Diabetic Macular Edema: Pathophysiology and Novel Therapeutic Targets

Hyperreflective foci in OCT image as a biomarker of poor prognosis in diabetic macular edema patients treating with Conbercept in China

Purpose

To investigate the dynamic changes of hyperreflective foci (HF) in diabetic macular edema (DME) patients during the intravitreal Conbercept treatment in China.

Methods

DME Patients receiving intravitreal Conbercept (IVC) injections during the year 2016–2017 were retrospectively investigated. Thirteen patients (26 eyes) were recruited in this study. They received IVC once a month for 3 consecutive months. The number and location of HFs, the best-corrected visual acuity (BCVA) and central macular thickness (CMT) at each visit were analyzed and compared.

Results

After the first injection, BCVA (LogMAR) was increased from 0.75 ± 0.48 to 0.43 ± 0.24 (p < 0.05), CMT improved from 575.9 ± 191.9 to 388.2 ± 198.5 μm (p = 0.014). However, the BCVA and CMT had no statistical difference after the second and third injection as compared with those after the first injection respectively. The baseline number of HFs was 5.39 ± 4.24, 5.15 ± 5.17 and 0.88 ± 1.90 in the inner retinal, outer retinal and subretinal layer respectively. The number of HFs in these three retinal layers decreased significantly after the first injection (p = 0.0045, p < 0.0001 and p = 0.0045, respectively). However, after the second injection, only the number of HFs in the inner retinal layer experienced a further decrease. After the third injection, no statistically significant HFs changes was observed in each retinal layers. Correlation analysis showed that there was a positive significant correlation between the baseline number of HFs in the inner retina, outer retina, subretina and final BCVA (r = 0.571, p = 0.002; r = 0.464, p = 0.017; r = 0.405, p = 0.04 respectively). There was also a significant positive correlation between outer retinal HFs reduction, total retinal HFs reduction and increase of BCVA (r = 0.40, p = 0.043 and r = 0.393, p = 0.04 respectively).

There were no severe ocular adverse reactions or systemic adverse events.

Conclusions

Conbercept is effective and safe in the treatment of DME. HFs can act as a biomarker of poor final visual outcome.

Insights into the pathogenesis of cystoid macular edema: leukostasis and related cytokines

Cystoid macular edema (CME) is the abnormal collection of intraretinal fluid in the macular region, especially in the inner nuclear and outer plexiform layers. CME leads to severe visual impairment in patients with various retinal diseases, such as diabetic retinopathy, retinal vascular occlusion, choroidal neovascularization, and uveitis. Although various retinal conditions lead to CME, a shared pathogenesis of CME is involved in these diseases. Accordingly, the pathogenesis of CME based on vasogenic mechanisms is first discussed in this review, including vascular hyperpermeability, leukostasis, and inflammation. We then describe cytotoxic mechanisms based on retinal Müller cell dysfunction. This comprehensive review will provide an understanding of the pathogenesis of CME for potential therapeutic strategies.

New Lipid Mediators in Retinal Angiogenesis and Retinopathy

Retinal diseases associated with vascular destabilization and the inappropriate proliferation of retinal endothelial cells have major consequences on the retinal vascular network. In extreme cases, the development of hypoxia, the upregulation of growth factors, and the hyper-proliferation of unstable capillaries can result in bleeding and vision loss. While anti-vascular endothelial growth factor therapy and laser retinal photocoagulation can be used to treat the symptoms of late stage disease, there is currently no treatment available that can prevent disease progression. Cytochrome P450 enzymes metabolize endogenous substrates (polyunsaturated fatty acids) to bioactive fatty acid epoxides that demonstrate biological activity with generally protective/anti-inflammatory and insulin-sensitizing effects. These epoxides are further metabolized by the soluble epoxide hydrolase (sEH) to fatty acid diols, high concentrations of which have vascular destabilizing effects. Recent studies have identified increased sEH expression and activity and the subsequent generation of the docosahexaenoic acid-derived diol; 19,20-dihydroxydocosapentaenoic acid, as playing a major role in the development of diabetic retinopathy. This review summarizes current understanding of the roles of cytochrome P450 enzyme and sEH–derived PUFA mediators in retinal disease.

The role of inflammation in diabetic eye disease

Mounting evidence suggests that immunological mechanisms play a fundamental role in the pathogenesis of diabetic retinopathy (DR) and diabetic macular edema (DME). Upregulation of cytokines and other proinflammatory mediators leading to persistent low-grade inflammation is believed to actively contribute to the DR-associated damage to the retinal vasculature, inducing breakdown of the blood-retinal barrier, subsequent macular edema formation, and promotion of retinal neovascularization. This review summarizes the current knowledge of the biological processes providing an inflammatory basis for DR and DME. In addition, emerging therapeutic approaches targeting inflammation are discussed, including blockade of angiopoietin 2 and other molecular targets such as interleukin (IL)-6, IL-1β, plasma kallikrein, and integrins.

ACUTE PSEUDOPHAKIC CYSTOID MACULAR EDEMA IMAGED BY OPTICAL COHERENCE TOMOGRAPHY ANGIOGRAPHY

PURPOSE

To study macular capillary changes and vessel density in acute pseudophakic cystoid macular edema (PCME) before and after treatment using optical coherence tomography angiography.

METHODS

Retrospective observational case-control study of seven consecutive patients (eight eyes) with PCME and eight age-matched control eyes imaged with optical coherence tomography angiography (RTVue XR Avanti; Optovue, Inc, Fremont, CA) using Projection Removal Artifacts software. Vessel density was calculated.

RESULTS

The mean time to diagnosis of PCME was 2.3 ± 0.9 months after surgery. At initial examination, the superficial capillary plexus pattern was near-normal in all PCME eyes, although it was attenuated in the deep capillary plexus. The mean vessel density of the superficial capillary plexus in PCME eyes was slightly but significantly lower than in control eyes (47.8 ± 3.8% vs. 52.9 ± 4.0%, P = 0.01), the difference being greater in the deep capillary plexus (44.1 ± 7.4% vs. 54.2 ± 3.2%, P = 0.007). After resolution of the edema, the deep capillary plexus completely recovered its normal pattern and the vessel density in both plexuses was no longer different from that observed in control eyes.

CONCLUSION

Macular vessel density after resolution of an acute PCME did not differ from that of normal control eyes in both the superficial capillary plexus and deep capillary plexus, unlike macular edema in retinal vaso-occlusive diseases.

Dexamethasone for unresponsive diabetic macular oedema: optical coherence tomography biomarkers

PURPOSE

To analyse the effects of intravitreal dexamethasone implant (DEX) in patients with diabetic macular oedema (DME) unresponsive to ranibizumab treatment, in relation to the inflammatory optical coherence tomography (OCT) retinal features, subfoveal neuroretinal detachment (SND) and hyperreflective retinal spots (HRS).

METHODS

Patients with DME poorly responsive to three injections of ranibizumab were treated with DEX. Best-corrected visual acuity (BCVA) and central macula thickness (CMT, measured by Spectralis SD-OCT) were assessed at baseline and at 1, 3, and 6 months.

RESULTS

Overall, 44 eyes were included in the study. In the whole group, mean BCVA (baseline 51.5 ± 8.3 letters) increased significantly at 1 month (to 56.9 ± 8.8 letters; Tukey HSD p = 0.017) and was 55.5 ± 8.8 letters at 3 months (Tukey HSD p = 0.128). Central macula thickness (CMT) reduced significantly at 1 and 3 months (417 ± 149 μm and 469 ± 128 μm, respectively, both Tukey HSD p < 0.001 versus baseline). Subgroup analysis showed a significant BCVA increase at 1 month in eyes with SND + HRS (from 51.2 ± 9.2 to 58.2 ± 9.0, p = 0.029), and a trend to BCVA increase in eyes with HRS (from 52.3 ± 6.4 to 56.8 ± 7.9, p = 0.080), with a significant CMT decrease in both groups (p < 0.001). No changes of either parameter were found in eyes without SND and HRS.

