or the choroid.

RESULTS

The presence of baseline DRIL, hyper-reflective foci in retina and disruption of ELM/EZ and COST were associated with worse baseline and subsequent VA up to 24 months after treatment. Improvement in DRIL (p=0.048), ELM/EZ (p=0.001) and COST (p=0.002) disruption after treatment was associated with greater improvement in VA at 12 months. Eyes with cystoid macular oedema (p=0.003, OR=8.18) and serous retinal detachment (p=0.011, OR=4.84) morphology were more likely to achieve at least 20% reduction in central subfield thickness.

CONCLUSION AND RELEVANCE

Baseline SD-OCT biomarkers and their subsequent change predict VA and improvement in vision in eyes with DMO treated with anti-VEGF injections. We proposed an SD-OCT-based system that can be readily used in real-life eye clinics to improve decision making in the management of DMO.

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

OBJECTIVE

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

MATERIAL AND METHODS

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

RESULTS

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

CONCLUSIONS

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

Retinal Morphologic Features in Patients with Large Macular Holes Treated by Autologous Neurosensory Retinal Transplantation

PURPOSE

To investigate the time courses of morphologic changes in the transplanted grafts, including the retinal layer, the ellipsoid zone (EZ) and the visual acuity (VA) after autologous retinal transplantation (ART) in patients with primary large macular holes (MHs).

DESIGN

Single-center, retrospective cohort study.

SUBJECTS

The study included 17 eyes of 17 patients who had undergone ART. All patients fulfilled the following criteria: (1) MH was the only disease-causing anatomic abnormality of the macula; (2) they could be followed up for at least 12 months after ART surgery; (3) they had no other systemic disorders; and (4) the MH was > 400 μm in diameter.

METHODS

Data of all patients who underwent assessment of the VA and spectral-domain (SD)-OCT at 1, 3, 6, and 12 months after surgery were analyzed. The morphologic features of the graft and the EZ were measured by SD-OCT.

MAIN OUTCOME MEASURES

Changes in the morphologic features of the graft (graft thickness, overall graft area, graft length, area of outer retina, and EZ) and VA over 1 year after surgery.

RESULTS

Closure of the MH was achieved in all patients. The VA was 0.59 ± 0.27 (logarithm of the minimal angle of resolution units) at 1-year postsurgery compared with 0.84 ± 0.22 before surgery (P < 0.05). The retinal layers gradually became smoothly connected. Although a decrease in graft thickness and overall graft area was observed, the length and area of the outer retina were maintained throughout the follow-up period. The presence of the EZ was observed in 9 patients (52.9%) and our analyses revealed significantly greater improvement of VA in these patients than in those without the EZ (P < 0.05). Moreover, the incidence of macular edema (ME) was higher in the group without the EZ (P = 0.04; chi-square test).

CONCLUSION

Patients showed significant improvements of the VA. Morphologically, the layers were gradually connected to each other, and the outer retina was particularly maintained. Especially, patients in whom an EZ was restored in the graft showed a low prevalence of ME and greater improvement of the VA.

FINANCIAL DISCLOSURE(S)

The author(s) have no proprietary or commercial interest in any materials discussed in this article.

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.

External Limiting Membrane, Photoreceptor Ellipsoid Zone Disruption, and Retinal Pigment Epithelium Alterations in Diabetic Retinopathy

Objective Diabetic retinopathy (DR), a microvascular complication of diabetes, is a leading cause of preventable blindness. Spectral domain optical coherence tomography (SD-OCT) provides cross-sectional and topographical imaging of the retina. SD-OCT resolves outer retinal layers into three hyperreflective bands—external limiting membrane (ELM), ellipsoid zone (EZ), and retinal pigment epithelium (RPE). In this article, we have studied the role of these outer retinal layers in structural and molecular changes taking place in DR.

Materials and Methods Articles with clinical features, pathogenesis, diagnosis, and treatment of DR were thoroughly studied. Articles were searched on PubMed, MEDLINE, and Cochrane Library from 2000 to 2020. Studies focusing on the role of ELM, EZ, and RPE in pathogenesis of DR based on SD-OCT were included.

Results The long-standing hyperglycemia leads to protein glycosylation resulting in formation of advanced glycation end products (AGEs). AGEs have an impact through their effect on retinal microvasculature, vascular endothelial growth factor (VEGF), intercellular adhesion molecule-1, nitrosative and oxidative stress, and vitamin D and calcium metabolism. All these factors have been linked with disruption of outer retinal layers. AGEs lead to vascular endothelial dysfunction and release of proangiogenic factors by increasing the expression of VEGF in retinal pericytes and RPE cells. This leads to leakage and fluid accumulation resulting in diabetic macular edema (DME). In DME, there is sequential disruption of ELM and EZ and decrease in visual acuity (VA). The RPE alterations have been reported to be associated with the severity of DR and decrease in VA. Anti-VEGF therapy, most common treatment of DME, leads to restoration of barrier effect of ELM, it was found to be restored first followed by EZ restoration. Newer anti-AGEs agents and their receptor blockers are being developed which have a positive effect on maintaining the health of RPE.

