Interaction between Solvatochromic Dyes and Water Sampled from a Natural Source Treated with High Dilutions of Phosphorus.

BACKGROUND: Highly diluted and succussed solutions interact with solvatochromic dyes, indicating that changes in solvent and solute polarity could be related to their mechanism of action. It is not known, however, how the activity associated with succussed high dilutions is transferred to untreated water and what the limits of this process are. AIMS: The aims of the present study were to ascertain whether a succussed high dilution of phosphorus (1.5 × 1-59 M; Phos 30cH) seeded into a natural water source that fed a fjord and two connected lakes could propagate itself through the lake system (total volume 2200 m3) and, moreover, whether the process could be tracked using solvatochromic dyes. METHODS: Samples of water were collected before and after seeding, at different times and places throughout the lake system. Controls comprised water taken from an untreated and adjacent, but independent, lake (1385 m3). RESULTS: Water samples taken up to 72 hours after the source treatment produced significant increases (p ≤ 0.03) in the absorbance of the solvatochromic dye methylene violet (MV), while samples from the control lake produced no changes. CONCLUSIONS: The study indicates that activity associated with Phos 30c can propagate itself through large volumes of water, causing changes throughout a whole connected lake system, and that these changes can be tracked using the solvatochromic dye MV. This in turn means the use of homeopathic medicines in large volumes of drinking water, in farming and ecological contexts, now has the potential to be assessed with physico-chemical monitoring.

Mat Seroprevalence Infers Low Rates of Toxoplasma gondii in Domestic Pigs from Yucatan, Mexico.

Toxoplasma gondii is a zoonotic parasite of worldwide distribution. The consumption of infected pork meat has been suggested to be an important source for human infection in the tropical area of Yucatan, Mexico. We performed a cross-sectional study of 12 farms across the state to investigate the seroprevalence of Toxoplasma gondii infection in domestic pigs. In total, 632 samples were obtained from 2 different environmental zones (tropical deciduous low forest and tropical sub-deciduous medium forest) and 2 abattoirs. The modified agglutination test (MAT) was used to assess the seroprevalence of T. gondii in pigs and to evaluate 2 globally used serological tests, the Dye test (DT) and ID Screen® ELISA multi-species, and a commercial ELISA kit (Human Toxo IgG, Human-diagnostics), which is widely used locally in this geographical area. The overall prevalence obtained with the MAT (cut-off ≥1:25) among the 632 pigs was 1.4% (95% CI, 0.6-2.7%). The seroprevalence obtained for the different age groups was 0.6%, 0.7%, 1.8%, and 6.8% among 2-3, 3-4, 4-5, and ≥5-mo-old pigs. This increase in the seroprevalence was statistically significant for the 2 older groups (odds ratio [OR] 3.9-7.1, P < 0.05) in comparison with younger groups. DT at >4 IU dilution had a perfect agreement and 100% of sensitivity and specificity when compared with the MAT. Although ID Screen® had only a fair agreement (κ = 0.389) with the MAT, the McNemar test showed that the results of these tests were comparable (P = 0.29). The Human Toxo ELISA showed no agreement with MAT, ID Screen®, and DT (κ = 0.000-0.023, McNemar P < 0.05). This ELISA was lacking in specificity, accuracy, and precision; hence, we do not recommend its use for T. gondii diagnosis in pig serum.

Cardiac output measurement during exercise in COPD: A comparison of dye dilution and impedance cardiography.

INTRODUCTION: Impedance cardiography (IC) derived from morphological analysis of the thoracic impedance signal is now commonly used for noninvasive assessment of cardiac output (CO) at rest and during exercise. However, in Chronic Obstructive Pulmonary Disease (COPD), conflicting findings put its accuracy into question. OBJECTIVES: We therefore compared concurrent CO measurements captured by IC (PhysioFlow: COIC ) and by the indocyanine green dye dilution method (CODD ) in patients with COPD. METHODS: Fifty paired CO measurements were concurrently obtained using the two methods from 10 patients (FEV1 : 50.5 ± 17.5% predicted) at rest and during cycling at 25%, 50%, 75% and 100% peak work rate. RESULTS: From rest to peak exercise COIC and CODD were strongly correlated (r = 0.986, P < 0.001). The mean absolute and percentage differences between COIC and CODD were 1.08 L/min (limits of agreement (LoA): 0.05-2.11 L/min) and 18 ± 2%, respectively, with IC yielding systematically higher values. Bland-Altman analysis indicated that during exercise only 7 of the 50 paired measurements differed by more than 20%. When data were expressed as changes from rest, correlations and agreement between the two methods remained strong over the entire exercise range (r = 0.974, P < 0.001, with no significant difference: 0.19 L/min; LoA: -0.76 to 1.15 L/min). Oxygen uptake (VO2 ) and CODD were linearly related: r = 0.893 (P < 0.001), CODD = 5.94 × VO2 + 2.27 L/min. Similar results were obtained for VO2 and COIC (r = 0.885, P < 0.001, COIC = 6.00 × VO2 + 3.30 L/min). CONCLUSIONS: These findings suggest that IC provides an acceptable CO measurement from rest to peak cycling exercise in patients with COPD.

