Determination of meropenem in plasma and filtrate-dialysate from patients under continuous veno-venous haemodiafiltration by SPE-LC.

Meropenem, a carbapenem antibiotic displaying a broad spectrum of antibacterial activity, is administered in Medical Intensive Care Unit to critically ill patients undergoing continuous veno-venous haemodiafiltration (CVVHDF). However, there are limited data available to substantial rational dosing decisions in this condition. In an attempt to refine our knowledge and propose a rationally designed dosage regimen, we have developed a HPLC method to determine meropenem after solid-phase extraction (SPE) of plasma and dialysate fluids obtained from patients under CVVHDF. The assay comprises the simultaneous measurement of meropenem's open-ring metabolite UK-1a, whose fate has never been studied in CVVHDF patients. The clean-up procedure involved a SPE on C18 cartridge. Matrix components were eliminated with phosphate buffer pH 7.4 followed by 15:85 MeOH-phosphate buffer pH 7.4. Meropenem and UK-1a were subsequently desorbed with MeOH. The eluates were evaporated under nitrogen at room temperature (RT) and reconstituted in phosphate buffer pH 7.4. Separation was performed at RT on a Nucleosil 100-5 microm C18 AB cartridge column (125 x 4 mm I.D.) equipped with a guard column (8 x 4 mm I.D.) with UV-DAD detection set at 208 nm. The mobile phase was 1 ml min(-1), using a step-wise gradient elution program: %MeOH/0.005 M tetrabutylammonium chloride pH 7.4; 10/90-50/50 in 27 min. Over the range of 5-100 microg ml(-1), the regression coefficient of the calibration curves (plasma and dialysate) were >0.998. The absolute extraction recoveries of meropenem and UK-1a in plasma and filtrate-dialysate were stable and ranged from 88-93 to 72-77% for meropenem, and from 95-104 to 75-82% for UK-1a. In plasma and filtrate-dialysate, respectively, the mean intra-assay precision was 4.1 and 2.6% for meropenem and 4.2 and 3.7% for UK-1a. The inter-assay variability was 2.8 and 3.6% for meropenem and 2.3 and 2.8% for UK-1a. The accuracy was satisfactory for both meropenem and UK-1a with deviation never exceeding 9.0% of the nominal concentrations. The stability of meropenem, studied in biological samples left at RT and at +4 degrees C, was satisfactory with < 5% degradation after 1.5 h in blood but reached 22% in filtrate-dialysate samples stored at RT for 8 h, precluding accurate measurements of meropenem excreted unchanged in the filtrate-dialysate left at RT during the CVVHDF procedure. The method reported here enables accurate measurements of meropenem in critically ill patients under CVVHDF, making dosage individualisation possible in such patients. The levels of the metabolite UK-1a encountered in this population of patients were higher than those observed in healthy volunteers but was similar to those observed in patients with renal impairment under hemodialysis.

A novel method for quantification of sulfolane (a metabolite of busulfan) in plasma by gas chromatography-tandem mass spectrometry.

The role of busulfan (Bu) metabolites in the adverse events seen during hematopoietic stem cell transplantation and in drug interactions is not explored. Lack of availability of established analytical methods limits our understanding in this area. The present work describes a novel gas chromatography-tandem mass spectrometric assay for the analysis of sulfolane (Su) in plasma of patients receiving high-dose Bu. Su and Bu were extracted from a single 100 μL plasma sample by liquid-liquid extraction. Bu was separately derivatized with 2,3,5,6-tetrafluorothiophenolfluorinated agent. Mass spectrometric detection of the analytes was performed in the selected reaction monitoring mode on a triple quadrupole instrument after electronic impact ionization. Bu and Su were analyzed with separate chromatographic programs, lasting 5 min each. The assay for Su was found to be linear in the concentration range of 20-400 ng/mL. The method has satisfactory sensitivity (lower limit of quantification, 20 ng/mL) and precision (relative standard deviation less than 15 %) for all the concentrations tested with a good trueness (100 ± 5 %). This method was applied to measure Su from pediatric patients with samples collected 4 h after dose 1 (n = 46), before dose 7 (n = 56), and after dose 9 (n = 54) infusions of Bu. Su (mean ± SD) was detectable in plasma of patients 4 h after dose 1, and higher levels were observed after dose 9 (249.9 ± 123.4 ng/mL). This method may be used in clinical studies investigating the role of Su on adverse events and drug interactions associated with Bu therapy.

