Risikofaktoren der altersbedingten Makuladegeneration

A bibliometric and visualization analysis of electrochemical biosensors for early diagnosis of eye diseases

Electrochemical biosensors can provide an economical, accurate and rapid method for early screening of disease biomarkers in clinical medicine due to their high sensitivity, selectivity, portability, low cost and easy manufacturing, and multiplexing capability. Tear, a fluid naturally secreted by the human body, is not only easily accessible but also contains a great deal of biological information. However, no bibliometric studies focus on applying electrochemical sensors in tear/eye diseases. Therefore, we utilized VOSviewer and CiteSpace, to perform a detailed bibliometric analysis of 114 papers in the field of research on the application of tear in electrochemical biosensors screened from Web of Science with the combination of Scimago Graphica and Microsoft Excel for visualization to show the current research hotspots and future trends. The results show that the research in this field started in 2008 and experienced an emerging period in recent years. Researchers from China and the United States mainly contributed to the thriving research areas, with 41 and 29 articles published, respectively. Joseph Wang from the University of California San Diego is the most influential author in the field, and Biosensors & Bioelectronics is the journal with the most published research and the most cited journal. The highest appearance keywords were "biosensor" and "tear glucose," while the most recent booming keywords "diagnosis" and "in-vivo" were. In conclusion, this study elucidates current trends, hotspots, and emerging frontiers, and provides future biomarkers of ocular and systemic diseases by electrochemical sensors in tear with new ideas and opinions.

Flicker-induced retinal vasodilatation is not dependent on complement factor H polymorphism in healthy young subjects

Purpose

The complement factor H (CFH) tyrosine 402 histidine (Y402H, rs1061170) variant is known to be significantly associated with age-related macular degeneration (AMD). Whether this genetic variant may impact retinal blood flow regulation is largely unknown. This study investigated whether flicker-induced vasodilation, an indicator for the coupling between neural activity and blood flow, is altered in subjects carrying the rs1061170 risk allele.

Methods

One hundred healthy subjects (aged between 18 and 45 years) were included in this study. Retinal blood flow regulation was tested by assessing retinal vessel calibres in response to stimulation with diffuse flicker light. Retinal vascular flicker responses were determined with a Dynamic Vessel Analyzer (DVA). In addition, genotyping for rs1061170 was performed.

Results

Eighteen subjects were homozygous for the risk allele C, 50 were homozygous for the ancestral allele T, and 31 subjects were heterozygous (CT). One subject had to be excluded from data evaluation, as no genetic analysis could be performed due to technical difficulties. Baseline diameters of retinal arteries (p = 0.39) and veins (p = 0.64) were comparable between the three groups. Flicker-induced vasodilation in both retinal arteries (p = 0.38) and retinal veins (p = 0.62) was also comparable between the three studied groups.

Conclusions

Our data indicate that homozygous healthy young carriers of the C risk allele at rs1061170 do not show abnormal flicker-induced vasodilation in the retina. This suggests that the high-risk genetic variant of CFH polymorphism does not impact neuro-vascular coupling in healthy subjects.

Role of vascular endothelial growth factor polymorphisms in the treatment success in patients with wet age-related macular degeneration

PURPOSE

Along with environmental risk factors such as smoking, hypertension, and atherosclerosis, genetic susceptibility is a primary contributor to the development and progression of exudative age-related macular degeneration (AMD). Vascular endothelial growth factor (VEGF) is a central angiogenic regulator and there has been general agreement now that it is an important trigger for the progression of exudative AMD. In the present study, we tested the hypothesis that VEGF gene polymorphisms play a role in the treatment success with VEGF inhibitors in patients with exudative AMD.

DESIGN

Prospective cohort study.

PARTICIPANTS

We included 185 eyes of 141 patients with exudative AMD who were scheduled for their first treatment with intravitreally administered bevacizumab in this trial.

METHODS

All patients were aged >50 years and had angiographically verified exudative AMD. Blood from the finger pad was collected on blood cards for genotyping for the VEGF polymorphisms rs1413711, rs3025039, rs2010963, rs833061, rs699947, rs3024997, and rs1005230. At each follow-up visit, visual acuity was reassessed and an ophthalmic examination was carried out. Visual acuity outcome, number of retreatments, and overall time of treatment were analyzed in dependence of the VEGF polymorphisms.

MAIN OUTCOME MEASURES

Mean change in visual acuity at the end of the treatment period.

RESULTS

The included patients were reinjected with bevacizumab 1 to 15 times, resulting in a total treatment period of 42 to 1182 days. In univariate analysis only the G/G genotypes of rs3024997 and rs2010963 compared with all other 5 single nucleotide polymorphisms (SNPs) showed a significantly lower visual acuity at the end of treatment. In multivariate analysis including parameters such as time, baseline visual acuity, and number of reinjections, none of the SNPs showed a significant correlation.

CONCLUSIONS

The current study indicates that VEGF polymorphisms are not major predictors of anti-VEGF treatment success in patients with exudative AMD.

Short- and mid-term repeatability of macular pigment optical density measurements using spectral fundus reflectance

BACKGROUND

Several methods have been proposed for measuring macular pigment optical density (MPOD). To date, none of the realized techniques can be considered as "gold standard". A key issue for the clinical applicability of a method is its repeatability. In this study, we investigated short- and mid-term repeatability of MPOD measurements using reflectometry.

METHODS

A total of 12 healthy young subjects were measured 5 times on 5 consecutive days. Repeatability over 6 months was investigated in patients with AMD. The data in AMD patients were taken from a recently published placebo controlled study investigating the effect of lutein supplementation on MPOD (n = 37; [1]). Four measurements over 6 months were used to calculate repeatability. Spectral fundus reflectance of the fovea was measured in a 2.3° detection field with a custom-built fundus reflectometer. Calculation of MPOD was based on a previously published fundus reflectance model.

RESULTS

The coefficients of variation were 6.2 ± 2.4% and 8.0 ± 5.5% in the healthy and AMD group, respectively. Bland-Altman plots indicate that the difference between measurements at day 1 and day 5 in healthy subjects and day 1 and month 6 in AMD patients was small. The maximum deviation in MPOD in a healthy subject was 0.07 (22.6%), and 0.17 (51.5%) in a patient with AMD.

CONCLUSIONS

Reflectometry provides adequate short-term and mid-term repeatability for measuring MPOD. Accordingly, the technique makes it possible to monitor MPOD in patients with AMD and to study the influence of supplementation in these subjects. In addition, the variability of the technique is small enough to allow for clinical trials with reasonable sample size.