Impact of metabolic control on macular thickness in diabetic macular oedema

Ocular complications of diabetes mellitus in a pediatric population and proposals for screening and follow-up programs

Background

Diabetes mellitus (DM) is one of the world's greatest health emergencies of the 21st century. Ocular complications of DM are commonly chronic and progressive, but vision loss can be effectively prevented or delayed with early detection and timely treatment. Therefore, regular comprehensive ophthalmologic examinations are mandatory. Ophthalmic screening and dedicated follow-up for adults with DM are well established, whereas, there is no consensus on optimal recommendations for the pediatric population, reflecting the lack of clarity about the current burden of disease in this age group.

Objectives

To determine the epidemiology of ocular complications of diabetes and to assess optical coherence tomography (OCT) and optical coherence tomography angiography (OCTA) macular features in a pediatric population with DM. To review ophthalmological screening and follow-up plans for the diabetic pediatric population.

Design

Observational study.

Methods

Retrospective consecutive cohort study of all 165 diabetic patients (330 eyes) aged 0-18 years, examined between January 2006 and September 2018 at the Pediatric Department of 'S. Maria della Misericordia' Udine Hospital who underwent at least one complete ophthalmologic examination at the Ophthalmology University Clinic at the Udine Hospital. OCT and OCTA data were available for 37 patients (72 eyes, 2 excluded). The associations between ocular complications and selected potential risk factors were evaluated by univariate analyses.

Results

No patient had signs of ocular diabetic complications or any macular morphological or micro-vascular impairment, regardless of any potential risk factor. The prevalence of strabismus and refractive errors in the study group, was found to be similar to non-diabetic pediatric populations.

Conclusion

Screening and follow-up of ocular diabetic complications in children and adolescents could be performed less frequently than in adults with diabetes. There is no need to screen potentially treatable visual disorders in diabetic children earlier or more frequently than in the healthy children thus reducing time spent in hospital and permitting a better tolerance to medical examinations in diabetic pediatric patients. We described the OCT and OCTA patterns in a pediatric population with DM.

A Cross-Sectional Study of Various Imaging and Biochemical Biomarkers in Patients with Diabetic Macular Edema in Different Stages of Diabetic Retinopathy

Purpose

To compare which imaging and biochemical biomarkers are associated with different stages of diabetic retinopathy (DR) in type 2 diabetes mellitus patients with diabetic macular edema (DME).

Patients and Methods

It was a cross-sectional, observational study that included 100 patients of DME with different stages of DR. Patients were divided into two groups: Group A – DME with non-proliferative diabetic retinopathy (NPDR) and Group B - DME with proliferative diabetic retinopathy (PDR). Group A was further subdivided into three subgroups: A (1) – DME with mild NPDR, A (2) – DME with moderate NPDR, and A (3) – DME with severe NPDR. The primary outcome measure was the association of imaging and biochemical biomarkers with different stages of DR in patients with DME.

Results

Out of 100 patients, Group A (1) had 1, Group A (2) 44, Group A (3) 29, and group: B had 29 patients. As Group A (1) had only one patient, we did not include it in the calculation. The overall mean age of the study population was 54.84+9.87 years, with a male preponderance (76%). The HbA1c levels, serum triglyceride level, serum cholesterol level, and microalbuminuria level showed no significant association with different stages of DR (P>0.05). Still, we found high serum urea levels (p=0.027) in Group B patients. The optical coherence tomography (OCT)-based imaging biomarkers – central subfield thickness (CST), cystoid macular edema (CME), subretinal fluid (SRF), and hyperreflective foci (HRF) – showed no significant association with various stages of DR. The presence of diffuse retinal thickness (DRT) (p=0.04) and the epiretinal membrane (ERM) (p=0.04) showed significant association with Group B patients.

Conclusion

The essential biochemical biomarkers such as serum urea levels and DRT and ERM may be considered an important imaging biomarker for the advanced stage of DR.

Influence of glycaemic control on macular thickness in diabetic retinopathy

Introduction

Diabetic macular oedema (DME) is one of the major cause of decreased visual acuity in patients with diabetic retinopathy. Poor glycaemic control is associated with increased incidence of DME.

Methods

A total of 112 eyes of 112 patients were studied in this cross‐sectional study and were classified into three groups based on HbA1c: group 1 included patients with good glycaemic control (HbA1c ≤7%), group 2 included patients with moderate glycaemic control (HbA1c between 7% and 9%) and group 3 included patients with poor glycaemic control (HbA1c ≥9%).