Combined use of fluorescence with a magnetic tracer and dilution effect upon sentinel node localization in a murine model.

BACKGROUND: Sentinel node biopsy using radioisotope and blue dye remains a gold standard for axillary staging in breast cancer patients with low axillary burden. However, limitations in the use of radioisotopes have resulted in emergence of novel techniques. This is the first in vivo study to assess the feasibility of combining the two most common novel techniques of using a magnetic tracer and indocyanine green (ICG) fluorescence. MATERIALS AND METHODS: A total of 48 mice were divided into eight groups. Groups 1 and 2, the co-localization groups, received an injection of magnetic tracers (Resovist® and Sienna+®, respectively) and ICG fluorescence; distilled water was used as the solvent of ICG. Groups 3 and 4, the diluted injection groups, received an injection of magnetic tracers (Resovist and Sienna+, respectively) and saline for dilution. Groups 5, 6, and 7, the control groups, received magnetic tracer (Resovist, Sienna+) and ICG alone, respectively. Fluorescent intensity assessment and iron quantification of excised popliteal lymph nodes were performed. Group 1', a co-localization group, received an injection of magnetic tracers (Resovist) and ICG' fluorescence: saline was used as the solvent for ICG. RESULTS: Lymphatic uptake of all tracers was confined to the popliteal nodes only, with co-localization confirmed in all cases and no significant difference in fluorescent intensity or iron content of ex vivo nodes between the groups (except for Group 1'). There was no impact of dilution on the iron content in the diluted Sienna+ group, but it significantly enhanced Resovist uptake (P=0.005). In addition, there was a significant difference in iron content (P=0.003) in Group 1'. CONCLUSION: The combination of a magnetic tracer (Resovist or Sienna+) and ICG fluorescence is feasible for sentinel node biopsy and will potentially allow for precise transcutaneous node identification, in addition to accurate intraoperative assessment. This radioisotope-free "combined technique" warrants further assessment within a clinical trial.

Quantitative analysis of cell proliferation by a dye dilution assay: Application to cell lines and cocultures.

Cell proliferation represents one of the most fundamental processes in biological systems, thus the quantitative analysis of cell proliferation is important in many biological applications such as drug screening, production of biologics, and assessment of cytotoxicity. Conventional proliferation assays mainly quantify cell number based on a calibration curve of a homogeneous cell population, and therefore are not applicable for the analysis of cocultured cells. Moreover, these assays measure cell proliferation indirectly, based on cellular metabolic activity or DNA content. To overcome these shortcomings, a dye dilution assay employing fluorescent cell tracking dyes that are retained within cells was applied and was diluted proportionally by subsequent cell divisions. Here, it was demonstrated that this assay could be implemented to quantitatively analyze the cell proliferation of different types of cell lines, and to concurrently analyze the proliferation of two types of cell lines in coculture by utilizing cell tracking dyes with different spectral characteristics. The mean division time estimated by the dye dilution assay is compared with the population doubling time obtained from conventional methods and values from literature. Additionally, dye transfer between cocultured cells was investigated and it was found that it is a characteristic of the cells rather than a characteristic of the dye. It was suggested that this method can be easily combined with other flow cytometric analyses of cellular properties, providing valuable information on cell status under diverse conditions. © 2017 International Society for Advancement of Cytometry.

Dynamic fluorescent imaging with the activatable probe, γ-glutamyl hydroxymethyl rhodamine green in the detection of peritoneal cancer metastases: Overcoming the problem of dilution when using a sprayable optical probe.

