Diabetic Macular Edema

A quantitative evaluation of the effect of meals on macular thickness in diabetic patients with diabetic macular edema

PURPOSE

Central subfoveal thickness measurement is used in a large number of clinical trials to monitor the progression and treatment response of diabetic macular edema (DME) in patients of diabetic retinopathy (DR). Several studies have been carried out to investigate various factors affecting the central subfoveal thickness in order to minimize errors in the testing. We planned a study to investigate the effect of meals on central macular thickness (CMT) in patients with DME and compare that with nondiabetic patients.

METHODS

In this observational study, 50 patients of diabetes with DME and 50 normal controls were included. Macular thickness was measured after overnight fasting and 2 h postprandial for both the groups. Any changes in morphology and CMT were evaluated.

RESULTS

Each group had 22 females and 28 males with a mean age of 60.6 ± 6.6 in the diabetic group and of 49.66 ± 11.13 in the control group. Reduction in the CMT was noticed after the meals (mean: -9.78 ± 12.77 μm; P < 0.001) in those with DME as compared to the control group. This was more prominent in those who had intraretinal cystic spaces (17.14 ± 10.33 μm) and neurosensory detachment (66 µ). Patients with high blood sugar levels had higher CMT and a greater reduction in thickness was noticed in them postprandially (r = 0.414; P = 0.0028).

CONCLUSION

The CMT values in patients with DME are significantly affected by meals. Hence, an attempt should be made to measure CMT during the fasting state for more accurate results.

Automatic generation of retinal optical coherence tomography images based on generative adversarial networks

SIGNIFICANCE

The automatic generation algorithm of optical coherence tomography (OCT) images based on generative adversarial networks (GAN) can generate a large number of simulation images by a relatively small number of real images, which can effectively improve the classification performance.

AIM

We proposed an automatic generation algorithm for retinal OCT images based on GAN to alleviate the problem of insufficient images with high quality in deep learning, and put the diagnosis algorithm toward clinical application.

APPROACH

We designed a generation network based on GAN and trained the network with a data set constructed by 2014_BOE_Srinivasan and OCT2017 to acquire three models. Then, we generated a large number of images by the three models to augment age-related macular degeneration (AMD), diabetic macular edema (DME), and normal images. We evaluated the generated images by subjective visual observation, Fréchet inception distance (FID) scores, and a classification experiment.

RESULTS

Visual observation shows that the generated images have clear and similar features compared with the real images. Also, the lesion regions containing similar features in the real image and the generated image are randomly distributed in the image field of view. When the FID scores of the three types of generated images are lowest, three local optimal models are obtained for AMD, DME, and normal images, indicating the generated images have high quality and diversity. Moreover, the classification experiment results show that the model performance trained with the mixed images is better than that of the model trained with real images, in which the accuracy, sensitivity, and specificity are improved by 5.56%, 8.89%, and 2.22%. In addition, compared with the generation method based on variational auto-encoder (VAE), the method improved the accuracy, sensitivity, and specificity by 1.97%, 2.97%, and 0.99%, for the same test set.

CONCLUSIONS

The results show that our method can augment the three kinds of OCT images, not only effectively alleviating the problem of insufficient images with high quality but also improving the diagnosis performance.

Real-World Evidence in the Management of Diabetic Macular Edema with Intravitreal Anti-VEGFs in Asia: A Systematic Literature Review

Purpose

To evaluate the visual outcomes and safety profile of intravitreal anti-vascular endothelial growth factor (anti-VEGF) therapy in the treatment of diabetic macular edema (DME) in real-world studies in Asian countries.

Methods

A systematic review of electronic literature databases (Embase, Medline, and the Cochrane Library from January 1, 2010, to March 16, 2021) was conducted to identify observational studies that reported clinical and safety outcomes of anti-VEGF treatments for DME in Asia. We analyzed baseline patient characteristics, treatment patterns, mean number of injections, best-corrected visual acuity (BCVA), retinal thickness, and safety outcomes.