CONCLUSION

Spectral domain OCT is useful in identifying some inflammatory features in DME. Among DME eyes 'poorly responsive' to ranibizumab, those with SND and HRS responded better to DEX implants than those without these features.

Correlation of retinal layer changes with vision gain in diabetic macular edema during conbercept treatment

Backgrounds

To assess the changes in individual retinal layer thickness and visual function associated with gains in visual acuity after an intravitreal conbercept injection in the diabetic macular edema (DME) on spectral domain optical coherence tomography (SD-OCT) and microperimetry during 1-year follow-up.

Methods

Retrospective observational study. Twenty patients with clinically significant DME in the study eye were imaged by SD-OCT every 3 months and MP1 microperimeter in the third month while receiving anti-vascular endothelial growth factor (VEGF) (conbercept) treatment. In each patient, seven retinal layers were segmented in 98 scans covering a 6 mm × 6 mm area of the macula at baseline and during 1 year of treatment. An automatic, full-threshold microperimetry of the central field (10° × 10°, 40 stimulated points) with the MP1 microperimeter. Thickness and microperimetry changes were quantitatively measured and evaluated for their correlation with increases in visual acuity.

Results

Although thicknesses of the inner nuclear layer (INL) and the outer nuclear layer (ONL) were reduced the most after treatment (p < 0.05), decreases of the ganglion cell layer (GCL) (r = 0.591, p = 0.006) and inner plexiform layer (IPL) (r = 0.663, p = 0.001) in central subfield area was associated with best-corrected visual acuity (BCVA) gain, and had the best estimation of BCVA gain (adjust R² = 0.544). Mean macular sensitivity in the central subfield was also well correlated with BCVA gain (r = 0.531, p = 0.016).

Conclusions

Neural recovery occurred after the resolution of edema during conbercept treatment, due to the decreases in GCL and IPL associating with gains in vision and improved microperimetry.

Electronic supplementary material

The online version of this article (10.1186/s12886-019-1131-0) contains supplementary material, which is available to authorized users.

Organ-On-A-Chip Technologies for Advanced Blood-Retinal Barrier Models

The blood-retinal barrier (BRB) protects the retina by maintaining an adequate microenvironment for neuronal function. Alterations of the junctional complex of the BRB and consequent BRB breakdown in disease contribute to a loss of neuronal signaling and vision loss. As new therapeutics are being developed to prevent or restore barrier function, it is critical to implement physiologically relevant in vitro models that recapitulate the important features of barrier biology to improve disease modeling, target validation, and toxicity assessment. New directions in organ-on-a-chip technology are enabling more sophisticated 3-dimensional models with flow, multicellularity, and control over microenvironmental properties. By capturing additional biological complexity, organs-on-chip can help approach actual tissue organization and function and offer additional tools to model and study disease compared with traditional 2-dimensional cell culture. This review describes the current state of barrier biology and barrier function in ocular diseases, describes recent advances in organ-on-a-chip design for modeling the BRB, and discusses the potential of such models for ophthalmic drug discovery and development.

Peripapillary Microvascular and Neural Changes in Diabetes Mellitus: An OCT-Angiography Study

Purpose

To evaluate peripapillary vessel density and morphology in patients with diabetes mellitus (DM) without clinical signs of diabetic retinopathy (DR) and with mild, nonproliferative DR and to correlate with peripapillary nerve fiber layer (NFL) thickness.

Methods

One hundred seventeen eyes (34 healthy controls, 54 patients with DM without DR [noDR group] and 24 patients with mild DR [DR group]) were prospectively evaluated. All subjects underwent peripapillary and macular optical coherence tomography angiography (OCT-A). Peripapillary NFL thickness was also recorded. OCT-A slab of radial peripapillary plexus (RPC) and macular superficial capillary plexus (SCP) were analysed in order to calculate perfusion density (PD) and vessel density (VD). Further an image analysis of RPC slab was performed to identify number of branches (NoB) and total branches length (tBL).

Results

In peripapillary area there was a significant decrease in VD (P = 0.003), NoB (P < 0.001), and tBL (P < 0.001) in noDR group versus controls; PD values were not different among groups (P = 0.126); there was a significant decrease in average NFL thickness in DR versus controls (P = 0.008) and in the inferior quadrant in noDR group versus controls (P = 0.03); there was a significant correlation between OCT-A and NFL thickness values (ρ ranging from 0.19-0.57). In macular region PD and VD were decreased only in DR group (P < 0.05).

Conclusions

There are early changes in the peripapillary vessel morphology and VD of the RPC in patients with DM without DR that correlate to NFL thinning. Earlier changes in superficial vessel density are documented in the peripapillary than in the macular region. These data may confirm a coexistence of an early neuronal and microvascular damage in patients with DM without clinical signs of DR.

Macular thickness amplitude changes when switching from discontinuous to continuous therapy for diabetic macular oedema

OBJECTIVE

To investigate if the mean central retinal thickness (CRT) amplitude, measured between visits, is consistently decreased when switching from discontinuous to continuous therapy for diabetic macular oedema (DME) following fluocinolone acetonide (FAc) administration.

METHODS AND ANALYSIS

In this retrospective cohort study, all patients with DME treated with FAc at a single centre were included. The primary outcome was CRT amplitude changes measured at each visit prior to and after FAc administration. Secondary outcomes included average number of DME treatments before and after FAc injection, visual acuity and intraocular pressure changes.

RESULTS

Nineteen eyes were included. The mean (SD) follow-up after FAc was 399 (222) days. The mean (SD) CRT amplitude before FAc was 194.6 (114.90) µm, and following FAc administration, the amplitude decreased to 70.8 (94.23) µm (95% CI -189.5 to -58.1; p≤0.001). After FAc, the number of treatments required per month significantly decreased from an average of 1 treatment every 2.7 months to every 6 months (p=0.009).

CONCLUSION

In patients with DME, the CRT amplitude values and number of treatments significantly decrease following FAc administration while maintaining vision. Further studies are needed to evaluate the significance of these interesting findings.

Single Retinal Layer Changes After Subthreshold Micropulse Yellow Laser in Diabetic Macular Edema

A pilot prospective, interventional study has been conducted on 10 patients with diabetic macular edema (DME) treated with subthreshold micropulse laser (SMPL) to evaluate changes of individual retinal layers and to correlate with functional changes. All patients underwent complete ophthalmologic evaluation including spectral-domain optical coherence tomography (OCT) and microperimetry at baseline, 3 months, 6 months, 9 months, and 12 months. Compared with baseline, a significant decrease was found in inner nuclear layer (INL) and outer retinal layer (ORL) thickness in the central 1 mm (P < .05). Increase in best-corrected visual acuity was significantly and inversely correlated to central retinal thickness (CRT) (P = .0027), INL (P = .0167), and outer nuclear layer (ONL) thickness (P = .0107). Increase in retinal sensitivity was significantly and inversely correlated to CRT and ONL thickness (P < .01). Therefore, SMPL showed to improve firstly functional parameters and then morphologic parameters. Functional parameters were inversely correlated to CRT, INL, and ONL thickness. The exact mechanism of reduction of INL thickness induced by SMPL remains to be further evaluated. [Ophthalmic Surg Lasers Imaging Retina. 2018;49:e218-e225.].

Indocyanine green angiography-guided focal navigated laser photocoagulation for diabetic macular edema

PURPOSE

To evaluate the efficacy of indocyanine-green angiography (ICGA)-guided navigated focal laser photocoagulation for diabetic macular edema (DME).