Optical fluorescence-guided imaging is increasingly used to guide surgery and endoscopic procedures. Activatable probes are particularly useful because of high target-to-background ratios that increase sensitivity for tiny cancer foci. However, green fluorescent activatable probes suffer from interference from autofluorescence found in biological tissue. The purpose of this study was to determine if dynamic imaging can be used to differentiate specific fluorescence arising from an activated probe in a tumor from autofluorescence in background tissues especially when low concentrations of the dye are applied. Serial fluorescence imaging was performed using various concentrations of γ-glutamyl hydroxymethyl rhodamine green (gGlu-HMRG) which was sprayed on the peritoneal surface with tiny implants of SHIN3-DsRed ovarian cancer tumors. Temporal differences in signal between specific green fluorescence in cancer foci and non-specific autofluorescence in background tissue were measured at 5, 10, 20 and 30 min after application of gGlu-HMRG and were processed into three kinetic maps reflecting maximum fluorescence signal (MF), wash-in rate (WIR), and area under the curve (AUC), respectively. Using concentrations up to 10 µM of gGlu-HMRG, the fluorescence intensity of cancer foci was significantly higher than that of small intestine but only at 30 min. However, on kinetic maps derived from dynamic fluorescence imaging, the signal of cancer foci was significantly higher than that of small intestine after only 5 min even at concentrations as low as 2.5 µM of gGlu-HMRG (p < 0.01). At lower concentrations, kinetic maps derived from dynamic fluorescence imaging were superior to unprocessed images for cancer detection.

Blue dye can be safely omitted in most sentinel node procedures for melanoma.

Sentinel node biopsy is a widely used staging procedure in melanoma. It is usually performed using the triple technique: lymphatic mapping after injection of a radiopharmaceutical, blue dye injection, and the use of a gamma probe. Blue dye offers visual confirmation of the location of the sentinel lymph node (SN). There are some disadvantages such as blurring of the surgical field, skin coloring, and possible anaphylactic reactions. We aimed to answer the question whether patent blue is truly necessary for correct intraoperative identification of the SN. One day preoperatively, lymphoscintigraphy (with or without single-photon emission computed tomography with integrated computed tomography) is performed and the location of the SN is marked on the skin. Perioperatively, patent blue is injected around the tumor. A handheld gamma-ray detection probe is used to determine the location of the incision and detect the SN during the operation. SNs are pursued in all regions indicated by imaging. In only six of the 681 patients (0.9%) a blue, not radioactive, sentinel node was removed. In one of them (0.15%), this was the only node excised. None of these lymph nodes harbored metastases. This study suggests that blue dye has no additional value in finding the sentinel node and is of low significance in detecting metastases. Therefore, blue dye can be safely omitted from the standardized triple technique. It may be useful in selected cases according to the surgeon's discretion.

Correlation of ultrasound estimated with dye-determined or directly measured amniotic fluid volume revisited.

BACKGROUND/AIMS: To examine the relationship of the amniotic fluid index (AFI) and single deepest pocket (SDP) with an AFV as modelled by Brace or Magann. METHODS: AFI and SDP were evaluated for their correlation with an actual AFV using the Spearman correlation coefficient. RESULTS: 482 AFI and 468 SDP pregnancies were evaluated. There was a significant association between the AFI and SDP and an actual AFV (p < 0.0001). The AFI range of 5.1-20 was better correlated than 5.1-24 for normal AFVs Brace (κ = 0.175) and Magann (κ = 0.356) versus 5.1-24 (κ = 0.150 and κ = 0.319), respectively. The agreement level t for the AFI (κ = 0.175) and SDP (κ = 0.126) using Brace was slight and for the AFI (κ = 0.356) and SDP (κ = 0.295) using Magann was fair. CONCLUSIONS: Both the AFI and SDP were correlated with actual AFV using both models. AFI of 5.1-20 better categorizes normal volumes. Although the Magann model correlates AFI/SDP and AFV better, the superiority is minimal.

Optimal back-extrapolation method for estimating plasma volume in humans using the indocyanine green dilution method.

