Relationship between Systemic Vascular Characteristics and Retinal Nerve Fiber Layer Loss in Patients with Type 2 Diabetes

Atrial fibrillation and flutter and ocular diseases. The Ural eye and medical study and the Ural very old study

PURPOSE

To assess associations between atrial fibrillation/atrial flutter (AF) and ocular parameters and diseases.

METHODS

The population-based Ural Eye and Medical Study (UEMS) and the Ural Very Old Study (UVOS) included 4894 individuals (age: 40+ years) and 835 individuals (age: 85+ years), respectively.

RESULTS

In the UEMS, AF prevalence (80/4894; 1.6%; 95% CI: 1.3, 2.0) increased from 1/1029 (0.1%) in the age group of 40 to <50 years to 29/619 (4.7%) and 12/159 (7.5%) in the age groups of 70 to <80 years and 80+ years, respectively. Higher AF prevalence correlated with older age (OR: 1.08; 95% CI: 1.04, 1.12; p < 0.001), urban region of habitation (OR: 1.08; 95% CI: 1.04, 1.12; p < 0.001), higher prevalence of cardiovascular disease/stroke (OR: 2.50; 95% CI: 1.32, 4.72; p < 0.001) and lower prevalence of neck pain (OR: 0.35; 95% CI: 0.14, 0.85; p = 0.02), higher serum concentration of bilirubin (OR: 1.03; 95% CI: 1.02, 1.05; p < 0.001) and lower prothrombin index (OR: 0.96; 95% CI: 0.93, 0.99; p = 0.003), higher stage of arterial hypertension (OR: 1.52; 95% CI: 1.01, 2.28; p = 0.04) and higher ankle-brachial index (OR: 22.1; 95% CI: 4.45, 1.10; p < 0.001). In that model, AF prevalence was not associated with ocular parameters such as intraocular pressure (p = 0.52), retinal nerve fibre layer thickness (p = 0.70), refractive error (p = 0.13), axial length (p = 0.14), nuclear cataract degree (p = 0.50) and prevalence (p = 0.40), cortical cataract degree (p = 0.43) and presence (p = 0.17), lens pseudoexfoliation (p = 0.58), status after cataract surgery (p = 0.38), age-related macular degeneration prevalence (p = 0.63), open-angle glaucoma presence (p = 0.90) and stage (p = 0.55), angle-closure glaucoma prevalence (p = 0.99) and stage (p = 0.99), diabetic retinopathy prevalence presence (p = 0.37) and stage (p = 0.32), and myopic macular degeneration (p = 0.98). In the UVOS, similar results were obtained.

CONCLUSIONS

In these multi-ethnic populations from Russia, AF prevalence was not associated with any major ocular disease and may not play a major role in the pathogenesis of these disorders.

Prevalence and Associations of Peripheral Arterial Disease in China: The Beijing Eye Study

PURPOSE

To explore the prevalence and associations of peripheral arterial disease (PAD) in China.

DESIGN

Population-based incidence estimate and cross-sectional study.

METHODS

The participants (n=3468) of the Beijing Eye Study underwent a detailed ophthalmologic and systemic examination including assessment of the ankle-brachial index (ABI). PAD was defined by an ABI of less than 0.9.

RESULTS

Blood pressure measurements of both arms and ankles were available for 1078 (31.1%) individuals. An ABI (mean: 1.09±0.11; median: 1.10; range: 0.25, 1.36) of <0.9 and <0.95 was found in 32 of 1078 participants (3.0%, 95% CI 2.0, 4.0) and 70 of 1078 individuals (6.5%, 95% CI 5.0, 8.0), respectively. Higher PAD prevalence (multivariable analysis) was associated with older age (odds ratio [OR] 1.08, 95% CI 1.02, 1.15; P = .009), lower level of education (OR 0.62, 95% CI 0.43, 0.90; P = .01), lower quality of life (OR 0.67, 95% CI 1.11, 2.32), higher glucose serum concentration (OR 1.36, 95% CI 1.09, 1.58; P = .006), lower estimated glomerular filtration rate (OR 0.98, 95% CI 0.96, 0.99; P = .04), and higher prevalence of retinal vein occlusions (OR 7.30, 95% CI 1.63, 32.6; P = .009). PAD prevalence was not associated with the prevalence of glaucoma (P = .53) (open-angle glaucoma: P = .42; angle-closure glaucoma: P = .57) and age-related macular degeneration (any AMD: P = .39; early AMD: P = .31; intermediate AMD: P = .92; late AMD: P = .99), prevalence (P = .26) and stage (P = .07) of diabetic retinopathy, prevalence (P = .38) and degree (P = .68) of nuclear cataract, prevalence (P = .39) and degree (P = .72) of cortical cataract, prevalence of subcapsular cataract (P = .86), prevalence of pseudoexfoliation (P = .65), intraocular pressure (P = .50), axial length (P = .56), and peripapillary retinal nerve fiber layer thickness (P = .68).