STUDY DESIGN

Prospective, interventional case series.

METHODS

Six patients (8 eyes) were enrolled in this study. Fluorescein angiography (FA) and ICGA were performed using the Heidelberg Retina Angiogram 2 (Heidelberg Engineering). Navigated focal laser photocoagulation was delivered to the microaneurysms on ICGA using Navilas^® (OD-OS GmbH, Germany). Central retinal thickness (CRT) and macular volume (MV) were measured by Cirrus HD-OCT (Carl Zeiss Meditec). At 6 months, the best-corrected visual acuity (BCVA), CRT and MV were compared to the values measured on day 0. The distances from the center of fovea to the closest microaneurysms (MAs) were measured on the pre-planned Navilas^® image.

RESULTS

All eyes had previous treatment history. At 6 months, ICGA-guided navigated focal laser photocoagulation significantly reduced the CRT and the MV (p<0.05), and there was improvement in the BCVA (p<0.05). At 3 months, 5 out of the 8 eyes (63%) underwent additional ICGA-guided navigated focal laser photocoagulation due to remnants of MAs that had been confirmed by ICGA. There was no observed recurrence of edema after the ICGA-guided navigated focal laser photocoagulation during the 6-month follow-up. The mean distance from the center of fovea to the closest MAs was 624.8 ± 377.7 μm (range 336.0-1438.9 μm).

CONCLUSION

Our data suggest ICGA-guided navigated focal laser photocoagulation may be effective for the treatment of DME.

Retinal Microvasculature and Visual Acuity after Intravitreal Aflibercept in Diabetic Macular Edema: An Optical Coherence Tomography Angiography Study

We investigated changes in retinal vascular area and the foveal avascular zone (FAZ) after intravitreal aflibercept in diabetic macular edema (DME) and the association of these changes with visual outcomes. The retinal vascular area in the superficial capillary plexus (SCP) and the deep capillary plexus (DCP) and the FAZ area were measured using optical coherence tomography angiography (OCTA) in 23 eyes of 23 patients with DME, before and after intravitreal aflibercept. Overall, there was no significant change in retinal vascular area or FAZ. Better BCVA after treatment was significantly associated with larger retinal vascular area in the SCP and the DCP, both at baseline (R² = 0.512, P < 0.001 and R² = 0.361, P = 0.002, respectively) and after intravitreal aflibercept (R² = 0.717, P < 0.001 and R² = 0.618, P < 0.001, respectively). MAs were observed in the DCP in 20 eyes (87%), but only detected in four eyes (17%) in the SCP before treatment. The number of eyes with MAs in the DCP significantly decreased to 13 (57%) after treatment (P = 0.049). The persistence of DME was associated with persistent MAs (P = 0.019) and less visual gain (P = 0.031) following treatment. Thus, preserving retinal perfusion and the resolution of MAs are associated with better vision and resolution of the DME after intravitreal aflibercept.

Intravitreal dexamethasone implant Ozurdex® in naïve and refractory patients with different subtypes of diabetic macular edema

Background

Diabetic macular edema (DME) can be treated with different alternatives, among them Dexamethasone intravitreal implant 0.7 mg (DEX 0.7) has demonstrated that may improve both central macular thickness (CMT) and best corrected visual acuity (BCVA). This study aimed to evaluate the effect of the intravitreal dexamethasone implant Ozurdex® in patients with different subtypes of diabetic macular edema over a 6-month follow-up period.

Methods

Eighty-four (29 naïve and 55 previously treated) eyes were included in this retrospective study. For each patient, the BCVA [Early Treatment Diabetic Retinopathy Study (ETDRS) charts] and macular thickness on optical coherence tomography (OCT) at baseline visit and within the 2nd, 4th, and 6th months of follow-up were obtained. The main outcomes measurements were the mean change in BCVA and in CMT with respect to the baseline value. The percentage of patients gaining ≥5 letters and ≥ 10 letters in BCVA was also analyzed. Results: A total of 84 eyes, 29 (34.5%) naïve and 55 (65.5%) non-naïve, from 69 patients were included in the study. BCVA at baseline was 58.8 (16.4) and 61.8 (11.6) in naïve and refractory patients, respectively, p = 0.4513. At every visit, BCVA significantly improved from baseline in naïve and non-naïve eyes (p < 0.0001 and p = 0.0003, respectively; Friedman rank sum test). At baseline, the mean CMT was 466.2 (189.7) μm and 448.1 (110.7) μm in the naïve and non-naïve patients, respectively (p = 0.5830); and decreased to 339.3 (92.5) μm and 357.5 (79.1) μm, respectively (p = 0.0004 and p < 0.0001, respectively, Wilcoxon signed-rank test). The proportion of patients gaining ≥10 letters was significantly greater in the naïve group, p = 0.0199.

Conclusion

The intravitreal dexamethasone implant (Ozurdex) is effective for the treatment of diabetic macular edema, even in refractory cases that have failed to respond to previous therapies.

Flavin Imbalance as an Important Player in Diabetic Retinopathy

The retina and RPE together constitute the most metabolically active ecosystem in the body, harboring high levels of flavins. Although diabetic patients have been reported to suffer from riboflavin deficiency and use of flavins as nutritional interventions to combat diabetic insult on other tissues have been investigated, such attempts have never been tested for the retina to avoid diabetic retinopathy. Furthermore, the role of flavins in pathophysiology of the retina and RPE has mostly been overlooked. Herein, we review the impact of flavins on various clinical manifestations of diabetic retinopathy and discuss possible ways to address them.

Intravitreal fluocinolone acetonide implant (ILUVIEN®) for diabetic macular oedema: a literature review

Diabetic macular oedema (DMO) is a common complication of diabetic retinopathy and may lead to severe visual loss. In this review, we describe the pathophysiology of DMO and review current therapeutic options such as macular laser photocoagulation, anti-vascular endothelial growth factor agents, and steroid implants with a focus on the new fluocinolone acetonide implant, ILUVIEN®. The results of the Fluocinolone Acetonide in Diabetic Macular Edema (FAME) studies are also presented together with the results of real-world studies to support the clinical use of ILUVIEN® in achieving efficient resolution of DMO and improving vision and macular anatomy in this challenging group of patients.

Glucose-regulated protein 78 in the aqueous humor in diabetic macular edema patients

In this study, we explored the presence and elevation of glucose-regulated protein 78 (GRP78) in aqueous humor of patients with diabetic macular edema (DME).After comparing DME patients with the controls, we analyzed GRP78 and vascular endothelial growth factor (VEGF) levels in DME patients. We examined factors associated with GRP78 levels in DME patients.GRP78 was detected in aqueous humor with elevated levels in DME patients. Stepwise backward regression analysis showed that GRP78 levels were associated with the VEGF levels and the duration of diabetes (P < .001 and P = .002, respectively). However, no statistical significance was observed between GRP78 levels and the decrease in CST following 3 monthly anti-VEGF treatments in univariate regression analysis (P = .695).We showed that GRP78 is elevated in DME patients. In addition, there is a correlation between GRP78 and VEGF levels in aqueous humor. However, GRP78 levels were not associated with the responsiveness of anti-VEGF in DME patients.

Vitreous and intraretinal macular changes in diabetic macular edema with and without tractional components

Diabetic macular edema (DME) is still one of the main causes of visual impairment. Repeated intravitreal injections of ranibizumab are considered the gold standard treatment, but the efficacy in patients with prominent cystic characteristics remains uncertain. In diabetic retinas, the identification of both antero-posterior and, particularly, tangential tractions is crucial to prevent misdiagnosis of tractional and refractory DME, and therefore to prevent poor treatment outcomes. The treatment of tractional DME with anti-VEGF injections could be poorly effective due to the influence of a tractional force. Pars plana vitrectomy (PPV) is a surgical procedure that has been widely used in the treatment of diffuse and refractory DME. Anatomical improvement, although stable and immediate, did not result in visual improvement. PPV with internal limiting membrane (ILM) peeling for the treatment of non-tractional DME in patients with prominent cysts (> 390 μm) causes subfoveal atrophy, defined as "floor effect". Epiretinal tangential forces and intraretinal change evaluation by SD-OCT of non-tractional DME are essential for determining appropriate management.