BACKGROUND: The indocyanine green dilution method is one of the methods available to estimate plasma volume, although some researchers have questioned the accuracy of this method. METHODS: We developed a new, physiologically based mathematical model of indocyanine green kinetics that more accurately represents indocyanine green kinetics during the first few minutes postinjection than what is assumed when using the traditional mono-exponential back-extrapolation method. The mathematical model is used to develop an optimal back-extrapolation method for estimating plasma volume based on simulated indocyanine green kinetics obtained from the physiological model. RESULTS: Results from a clinical study using the indocyanine green dilution method in 36 subjects with type 2 diabetes indicate that the estimated plasma volumes are considerably lower when using the traditional back-extrapolation method than when using the proposed back-extrapolation method (mean (standard deviation) plasma volume = 26.8 (5.4) mL/kg for the traditional method vs 35.1 (7.0) mL/kg for the proposed method). The results obtained using the proposed method are more consistent with previously reported plasma volume values. CONCLUSIONS: Based on the more physiological representation of indocyanine green kinetics and greater consistency with previously reported plasma volume values, the new back-extrapolation method is proposed for use when estimating plasma volume using the indocyanine green dilution method.

Influence of the para-aminohippuric acid analysis method on the net hepatic flux of nutrients in lactating cows.

Para-aminohippuric acid (pAH) is a marker frequently used to measure plasma or blood flow. In sheep studies, it is recognized that its determination must include a deacetylation step to counteract the hepatic acetylation of pAH. Such a procedure is not of common usage in cattle studies although a recent suggestion of hepatic pAH acetylation in dairy cows may have important consequences for hepatic nutrient fluxes. The aims of this study were to evaluate pAH analytical methods according to international procedures of metrology and confirm hepatic acetylation of pAH in dairy cows. The effect of the matrix used to prepare the standard curve was tested, and the influence of the pAH analytical method on blood flows and subsequent net hepatic fluxes of nutrients was determined. For the first objective, accuracy profiles were established and bias, indicators of precision, and limits of quantification were reported for 2 analytical methods (without and with a pAH deacetylation step) using 2 different standard matrices (water and plasma). Second, the net hepatic flux of different nutrients was determined including or not the deacetylation step and preparing the standard curves in plasma using samples collected from 5 multicatheterized lactating Jersey cows. The choice of the matrix had a significant impact on plasma pAH concentrations as illustrated by accuracy profiles. Water matrix decreased (P < 0.01) the slope, y-intercept, and the absorbance at concentration 0 mg pAH/L of the standard curve in both methods (without and with the deacetylation), supporting that standards prepared in water should not be used to analyze plasma samples. Samples collected on cows confirmed hepatic acetylation of pAH across the liver. Deacetylation, performed using plasma as the standard matrix, increased (P < 0.05) plasma pAH concentrations from 18.4, 26, and 23.5 to 21.4, 28.9, and 27.3 mg/L in the artery, portal vein, and hepatic vein, respectively. Deacetylation decreased the hepatic venous and arterial plasma and blood flows (P < 0.05) by 9 and 55%, respectively, modifying the net hepatic flux of acetate, total amino acid, and oxygen by more than 19% (P < 0.05). In conclusion, our results highlight the importance of including a deacetylation step in the pAH analysis method in cattle studies and of using plasma as standard matrix.

A century of indicator dilution technique.

This review imparts the history and the present status of the indicator dilution technique with quantitative bolus injection. The first report on flow measurement with this technique appeared 100 years ago. In 1928, the use of intravascular dyes made possible a widespread application in animals and human during the next decades. Multiple indicators, radioactive tracers, inlet-outlet detection and residue detection were introduced in the 1950s and 1960s, and refined along with the development of indicator kinetics. From the 1970s, a wide clinical use in the study of heart, brain, lungs, liver and kidneys developed, and powerful computers in the 1980s and 1990s accorded the technique a new dimension. Today, the indicator dilution technique, on one hand, is applied in the same way as 100 years ago, on the other hand it forms the basis of quantitative SPECT, positron emission tomography, and dynamic MR scans. The technique still undergoes refinement and elaboration as a lasting concept with a high potential for further development.

Amniotic fluid volume in normal singleton pregnancies: modeling with quantile regression.