Results

Seventy-one studies were included in this review. Most studies reported treatment of DME with ranibizumab (n = 33), followed by aflibercept (n = 13), bevacizumab (n = 28), and conbercept (n = 9). At 12 months, the cumulative mean number of injections for ranibizumab, aflibercept, and conbercept was 5.2, 4.6, and 6, respectively. At the 12-month follow-up, the cumulative mean BCVA gain was 6.8 letters (ranibizumab), 4.6 letters (aflibercept), 4.9 letters (bevacizumab), and 8.3 letters (conbercept). The cumulative mean reduction in retinal thickness at 12 months was 116.9 μm (ranibizumab), 105.9 μm (aflibercept), 81.7 μm (bevacizumab), and 135.2 μm (conbercept). A strong positive correlation (r = 0.78) was observed between mean number of injections and change in BCVA at 12 months. A moderate positive correlation (r = 0.54) was observed between mean number of injections and mean reduction in retinal thickness at 12 months. A weak positive correlation was observed between baseline retinal thickness and visual acuity at 12 months. Baseline BCVA and mean number of injections were predictors of BCVA at 12 months.

Conclusion

All anti-VEGFs were effective in the treatment of DME in Asia. The data suggest that a greater number of anti-VEGF injections was associated with better improvement in BCVA and moderate reduction in retinal thickness at the 1-year follow-up.

Saudi Arabia Guidelines for diabetic macular edema: A consensus of the Saudi Retina Group

Diabetes mellitus (DM) and its complications are major public health burdens in Saudi Arabia. The prevalence of diabetic retinopathy (DR) is 19.7% and the prevalence of diabetic macular edema (DME) is 5.7% in Saudi Arabia. Diabetic macular edema is a vision-threatening complication of DR and a major cause of vision loss worldwide. Ocular treatments include retinal laser photocoagulation, anti-vascular endothelial growth factor (anti-VEGF) agents, intravitreal corticosteroids, and vitreoretinal surgery when necessary. The present consensus was developed as a part of the Saudi Retina Group's efforts to generate Saudi guidelines and consensus for the management of DME, including recommendations for its diagnosis, treatment, and best practice. The experts' panel stipulates that the treatment algorithm should be categorized according to the presence of central macula involvement. In patients with no central macular involvement, laser photocoagulation is recommended as the first-line option. Patients with central macular involvement and no recent history of cardiovascular (CVS) or cerebrovascular disorders can be offered anti-VEGF agents as the first-line option. In the case of non-responders (defined as an improvement of <20% in optical coherence tomography or a gain of fewer than 5 letters in vision), switching to another anti-VEGF agent or steroids should be considered after 3 injections. Within the class of steroids, dexamethasone implants are recommended as the first choice. In patients with a recent history of CVS events, the use of anti-VEGF agents is not recommended, regardless of their lens status. The experts' panel recommends that a future study be conducted to provide a cut-off point for early switching to steroid implants in pseudo-phakic eyes.

Correlation between optical coherence tomography, multifocal electroretinogram findings and visual acuity in diabetic macular edema

AIM

To analyze the correlation between macular morphology and function in eyes with diabetic macular edema (DME).

METHODS

Fifty-five eyes with different visual acuity (VA) of 32 patients who suffered from DME were analyzed using multifocal electroretinography (mfERG) and optical coherence tomography (OCT). The parameters of mfERG including implicit times and response amplitude were compared to those of 50 normal eyes of 36 age-matched subjects. Correlation analysis was performed between VA, the parameters of mfERG including implicit times and response amplitude, and the central macular thickness (CMT).

RESULTS

The amplitude of N1 and P1 were significantly decreased and their latency were significantly increased in five ring regions of the retina in patients with DME. There was statistically significant correlation between logMAR BCVA and P1 amplitude densities in rings 1-4 (r=-0.306, -0.536, -0.470, -0.362; P=0.023, <0.01, <0.01, 0.007 respectively), N1 amplitude in ring 2 and ring 3 (r=-0.035, -0.286; P=0.019, 0.034 respectively). There was poor correlation between the CMT and best-corrected visual acuity (BCVA; r=0.288, P=0.033), but there was no significant correlation between CMT and amplitude or implicit time of N1 and P1 (P>0.05) in the central macular ring. Multiple stepwise regression analysis showed that P1 amplitude density in ring 2 was the only contributor to the VA.

CONCLUSION

It seems to be more appropriate of combining use of mfERG with OCT for the evaluation of macular function in eyes with DME.