It Takes Two: Endothelial-Perivascular Cell Cross-Talk in Vascular Development and Disease

The formation of new blood vessels is a crucial step in the development of any new tissue both during embryogenesis and in vitro models as without sufficient perfusion the tissue will be unable to grow beyond the size where nutrition and oxygenation can be managed by diffusion alone. Endothelial cells are the primary building block of blood vessels and are capable of forming tube like structures independently however they are unable to independently form functional vasculature which is capable of conducting blood flow. This requires support from other structures including supporting perivascular cells and the extracellular matrix. The crosstalk between endothelial cells and perivascular cells is vital in regulating vasculogenesis and angiogenesis and the consequences when this is disrupted can be seen in a variety of congenital and acquired disease states. This review details the mechanisms of vasculogenesis in vivo during embryogenesis and compares this to currently employed in vitro techniques. It also highlights clinical consequences of defects in the endothelial cell-pericyte cross-talk and highlights therapies which are being developed to target this pathway. Improving the understanding of the intricacies of endothelial-pericyte signaling will inform pathophysiology of multiple vascular diseases and allow the development of effective in vitro models to guide drug development and assist with approaches in tissue engineering to develop functional vasculature for regenerative medicine applications.

Evaluation of markers of outcome in real-world treatment of diabetic macular edema

Objective

To evaluate short-term markers of outcome in diabetic macular edema (DME).

Methods

Prospective interventional case series included 122 eyes of 122 patients with recently diagnosed DME. Eyes were treated with a 3-monthly loading dose of ranibizumab or aflibercept and pro re nata thereafter. Serial enhanced deep imaging SD-OCT high resolution scans were used to measure subfoveal choroidal thickness (SFCT) and central retinal thickness (CRT). Anatomic (10% CRT decrease) and functional responses (best corrected visual acuity, BCVA gain ≥5 letters) were assessed at 3 months and 6 months using univariate and multivariate analyses. Parameters tested were gender, duration of diabetes, HbA1c, hypertension, CRT, SFCT, BCVA, ellipsoid zone (EZ) status, subfoveal neuroretinal detachment (SND), anti-VEGF used and laser naivety. A logistic regression model was applied to find independent markers outcome.

Results

BCVA increased, CRT and SFCT decreased at 3 months and 6 months. Good metabolic control (p = 0.003), intact baseline EZ (p = 0.030), EZ re-grading at 3 M (p < 0.001) and laser naivety (p = 0.001) were associated with better functional outcome. The multivariate linear regression model showed that baseline SND and CRT are predictors of anatomic response, while lower baseline BCVA and intact EZ are predictors of functional response.

Conclusion

The presence of SND predicts anatomic response only, while an intact EZ is critical to achieve a good functional outcome in DME.

Electronic supplementary material

The online version of this article (10.1186/s40662-018-0119-9) contains supplementary material, which is available to authorized users.

Long-term efficacy and duration of action of dexamethasone implant, in vitrectomised and non-vitrectomised eyes with persistent diabetic macular oedema

PURPOSE

To evaluate the efficacy and duration of action of an intravitreal (dexamethasone (Ozurdex)) implant in vitrectomised and non-vitrectomised eyes with persistent diabetic macular oedema (DMO).

METHODS

We retrospectively analysed the records for 18 eyes that had or had not been vitrectomised but required an intravitreal dexamethasone implant for DMO after a poor response to anti-vascular endothelial growth factor. Optical coherence tomography and visual acuity (VA) examinations were performed before and 1, 3 and 6 months after implantation. The six months following implantation constituted one treatment round; up to three rounds were studied.

RESULTS

Ten of 18 eyes had undergone vitrectomy. Best-corrected visual acuity (BCVA) and central macular thickness (CMT) were significantly improved by months 1-3 after implantation of the Ozurdex device in all rounds of treatment. The BCVA and CMT deteriorated gradually after month 3 through to month 6 post implantation. There were no statistically significant differences between the vitrectomised and non-vitrectomised groups at any time point. When the implantation interval was <6 weeks from the end of each treatment round, the improvement in BCVA and CMT was obvious even after 18 months of treatment.

CONCLUSIONS

Vitrectomy did not have a negative effect on the duration of action or efficacy of the Ozurdex implant in patients with persistent DMO. The implant started working from the first month after implantation regardless of whether vitrectomy had or had not been performed. The maximum functional and anatomic improvement was achieved in the first 3 months post implantation in all treatment rounds.

Pathophysiology of Diabetic Retinopathy: The Old and the New

Vision loss in diabetic retinopathy (DR) is ascribed primarily to retinal vascular abnormalities-including hyperpermeability, hypoperfusion, and neoangiogenesis-that eventually lead to anatomical and functional alterations in retinal neurons and glial cells. Recent advances in retinal imaging systems using optical coherence tomography technologies and pharmacological treatments using anti-vascular endothelial growth factor drugs and corticosteroids have revolutionized the clinical management of DR. However, the cellular and molecular mechanisms underlying the pathophysiology of DR are not fully determined, largely because hyperglycemic animal models only reproduce limited aspects of subclinical and early DR. Conversely, non-diabetic mouse models that represent the hallmark vascular disorders in DR, such as pericyte deficiency and retinal ischemia, have provided clues toward an understanding of the sequential events that are responsible for vision-impairing conditions. In this review, we summarize the clinical manifestations and treatment modalities of DR, discuss current and emerging concepts with regard to the pathophysiology of DR, and introduce perspectives on the development of new drugs, emphasizing the breakdown of the blood-retina barrier and retinal neovascularization.

Comparison of the effect of ranibizumab and dexamethasone implant on serous retinal detachment in diabetic macular edema

PURPOSE

To compare the efficacy of intravitreal ranibizumab (IVR) and intravitreal dexamethasone implant (IDI) on neurosensory retinal detachment (SRD) associated with diabetic macular edema (DME) in the early treatment period.

METHODS

This was a retrospective, interventional, case-control study. After three monthly loading doses of IVR or an initial IDI injection, the changes in best-corrected visual acuity (BCVA), central macular thickness (CMT) on OCT, and presence and height of SRD were evaluated.

RESULTS

The IVR and IDI groups consisted of 101 and 35 eyes, respectively. The mean changes in CMT in the IVR and IDI groups were 204.4±176.6 and 311.4±163, respectively (P<0.001). The mean changes in SRD height in the IVR and IDI groups were 133.6±92.1 and 168.6±103.9μm, respectively. The decrease in SRD height was significantly greater in the IDI group than in the IVR group (P=0.002). The SRD resolved completely in 72.2% and 71.4% of the patients in the IVR and IDI groups, respectively (P=0.9).

CONCLUSION

The mean reduction in CMT and SRD height was greater in the IDI group than in the IVR group. There was a negative correlation between baseline best-corrected visual acuity (BCVA) and SRD height and also between BCVA and CMT.

Aqueous humor cytokine levels in patients with diabetic macular edema refractory to anti-VEGF treatment

PURPOSE

To determine aqueous cytokines association with response to intravitreal bevacizumab (IVB) injection in diabetic macular edema (DME).

METHOD

We compared the concentrations of IL (interleukin)-1β, IL-2, IL-8, IL-10, IL-17, placental growth factor (PlGF), and vascular endothelial growth factor (VEGF) in the aqueous humor of 64 naïve DME patients with those of 13 cataract patients. Factors associated with central subfield thickness (CST) in DME patients were identified. DME patients were then subgrouped in terms of responsiveness to three IVB injections; cytokine concentrations were compared, and factors associated with responsiveness were identified.