PURPOSE: To develop uniform and reliable reference ranges for amniotic fluid volume (AFV) across gestation in normal singleton pregnancies using quantile regression (QR). METHODS: An analysis of true AFVs determined by dye-dilution techniques or by direct measurement at cesarean delivery in normal singleton pregnancies. AFV centiles were established by QR, a flexible semi-parametric approach of estimating rates of change across the entire distribution of AFV rather than just in the mean as is observed with standard linear regression. RESULTS: The study evaluated 379 women with normal singleton pregnancies between 16 and 41 weeks gestation. QR was used to determine the association between AFV and gestational age (GA). A second-order quantile regression model indicated a nonlinear relationship between AFV and gestational age at the upper centile range (≥80th percentile). CONCLUSION: This study defines normative centile charts for true AFVs between 16 and 41 weeks gestation in normal singleton pregnancies using QR. This statistical approach more appropriately reflects true AFV across gestation at each centile of interest (e.g. 5th, 50th, 95th, etc.) as compared to standard linear regression.

Sentinel node mapping in anal canal cancer: systematic review and meta-analysis.

BACKGROUND & AIMS: The pathological condition of inguinal lymph nodes is an independent prognostic factor in predicting tumor recurrence and overall survival in anal canal cancer. Sentinel node mapping is a non-invasive method for the detection of inguinal lymph node involvement in anal cancer. In the current study, we conducted a comprehensive search of literature in this regard and then interpreted the final results in a systematic review and meta-analysis format. METHODS: Medline, SCOPUS, and ISI Web of Knowledge were searched with the following search terms: (anal OR anus) AND sentinel. Outcomes of interest were inguinal detection rate and inguinal recurrence in patients receiving inguinal sparing radiotherapy due to pathologically negative inguinal sentinel nodes (false negative cases). RESULTS: Overall 16 studies (323 patients) were included in the meta-analysis. Pooled inguinal detection rate was 86.2%: 73.4-93.4%: for studies using both blue dye and radiotracer it was 90.1% [78.7-95.8] and for studies using radiotracer alone it was 72.4% [46.3-88.9]. Pooled sensitivity was 90% [79-97%]. CONCLUSIONS: Sentinel node biopsy is a promising method for inguinal lymph node staging in anal cancer. Combined blue dye and radiotracer technique can maximize the inguinal detection rate. Location of the tumor is highly associated with the detection of inguinal sentinel nodes. Despite fairly high pooled sensitivity, no definite conclusion can be made regarding false negative rate of this technique due to low sample size and sub-optimal quality of the included studies. Large multicenter studies with long and consistent follow up are needed to definitely validate this technique in the future.

A method for evaluating the use of fluorescent dyes to track proliferation in cell lines by dye dilution.

Labeling nonquiescent cells with carboxyfluorescein succinimidyl ester (CFSE)-like dyes gives rise to a population width exceeding the threshold for resolving division peaks by flow cytometry. Width is a function of biological heterogeneity plus extrinsic and intrinsic error sources associated with the measurement process. Optimal cytometer performance minimizes extrinsic error, but reducing intrinsic error to the point of facilitating peak resolution requires careful fluorochrome selection and fluorescent cell sorting. In this study, we labeled the Jurkat and A549 cell lines with CFSE, CellTraceViolet (CTV), and eFluor 670 proliferation dye (EPD) to test if we could resolve division peaks in culture after reducing the labeled input widths by cell sorting. Reanalysis of the sorted populations to ascertain the level of reduction achieved always led to widths exceeding the gated limits due to the contribution of errors. Measuring detector-specific extrinsic error by sorting uniform fluorescent particles with similar spectral properties to the tracking dyes allowed us to determine the intrinsic error for each dye and cell type using a simple mathematical approach. We found that cell intrinsic error ultimately dictated whether we could resolve division peaks, and that as this increased, the required sort gate width to resolve any division peaks decreased to the point whereby issues with yield made A549 unsuitable for this approach. Finally, attempts to improve yields by setting two concurrent sort gates on the fluorescence distribution enriched for cells in different stages of the cell cycle that had nonequivalent proliferative properties in culture and thus should be practiced with caution.

[Extravascular lung water: from genes to telemedicine]. / Acqua extravascolare polmonare: dalla genetica alla telemedicina.

Extravascular lung water is a crucial parameter for the management of many different pathological conditions, especially heart failure. Many modalities can be employed for its evaluation, each with different advantages and limitations. In a near future, we hope that extravascular lung water assessment could be performed by non-invasive wearable devices, allowing remote continuous monitoring of pulmonary congestion. Recently, it has been proposed that some specific genetic variations may be responsible for the heterogeneous individual response to the development of extravascular lung water. These data could be relevant to titrate and personalize both treatments and preventive interventions.