Results

We included 112 eyes of 112 patients. The mean duration of diabetes mellitus (DM) was 11.37 years. In statistical analysis, CMT (mean 188.80 ± 27.64 μm) positively correlated with mean HbA1c level (7.95 ± 1.29%) (r = 0.238, p < .05). There was a significant difference in CMT values among the three groups of HbA1c (F (2,109) = 19.39, p < .001). Post hoc analysis showed statistical significance between HbA1c≤7% and HbA1c ≥9% group and HbA1c 7%–9% and ≥9% group. However, statistical significance was not found among HbA1c ≤7% group and HbA1c 7%–9% group. Multiple regression analyses showed a significant correlation between CMT and HbA1c after adjusting for age and duration of diabetes.

Conclusion

Serum HbA1c level has a significant correlation with CMT in diabetic patients.

Efficacy of topical dorzolamide 2% in diabetic cystoid macular edema

AIM

To study the effect of topical dorzolamide 2% on macular thickness reduction in diabetic cystoid macular edema (CME).

METHODS

This was a prospective, non-randomized, open study including eyes with diabetic macular edema (DME). All eyes received topical dorzolamide 2% three times daily for one month. Changes in best-corrected visual acuity (BCVA), and central macular thickness (CMT) by optical coherence tomography) were evaluated at 1wk, 1, and 3mo post-treatment.

RESULTS

Ninety-three eyes (84 patients) were included. Mean±SD (logMAR) BCVA improved significantly from 1.08±0.26 pretreatment to 0.66±0.24 at 1mo and 0.87±0.26 at 3mo post-treatment (P<0.001 both). The mean±SD CMT was significantly reduced from 535.27±97.4 µm at baseline to 357.43±125.8 µm at 1mo and 376.23±114.5 µm at 3mo post-treatment (P<0.001 both). No significant ocular or systemic side effects were recorded.

CONCLUSION

Topical dorzolamide 2% results in significant improvement of mean BCVA and reduction of mean CMT at 3mo post-treatment. It can be used as an effective, affordable, and safe therapy for treatment of non-refractory diabetic CME.

Systemic risk factors contribute differently to the development of proliferative diabetic retinopathy and clinically significant macular oedema

AIMS/HYPOTHESIS

The purpose of screening for diabetic retinopathy is to detect either of the two sight-threatening complications: proliferative diabetic retinopathy (PDR) or clinically significant diabetic macular oedema (DME). The aim of the study was to evaluate whether systemic risk factors affect the risk of developing these two complications differently.

METHODS

Survival analysis with death as a competing risk was used to describe the effect of sex, age and time of onset of diabetes, systolic (SBP) and diastolic (DBP) BPs, and the weighted exposure and CV of HbA_1c for the development of PDR and DME from all 2773 patients treated for diabetic retinopathy in a defined population from the Aarhus area, Denmark, between 1 July 1994 and 1 July 2019.

RESULTS

Increasing HbA_1c above normal increased the risk of developing both PDR and DME (p < 0.04), and values below normal increased the risk of developing PDR (p < 0.013). Increasing DBP increased the risk of developing both PDR and DME (p < 0.0001), whereas increasing SBP increased the risk of developing DME (p < 0.0001), but not PDR (p > 0.08). The risk of developing PDR increased with decreasing age of onset of diabetes (p < 0.0001), whereas the risk of developing DME was maximal for a known onset of diabetes at about 30 years of age and decreased significantly for both lower and higher ages of onset (p < 0.0001). The risk of developing both PDR and DME was lower in women than in men (p < 0.004) and was reduced with lower variability of repeated HbA_1c measurements (p < 0.0001).

CONCLUSIONS/INTERPRETATION

Systemic risk factors such as metabolic regulation, arterial BP and the age of onset of diabetes contribute differently to the development of PDR and DME. The overall risk of developing treatment-requiring diabetic retinopathy should be calculated from the risks of reaching each of the two complications separately.

Ranibizumab versus aflibercept for diabetic macular edema: 18-month results of a comparative, prospective, randomized study and multivariate analysis of visual outcome predictors

PURPOSE

The purpose of this study was to compare the anatomical and functional outcomes of ranibizumab versus aflibercept for the treatment of diabetic macular edema (DME) in a long-term follow-up.

METHODS

Participants in this prospective study were 112 treatment naïve patients with DME, who received treatment with either intravitreal ranibizumab (n = 54) or aflibercept (n = 58). The demographic data, the best-corrected visual acuity (BCVA) and spectral-domain optical coherence tomography (SD-OCT) characteristics were evaluated at baseline and at month 1, 2, 3, 6, 12, and 18 post treatment, while factors affecting visual outcome were determined using multivariate analysis.