RESULTS

Levels of IL-2, IL-8, PlGF, and VEGF were significantly elevated in DME patients (p = 0.007, p < 0.001, p < 0.001, and p = 0.004 respectively). Regression analysis showed that the preoperative CST was associated with the preoperative best-corrected visual acuity and the aqueous IL-10 level (p < 0.001, p = 0.006, respectively). Of the 64 DME patients, 28 (43.75%) exhibited either CST < 300 μm or reduction in CST ≥ 50 μm after three consecutive IVB injections. On sub-group analysis, the mean IL-8 concentration was higher in the refractory group than in the responsive group, and multivariate logistic regression analysis showed that the IL-8 was the only factor associated with responsiveness (OR = 0.95, p = 0.017).

CONCLUSIONS

The IL-8 concentration in the aqueous humor was associated with responsiveness to IVB in DME patients.

Investigating the Fractal Dimension of the Foveal Microvasculature in Relation to the Morphology of the Foveal Avascular Zone and to the Macular Circulation in Patients With Type 2 Diabetes Mellitus

In this study, we examined the relationship between the fractal dimension (FD), the morphology of the foveal avascular zone (FAZ) and the macular circulation in healthy controls and patients with type 2 diabetes mellitus (T2DM) with and with no diabetic retinopathy (DR). Cross-sectional data of 47 subjects were analyzed from a 5-year longitudinal study using a multimodal optical imaging approach. Healthy eyes from nondiabetic volunteers (n = 12) were selected as controls. Eyes from patients with T2DM were selected and divided into two groups: diabetic subjects with mild DR (MDR group, n = 15) and subjects with DM but without DR (DM group, n = 20). Our results demonstrated a higher FD in the healthy group (mean, 1.42 ± 0.03) than in the DM and MDR groups (1.39 ± 0.02 and 1.35 ± 0.03, respectively). Also, a bigger perimeter, area, and roundness of the FAZ were found in MDR eyes. A significant difference in area and perimeter (p ≤ 0.005) was observed for the MDR group supporting the enlargement of the FAZ due to diabetic complications in the eye. A moderate positive correlation (p = 0.014, R² = 43.8%) between the FD and blood flow rate (BFR) was only found in the healthy control group. The BFR calculations revealed the lowest values in the MDR group (0.98 ± 0.27 μl/s vs. 1.36 ± 0.86 μl/s and 1.36 ± 0.57 μl/sec in the MDR, DM, and healthy groups, respectively, p = 0.2). Our study suggests that the FD of the foveal vessel arborization could provide useful information to identify early morphological changes in the retina of patients with T2DM. Our results also indicate that the enlargement and asymmetry of the FAZ might be related to a lower BFR because of the DR onset and progression. Interestingly, due to the lack of FAZ symmetry observed in the DM and MDR eyes, it appears that the distribution of flow within the retinal vessels loses complexity as the vascular structures distributing the flow are not well described by fractal branching. Further research could determine how our approach may be used to aid the diagnosis of retinal neurodegeneration and vascular impairment at the early stage of DR.

Intravitreal pro-inflammatory cytokines in non-obese diabetic mice: Modelling signs of diabetic retinopathy

Diabetic retinopathy is a vascular disease of the retina characterised by hyperglycaemic and inflammatory processes. Most animal models of diabetic retinopathy are hyperglycaemia-only models that do not account for the significant role that inflammation plays in the development of the disease. In the present study, we present data on the establishment of a new animal model of diabetic retinopathy that incorporates both hyperglycaemia and inflammation. We hypothesized that inflammation may trigger and worsen the development of diabetic retinopathy in a hyperglycaemic environment. Pro-inflammatory cytokines, IL-1β and TNF-α, were therefore injected into the vitreous of non-obese diabetic (NOD) mice. CD1 mice were used as same genetic background controls. Fundus and optical coherence tomography images were obtained before (day 0) as well as on days 2 and 7 after intravitreal cytokine injection to assess vessel dilation and beading, retinal and vitreous hyper-reflective foci and retinal thickness. Astrogliosis and microgliosis were assessed using immunohistochemistry. Results showed that intravitreal cytokines induced vessel dilation, beading, severe vitreous hyper-reflective foci, retinal oedema, increased astrogliosis and microglia upregulation in diabetic NOD mice. Intravitreal injection of inflammatory cytokines into the eyes of diabetic mice therefore appears to provide a new model of diabetic retinopathy that could be used for the study of disease progression and treatment strategies.

Shall we stay, or shall we switch? Continued anti-VEGF therapy versus early switch to dexamethasone implant in refractory diabetic macular edema

AIMS

To compare functional and anatomical outcomes of continued anti-vascular endothelial growth factor (VEGF) therapy versus dexamethasone (DEX) implant in eyes with refractory diabetic macular edema (DME) after three initial anti-VEGF injections in a real-world setting.

METHODS

To be included in this retrospective multicenter, case-control study, eyes were required: (1) to present with early refractory DME, as defined by visual acuity (VA) gain ≤ 5 letters or reduction in central subfield thickness (CST) ≤ 20%, after a loading phase of anti-VEGF therapy (three monthly injections) and (2) to treat further with (a) anti-VEGF therapy or (b) DEX implant. Main outcome measures were change in visual acuity (VA) and central subfield thickness (CST) at 12 months. Due to imbalanced baseline characteristics, a matched anti-VEGF group was formed by only keeping eyes with similar baseline characteristics as those in the DEX group.

RESULTS

A total of 110 eyes from 105 patients were included (anti-VEGF group: 72 eyes, DEX group: 38 eyes). Mean change in VA at 12 months was - 0.4 ± 10.8 letters (anti-VEGF group), and + 6.1 ± 10.6 letters (DEX group) (P = 0.004). Over the same period, mean change in CST was + 18.3 ± 145.9 µm (anti-VEGF group) and - 92.8 ± 173.6 µm (DEX group) (P < 0.001). Eyes in the DEX group were more likely to gain ≥ 10 letters (OR 3.71, 95% CI 1.19-11.61, P = 0.024) at month 12.

CONCLUSIONS

In a real-world setting, eyes with DME considered refractory to anti-VEGF therapy after three monthly injections which were switched to DEX implant and had better visual and anatomical outcomes at 12 months than those that continued treatment with anti-VEGF therapy.

Protective effects of a novel drug RC28-E blocking both VEGF and FGF2 on early diabetic rat retina

AIM

To investigate protective effects of a novel recombinant decoy receptor drug RC28-E on retinal damage in early diabetic rats.

METHODS

The streptozotocin (STZ)-induced diabetic rats were randomly divided into 6 groups: diabetes mellitus (DM) group (saline, 3 µL/eye); RC28-E at low (0.33 µg/µL, 3 µL), medium (1 µg/µL, 3 µL), and high (3 µg/µL, 3 µL) dose groups; vascular endothelial growth factor (VEGF) Trap group (1 µg/µL, 3 µL); fibroblast growth factor (FGF) Trap group (1 µg/µL, 3 µL). Normal control group was included. At week 1 and 4 following diabetic induction, the rats were intravitreally injected with the corresponding solutions. At week 6 following the induction, apoptosis in retinal vessels was detected by TUNEL staining. Glial fibrillary acidic protein (GFAP) expression was examined by immunofluorescence. Blood-retinal barrier (BRB) breakdown was assessed by Evans blue assay. Ultrastructural changes in choroidal and retinal vessels were analyzed by transmission electron microscopy (TEM). Content of VEGF and FGF proteins in retina was measured by enzyme linked immunosorbent assay (ELISA). The retinal expression of intercellular cell adhesion molecule-1 (ICAM-1), tumor necrosis factor-α (TNF-α), VEGF and FGF genes was examined by quantitative polymerase chain reaction (qPCR).

