Andréas Josef Kreis

Dietary antioxidants and primary prevention of age related macular degeneration: systematic review and meta-analysis.

Objective To evaluate the effectiveness of dietary antioxidants in the primary prevention of age related macular degeneration (AMD). Design Systematic review and meta-analysis. Data sources Search of seven databases without limits on year or language of publication, and retrieval of references in pertinent reviews and articles. Methods Two reviewers independently searched the databases and selected the studies, using standardised criteria. Randomised clinical trials and prospective cohort studies were included. Of the 4192 abstracts initially identified, 12 studies (nine prospective cohort studies and three randomised clinical trials) met the selection criteria and were included. Data extraction and study quality evaluation were independently reviewed, using standardised criteria. Results were pooled quantitatively using meta-analytic methods. Results The nine prospective cohort studies included 149 203 people, with 1878 incident cases of early AMD. The antioxidants investigated differed across studies, and not all studies contributed to the meta-analysis of each antioxidant. Pooled results from prospective cohort studies indicated that vitamin A, vitamin C, vitamin E, zinc, lutein, zeaxanthin, α carotene, β carotene, β cryptoxanthin, and lycopene have little or no effect in the primary prevention of early AMD. The three randomised clinical trials did not show that antioxidant supplements prevented early AMD. Conclusions There is insufficient evidence to support the role of dietary antioxidants, including the use of dietary antioxidant supplements, for the primary prevention of early AMD.

Flicker Light-Induced Retinal Vasodilation in Diabetes and Diabetic Retinopathy

OBJECTIVE Flicker light–induced retinal vasodilation may reflect endothelial function in the retinal circulation. We investigated flicker light–induced vasodilation in individuals with diabetes and diabetic retinopathy. RESEARCH DESIGN AND METHODS Participants consisted of 224 individuals with diabetes and 103 nondiabetic control subjects. Flicker light–induced retinal vasodilation (percentage increase over baseline diameter) was measured using the Dynamic Vessel Analyzer. Diabetic retinopathy was graded from retinal photographs. RESULTS Mean ± SD age was 56.5 ± 11.8 years for those with diabetes and 48.0 ± 16.3 years for control subjects. Mean arteriolar and venular dilation after flicker light stimulation were reduced in participants with diabetes compared with those in control subjects (1.43 ± 2.10 vs. 3.46 ± 2.36%, P < 0.001 for arteriolar and 2.83 ± 2.10 vs. 3.98 ± 1.84%, P < 0.001 for venular dilation). After adjustment for age, sex, diabetes duration, fasting glucose, cholesterol and triglyceride levels, current smoking status, systolic blood pressure, and use of antihypertensive and lipid-lowering medications, participants with reduced flicker light–induced vasodilation were more likely to have diabetes (odds ratio 19.7 [95% CI 6.5–59.1], P < 0.001 and 8.14 [3.1–21.4], P < 0.001, comparing lowest vs. highest tertile of arteriolar and venular dilation, respectively). Diabetic participants with reduced flicker light–induced vasodilation were more likely to have diabetic retinopathy (2.2 [1.2–4.0], P = 0.01 for arteriolar dilation and 2.5 [1.3–4.5], P = 0.004 for venular dilation). CONCLUSIONS Reduced retinal vasodilation after flicker light stimulation is independently associated with diabetes status and, in individuals with diabetes, with diabetic retinopathy. Our findings may therefore support endothelial dysfunction as a pathophysiological mechanism underlying diabetes and its microvascular manifestations.

Alcohol consumption and the risk of age-related macular degeneration: a systematic review and meta-analysis.