Surgical outcomes of Baerveldt aqueous shunt implantation versus combined phacoemulsification and Baerveldt aqueous shunt implantation

Purpose: To examine the efficacy and safety of Baerveldt shunt (BS) implantation compared to combined phacoemulsification and Baerveldt shunt implantation (PBS). This study was designed to detect a difference in IOP reduction of 20% (~4mmHg) between groups with 90% power. Methods: Sixty patients with medically uncontrolled glaucoma, prospectively underwent either or BS implantation with phacoemulsification (Group PBS; n=30) or BS implantation alone (group BS; n=30, pseudophakic eyes only). Groups were matched for age, glaucoma subtype and length of follow-up. Pre and post-operative measures recorded included patient demographics, visual acuity, IOP, number of glaucoma medications (GMs) and all complications. Success was defined as IOP≤21mmHg and 20% reduction in IOP from baseline with or without GMs. Results: Age of PBS and BS groups was 61 vs 62 years respectively (p=0.72*). There were no significant differences in preoperative baseline characteristics: PBS vs PB, mean IOP =25.5mmHg (standard deviation (SD); ±10.3mmHg) vs 26.1mmHg (SD ±10.6mmHg), p=0.81*; mean GMs=3.0 (SD ±1.1) vs 3.1 (SD ±1.0), p=0.83*; mean VA=0.3 vs 0.3, p=0.89*. At year one there were no significant differences observed between groups in post-operative IOP, GMs or VA, mean IOP =14.1mmHg (SD ±5.4mmHg) vs 11.5 mmHg (SD ±4.2mmHg), p=0.12*; mean GMs=1.6 (SD ±1.4) vs 1.1 (SD ±1.1), p=0.23*; mean VA=0.5 vs 0.4, p=0.46*. Complication rates were similar between the two groups (7% vs 14%). Success rate was lower in eyes with PBS (71%) than with BS (88%), however this did not reach statistical significance (p=0.95, log-rank test). * two-sample t-test Conclusions: There were no significant differences at year one in success or complication rates between PBS and BS groups suggesting that simultaneous phacoemulsification does not have a marked (difference of >4mmHg) effect on tube function. IOP reduction and success were less in the PBS group, a larger sample (n=120) would be required to investigate if there is a 10% difference in IOP reduction between groups, however it is unclear if this would be a clinically significant difference to justify separate surgeries.

FTO genotype is associated with phenotypic variability of body mass index.

There is evidence across several species for genetic control of phenotypic variation of complex traits, such that the variance among phenotypes is genotype dependent. Understanding genetic control of variability is important in evolutionary biology, agricultural selection programmes and human medicine, yet for complex traits, no individual genetic variants associated with variance, as opposed to the mean, have been identified. Here we perform a meta-analysis of genome-wide association studies of phenotypic variation using ∼170,000 samples on height and body mass index (BMI) in human populations. We report evidence that the single nucleotide polymorphism (SNP) rs7202116 at the FTO gene locus, which is known to be associated with obesity (as measured by mean BMI for each rs7202116 genotype), is also associated with phenotypic variability. We show that the results are not due to scale effects or other artefacts, and find no other experiment-wise significant evidence for effects on variability, either at loci other than FTO for BMI or at any locus for height. The difference in variance for BMI among individuals with opposite homozygous genotypes at the FTO locus is approximately 7%, corresponding to a difference of ∼0.5 kilograms in the standard deviation of weight. Our results indicate that genetic variants can be discovered that are associated with variability, and that between-person variability in obesity can partly be explained by the genotype at the FTO locus. The results are consistent with reported FTO by environment interactions for BMI, possibly mediated by DNA methylation. Our BMI results for other SNPs and our height results for all SNPs suggest that most genetic variants, including those that influence mean height or mean BMI, are not associated with phenotypic variance, or that their effects on variability are too small to detect even with samples sizes greater than 100,000.