RESULTS

TUNEL staining showed that the aberrantly increased apoptotic cells death in diabetic retinal vascular network was significantly reduced by treatments of medium and high dose RC28-E, VEGF Trap, and FGF Trap (all P<0.05), the effects of medium and high dose RC28-E or FGF Trap were greater than VEGF Trap (P<0.01). GFAP staining suggested that reactive gliosis was substantially inhibited in all RC28-E and VEGF Trap groups, but the inhibition in FGF Trap group was not as prominent. Evans blue assay demonstrated that only high dose RC28-E could significantly reduce vascular leakage in early diabetic retina (P<0.01). TEM revealed that the ultrastructures in choroidal and retinal vessels were damaged in early diabetic retina, which was ameliorated to differential extents by each drug. The expression of VEGF and FGF2 proteins was significantly upregulated in early diabetic retina, and normalized by RC28-E at all dosages and by the corresponding Traps. The upregulation of ICAM-1 and TNF-α in diabetic retina was substantially suppressed by RC28-E and positive control drugs.

CONCLUSION

Dual blockade of VEGF and FGF2 by RC28-E generates remarkable protective effects, including anti-apoptosis, anti-gliosis, anti-leakage, and improving ultrastructures and proinflammatory microenvironment, in early diabetic retina, thereby supporting further development of RC28-E into a novel and effective drug to diabetic retinopathy (DR).

Evaluation of Navigated Laser Photocoagulation (Navilas 577+) for the Treatment of Refractory Diabetic Macular Edema

Purpose

To evaluate navigated laser photocoagulation for the treatment of refractory diabetic macular edema (DME).

Methods

Retrospective study of 25 eyes (21 patients) treated with Navilas 577+ focal laser system. Best-corrected visual acuity (BCVA) and spectral-domain optical coherence tomography (OCT) parameters were measured at baseline, 1, 3, and 6 months, and final visit.

Results

The mean follow-up period was 12.8 ± 2.4 (7–16 months). All subjects had history of previous treatment which was injection of triamcinolone acetonide or antivascular endothelial growth factor (VEGF) agents. The navigated laser photocoagulation was delivered to the microaneurysms on indocyanine green angiography (ICGA) in 21 of 25 eyes (84%), fluorescein angiography (FA) guided in 3 eyes, and OCT angiography guided in 1 eye. After initial navigated laser treatment, 16 of 25 eyes (64%) were needed additional navigated laser photocoagulation, injection of triamcinolone acetonide, and/or injection of VEGF agents. Although median BCVA remained stable, the central retinal thickness and macular volume were significantly decreased over 6 months (p < 0.05). All patients were treated without complications.

Conclusions

Focal photocoagulation using Navilas 577+ showed to be effective in treating DME with improvement in macular edema on OCT over 6 months. Navilas 577+ was beneficial to perform navigated laser photocoagulation based on three modalities (ICGA, FA, and OCT angiography).

Subthreshold micropulse laser reduces anti-VEGF injection burden in patients with diabetic macular edema

PURPOSE

To evaluate the efficacy of micropulse laser in the early treatment of diabetic macular edema (DME) and its associated burden of anti-vascular endothelial growth factor (VEGF) injections.

METHODS

This retrospective comparative study compared a group of 19 eyes with DME treated with micropulse laser to a matched control group of 19 eyes with DME treated with ranibizumab injections without micropulse laser. Recorded parameters included previous medical and ocular history, previous and subsequent ranibizumab injections administered for DME, visual acuity (VA), central macular thickness throughout the follow-up period, and the occurrence of any complications.

RESULTS

The improvement in VA was comparable in both groups, at 12 months and at the final follow-up. Patients treated with micropulse laser required significantly fewer ranibizumab injections than their controls, both at 12 months (1.7 ± 2.3 vs 5.6 ± 2.1) and by the end of the follow-up (2.6 ± 3.3 vs 9.3 ± 5.1) (p<0.001 for both). No complications related to the micropulse laser were encountered.

CONCLUSIONS

Micropulse laser is a safe and effective treatment for DME, which may achieve comparable improvement in VA along with a significant reduction in the burden of anti-VEGF injections. We suggest a treatment approach for its inclusion in the early stages of DME.

Clinical Decision-Making when Treating Diabetic Macular Edema Patients with Dexamethasone Intravitreal Implants

Diabetes mellitus (DM) is a metabolic disease frequently associated with comorbidities that include diabetic macular edema (DME). The current medical approach to treating DME involves intravitreal injections with either anti-vascular endothelial growth factors or steroids. However, the burden associated with intravitreal injections and DM-derived complications is high, underlining the need to find optimal treatment regimens. In this article we describe the considerations we apply when treating DME patients with dexamethasone intravitreal implants (Ozurdex®), particularly those that influence the clinical decision-making process during the follow-up period. These considerations are based both on the available medical literature and on our clinical experience following the use of these implants in this type of patient, the goal being to optimize the number of injections and the clinical outcome of this therapy. We also provide a general overview of the pathophysiology of DME, highlighting the inflammatory component as a rationale to use steroids in these patients.

Observation of neovascularization of the disc associated with proliferative diabetic retinopathy using OCT angiography

PURPOSE

To describe the relationship between the vitreous and the neovascularization of the disc (NVD) using swept source optical coherence tomography (SS-OCT) and OCT angiography (OCTA).

STUDY DESIGN

Retrospective.

METHODS

We examined 17 eyes of 11 consecutive patients diagnosed as NVD associated with proliferative diabetic retinopathy (PDR). The location of the NVD feeder or collector vessels were examined by using RTVue XR Avanti. To determine the condition of the posterior vitreous detachment (PVD) and the proliferative tissue of the NVD, we performed 12 mm horizontal and vertical scans through the disc using SS-OCT.

RESULTS

OCT images of all 17 cases indicated there was no PVD on the optic disc. OCTA showed that the locations of the newly formed vessels from the optic disc were overwhelmingly outside the physiological cupping (95%). No cases exhibited formation of neovascularization inside the physiological cupping. OCT images revealed all 17 eyes had proliferative tissues located under the posterior wall of the vitreous, with 12 out of 17 eyes exhibiting additional invasion of the proliferative tissue into the vitreous through the posterior wall. Epiretinal membrane or a thickened posterior wall of the vitreous was present in 10 out of the 17 eyes.

CONCLUSIONS

NVD associated with PDR arises from outside the physiological cupping and grows along the posterior wall of the vitreous. The absence of PVD on the optic disc is essential to the growth of NVD.

Retinal Vascular and Neural Remodeling Secondary to Optic Nerve Axonal Degeneration: A Study Using OCT Angiography

PURPOSE

To investigate the pathophysiologic interrelations between retinal neural and vascular changes, detected by spectral-domain OCT (SD-OCT) and OCT angiography (OCTA), resulting from optic nerve axonal degeneration.

DESIGN

Institutional, observational, case-control study with prospective enrollment.

PARTICIPANTS

Twenty-six patients affected by optic nerve axonal degeneration secondary to posterior optic pathway glioma (OPG) involving the chiasma, the postchiasmatic visual pathway, or both (but not involving optic nerves) and 24 gender- and age-matched healthy participants were included consecutively.

METHODS

Best-corrected visual acuity (Early Treatment Diabetic Retinopathy Study score) was measured and SD-OCT (Heidelberg Engineering, Heidelberg, Germany) and OCTA (Nidek RS-3000 Advance device; Nidek, Gamagori, Japan) were performed.