Conclusion A complex molecular association exists between the structural changes in ELM, EZ, and RPE in DR. SD-OCT is an indispensable tool to study these changes as integrity of these outer layers of retina is essential for maintaining visual function of retina in DR.

Semi-Automated Quantification of Retinal and Choroidal Biomarkers in Retinal Vascular Diseases: Agreement of Spectral-Domain Optical Coherence Tomography with and without Enhanced Depth Imaging Mode

BACKGROUND

We compared with and without enhanced depth imaging mode (EDI) in semi-automated quantification of retinal and choroidal biomarkers in optical coherence tomography (OCT) in patients with diabetic retinopathy (DR) or retinal vein occlusion (RVO) complicated by macular edema. We chose to study three OCT biomarkers: the numbers of hyperreflective foci (HF), the ellipsoid zone reflectivity ratio (EZR) and the choroidal vascularity index (CVI), all known to be correlated with visual acuity changes or treatment outcomes.

METHODS

In a single examination, one eye of each patient (n = 60; diabetic retinopathy: n = 27, retinal vein occlusion: n = 33) underwent macular 870 nm spectral domain-OCT (SD-OCT) B-scans without and with EDI mode. Semi-automated quantification of HF, EZR and CVI was applied according to preexisting published protocols. Paired Student's t-test or Wilcoxon rank-sum test was used to test for differences in subgroups. Intraclass correlation coefficient (ICC) and Bland-Altman plots were applied to describe the agreement between quantification in EDI and conventional OCT mode. The effect of macular edema on semi-automated quantification was evaluated.

RESULTS

For the entire cohort, quantification of all three biomarkers was not significantly different in SD-OCT scans with and without EDI mode (p > 0.05). ICC was 0.78, 0.90 and 0.80 for HF, EZR and CVI. The presence of macular edema led to significant differences in the quantification of hyperreflective foci (without EDI: 80.00 ± 33.70, with EDI: 92.08 ± 38.11; mean difference: 12.09, p = 0.03), but not in the quantification of EZR and CVI (p > 0.05).

CONCLUSION

Quantification of EZR and CVI was comparable whether or not EDI mode was used. In conclusion, both retinal and choroidal biomarkers can be quantified from one single 870 nm SD-OCT EDI image.

[Treatment response to Conbercept of different types of diabetic macular edema classified based on optical coherence tomography]

OBJECTIVE

To compare different types of diabetic macular edema (DME) classified based on optical coherence tomography (OCT) for their responses to Conbercept injection and analyze the factors that affect the treatment responses.

METHODS

We retrospectively analyzed the clinical data of 65 patients (76 eyes) with DME diagnosed and treated with intravitreal injection of Conbercept (1+PRN) in our hospital from February, 2019 to February, 2021. According to OCT findings, DME in these patients was classified into cystic macular edema (CME; 28 eyes), serous retinal detachment (SRD; 33 eyes), and diffuse retinal thickening (DRT; 15 eyes). The best corrected visual acuity (BCVA) and central retinal thickness (CRT) were measured before and at 3 months after the first treatment. The baseline OCT characteristics of different types of DME were compared, and the correlation of these OCT characteristics with the treatment response to Conbercept was analyzed.

RESULTS

All the patients showed significant improvement of the BCVA 3 months after the treatment (P < 0.05). For all the 3 types of DME, the CRT at 3 months after the first treatment was significantly reduced as compared to the baseline (P < 0.05). The number of hyperreflective foci (HF) in the outer retina and the proportion of ellipsoid zone (EZ) interruption were the greatest in SRD group (P < 0.05). The baseline outer retinal HF was significantly correlated with the baseline CRT, CRT changes and CRT after treatment (all P < 0.05). The patients with baseline outer limiting membrane (ELM)/ EZ disruption had poorer baseline BCVA, greater baseline CRT, greater variation of CRT and poorer BCVA at 3 months after treatment (all P < 0.05).

CONCLUSION

For all the 3 types of DME, treatment with intravitreal injection of Conbercept can significantly improve the BCVA and CRT of the patients. DME of the SRD type has the best morphological response to Conbercept, while the DRT type has a relatively poor response. A greater number of HF at baseline may indicate a better morphological response to Conbercept treatment, and baseline ELM/EZ disruption may suggest a poor visual prognosis at 3 months after treatment.