Radiation and energy balance of lettuce culture inside a polyethylene greenhouse

The objective of this paper was to describe the radiation and energy balance, during the lettuce (Lactuca sativa, L. cv. Verônica) crop cycle inside a polyethylene greenhouse. The radiation and energy balance was made inside a tunnel greenhouse with polyethylene cover (100 mum) and in an external area, both areas with 35 m². Global, reflected and net radiation, soil heat flux and air temperature (dry and humid) were measured during the crop cycle. A Datalogger, which operated at 1 Hz frequency, storing 5 minutes averages was utilized. The global (K¯) and reflected (K­) radiations showed that the average transmission of global radiation (K¯in / K¯ex) was almost constant, near to 79.59%, while the average ratio of reflected radiation (K­in / K­ex) was 69.21% with 8.47% standard-deviation. The normalized curves of short-wave net radiation, in relation to the global radiation (K*/ K¯), found for both environments, were almost constant at the beginning of cycle; this relation decreased in the final stage of culture. The normalized relation (Rn/ K¯) was bigger in the external area, about 12%, when the green culture covered the soil surface. The long-wave radiation balance average (L*) was bigger outside, about 50%. The energy balance, estimated in terms of vertical fluxes, showed that, for the external area, in average, 83.07% of total net radiation was converted in latent heat evaporation (LE), and 18% in soil heat flux (G), and 9.96% in sensible heat (H), while inside of the greenhouse, 58.71% of total net radiation was converted in LE, 42.68% in H, and 28.79% in G.

Time invested in the global respiratory care of cystic fibrosis paediatrics patients.

INTRODUCTION: Respiratory therapy is a keystone of the treatment for cystic fibrosis (CF) lung disease, but it is time consuming. OBJECTIVES: We aimed to assess the total time spent on respiratory therapy, including chest physiotherapy (CPT) and physical activity (PA), as well as inhalation therapy (IT) and maintenance of materials (MM) to rationalise and optimise treatment. METHODS: A cross-sectional prospective study in a paediatric CF cohort. A questionnaire was developed to look at the time spent on respiratory care over 3 months. Enrolled in this study are all CF patients aged from 6 to 16 years (the exclusion criterion was lung transplantation). RESULTS: Of the 40 enrolled patients, 22 participated (13 boys and 9 girls), with a mean age of 11 years. The patients spent approximately 19.46 h per week (standard deviation ± 7.53, 8.00-35.25 h) on therapy: CPT (30.58%), IT (15.11%), PA (50%) and MM (4.32%), without statistical significance between sexes. CONCLUSION: In our cohort, CF patients spent an average of nearly 20 h a week in respiratory therapy, within a wide range of between 8 h to almost 36 h a week. PA consumes almost half of the time. Physicians have to take into consideration the burden of the treatment, to optimise the therapy.

A LC-tandem MS assay for the simultaneous measurement of new antiretroviral agents: Raltegravir, maraviroc, darunavir, and etravirine.

Raltegravir (RAL), maraviroc (MVC), darunavir (DRV), and etravirine (ETV) are new antiretroviral agents with significant potential for drug interactions. This work describes a sensitive and accurate liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for the determination of plasma drug levels. Single-step extraction of RAL, MVC, DRV, ETV and RTV from plasma (100 microl) is performed by protein precipitation using 600 microl of acetonitrile, after the addition of 100 microl darunavir-d(9) (DRV-d(9)) at 1000 ng/ml in MeOH/H(2)O 50/50 as internal standard (I.S.). The mixture is vortexed, sonicated for 10 min, vortex-mixed again and centrifuged. An aliquot of supernatant (150 microl) is diluted 1:1 with a mixture of 20 mM ammonium acetate/MeOH 40/60 and 10 microl is injected onto a 2.1 x 50 mm Waters Atlantis-dC18 3 microm analytical column. Chromatographic separations are performed using a gradient program with 2 mM ammonium acetate containing 0.1% formic acid and acetonitrile with 0.1% formic acid. Analytes quantification is performed by electrospray ionisation-triple quadrupole mass spectrometry using the selected reaction monitoring detection in the positive mode. The method has been validated over the clinically relevant concentrations ranging from 12.5 to 5000 ng/ml, 2.5 to 1000 ng/ml, 25 to 10,000 ng/ml, 10 to 4000 ng/ml, and 5 to 2000 ng/ml for RAL, MRV, DRV, ETV and RTV, respectively. The extraction recovery for all antiretroviral drugs is always above 91%. The method is precise, with mean inter-day CV% within 5.1-9.8%, and accurate (range of inter-day deviation from nominal values -3.3 to +5.1%). In addition our method enables the simultaneous assessment of raltegravir-glucuronide. This is the first analytical method allowing the simultaneous assay of antiretroviral agents targeted to four different steps of HIV replication. The proposed method is suitable for the Therapeutic Drug Monitoring Service of these new regimen combinations administered as salvage therapy to patients having experienced treatment failure, and for whom exposure, tolerance and adherence assessments are critical.