CONCLUSIONS

The PAD prevalence (3.0%, 95% CI 2.0%, 4.0%) was relatively low in this cohort from rural and urban Beijing, with older age, lower educational level, lower quality of life, higher glucose serum concentration, lower estimated glomerular filtration rate, and higher prevalence of retinal vein occlusions as main associated factors.

Ankle-brachial index and ocular diseases in a Russian population

Background

To assess potential associations between the ankle-brachial blood pressure index (ABI) and ocular disorders.

Methods

In the population-based cross-sectional Russian Ural Eye and Medical Study including 5,899 (80.5%) out of 7328 eligible participants aged 40+ years, the participants underwent a series of ocular and medical examinations including measurement of ABI.

Results

Blood pressure measurements of both arms and ankles were available for 3187 (54.0%) individuals. The mean ABI was 1.26 ± 0.19 (median:1.20; range: 0.61, 2.20). In multivariate analysis, a higher ABI was associated with younger age (P < 0.001; non-standardized regression coefficient B: −0.001; 95% confidence interval (CI): −0.002, −0.001), female sex (P < 0.001; B: 0.03; 95% CI: 0.02, 0.04), lower body mass index (P < 0.001; B: −0.004; 95% CI: −0.006, −0.003), lower waist-to-hip ratio (P = 0.01; B: −0.10; 95% CI: −0.17, −0.02), lower glucose serum concentration (P = 0.008; B: −0.005; 95% CI: −0.009, −0.001), lower prevalence of arterial hypertension (P < 0.001; B: −0.14; 95% CI: −0.16, −0.12), higher mean systolic blood pressure (P < 0.001; B: 0.003; 95% CI: 0.002, 0.003), and higher prevalence of any alcohol consumption (P < 0.001; B: 0.03; 95% CI: 0.02, 0.04). In that multivariate model, prevalence of glaucoma (P = 0.67) as a whole, open-angle glaucoma (P = 0.86) and angle-closure glaucoma (P = 0.54), stage of glaucomatous optic neuropathy (P = 0.57), prevalence of age-related macular degeneration (P = 0.88), prevalence and stage of diabetic retinopathy (P = 0.30, and P = 0.29, respectively), nuclear cataract (P = 0.32, and P = 0.41, resp.), cortical cataract (P = 0.33, and P = 0.92, resp.), subcapsular cataract (P = 0.74 and P = 0.60, resp.), and pseudoexfoliation (P = 0.44 and P = 0.47, resp.), intraocular pressure (P = 0.52), axial length (P = 0.20), and peripapillary retinal nerve fibre layer thickness (P = 0.55) were not significantly associated with the ABI.

Conclusions

In this ethnically mixed population from Russia, none of the major ocular diseases was associated with ABI suggesting that subclinical atherosclerosis is not markedly associated with the aetiology of these ocular disorders.

Analysis of Glycemic Control and Low-Density Lipoprotein Cholesterol with Glaucomatous Optic Neuropathy as a Microvascular Complication in Patients with Type 2 Diabetes Mellitus: A Cross-sectional Study in North Sumatera, Indonesia

BACKGROUND: Diabetes mellitus (DM) is an important health problem that induces microvascular complication such as retinopathy, nephropathy, and neuropathy. Ocular complications associated with type 2 DM are progressive and rapidly becoming the world’s most significant cause of morbidity and preventable with early detection and timely treatment. AIM: This study to analyze of glycemic control and low-density lipoprotein cholesterol (LDL-C) with glaucomatous optic neuropathy as a microvascular complication in patients with type 2 DM. MATERIALS AND METHODS: A prospective, analytical observational with cross-sectional study was conducted in Universitas Sumatera Utara Hospital and Satellite Hospital, Medan, Indonesia, from April 2020 to August 2020. The study included 66 participants with type 2 DM. The patients were investigated for hemoglobin A1c (HbA1c) level, LDL-C level, and ophthalmology examination including visual acuity (VA), intraocular pressure (IOP) measurement by Goldmann Applanation Tonometer, retinal nerve fiber layer (RNFL) thickness with spectral domain Optovue optical coherence tomography, and visual field defect with Octopus Perimeter. RESULTS: This study showed a significant correlation between HbA1c with VA (p = 0.030), IOP (p = 0.035), RNFL thickness (p = 0.002), visual field defect (p = 0.032), and duration of DM (p = 0.003) and showed significant correlation between LDL-C with VA (p = 0.048), IOP (p = 0.006), and duration of DM (p = 0.042). CONCLUSION: Higher HbA1c and LDL-C correlated with Glaucomatous Optic Neuropathy as a microvascular complication in type 2 DM. Advantage of research is still rarely studied.