PURPOSE To review systematically the evidence currently available on alcohol consumption and the risk of age-related macular degeneration (AMD). DESIGN Systematic review and meta-analysis of observational studies. METHODS Seven databases were searched systematically with no limits on the year or language of publication for prospective cohort studies. References identified from pertinent reviews and articles also were retrieved. Two reviewers independently searched the above databases and selected the studies using prespecified standardized criteria. These criteria included appropriate adjustment for age and smoking in the analysis. Of the 441 studies identified initially, five cohort studies met the selection criteria. Data extraction and study quality evaluation were performed independently by two reviewers and results were pooled quantitatively using meta-analytic methods. RESULTS The five cohort studies included 136,946 people, among whom AMD developed in 1923 (1,513 early and 410 late). Pooled results showed that heavy alcohol consumption was associated with an increased risk of early AMD (pooled odds ratio, 1.47; 95% confidence interval, 1.10 to 1.95), whereas the association between heavy alcohol consumption and risk of late AMD was inconclusive. There were insufficient data to evaluate a dose-response association between alcohol consumption and AMD or the association between moderate alcohol consumption and AMD. CONCLUSIONS Heavy alcohol consumption (more than three standard drinks per day) is associated with an increased risk of early AMD. Although this association seems to be independent of smoking, residual confounding effects from smoking cannot be excluded completely.

Correlation of Light-Flicker–Induced Retinal Vasodilation and Retinal Vascular Caliber Measurements in Diabetes

PURPOSE Subtle changes in retinal vascular caliber have been shown to predict diabetic retinopathy and other diabetic complications. This study was undertaken to investigate whether retinal vascular caliber correlates with light-flicker-induced retinal vasodilation, a measure of endothelial function. METHODS The participants were 224 persons with diabetes (85 type 1 and 139 type 2) and 103 persons without diabetes (controls). Flicker-induced retinal vasodilation (percentage increase over baseline diameter) was measured with a vessel analyzer. Retinal vascular caliber was measured from digital retinal photographs according to a standardized, validated protocol. Data from both right and left eyes were used and modeled with generalized estimating equations to account for correlation between eyes. RESULTS In persons with diabetes, after adjustment for age and sex, reduced flicker-induced vasodilation was associated with wider retinal vascular caliber. Eyes with the lowest tertiles of flicker-induced arteriolar dilation had wider arteriolar caliber (5.40 mum; 95% confidence interval [CI], 1.76-9.05) and eyes with the lowest tertiles of flicker-induced venular dilation had corresponding wider venular caliber (12.4 mum; 95% CI, 6.48-18.2), respectively, than eyes with the highest tertile of vasodilation. These associations persisted after further adjusting for diabetes duration, systolic blood pressure, fasting glucose, lipids, body mass index, current smoking, and presence of diabetic retinopathy. No associations were evident in persons without diabetes. CONCLUSIONS Changes in retinal vascular caliber (wider arterioles and venules) are associated with impaired flicker-induced vasodilation in persons with diabetes. Determining whether endothelial dysfunction explains the link between retinal vascular caliber and risks of diabetic microvascular complications calls for further study.

Diabetic Retinopathy Is Related to Both Endothelium-Dependent and Independent Responses of Skin Microvascular Flow

OBJECTIVE Endothelial dysfunction has been hypothesized as a possible pathogenic factor in the development of diabetic retinopathy (DR). We examined the relationship of DR to endothelium-dependent and endothelium-independent responses in skin microvascular flow. RESEARCH DESIGN AND METHODS Participants consisted of 224 individuals with diabetes: 85 with type 1 diabetes and 139 with type 2 diabetes. Sodium nitroprusside (SNP) and acetylcholine (ACh) were delivered across the skin by iontophoresis. Laser Doppler flowmetry was used to assess the skin microcirculation response to SNP (endothelium-independent response) and ACh (endothelium-dependent response). The presence and severity of DR were graded from retinal photographs using a standard protocol. RESULTS Of 224 participants, 64.3% had DR. After multivariable adjustment, participants with reduced responses to SNP or ACh were more likely to have DR, with an odds ratio (OR) of 2.33 (95% CI 1.09–5.01) for SNP and 2.20 (1.05–4.61) for ACh, comparing participants with responses below and above the median values. Participants with reduced responses (below the median) to both SNP and ACh were nearly four times more likely to have DR (OR 3.86 [1.45–10.3]) than those with SNP and ACh both above the median values. CONCLUSIONS The presence of DR was associated with a reduction in skin microcirculation responses to iontophoresis of both SNP and ACh, suggesting that vascular processes associated with both endothelial dysfunction and endothelial function-independent mechanisms may be pathogenically related to DR.