Some common indexes of group diversity: upper boundaries

Workgroup diversity can be conceptualized as variety, separation, or disparity. Thus, the proper operationalization of diversity depends on how a diversity dimension has been defined. Analytically, the minimal diversity must be obtained when there are no differences on an attribute among the members of a group, however maximal diversity has a different shape for each conceptualization of diversity. Previous work on diversity indexes indicated maximum values for variety (e.g., Blau"s index and Teachman"s index), separation (e.g., standard deviation and mean Euclidean distance), and disparity (e.g., coefficient of variation and the Gini coefficient of concentration), although these maximum values are not valid for all group characteristics (i.e., group size and group size parity) and attribute scales (i.e., number of categories). We demonstrate analytically appropriate upper boundaries for conditional diversity determined by some specific group characteristics, avoiding the bias related to absolute diversity. This will allow applied researchers to make better interpretations regarding the relationship between group diversity and group outcomes.

Cardiovascular effects in patrol officers are associated with fine particulate matter from brake wear and engine emissions

Background: Exposure to fine particulate matter air pollutants (PM2.5) affects heart rate variability parameters, and levels of serum proteins associated with inflammation, hemostasis and thrombosis. This study investigated sources potentially responsible for cardiovascular and hematological effects in highway patrol troopers. Results: Nine healthy young non-smoking male troopers working from 3 PM to midnight were studied on four consecutive days during their shift and the following night. Sources of in-vehicle PM2.5 were identified with variance-maximizing rotational principal factor analysis of PM2.5-components and associated pollutants. Two source models were calculated. Sources of in-vehicle PM2.5 identified were 1) crustal material, 2) wear of steel automotive components, 3) gasoline combustion, 4) speed-changing traffic with engine emissions and brake wear. In one model, sources 1 and 2 collapsed to a single source. Source factors scores were compared to cardiac and blood parameters measured ten and fifteen hours, respectively, after each shift. The "speed-change" factor was significantly associated with mean heart cycle length (MCL, +7% per standard deviation increase in the factor score), heart rate variability (+16%), supraventricular ectopic beats (+39%), % neutrophils (+7%), % lymphocytes (-10%), red blood cell volume MCV (+1%), von Willebrand Factor (+9%), blood urea nitrogen (+7%), and protein C (-11%). The "crustal" factor (but not the "collapsed" source) was associated with MCL (+3%) and serum uric acid concentrations (+5%). Controlling for potential confounders had little influence on the effect estimates. Conclusion: PM2.5 originating from speed-changing traffic modulates the autonomic control of the heart rhythm, increases the frequency of premature supraventricular beats and elicits proinflammatory and pro-thrombotic responses in healthy young men. [Authors]

Soil Tracking Paint Test, MLR-89-13, 1989

A new paint testing device was built to determine the resistance of paints to darkening due to road grime being tracked onto them. The device consists of a tire rotating on a sample drum. Soil was applied to the tire and then tracked onto paint samples which were attached to the drum. A colorimeter was used to measure the lightness of the paints after being tracked. Lightness is measured from 0 (absolute black) to 100 (absolute white). Four experiments were run to determine the optimum time length to track a sample, the reproducibility, the effects of different soils, and the maximum acceptable level for darkening of a paint. The following conclusions were reached: 1) the optimum tracking time was 10 minutes; 2) the reproducibility had a standard deviation of 1.5 lightness units; 3) different soils did not have a large effect on the amount of darkening on the paints; 4) a maximum acceptable darkness could not be established based on the limited amount of data; and 5) a correlation exists between the paints which were darkening in the field and the paints which were turning the darkest on the tracking wheel.

High-magnification vascular imaging to reject false-positive sites in situ during Hexvix® fluorescence cystoscopy

Fluorescence imaging for detection of non-muscle-invasive bladder cancer is based on the selective production and accumulation of fluorescing porphyrins-mainly, protoporphyrin IX-in cancerous tissues after the instillation of Hexvix®. Although the sensitivity of this procedure is very good, its specificity is somewhat limited due to fluorescence false-positive sites. Consequently, magnification cystoscopy has been investigated in order to discriminate false from true fluorescence positive findings. Both white-light and fluorescence modes are possible with the magnification cystoscope, allowing observation of the bladder wall with magnification ranging between 30× for standard observation and 650×. The optical zooming setup allows adjusting the magnification continuously in situ. In the high-magnification (HM) regime, the smallest diameter of the field of view is 600 microns and the resolution is 2.5 microns when in contact with the bladder wall. With this cystoscope, we characterized the superficial vascularization of the fluorescing sites in order to discriminate cancerous from noncancerous tissues. This procedure allowed us to establish a classification based on observed vascular patterns. Seventy-two patients subject to Hexvix® fluorescence cystoscopy were included in the study. Comparison of HM cystoscopy classification with histopathology results confirmed 32/33 (97%) cancerous biopsies and rejected 17/20 (85%) noncancerous lesions.