Levosulpiride Increases the Levels of Prolactin and Antiangiogenic Vasoinhibin in the Vitreous of Patients with Proliferative Diabetic Retinopathy

Purpose

High circulating levels of the hormone prolactin (PRL) protect against experimental diabetic retinopathy (DR) due to the retinal accumulation of vasoinhibin, a PRL fragment that inhibits blood vessel permeability and growth. A phase 2 clinical trial is investigating a new therapy for DR based on elevating serum PRL levels with levosulpiride, a prokinetic dopamine D2 receptor blocker. Here, we tested whether levosulpiride-induced hyperprolactinemia elevates PRL and vasoinhibin in the vitreous of volunteer patients with proliferative DR (PDR) undergoing elective pars plana vitrectomy.

Methods

Patients were randomized to receive placebo (lactose pill, orally TID; n = 19) or levosulpiride (25 mg orally TID; n = 18) for the 7 days before vitrectomy. Vitreous samples from untreated non-diabetic (n = 10) and PDR (n = 17) patients were also studied.

Results

Levosulpiride elevated the systemic (101 ± 13 [SEM] vs. 9.2 ± 1.3 ng/mL, P < 0.0001) and vitreous (3.2 ± 0.4 vs. 1.5 ± 0.2 ng/mL, P < 0.0001) levels of PRL, and both levels were directly correlated (r = 0.58, P < 0.0002). The vitreous from non-diabetic patients or from PDR patients treated with levosulpiride, but not from placebo-treated PDR patients, inhibited the basic fibroblast growth factor (bFGF)- and vascular endothelial growth factor (VEGF)-induced proliferation of endothelial cells in culture. Vasoinhibin-neutralizing antibodies reduced the vitreous antiangiogenic effect. Matrix metalloproteases (MMPs) in the vitreous cleaved PRL to vasoinhibin, and their activity was higher in non-diabetic than in PDR patients.

Conclusions

Levosulpiride increases the levels of PRL in the vitreous of PDR patients and promotes its MMP-mediated conversion to vasoinhibin, which can inhibit angiogenesis in DR.

Translational Relevance

These findings support the potential therapeutic benefit of levosulpiride against vision loss in diabetes. 

One-Year Effectiveness Study of Intravitreously Administered Conbercept® Monotherapy in Diabetic Macular Degeneration: A Systematic Review and Meta-Analysis

INTRODUCTION

The evidence on efficacy of intravitreously administered Conbercept (IVC) monotherapy for diabetic macular degeneration was still limited.

METHODS

A systematic review was conducted in November 2019 to summarize the current evidence on visual acuity (VA) changes with IVC monotherapy in the treatment of diabetic macular edema (DME) from Pubmed, ClinicalTrials.gov, EMbase, China National Knowledge Infrastructure (CNKI), Wanfang Database, Chin VIP Information (VIP), and Chinese Biomedical Database (CBM). Retrospective or prospective clinical studies which used IVC injection for the treatment of DME were included. Outcomes included in the analysis were change in best-corrected visual acuity (BCVA) and central macular thickness (CMT). A meta-regression was conducted to assess 1-year BCVA and CMT changes against numbers of injections.

RESULTS

A total of 20 studies were included in current study. At 12-month follow-up, an overall increase of 0.67 logarithm of the minimum angle of resolution (logMAR) BCVA score [95% confidence interval (CI) 0.24-1.11; P = 0.003] and 1.03 Early Treatment Diabetic Retinopathy Study (ETDRS) letters (95% CI 0.69-1.38; P < 0.001) was shown with IVC injection compared to baseline. Decrease in CMT was 142.79 μm (95% CI 112.71-172.87; P < 0.001) compared to baseline. The meta-regression showed a significant increase in effect size between number of injections and 12-month logMAR BCVA scale change as well as CMT.

CONCLUSION

Our findings suggest improved VA and CMT outcomes during 1-year follow-up in patients with DME who underwent IVC monotherapy. Increased injection frequency demonstrates a significant trend with improved outcomes at 12 months.

Knowledge and practices of fundoscopy among general practitioners in Qassim Province, Saudi Arabia, for the management of diabetic retinopathy and diabetic macular edema: A cross-sectional study

Objectives:

Blindness is one of the most widespread final pathways of diabetic retinopathy and its associated diabetic macular edema. The general practitioners are the first to encounter these diabetic patients. Fundoscopy is now considered as an ideal way for the diagnosis of patients with diabetic retinopathy. Therefore, this study was undertaken to know the ability and skills of general practitioners for the diagnosis and management of patients with diabetic retinopathy and diabetic macular edema.