[A dye densitometry analysis method for noninvasive measurement of cardiac output based on NIRS].

Currently, there exist technology problems in cardiac output (CO) parameter detection clinically, such as invasive and complex operation, as well as possibility of infection and death for patients. In order to solve these problems, a noninvasive and continuous method based on NIRS for CO detection was presented. In this way, the concentration changing of indocyanine green (ICG) dye in the patient's arterial blood was dynamically measured and analyzed, so that the CO could be noninvasively and continuously measured according to the characteristic parameters of dye densitometry curve. While the ICG dye was injected into the patient's body by the median cubital vein, block of photoelectric pulse dye densitometry measurement system as the lower machine acquired pulse wave data and uploaded the data to upper computer. In the scheme, two specialized light sources of LED at 940 and 805 nm were used to capture the signals of sufferer's fingertip pulse wave synchronously and successively. The CO value could then be successfully calculated through drawing complete ICG concentration variation of dye dilution and excretion process and computing mean transmission time (MTT) by upper computer. Compared with the "gold standard" method of thermodilution, the maximum relative error of this method was below 9. 76%, and the mean relative error was below 4. 39%. The result indicates that the method can be used as a kind of convenient operation, noninvasive and continuous solution for clinical CO measurement.

Amniotic fluid and the clinical relevance of the sonographically estimated amniotic fluid volume: oligohydramnios.

The amniotic fluid volume (AFV) is regulated by several systems, including the in-tramembranous pathway, fetal production (fetal urine and lung fluid) and uptake (fetal swallowing), and the balance of fluid movement via osmotic gradients. The normal AFV across gestation has not been clearly defined; consequently, abnormal volumes are also poorly defined. Actual AFVs can be measured by dye dilution techniques and directly measured at cesarean delivery; however, these techniques are time-consuming, are invasive, and require laboratory support, and direct measurement can only be done at cesarean delivery. As a result of these limitations, the AFV is estimated by the amniotic fluid index (AFI), the single deepest pocket, and subjective assessment of the AFV. Unfortunately, sonographic estimates of the AFV correlate poorly with dye-determined or directly measured amniotic fluid. The recent use of color Doppler sonography has not improved the diagnostic accuracy of sonographic estimates of the AFV but instead has led to overdiagnosis of oligohydramnios. The relationship between the fixed cutoffs of an AFI of 5 cm or less and a single deepest pocket of 2 cm or less for identifying adverse pregnancy outcomes is uncertain. The use of the single deepest pocket compared to the AFI to identify oligohydramnios in at-risk pregnancies seems to be a better choice because the use of the AFI leads to an increase in the diagnosis of oligohydramnios, resulting in more labor inductions and cesarean deliveries without any improvement in peripartum outcomes.

[Quantification of fluorescein angiography in patients with non-arteritic anterior ischemic optic neuropathy]. / Quantifizierung von Fluoreszenzangiographien bei Patienten mit nichtarteriitischer anteriorer ischämischer Optikusneuropathie.

PURPOSE: The aim of this study was to evaluate the retinal hemodynamics and optic disc leakage by fluorescein angiography in patients with non-arteritic anterior ischemic optic neuropathy (NAION) and to correlate fluorescein angiography findings with the extent and topography of visual field loss. METHODS: A total of 26 patients with acute NAION were included in the study. Fluorescein angiograms were performed by means of a scanning laser ophthalmoscope. The extent of early-phase optic disc leakage was assessed using a semiquantitative approach (focal versus diffuse type of leakage). Retinal arteriovenous passage (AVP) times were measured using dye dilution curves and digital image analysis for each hemisphere. The number of defective visual field points (StatPac: p<0.5%, uncorrected deviation plot) were evaluated (30/2 SITA, Humphrey-Zeiss) for the hemifields and different sectors. RESULTS: In this study of patients with NAION the mean AVP was 1.79 s±0.43 which was not significantly correlated to the number of defective points. Furthermore, AVP was not significantly different in focal versus diffuse optic disc leakage. The number of defective points were not significantly different in focal versus diffuse leakage of the optic disc (p=0.57). CONCLUSION: Retinal perfusion is not linked to the type and topography of disc leakage or the extent and topography of visual field damage in NAION. A global circulatory disorder e.g. due to a compartment syndrome of the optic nerve might account for these results.