Ellipsoid Zone Integrity and Visual Acuity Changes during Diabetic Macular Edema Therapy: A Longitudinal Study

PURPOSE

Ellipsoid zone (EZ) integrity is identified as a potential biomarker for therapy surveillance and outcome prediction of visual acuity (VA). However, only a few studies report long-term results of over 1 year of clinical and anatomical changes in patients with diabetic macular edema (DME). This study is aimed at describing the long-term VA and anatomical outcomes in spectral domain optical coherence tomography (OCT) (relative ellipsoid zone reflectivity ratio, central macular thickness, and volume) in patients with DME treated with antivascular endothelial growth factor (anti-VEGF) therapy. Furthermore, we studied the correlation between EZ integrity and changes in visual acuity.

METHODS

71 eyes of 71 patients were included in this retrospective study. Clinical characteristics were reviewed yearly. OCT data were assessed at baseline and after 1, 3, and 5 years. EZ parameters were quantified automatically. OCT parameters and visual outcome were correlated and analyzed in multivariable regression models.

RESULTS

EZ reflectivity ratio correlated with functional outcome in DME patients from baseline to fifth year at all time points (for all p < 0.05). EZ reflectivity improved the most in the first year of treatment (0.68 to 0.75; p < 0.05) and declined gradually until year 5 of therapy (0.71; compared to baseline p > 0.05). Similarly, best VA was achieved after 1 year (0.40 logarithm of the minimum angle of resolution (logMAR) to 0.28 logMAR; p < 0.001) and declined gradually until year 5. Final VA in year 5 was comparable to baseline (0.45 logMAR, compared to baseline p > 0.05). Together with baseline VA, baseline EZ parameters did predict VA outcome after 1 year (p < 0.05). Concordantly, VA and EZ parameters from year 1 were associated with VA outcome in year 2.

CONCLUSION

This study described the long-term course of EZ changes during anti-VEGF treatment in DME patients. In addition, our results underlined the potential of EZ parameters as novel OCT biomarkers for prediction of VA outcomes during therapy.

Challenges in Diabetic Macular Edema Management: An Expert Consensus Report

Purpose

This paper aimed to present daily-practice recommendations for the management of diabetic macular edema (DME) patients based on available scientific evidence and the clinical experience of the consensus panel.

Methods

A group of Spanish retina experts agreed to discuss different aspects related with the clinical management of DME patients.

Results

Panel was mainly focused on therapeutic objectives in DME management; definition terms; and role of biomarkers as prognostic and predictive factors to intravitreal treatment response. The panel recommends to start DME treatment as soon as possible in those eyes with a visual acuity less than 20/25 (always according to the retina unit capacity). Naïve patient was defined, in a strict manner, as a patient who, up to that moment, had never received any treatment. A refractory DME patient may be defined as the one who did not achieve a complete resolution of the disease, regardless of the treatment administered. Different optical coherence tomography biomarkers, such as disorganization of the retinal inner layers, hyperreflective dots, and cysts, have been identified as prognostic factors.

Conclusion

This document has sought to lay down a set of recommendations and to identify key issues that may be useful for the daily management of DME patients.

External limiting membrane and ellipsoid zone structural integrity in diabetic macular edema

The external limiting membrane (ELM) and ellipsoid zone (EZ) can be observed exquisitely by SD-OCT. In diabetic macular edema (DME), dysfunction of mitochondria, represented by the EZ in the foveal photoreceptors results in reduced visual acuity (VA). An increase in VEGF was found to correlate with increased severity of DR, increased central subfield thickness (CST), and sequential disruption of ELM and EZ. The mechanism of ELM and EZ restoration after anti-VEGF therapy in DME has been discovered. The ELM restores first followed by EZ restoration. Thus, authors have discovered and established ELM as a novel retinal structural barrier.

Interpretation of anatomic correlates of outer retinal bands in optical coherence tomography

By providing the sectioning capability to differentiate individual retinal layers, optical coherence tomography (OCT) is revolutionizing eye disease diagnosis and treatment evaluation. A better understanding of the hyper- and hypo-reflective bands in retinal OCT is essential for accurate interpretation of clinical outcomes. In this article, we summarize the interpretations of clinical OCT and adaptive optics (AO) OCT (AO-OCT) of the outer retina in the human eye, and briefly review OCT investigation of the outer retina in animal models. Quantitative analysis of outer retinal OCT bands is compared to established parameters of retinal histology. The literature review and comparative analysis support that both inner/outer segment (IS/OS) junction and IS ellipsoid zone nonexclusively contribute to the second band; and OS, OS tips, and retinal pigment epithelium apical processes contribute to the third band in conventional OCT. In contrast, AO-OCT might predominantly detect the IS/OS junction and OS tip signals at the second and third bands due to its improved sectioning capability and possible AO effect on the sensitivities for recording ballistic and diffusive photons from different regions of the outer retina.