Methods:

This study was conducted in all major cities in Qassim province of Saudi Arabia during January to May 2017. A validated questionnaire was used to assess the general practitioners’ knowledge and practice for the management of diabetic retinopathy and diabetic macular edema. Questions related to referrals, diagnosis, and treatment options to diabetic retinopathy and diabetic macular edema were asked to the general practitioners.

Results:

Of 96 general practitioners, 76 returned the questionnaire with a response rate of 79.2%. Only 26.3% general practitioners referred patients with type 1 diabetes to ophthalmologists as per guidelines set by the American Academy of Ophthalmology, whereas 74% of general practitioners showed good knowledge for referring patients with type 2 diabetes to ophthalmology clinics. Lack of knowledge was also noticed for the treatment of diabetic retinopathy, as only 36.8% of general practitioners replied positive for dilated fundus examination option, whereas 78.9% of general practitioners chose laser photocoagulation as a treatment option. Similar response from them was observed for patients with diabetic macular edema. Furthermore, data also showed years in practice of general practitioners was well correlated with their knowledge for the management of diabetic retinopathy and diabetic macular edema.

Conclusion:

The general practitioners included in this study showed lack of knowledge in handling patients with diabetic retinopathy and diabetic macular edema. Therefore, refresher courses are needed that highlight the acquisition of their skills in fundoscopy.

Identifying Genetic Risk Factors for Diabetic Macular Edema and the Response to Treatment

Diabetic retinopathy (DR) is the most common microvascular complication of diabetes mellitus (DM). DR is complex and the term encompasses several clinical subtypes of diabetic eye disease, including diabetic macular edema (DME), the most frequent cause of central vision loss in DR patients. Both genetic and environmental factors contribute to the pathophysiology of DR and its subtypes. While numerous studies have identified several susceptibility genes for DR, few have investigated the impact of genetics on DME susceptibility. This review will focus on the current literature surrounding genetic risk factors associated with DME. We will also highlight the small number of studies investigating the genetics of response to antivascular endothelial growth factor (anti-VEGF) injection, which is used to treat DME.

Impact of Intravitreal Ranibizumab Therapy on Vision Outcomes in Diabetic Macular Edema Patients: A Meta-Analysis

PURPOSE

Evaluation of the impact of the injection frequency of ranibizumab on best-corrected visual acuity (BCVA) outcomes in patients with diabetic macular edema (DME).

METHODS

A meta-analysis of randomized controlled trials (RCTs) and real-world studies was performed to quantify the effect of ranibizumab treatment on BCVA and central foveal thickness (CFT) in DME as well as the relationship between the number of injections and the change in BCVA/CFT.

RESULTS

All combined sources (29 RCTs and 11 real-life studies) showed a significant increase in BCVA from baseline following anti-vascular endothelial growth factor (VEGF) treatment (8.2, 9.4, and 10.3 ETDRS letters gained after 12, 24, and 36 months of ranibizumab treatment, respectively). The largest changes in BCVA were observed in RCTs and the smallest in real-life studies at 12 months. A significant relationship was found between the number of injections and change in BCVA at 12 months.

CONCLUSIONS

Inferior vision outcomes were observed in clinical practice compared with RCTs and might be partly attributable to administration of fewer anti-VEGF injections. Physicians should be aware that early and appropriate anti-VEGF treatment regimens are necessary to obtain the results reported in RCTs and help prevent irreversible vision loss in DME patients.

Angiopoietins in Diabetic Retinopathy: Current Understanding and Therapeutic Potential

Diabetic retinopathy (DR) is the commonest cause of blindness in the working-age population of the developed world. The molecular pathophysiology of DR is complex, and a complete spatiotemporal model of the disease is still being elucidated. Recently, a role for angiopoietin (Ang) proteins in the pathophysiology of DR has been proposed by several research groups, and several aspects of Ang signalling are being explored as novel therapeutic strategies. Here, we review the role of the Ang proteins in two important forms of DR, diabetic macular oedema and proliferative diabetic retinopathy. The function of the Ang proteins in regulating blood vessel permeability and neovascularisation is discussed, and we also evaluate recent preclinical and clinical studies highlighting the potential benefits of modulating Ang signalling as a treatment for DR.