Plasma miR-26a-5p is a biomarker for retinal neurodegeneration of early diabetic retinopathy

PURPOSE

Retinal neurodegeneration is an early pathological change in diabetic retinopathy (DR). Early-stage retinal neurodegeneration is usually asymptomatic. This study aims to identify circulating microRNAs (miRNAs) as sensitive biomarkers for early retinal neurodegeneration.

METHODS

We profiled the plasma miRNA expression in three mild nonproliferative diabetic retinopathy (NPDR) cases and three matched non-DR patients using RNA sequencing. The differential miRNAs were validated with qRT-PCR. The retinal nerve fibre layer (RNFL) thickness of the eyes was measured using spectral-domain Optical coherence tomography (SD-OCT). The association between differential miRNAs and RNFL thickness was analysed using the Pearson correlation analysis. Bioinformatics tools were used to predict potential targets of miRNA associated with RNFL thickness and investigate the functions of the potential target genes.

RESULTS

RNA sequencing identified 69 differential miRNAs and eight of them were reported to be associated with DR. The qRT-PCR for these eight miRNAs validated the down-regulation of circulating miR-26a-5p and miR-126-5p in a larger validating cohort. A positive correlation between plasma miR-26a-5p level and the RNFL thickness of the superior quadrant of both eyes was identified in another cohort, including 33 mild NPDR cases, 33 matched non-DR patients and 20 healthy controls. Furthermore, 367 candidate targets of miR-26a-5p were predicted. The functional studies revealed that these target genes are profoundly involved in various cellular functions and signalling pathways.

CONCLUSIONS

Circulating miR-26a-5p is a potential biomarker for early-stage retinal neurodegeneration and it may be involved in the development of DR via profoundly influencing the functions of retinal cells.

Analysis of retinal nerve fiber layer birefringence in patients with glaucoma and diabetic retinopathy by polarization sensitive OCT

The retinal nerve fiber layer (RNFL) is a fibrous tissue that shows form birefringence. This optical tissue property is related to the microstructure of the nerve fiber axons that carry electrical signals from the retina to the brain. Ocular diseases that are known to cause neurologic changes, like glaucoma or diabetic retinopathy (DR), might alter the birefringence of the RNFL, which could be used for diagnostic purposes. In this pilot study, we used a state-of-the-art polarization sensitive optical coherence tomography (PS-OCT) system with an integrated retinal tracker to analyze the RNFL birefringence in patients with glaucoma, DR, and in age-matched healthy controls. We recorded 3D PS-OCT raster scans of the optic nerve head area and high-quality averaged circumpapillary PS-OCT scans, from which RNFL thickness, retardation and birefringence were derived. The precision of birefringence measurements was 0.005°/µm. As compared to healthy controls, glaucoma patients showed a slightly reduced birefringence (0.129 vs. 0.135°/µm), although not statistically significant. The DR patients, however, showed a stronger reduction of RNFL birefringence (0.103 vs. 0.135°/µm) which was highly significant. This result might open new avenues into early diagnosis of DR and related neurologic changes.

Optic Disc Measures in Obstructive Sleep Apnea: A Community-based Study of Middle-aged and Older Adults

PRéCIS:: This study found an association between thinner superotemporal retinal nerve fiber layer (RNFL) and obstructive sleep apnea (OSA). However, the lack of association of sleep apnea with other disc measures does not support a link with glaucoma.

AIM

Previous findings on the link between OSA and increased glaucoma risk have been inconsistent. In a community-based study of middle-aged and older adults, we explored for differences in optic disc measures that may resemble preclinical glaucomatous changes in relation to OSA status and severity.

METHODS

A total of 865 participants (46 to 67 y; 45% male) underwent an at-home sleep study during which their apnea-hypopnea index (AHI) and sleep oxygen saturation level were measured. Participants were determined to have no OSA (AHI<5 events/h), mild (AHI 5 to 15), moderate (AHI 16 to 30), or severe OSA (AHI>30). At a 6-year follow-up visit, the optic discs of both eyes were imaged using spectral domain optic coherence tomography to measure the Bruch membrane opening-minimum rim widths and RNFL thicknesses.