Continuous determination of optimal cerebral perfusion pressure in traumatic brain injury.

OBJECTIVES: We have sought to develop an automated methodology for the continuous updating of optimal cerebral perfusion pressure (CPPopt) for patients after severe traumatic head injury, using continuous monitoring of cerebrovascular pressure reactivity. We then validated the CPPopt algorithm by determining the association between outcome and the deviation of actual CPP from CPPopt. DESIGN: Retrospective analysis of prospectively collected data. SETTING: Neurosciences critical care unit of a university hospital. PATIENTS: A total of 327 traumatic head-injury patients admitted between 2003 and 2009 with continuous monitoring of arterial blood pressure and intracranial pressure. MEASUREMENTS AND MAIN RESULTS: Arterial blood pressure, intracranial pressure, and CPP were continuously recorded, and pressure reactivity index was calculated online. Outcome was assessed at 6 months. An automated curve fitting method was applied to determine CPP at the minimum value for pressure reactivity index (CPPopt). A time trend of CPPopt was created using a moving 4-hr window, updated every minute. Identification of CPPopt was, on average, feasible during 55% of the whole recording period. Patient outcome correlated with the continuously updated difference between median CPP and CPPopt (chi-square=45, p<.001; outcome dichotomized into fatal and nonfatal). Mortality was associated with relative "hypoperfusion" (CPP<CPPopt), severe disability with "hyperperfusion" (CPP>CPPopt), and favorable outcome was associated with smaller deviations of CPP from the individualized CPPopt. While deviations from global target CPP values of 60 mm Hg and 70 mm Hg were also related to outcome, these relationships were less robust. CONCLUSIONS: Real-time CPPopt could be identified during the recording time of majority of the patients. Patients with a median CPP close to CPPopt were more likely to have a favorable outcome than those in whom median CPP was widely different from CPPopt. Deviations from individualized CPPopt were more predictive of outcome than deviations from a common target CPP. CPP management to optimize cerebrovascular pressure reactivity should be the subject of future clinical trial in severe traumatic head-injury patients.

A multicentre, retrospective case-control study assessing the role of trabecular bone score (TBS) in menopausal Caucasian women with low areal bone mineral density (BMDa): Analysing the odds of vertebral fracture.

INTRODUCTION: The trabecular bone score (TBS) is a new parameter that is determined from grey level analysis of DXA images. It relies on the mean thickness and volume fraction of trabecular bone microarchitecture. This was a preliminary case-control study to evaluate the potential diagnostic value of TBS, both alone and combined with bone mineral density (BMDa), in the assessment of vertebral fracture. METHODS: Out of a subject pool of 441 Caucasian, postmenopausal women between the ages of 50 and 80 years, we identified 42 women with osteoporosis-related vertebral fractures, and compared them with 126 age-matched women without any fractures (1 case: 3 controls). Primary outcomes were BMDa and TBS. Inter-group comparisons were undertaken using Student's t-tests and Wilcoxon signed ranks tests for parametric and non-parametric data, respectively. Odds ratios for vertebral fracture were calculated for each incremental one standard deviation decrease in BMDa and TBS, and areas under the receiver operating curve (AUC) calculated and sensitivity analysis were conducted to compare BMDa alone, TBS alone, and the combination of BMDa and TBS. Subgroup analyses were performed specifically for women with osteopenia, and for women with T-score-defined osteoporosis. RESULTS: Across all subjects (n=42, 126) weight and body mass index were greater and BMDa and TBS both less in women with fractures. The odds of vertebral fracture were 3.20 (95% CI, 2.01-5.08) for each incremental decrease in TBS, 1.95 (1.34-2.84) for BMDa, and 3.62 (2.32-5.65) for BMDa + TBS combined. The AUC was greater for TBS than for BMDa (0.746 vs. 0.662, p=0.011). At iso-specificity (61.9%) or iso-sensitivity (61.9%) for both BMDa and TBS, TBS + BMDa sensitivity or specificity was 19.1% or 16.7% greater than for either BMDa or TBS alone. Among subjects with osteoporosis (n=11, 40) both BMDa (p=0.0008) and TBS (p=0.0001) were lower in subjects with fractures, and both OR and AUC (p=0.013) for BMDa + TBS were greater than for BMDa alone (OR=4.04 [2.35-6.92] vs. 2.43 [1.49-3.95]; AUC=0.835 [0.755-0.897] vs. 0.718 [0.627-0.797], p=0.013). Among subjects with osteopenia, TBS was lower in women with fractures (p=0.0296), but BMDa was not (p=0.75). Similarly, the OR for TBS was statistically greater than 1.00 (2.82, 1.27-6.26), but not for BMDa (1.12, 0.56-2.22), as was the AUC (p=0.035), but there was no statistical difference in specificity (p=0.357) or sensitivity (p=0.678). CONCLUSIONS: The trabecular bone score warrants further study as to whether it has any clinical application in osteoporosis detection and the evaluation of fracture risk.