Spotlight on fundus autofluorescence

Fundus autofluorescence (FAF) imaging is based on the fluorescence from ocular endogenous fluorophores located in the retinal pigment epithelium and choroid, mainly lipofuscin and melanin. It is a noninvasive technique that provides information about the spatial distribution of lipofuscin/melanin and retinal pigment epithelium health status. An overview about the fluorophores responsible for FAF imaging and the usefulness of FAF imaging in the noninvasive assessment and monitoring of retinal diseases, such as age-related macular degeneration, diabetic retinopathy, diabetic macular edema, central serous chorioretinopthy, retinitis pigmentosa and retinal dystrophies, are discussed in this review.

Effect of carotenoids dietary supplementation on macular function in diabetic patients

Background

Diabetic retinopathy is a major cause of visual impairment and blindness among working-age people worldwide. The aim of our study was to investigate the effects of a carotenoid supplementation on retinal thickness and macular function of patients with diabetes using optical coherence tomography (OCT) and multifocal electroretinography (mfERG).

Methods

A retrospective study of one hundred and twenty eyes of sixty patients age between 40 and 60 years with non-insulin dependent type 2 diabetes mellitus without diabetic retinopathy who underwent OCT and mfERG and took vitamin supplements for a period of two years. Patients received a carotenoid supplement containing lutein (10 mg), zeaxanthin (2 mg) and meso-zeaxanthin (10 mg) once a day for two years. The thickness of the fovea was evaluated using OCT and the macular function was tested by mfERG.

Results

OCT showed an increase in the central foveal thickness and mfERG revealed increased retinal response density within the central 13° surrounding the fovea (rings 1 to 3) at two years after the onset of carotenoids supplement intake.

Conclusion

The use of carotenoid supplements may be of benefit for improving visual function of type 2 diabetes patients. However, further study is needed to assess the treatment’s long-term efficacy.

Plasma homocysteine levels are associated with macular thickness in type 2 diabetes without diabetic macular edema

PURPOSE

To explore the relationships between macular thickness and the plasma concentrations of homocysteine, vitamin B12, folate, and other known risk factors for patients with diabetes without diabetic macular edema (DME).

METHODS

Fasting venous blood samples were collected from 252 subjects (126 relatively healthy subjects with type 2 diabetes without diabetic macular edema and 126 age- and gender-matched controls). Measurement of macular thickness and volume was performed for those subjects using SD-OCT. The plasma concentrations of homocysteine, vitamin B12, folate, and other known risk factors were analyzed in all the patients and controls using multiple linear regression models.

RESULTS

An increase in the serum levels of homocysteine was present within patients with type 2 diabetes compared to healthy individuals. The mean total plasma homocysteine levels were associated with a greater central subfield macular thickness (CSMT), average macular thickness (AMT), and average macular volume (AMV) in patients with type 2 diabetes without DME, after adjusting for age, sex, duration of diabetes, and HbA1c. Each 1 mmol/L increase in tHcy level was associated with a 6.57 µm greater CSMT (95% confidence interval [CI] 1.78, 11.36), a 4.51 µm greater AMT (95% CI 1.05, 7.98), and a 4.72 mm³ greater AMV (95% CI 1.23, 8.21).

CONCLUSIONS

Higher homocysteine levels were associated with an increased CSMT, AMT, and AMV in diabetic patients without DME. This link may indicate that patients with type 2 diabetes with increased levels of plasma tHcy are more prone to develop a clinical manifestation of DME.

Magnetic nanoparticles: a strategy to target the choroidal layer in the posterior segment of the eye

Despite the higher rate of blindness due to population aging, minimally invasive and selective drug delivery to the eye still remains an open challenge, especially in the posterior segment. The retina, the retinal pigment epithelium (RPE) and the choroid are posterior segment cell layers, which may be affected by several diseases. In particular, damages to the choroid are associated with poor prognosis in the most severe pathologies. A drug delivery approach, able to target the choroid, is still missing. Recently, we demonstrated that intravitreally injected magnetic nanoparticles (MNP) are able to rapidly and persistently localise within the RPE in an autonomous manner. In this work we functionalised the MNP surface with the vascular endothelial growth factor, a bioactive molecule capable of transcytosis from the RPE towards more posterior layers. Such functionalisation successfully addressed the MNPs to the choroid, while MNP functionalised with a control polypeptide (poly-L-lysine) showed the same localisation pattern of the naked MNP particles. These data suggest that the combination of MNP with different bioactive molecules could represent a powerful strategy for cell-specific targeting of the eye posterior segment.