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.

Factors associated with 1-year visual response following intravitreal bevacizumab treatment for diabetic macular edema: a retrospective single center study

Background

To explore the association of clinical characteristics and retinal microstructural features on optical coherence tomography in predicting 1-year visual response following intravitreal bevacizumab injections in eyes with visual impairment from center-involved diabetic macular edema (CI-DME).

Methods

Medical records of patients with visual impairment from CI-DME, who initiated intravitreal bevacizumab injections between Jan 2012 and Dec 2016 and were followed for a minimum of 12 months were retrospectively reviewed.

Results

The study included 226 eyes with a mean (SD) baseline visual acuity (VA) of 51.8 (19.1) letters. At week 12, following the three initial treatments, a mean (SD) VA improved to 61.7 (17.8) letters. Visual gain ≥ 10 letters was observed in 109 eyes (48.2%), while a limited early visual gain < 5 letters was noted in 80 eyes (35.4%). At one year, 110 eyes (48.7%) achieved a good VA gain ≥ 10 letters. In addition, eyes with poor baseline VA had a higher proportion of eyes that obtained limited early VA gained at week 12 (< 5 letters) and maintained in this visual response category at moth 12 compared to eyes with better baseline VA (74.1% versus 59.1%). In the multivariable logistic regression, the following factors reduced the probability of 1-year visual gain ≥ 10 letters: elderly (p = 0.040), better baseline vision (p = 0.001), and limited early visual gain < 5 letters at week 12 (p < 0.001). In multivariable linear regression, male (p = 0.010) and eyes with the presence of hyperreflective foci on baseline OCT (p = 0.010) were likely to have higher VA improvement. However, eyes with better baseline VA (p = 0.002), limited early VA gain at week 12 (p < 0.001), and a presence of EZ disruption at week 12 (p = 0.002) were likely to have less VA improvement.

Conclusions

Although bevacizumab is considered as effective management for CI-DME, variability in treatment responses is expected. This study revealed that baseline characteristics and visual responses at week 12 might help predict the long-term treatment response. Eyes with characteristics at risk of limited long-term visual outcome may require attention in optimizing their individual treatment strategies.

External limiting membrane: retinal structural barrier in diabetic macular edema

Advances in spectral-domain optical coherence tomography (SD-OCT) technology have enhanced the understanding of external limiting membrane (ELM) and ellipsoid zone (EZ) in diabetic macular edema. An increase in VEGF has been demonstrated to be associated with sequential ELM and EZ disruption on SD-OCT. An intact ELM is a prerequisite for an intact EZ in DME. Anti-VEGF therapy leads to restoration of barrier effect of ELM. The ELM restores first followed by EZ restoration.

Effect of Dexamethasone Intravitreal Implant on Visual Acuity and Foveal Photoreceptor Integrity in Macular Edema Secondary to Retinal Vascular Disease

PURPOSE

The aim of this study was to evaluate the effect of the dexamethasone intravitreal (DEX) implant on the external limiting membrane (ELM) and ellipsoid zone (EZ) integrity in treatment-naïve patients with macular edema (ME) secondary to retinal vascular disease (RVD).

METHODS

This is a retrospective study conducted on patients with ME secondary to RVD, who underwent a DEX implant.

RESULTS

One-hundred eyes were included. Mean age was 70.3 ± 11.1 years. Mean ELM integrity significantly improved from 1,575.9 ± 285.9 μm at baseline to 1,711.7 ± 244.0 μm at month 3 (p < 0.0001). Similarly, there was a significant improvement in EZ integrity from baseline to month 3 (1,531.5 ± 317.1 vs. 1,694.3 ± 252.8 μm, respectively, p < 0.0001). At month 3, mean visual acuity (VA) gain was 9.9 ± 14.1 letters (p < 0.0001). Mean central retinal thickness (CRT) significantly decreased by -193.2 ± 185.7 μm from baseline to month 3 (p < 0.0001). Mean changes in VA and CRT were significantly correlated with baseline ELM integrity (p = 0.0065 and p = 0.0046, respectively) and EZ integrity (p = 0.0300 and p = 0.0035, respectively). At month 3, the proportion of eyes which had an intact ELM (mean difference 16.0%, 95% CI 5.4-26.4%, p = 0.0033) and EZ (mean difference 12.0%, 95% CI 1.8-22.1%, p = 0.0210) was significantly higher than at baseline.

CONCLUSIONS

DEX implant was able to significantly improve ELM and EZ integrity in naïve patients with ME.