MAIN OUTCOME MEASURES

Peripapillary retinal nerve fiber layer (pRNFL), macular ganglion cell complex (GCC), and inner nuclear layer (INL) were analyzed using SD-OCT. The radial peripapillary capillary plexus, full-thickness peripapillary retina vascularization, and the macular superficial plexus (SCP) and deep capillary plexus (DCP) were analyzed using OCTA.

RESULTS

Peripapillary retinal nerve fiber layer and GCC thickness were reduced in eyes affected by OPG (P < 0.0001). Radial peripapillary capillary plexus perfusion also was reduced, as well as full-thickness peripapillary retina vascularization (P < 0.01 and P < 0.05, respectively). Macular DCP perfusion was reduced in eyes affected by OPG, whereas macular SCP perfusion did not differ between the 2 groups (P < 0.05 and P > 0.05, respectively). Global pRNFL thickness reduction correlated with the reduction of peripapillary perfusion (P < 0.01). Macular GCC thickness reduction did not correlate with SCP reduction (P > 0.05). The reduction of macular DCP perfusion did not correlate with inner nuclear layer thickness (P > 0.05).

CONCLUSIONS

Retinal neural remodeling secondary to optic nerve axonal degeneration resulting from OPG located at or posterior to the chiasm is accompanied by a secondary retinal vascular remodeling involving not only the peripapillary area, but also the macular area (DCP).

Improvement of Recalcitrant Diabetic Macular Edema After Peritoneal Dialysis

Nephropathy may be an independent and contributory risk factor for diabetic macular edema (DME). A 69-year-old man who had previously been treated with panretinal laser photocoagulation for proliferative diabetic retinopathy as well as with steroid and anti-vascular endothelial growth factor injections for DME declined additional treatment for the DME, which was worse in the right eye. The DME was observed without further treatment for the next 36 months. Despite well-controlled blood sugar, blood pressure, and lipid levels, the DME remained unchanged. Peritoneal dialysis was started due to end-stage renal disease. Three months after commencing dialysis, the DME improved significantly. [Ophthalmic Surg Lasers Imaging Retina. 2017;48:834-837.].

Management of diabetic macular edema in Japan: a review and expert opinion

Diabetic retinopathy is a frequent cause of visual impairment in working-age adults (≥ 30 years) and in Japan is most commonly observed in those aged 50-69 years. Diabetic macular edema (DME) is one of the main causes of vision disturbance in diabetic retinopathy, which is a clinically significant microvascular complication of diabetes. Anti-vascular endothelial growth factor (VEGF) therapy is becoming the mainstay of treatment for DME. However, to achieve sustained long-term improvement in visual acuity, conventional laser photocoagulation, vitrectomy and steroid therapy are also expected to play a role in the treatment of DME. This review summarizes the epidemiology and pathology of diabetic retinopathy and DME, evaluates the findings regarding the diagnosis and treatment of DME, and underscores the importance of systemic management of the disease in the context of the current health care situation in Japan. Finally, the unmet needs of patients with DME and prospects for research are discussed. The weight of evidence suggests that it is important to establish a multipronged treatment strategy centered on anti-VEGF therapy.

Dexamethasone Intravitreal Implant in Diabetic Macular Edema: Real-Life Data from a Prospective Study and Predictive Factors for Visual Outcome

INTRODUCTION

The purpose of the study was to evaluate the long-term anatomical and functional outcomes in patients with diabetic macular edema (DME) treated with intravitreal dexamethasone implant and to determine the predictive factors for the final visual outcome.

METHODS

The study included 54 patients with DME refractory to previous antivascular endothelial growth factor (anti-VEGF) who were treated with intravitreal dexamethasone implant. Predictive factors for visual outcome were assessed. In addition, the change in best-corrected visual acuity (BCVA) and the percentage of patients with edema resolution were evaluated.

RESULTS

At the end of the 12-month follow-up, patients with DME gained + 5.2 letters (about 1 Snellen line), while 57.4% of patients presented total resolution of macular edema. Negative predictive factors for the final visual outcome were found to be increasing age, increasing macular thickness, phakic status, the presence of intraretinal fluid, hyperreflective foci, hard exudates, as well as external limiting membrane and ellipsoid zone disruption. The mean number of injections was 2.1.

CONCLUSIONS

The various predictive factors that determine the visual outcome and possibly define patient prognosis after dexamethasone intravitreal implant in DME cases have been studied. The long follow-up showed that dexamethasone intravitreal implant seems to be a safe and effective treatment for this disease, requiring a limited number of injections.

DIABETES ALTERS THE MAGNITUDE OF VITREOMACULAR ADHESION

PURPOSE

To quantify the changes in vitreomacular interactions that occur with aging in diabetic eyes in comparison with age-matched control eyes.

METHODS

Spectral-domain optical coherence tomography (Spectralis; Heidelberg Engineering) foveal scans of diabetic patients, without evidence of cystoid macular edema, were included. Twenty-five raster foveal scans were performed on every subject. Area of vitreomacular adhesion was delineated using the Spectralis drawing tool and calculated in square millimeter. Data collected included gender, race, best-corrected visual acuity, and posterior vitreous detachment status. Subjects were divided into age groups according to decade of life.

RESULTS

Spectral-domain optical coherence tomography scans from 141 diabetic patients were analyzed. Area of vitreomacular adhesion (mm) showed a hyperbolic decline in diabetic patients (35.5 ± 0, 35.0 ± 3, 34.0 ± 3, 33.9 ± 5, 33.7 ± 6, 29.0 ± 11, 23 ± 15, 13 ± 15). With aging, incidence of posterior vitreous detachment increased and incidence of complete attachment decreased.

CONCLUSION

Diabetes affects the magnitude of attachment of the vitreous gel to the macula that results in stronger and longer lasting attachment of the gel throughout life. Gender differences were not noticed in diabetic patients, suggesting that vitreomacular adhesion remains robust in both genders in diabetes despite aging.

Lack of Evidence for Vasoactive and Inflammatory Mediators in the Promotion of Macular Edema Associated with Epiretinal Membranes

The development of symptoms in patients with epiretinal membranes (ERMs) often corresponds with the accumulation of interstitial fluid in the retina [i.e., the development of macular edema, (ME)]. To explore the potential value of pharmacologic therapeutic options to treat ME in patients with ERMs, we examine here the expression of vasoactive and inflammatory mediators in the vitreous of patients with idiopathic ERMs. We observed that vitreous concentrations of classic vasoactive factors (e.g., vascular endothelial growth factor) were similar in ERM patients with ME compared to controls. Using an array assessing the expression of 102 inflammatory cytokines we similarly did not observe a marked difference in cytokine expression in the vitreous of most ERM patients with ME compared to control patients. While the array data did implicate a group of inflammatory cytokines that were elevated in a subset of ERM patients who had severe ME (central subfield thickness ≥450 μm on spectral domain optical coherence tomography), expression of 3 of these inflammatory cytokines, all previously implicated in the promotion of ME in ischemic retinal disease, were not elevated by quantitative enzyme-linked immunosorbent assay. We conclude that therapies modulating vasoactive mediators or inflammatory cytokines may not affect ME in ERM patients.

Insulin resistance correlates with maculopathy and severity of retinopathy in young adults with Type 1 Diabetes Mellitus

AIMS

To assess the relationship between insulin resistance (IR), retinopathy and maculopathy in young adults with Type 1 diabetes mellitus.

METHODS

A cross-sectional study at a regional Australian tertiary hospital. Retinal pathology, assessed by colour fundus photography, was correlated with two surrogate measures of IR: estimated Glucose Disposal Rate (eGDR) and Insulin Sensitivity Score (ISS), where lower scores reflect greater IR.