RESULTS

At month 18, the mean BCVA of ranibizumab-treated eyes increased 7.9 letters compared to 6.9 letters for eyes receiving aflibercept, with greater number of injections in ranibizumab group (9.2 ± 2.3 vs. 7.6 ± 2.1 injections in the ranibizumab and aflibercept group respectively, p = 0.0002). The difference in letters between the two groups was not statistically significant, nor the difference in central subfield thickness at month 18. Factors associated with poorer BCVA were found to be increasing age, HbA1c ≥7.5%, increasing central retinal thickness and disrupted ellipsoid zone.

CONCLUSIONS

Ranibizumab and aflibercept presented similar anatomical and functional outcomes in 18-month follow-up in patients with DME. It is important to determine factors, affecting VA, so as to provide individualized treatment.

Genotypes and Phenotypes: A Search for Influential Genes in Diabetic Retinopathy

Although gene–environment interactions are known to play an important role in the inheritance of complex traits, it is still unknown how a genotype and the environmental factors result in an observable phenotype. Understanding this complex interaction in the pathogenesis of diabetic retinopathy (DR) remains a big challenge as DR appears to be a disease with heterogenous phenotypes with multifactorial influence. In this review, we examine the natural history and risk factors related to DR, emphasizing distinct clinical phenotypes and their natural course in retinopathy. Although there is strong evidence that duration of diabetes and metabolic factors play a key role in the pathogenesis of DR, accumulating new clinical studies reveal that this disease can develop independently of duration of diabetes and metabolic dysfunction. More recently, studies have emphasized the role of genetic factors in DR. However, linkage analyses, candidate gene studies, and genome-wide association studies (GWAS) have not produced any statistically significant results. Our recently initiated genomics study, the Diabetic Retinopathy Genomics (DRGen) Study, aims to examine the contribution of rare and common variants in the development DR, and how they can contribute to clinical phenotype, rate of progression, and response to available therapies. Our preliminary findings reveal a novel set of genetic variants associated with proangiogenic and inflammatory pathways that may contribute to DR pathogenesis. Further investigation of these variants is necessary and may lead to development of novel biomarkers and new therapeutic targets in DR.

Association of Body Fluid Expansion With Optical Coherence Tomography Measurements in Diabetic Retinopathy and Diabetic Macular Edema

Purpose

To evaluate associations of body fluid status with optical coherence tomography measurements in patients with diabetic retinopathy (DR).

Methods

This prospective, cross-sectional study enrolled a total of 104 eyes from 104 patients with diabetes mellitus for fundus evaluations of DR and optical coherence tomography examinations. DR severity was graded via fundus photography. Systemic body fluid status was recorded via a body composition monitor with output values of total body water, extracellular water (ECW), intracellular water, and overhydration (OH). Relative overhydration (ROH) was defined as OH/ECW. Volume overload was defined as ROH ≥7%. Correlations of central subfield thickness (CST) with body fluid status were analyzed by partial correlation with adjustment for age, sex, and body mass index (BMI). Logistic regression analysis was used to evaluate factors associated with diabetic macular edema (DME).

Results

Higher levels of ECW, OH, and ROH were correlated with thick CST in patients with DR (P = 0.006, 0.021, and 0.008, respectively), but not in those without any DR (all P > 0.05), after adjusting for age, sex, and BMI. Patients with DME (n = 31) had higher OH than DR patients without DME (n = 28) or those without any DR (n = 45) (P = 0.002 and P < 0.001, respectively). Multiple regression model showed that volume overload was the independent factor for the presence of DME (odds ratio, 9.532; 95% confidence interval, 2.898-31.348; P < 0.001).

Conclusions

While both ECW and OH reflect CST in patients with DR, overhydration had particularly strong associations with DME. This study provides a novel insight into our current understanding regarding the pathogenesis for DME.

Macular thickness measurements of healthy, naïve cynomolgus monkeys assessed with spectral-domain optical coherence tomography (SD-OCT)

The purpose of this study was to measure central macular thickness in an unprecedented number of cynomolgus monkeys. Macular thickness was measured with Heidelberg spectral-domain OCT in 320 eyes of healthy and treatment-naïve cynomolgus monkeys (80 males and 80 females). The macula was successfully measured in all 320 eyes. Macular thickness was not significantly different between the sexes. The mean central macular thickness was 244 μm (+/- 21 μm). Macular thicknesses in the quadrants were 327 +/-17 μm (temporal inner), 339 +/- 17 μm (inferior inner), 341 +/- 14 μm (superior inner), 341 +/-18 μm (nasal inner), and 299 +/- 20 μm (temporal outer), 320 +/- 16 μm (superior outer), 332 +/-23 μm (inferior outer), and 337 +/-18 μm (nasal outer). Highly significant differences between the nasal and temporal quadrants were detected. This study successfully demonstrated the feasibility of retinal thickness measurements in healthy cynomolgus monkeys. The present findings indicate that the macula is thicker in cynomolgus monkeys than in humans and provide important normative data for future studies.