Reliability of Different Image Analysis Methods for Scanning Laser Doppler Flowmetry

Purpose: To assess reliability and reproducibility of different analysis methods for retinal capillary flow, volume, and velocity from scanning laser Doppler flowmetry (SLDF) topography. Material and Methods: SLDF topography analysis using the default retinal flowmeter (HRF) were compared to that using automatic full-field perfusion image analyzer (AFFPIA) and quantified as intraclass correlation coefficients (ICC). Results: The AFFPIA full-field method had the highest reliability, with ICC 0.99 for capillary flow. The reproducibility using the AFFPIA full-field method was high ICC 0.74 for capillary flow. Conclusions: The AFFPIA full-field method is highly reliable and superior to the default HRF software.

Reproducibility of the Retinal Vascular Response to Flicker Light in Asians

Purpose: Dilation of retinal vessels in response to diffuse luminance flicker may reflect endothelial function. Although this has previously been shown to be reproducible in whites, there have been no similar data in Asians. We assess the reproducibility of repeated measurements of this response in Asians. Material and Methods: Healthy Asians (n = 33) with normal vision and no history of glaucoma, age-related macular degeneration, cataract, or retinal arterial/venous occlusion participated in this study. Repeated measures from the same subjects were taken 30–60 min apart using the Dynamic Vessel Analyser (DVA, IMEDOS, Jena, Germany). Modification was made to the shape of the light source for Asian participants. Correlations of the first and second measures were assessed using Pearson correlation (R2), and agreement between the two measures was shown using Bland–Altman plots. Results: After modification to the shape of the light source, almost perfect correlation was found between the 1st and 2nd measurements of baseline arteriolar (R2 = 0.95) and venular diameters (R2 = 0.98) of arteriolar maximum dilation (R2 = 0.85). Substantially high correlation between the 1st and 2nd measurements of venular maximum dilation was found (R2 = 0.80). Conclusions: Measurements of the dilation response of retinal vessels to diffuse luminance flicker an Asian sample using the DVA show high reproducibility for repeated measures over a short period of time. Such measurements may allow non-invasive quantification of endothelial function to study its association with systemic and ocular diseases.

Acute Retinal Arteriolar Emboli After Cardiac Catheterization

Background and Purpose— There are concerns that cardiac catheterization may cause retinal embolization, a risk marker for cerebrovascular emboli and stroke. We describe the incidence of acute retinal embolism after cardiac catheterization. Methods— One hundred unselected patients attending a tertiary referral center for diagnostic cardiac catheterization were recruited. Digital retinal photography (optic disc and macular fields) was performed precatheterization and within 3 hours postcatheterization. New retinal emboli were identified by a senior researcher and confirmed by a retinal specialist. Results— There was one case of retinal embolus precatheterization. Two patients (incidence 2.02%; 95% CI, 0.25 to 7.11) developed new retinal arteriolar emboli after catheterization. No patient developed clinically apparent visual or neurological changes. Conclusions— The risk of acute retinal embolism immediately after cardiac catheterization is 2%. This finding indicates that the retinal, and possibly the cerebral circulation, may be compromised more frequently than is clinically apparent as a complication of cardiac catheterization.

Are Retinal Microvascular Caliber Changes Associated with Severity of Coronary Artery Disease in Symptomatic Cardiac Patients

Objectives: Recent population‐based studies have shown that retinal vascular caliber may predict the risk of clinical coronary artery disease (CAD) events. Whether this association is related to macro‐ or microvascular mechanisms remains unknown. We investigated the relationship of retinal vascular caliber with severity and extent of CAD in symptomatic cardiac patients.

'Flow out technique' for safe and complete removal of ophthalmic viscosurgical devices after phacoemulsification cataract surgery.

Objective: Ophthalmic viscosurgical devices (OVDs) are widely used in phacoemulsification cataract surgery. The adverse effects of OVDs retained after cataract surgery are well known, and complete OVD removal should be achieved in every case. Methods: We describe a novel and simple technique using a two-handed irrigation and aspiration (I/A) for safer removal of OVDs. Results: The technique was successfully used in 125 eyes of 125 patients after the completion of phacoemulsification cataract surgery. No intra or postoperative complications were observed. Conclusions: The technique described is safe and uses the anatomy of the capsular bag and the dynamics of the I/A ports for the complete removal of OVDs.