RESULTS

107 patients were recruited, with mean age 24.7years, 53% male, and mean duration of disease 10.8years. Mean eGDR scores (5.6vs 8.0 p<0.001) and ISS (4.7vs 7.9, p<0.001) were lower in subjects having at least moderate non-proliferative diabetic retinopathy (NPDR; relative to nil/mild-NPDR). Similarly, mean eGDR (4.2vs 6.2, p=0.001) and ISS (3.8vs 6.1, p=0.003) were lower in patients with maculopathy. Multivariate logistic regression modelling was used to control for confounding. For retinopathy severity, a unit increase in eGDR or ISS (representing lower IR) was associated with a 50% decrease in odds of moderate-NPDR or worse (eGDR OR 0.5, 95%CI 0.32-0.77, p=0.002; ISS OR 0.49, 95%CI 0.29-0.84, p=0.01). A unit increase in eGDR or ISS was associated with a 46-56% decrease in odds of maculopathy (eGDR OR 0.54, 95%CI 0.37-0.81, p=0.003; ISS OR 0.44, 95%CI 0.22-0.88, p=0.02).

CONCLUSIONS

IR correlates with more severe retinopathy in young adults with Type 1DM. This is the first description of a correlation between IR and maculopathy in Type 1DM, warranting further evaluation. Prospective studies examining whether reducing IR can improve microvascular complications are required.

ROCK-1 mediates diabetes-induced retinal pigment epithelial and endothelial cell blebbing: Contribution to diabetic retinopathy

In diabetic retinopathy, the exact mechanisms leading to retinal capillary closure and to retinal barriers breakdown remain imperfectly understood. Rho-associated kinase (ROCK), an effector of the small GTPase Rho, involved in cytoskeleton dynamic regulation and cell polarity is activated by hyperglycemia. In one year-old Goto Kakizaki (GK) type 2 diabetic rats retina, ROCK-1 activation was assessed by its cellular distribution and by phosphorylation of its substrates, MYPT1 and MLC. In both GK rat and in human type 2 diabetic retinas, ROCK-1 is activated and associated with non-apoptotic membrane blebbing in retinal vessels and in retinal pigment epithelium (RPE) that respectively form the inner and the outer barriers. Activation of ROCK-1 induces focal vascular constrictions, endoluminal blebbing and subsequent retinal hypoxia. In RPE cells, actin cytoskeleton remodeling and membrane blebs in RPE cells contributes to outer barrier breakdown. Intraocular injection of fasudil, significantly reduces both retinal hypoxia and RPE barrier breakdown. Diabetes-induced cell blebbing may contribute to ischemic maculopathy and represent an intervention target.

Patients' preferences for involvement in the decision-making process for treating diabetic retinopathy

BACKGROUND

To assess factors associated with the preferred role of the attending ophthalmologist in the decision-making processes before treating diabetic retinopathy (DR).

METHODS

Cross-sectional study of 810 adults attending secondary diabetes care centers (NCT02311504). Diabetes patients were classified using a validated questionnaire in an ophthalmologist-dominant decision-making (ODM), shared decision-making (SDM) and patient-dominant decision-making (PDM) style. Multivariate logistic regression was performed to determine factors associated with the decision-making process.

RESULTS

A majority of 74.3% patients preferred SDM between ophthalmologist and patient, 17.4% patients wanted ODM, delegating the decision-making process to the ophthalmologist, 8.3% preferred the autonomous style of PDM. Patients wanting ODM were older (OR = 1.2 per decade, p = 0.013), had a lower level of education (OR = 1.4, p = 0.001) and had a higher frequency of consultations per year (OR = 1.3, p = 0.022). Patients with better basic knowledge in DR and memorizing their HbA₁c level showed a higher propensity for SDM (OR = 1.1, p = 0.037). Patients wanting PDM had a significantly higher education (OR = 1.3, p = 0.036) and a greater desire for receiving information from self-help groups (OR = 1.3, p = 0.015).

CONCLUSIONS

The first evaluation of the general patient wishes for the treatment of DR confirmed the concept of SDM, which was favored by three quarters. In particular, older patients with low educational attainment wanted to delegate the decision-making process to the ophthalmologist. Amelioration of ophthalmologic education in diabetic programs might take up patients' propensity for SDM. Regardless of the decision-making group, nearly all patients wanted the medical and scientific information to be transferred by and shared with the ophthalmologist.

TRIAL REGISTRATION

The study was registered on www.clinicaltrials.gov (identifier: NCT02311504) on December 4th 2014.

Imaging retinal inflammatory biomarkers after intravitreal steroid and anti-VEGF treatment in diabetic macular oedema

PURPOSE

To evaluate changes of specific retinal imaging biomarkers [intraretinal hyper-reflective retinal spots: HRS ; subfoveal neuroretinal detachment: SND; and increased foveal autofluorescence: IFAF after intravitreal steroid or anti-vascular endothelial growth factor treatment in diabetic macular oedema (DME)] as possible indicators of retinal inflammatory condition.

METHODS

Retrospective analysis of images and clinical charts of 49 eyes (49 patients) with DME treated with intravitreal dexamethasone (dexamethasone, 23 eyes) or intravitreal ranibizumab (ranibizumab, 26 eyes). All patients had fundus colour photograph, spectral domain optical coherence tomography (SD OCT) and fundus autofluorescence (FAF), best-corrected visual acuity (BCVA) and microperimetry recorded before and 1 month after the end of treatment. Central macular thickness (CMT), number of HRS and presence of SND were evaluated by SD OCT. Fundus autofluorescence images were evaluated for area of (IFAF). Retinal sensitivity within 4° and 12° from fovea was quantified by microperimetry. Changes in morphologic and functional parameters were assessed, and correlation was performed by Pearson's correlation.

RESULTS

Best-corrected visual acuity and CMT improved in all patients, (p < 0.05, for both groups). Mean number of HRS decreased after both treatments (p < 0.0001). Subfoveal neuroretinal detachment resolved in 85.7% dexamethasone-treated eyes (p = 0.014) and in 50% ranibizumab-treated eyes (p = 0.025). Mean IFAF area decreased in both groups, (p < 0.0001, for both). A significantly higher decrease in CMT was observed in dexamethasone- versus ranibizumab-treated eyes, (p = 0.032). In dexamethasone group, higher number of HRS at baseline and larger IFAF were correlated with higher increase in retinal sensitivity; eyes with SND at baseline had major decrease in CMT versus those without SND, (p = 0.003).

CONCLUSION

Higher number of HRS, larger area of IFAF and presence of SND may indicate a prevalent inflammatory condition in DME with specific response to targeted treatment.

Concentration of acute phase factors in vitreous fluid in diabetic macular edema

PURPOSE

Diabetic retinal maculopathy is associated with acute and chronic local inflammation. We measured the concentrations of acute phase factors in vitreous fluid of patients with diabetic macular edema (DME) and examined their relations to visual acuity and central retinal thickness (CRT) both before and after vitrectomy.

STUDY DESIGN

Retrospective.

METHODS

Vitreous fluid was collected during vitreoretinal surgery from 19 patients with DME and 12 control subjects with epiretinal membrane. The concentrations of acute phase factors (α2-macroglobulin, haptoglobin, C-reactive protein, serum amyloid P and A, procalcitonin, ferritin, tissue plasminogen activator, fibrinogen) and vascular endothelial growth factor (VEGF) were measured with multiplex assays. CRT of macular edema was measured by optical coherence tomography (OCT).

RESULTS

The levels of serum amyloid P, procalcitonin, ferritin, and fibrinogen in vitreous fluid were increased in DME patients compared with control subjects. The levels of procalcitonin and fibrinogen in DME patients were inversely correlated with visual acuity both before and 3 months after vitrectomy but not 6 months postsurgery. The concentrations of these four factors were not correlated with either CRT or the vitreous levels of VEGF in DME patients.

CONCLUSION

Acute phase factors may contribute to local inflammation in DME and may therefore influence disease progression.