Tire traces: discrimination and classification of pyrolysis-GC/MS profiles

Tire traces can be observed on several crime scenes as vehicles are often used by criminals. The tread abrasion on the road, while braking or skidding, leads to the production of small rubber particles which can be collected for comparison purposes. This research focused on the statistical comparison of Py-GC/MS profiles of tire traces and tire treads. The optimisation of the analytical method was carried out using experimental designs. The aim was to determine the best pyrolysis parameters regarding the repeatability of the results. Thus, the pyrolysis factor effect could also be calculated. The pyrolysis temperature was found to be five time more important than time. Finally, a pyrolysis at 650 °C during 15 s was selected. Ten tires of different manufacturers and models were used for this study. Several samples were collected on each tire, and several replicates were carried out to study the variability within each tire (intravariability). More than eighty compounds were integrated for each analysis and the variability study showed that more than 75% presented a relative standard deviation (RSD) below 5% for the ten tires, thus supporting a low intravariability. The variability between the ten tires (intervariability) presented higher values and the ten most variant compounds had a RSD value above 13%, supporting their high potential of discrimination between the tires tested. Principal Component Analysis (PCA) was able to fully discriminate the ten tires with the help of the first three principal components. The ten tires were finally used to perform braking tests on a racetrack with a vehicle equipped with an anti-lock braking system. The resulting tire traces were adequately collected using sheets of white gelatine. As for tires, the intravariability for the traces was found to be lower than the intervariability. Clustering methods were carried out and the Ward's method based on the squared Euclidean distance was able to correctly group all of the tire traces replicates in the same cluster than the replicates of their corresponding tire. Blind tests on traces were performed and were correctly assigned to their tire source. These results support the hypothesis that the tested tires, of different manufacturers and models, can be discriminated by a statistical comparison of their chemical profiles. The traces were found to be not differentiable from their source but differentiable from all the other tires present in the subset. The results are promising and will be extended on a larger sample set.

Inter- and intraobserver variability of measurements with Pentacam HR® in patients with mild to moderate keratoconus

Purpose: To evaluate inter- and intraobserver variability of indices crucial for detection of keratoconus progression derived from the Pentacam HR® (high-resolution) tomographer (OCULUS Optikgeräte GmbH, Wetzlar, Germany) in patients with mild to moderate keratoconus. Methods: Three repeated corneal topography measurements in the 25-picture mode by two independent observers were performed. The extent of variability across a large range of measurement parameters was analyzed including anterior and posterior corneal surface measurements, pachymetry values, corneal volume, anterior chamber volume and depth, and iridocorneal angle. The intraclass correlation coefficient (ICC) between and within each investigator was calculated to assess reproducibility and repeatability, respectively. Results: 31 eyes of 20 patients (mean age 31.6, SD ± 8.6) were included. Overall, the repeatability and reproducibility were excellent. The range of variability was reported by calculating the standard deviation of measurements. The detailed results are shown in Table 1. Conclusions: This study shows that the Pentacam HR® tomographer provides reliable measurements in patients with mild to moderate keratoconus. However, all parameters showed a certain range of variability. This should be taken into account when assessing keratoconus progression in order to distinguish true progression from variability in measurements. In addition, the excellent reproducibility suggests that the measurements can be reliably performed by different individuals from one visit to another.