RESULTS

On the basis of the AHI, 411 participants (48%) had OSA, of whom 92 (11% of total sample) and 26 (3%) had moderate and severe OSA, respectively. In the multivariate analysis, participants with severe OSA had thinner RNFL superotemporally than those without OSA or with mild OSA (P<0.001 and 0.001, respectively). In addition, superotemporal RNFL was inversely associated with AHI (P=0.004) and sleep time with oxygen saturation level <90% (P=0.005). There was no association between OSA measures and Bruch membrane opening-minimum rim widths.

CONCLUSIONS

Our findings do not provide strong evidence of a link between measures of OSA and the optic disc. However, the association between increased OSA severity and thinner superotemporal RNFL has been reported consistently in previous studies and thus warrants further evaluation.

Relationship Between Renal Function and Choroidal Thickness in Type 2 Diabetic Patients Detected by Swept-Source Optical Coherence Tomography

Purpose

To investigate the relationship between renal function and choroidal thickness (CT) in ocular treatment-naïve patients with diabetes mellitus using swept-source optical coherence tomography (SS-OCT).

Methods

This cross-sectional study recruited type 2 diabetes mellitus (T2DM) patients with no history of ocular treatment from communities in Guangzhou, China. The estimated glomerular filtration rates (eGFR) were calculated by using the Xiangya formula. The impaired renal function was defined as eGFR < 60 mL/(min 1.73 m²). The choroid was imaged by using an SS-OCT, and the macular CT was quantified automatically in Early Treatment Diabetic Retinopathy Study maps, and only data from one eye was used. Univariate and multivariate linear regression analyses were performed to explore the influence of eGFR on CT.

Results

A total of 1395 patients with T2DM were included in the final analysis. The CT of all macular regions were significantly thinner in patients with renal impairment (all P < 0.001). A significantly positive correlation was observed between the average CT and eGFR (β = 0.4; 95% confidence interval, 0.041-0.8; P = 0.029) independent of age, sex, and other potential confounding factors. After adjusting for other factors, a higher eGFR was also associated with higher CT values in the central field (P = 0.019) and in the outer superior (P = 0.047), inner superior (P = 0.018), inner inferior (P = 0.025), and inner temporal (P = 0.038) regions.

Conclusions

CT decreased in parallel with renal impairment in ocular treatment naïve diabetic patients, providing an accessible window for monitoring renal status.

Translational Relevance

Knowledge of association between retinal microvasculature and renal microcirculation would allow applying in both clinical and research settings.

Intraocular pressure fluctuation and neurodegeneration in the diabetic rat retina

BACKGROUND AND PURPOSE

Early retinal neurodegeneration occurs as one of the complications of diabetes even before clinically detectable diabetic vascular retinopathy. The pathogenesis of retinal diabetic neuropathy is still not well understood. We investigated the serial changes or fluctuations in intraocular pressure (IOP) and examined their roles in the pathogenesis of neuronal degeneration in diabetic retina.

EXPERIMENTAL APPROACH

Male Sprague Dawley rats with streptozotocin-induced diabetes were treated with ophthalmic preparations of brinzolamide, latanoprost, both drugs (combined treatment) or saline for 8 weeks. IOP was measured daily under general anaesthesia using a rebound tonometer. Antegrade axoplasmic flow in the optic nerve was assessed with a fluorescent substrate. Immunohistochemical staining, TUNEL assays and western blots were also used.

KEY RESULTS

The fluctuation of IOP was higher in the diabetes group than in the normal control or the combined treatment group. Diabetes-induced apoptosis of retinal ganglion cells was decreased by combined treatment. Increased expression of glial fibrillary acidic protein or Iba-1 in the retina or optic nerve head, induced by diabetes, was attenuated only by the combined treatment. Intercellular adhesion molecule-1 was increased in diabetic rats but not in the combined treatment group. Diabetes-induced loss of antegrade axoplasmic transport was partially relieved with combined treatment.

CONCLUSION AND IMPLICATIONS

Elevated IOP fluctuations seemed to be associated with the gliosis, neuroinflammation, and neurodegeneration induced by diabetes. The loss of retinal ganglion cells might be relieved by IOP-lowering medication. The improvement of unstable perfusion pressure could play a role in neuroprotection in the diabetic retina.