Eccentricity-paced geomagnetic field and monsoon rainfall variations over the last 870 kyr.

Whether there are links between geomagnetic field and Earth's orbital parameters remains unclear. Synchronous reconstructions of parallel long-term quantitative geomagnetic field and climate change records are rare. Here, we present 10Be-derived changes of both geomagnetic field and Asian monsoon (AM) rainfall over the last 870 kyr from the Xifeng loess-paleosol sequence on the central Chinese Loess Plateau. The 10BeGM flux (a proxy for geomagnetic field-induced 10Be production rate) reveals 13 consecutive geomagnetic excursions in the Brunhes chron, which are synchronized with the global records, providing key time markers for Chinese loess-paleosol sequences. The 10Be-derived rainfall exhibits distinct ~100 kyr glacial-interglacial cycles, and superimposed precessional (~23 kyr) cycles that match with those in Chinese speleothem δ18O record. We find that changes in the geomagnetic field and AM rainfall share a common ~100 kyr cyclicity, implying a likely eccentricity modulation of both the geomagnetic field and climate.

Featural Representation and Internal Noise Underlie the Eccentricity Effect in Contrast Sensitivity.

Human visual performance for basic visual dimensions (e.g., contrast sensitivity and acuity) peaks at the fovea and decreases with eccentricity. The eccentricity effect is related to the larger visual cortical surface area corresponding to the fovea, but it is unknown if differential feature tuning contributes to this eccentricity effect. Here, we investigated two system-level computations underlying the eccentricity effect: featural representation (tuning) and internal noise. Observers (both sexes) detected a Gabor embedded in filtered white noise which appeared at the fovea or one of four perifoveal locations. We used psychophysical reverse correlation to estimate the weights assigned by the visual system to a range of orientations and spatial frequencies (SFs) in noisy stimuli, which are conventionally interpreted as perceptual sensitivity to the corresponding features. We found higher sensitivity to task-relevant orientations and SFs at the fovea than that at the perifovea, and no difference in selectivity for either orientation or SF. Concurrently, we measured response consistency using a double-pass method, which allowed us to infer the level of internal noise by implementing a noisy observer model. We found lower internal noise at the fovea than that at the perifovea. Finally, individual variability in contrast sensitivity correlated with sensitivity to and selectivity for task-relevant features as well as with internal noise. Moreover, the behavioral eccentricity effect mainly reflects the foveal advantage in orientation sensitivity compared with other computations. These findings suggest that the eccentricity effect stems from a better representation of task-relevant features and lower internal noise at the fovea than that at the perifovea.

Parafoveal vision reveals qualitative differences between fusiform face area and parahippocampal place area.

The center-periphery visual field axis guides early visual system organization with enhanced resources devoted to central vision leading to reduced peripheral performance relative to that of central vision (i.e., behavioral eccentricity effect) for many visual functions. The center-periphery organization extends to high-order visual cortex where, for example, the well-studied face-sensitive fusiform face area (FFA) shows sensitivity to central vision and the place-sensitive parahippocampal place area (PPA) shows sensitivity to peripheral vision. As we have recently found that face perception is more sensitive to eccentricity than place perception, here we examined whether these behavioral findings reflect differences in FFA's and PPA's sensitivities to eccentricity. We assumed FFA would show higher sensitivity to eccentricity than PPA would, but that both regions' modulation by eccentricity would be invariant to the viewed category. We parametrically investigated (fMRI, n = 32) how FFA's and PPA's activations are modulated by eccentricity (≤8°) and category (upright/inverted faces/houses) while keeping stimulus size constant. As expected, FFA showed an overall higher sensitivity to eccentricity than PPA. However, both regions' activation modulations by eccentricity were dependent on the viewed category. In FFA, a reduction of activation with growing eccentricity ("BOLD eccentricity effect") was found (with different amplitudes) for all categories. In PPA however, qualitatively different BOLD eccentricity effect modulations were found (e.g., at 8° mild BOLD eccentricity effect for houses but a reverse BOLD eccentricity effect for faces and no modulation for inverted faces). Our results emphasize that peripheral vision investigations are critical to further our understanding of visual processing.

Left ventricular shape index and eccentricity index with ECG-gated Nitrogen-13 ammonia PET/CT in patients with myocardial infarction, ischemia, and normal perfusion.

BACKGROUND: LV geometry with shape index (SI) and eccentricity index (EI) measured by myocardial perfusion positron emission tomography/computed tomography (PET/CT) may allow the evaluation of left ventricular (LV) adverse remodeling. This first study aims to explore the relationship of SI and EI values acquired by Nitrogen-13 ammonia PET/CT in patients with normal perfusion, ischemia, and myocardial infarction. And evaluate the correlations between the variables of LV geometry, and with the variables of LV function. METHODS AND RESULTS: One hundred and forty patients who underwent an electrocardiogram (ECG)-gated PET/CT were selected and classified into 4 groups according to ischemia or infarction burden (normal perfusion, mild ischemia, moderate-severe ischemia, and infarction). The variables were automatically retrieved using dedicated software (QPS/QGS; Cedars-Sinai, Los Angeles, CA, USA). On multicomparison analysis (one-way ANOVA and Dunnett's Test), subjects in the infarction group had significant higher values of SI end-diastolic rest (P < 0.001), and stress (P = 0.003), SI end-systolic rest (P = 0.002) and stress (P < 0.001) as well as statistically significant lower values of EI rest (P < 0.001) and stress (P < 0.001) when compared with all other groups. Regarding Pearson correlation, in the infarcted group all the variables of SI and EI were significantly correlated (P < 0.001) with strong correlation coefficients (>0.60). SI end-systolic correlated significantly with the variables of LV function independently of the group of patients (P < 0.05). CONCLUSIONS: Shape and eccentricity indices differ in patients with myocardial infarction as compared to patients with ischemia or normal perfusion. This encourage further research in their potential for detecting LV adverse remodeling.

Effect of eccentric fixation on the steady-state pattern electroretinogram.

PURPOSE: The steady-state pattern electroretinogram (ssPERG) is used to assess retinal ganglion cell function in a variety of research contexts and diagnostic applications. In certain groups of patients or study participants, stable central fixation of the stimulus is not guaranteed. The present study aimed at assessing the effects of misfixation on the ssPERG response to checkerboard reversal stimuli. METHODS: Using two check sizes (0.8° and 15°), we compared ssPERG responses for several amounts of fixation deviation, ranging from 0° to 19° horizontally and from 0° to 14° diagonally. The stimulus area extended to 15° eccentricity, stimulus reversal rate was 15/s. RESULTS: Up to around 7° eccentricity, there was no sizable effect of fixation deviation under most conditions. Effects were somewhat larger for nasal than for temporal deviation, in particular for small checks. Diagonal deviation was associated with a response to luminance onset/offset at 7.5 Hz (subharmonic of the reversal rate), most prominently when the interior of a large check was fixated. CONCLUSION: Generally, moderate inaccuracies of fixation do not have a sizable effect on ssPERG amplitude. However, with large checks, the luminance response has to be considered.

Eccentricity forcing of East Asian monsoonal systems over the past 3 million years.

The East Asian summer monsoon and the precipitation it brings are relevant for millions of people. Because of the monsoon's importance, there has been a substantial amount of work attempting to describe the driving mechanisms behind its past variability. However, discrepancies exist, with speleothem-based East Asian monsoon reconstructions differing from those based on loess records from the Chinese Loess Plateau during the late Quaternary. The periodicity of wet and dry phases experienced by desert areas that lie on the periphery of the East Asian monsoon's influence offer another independent view of monsoonal variability. Here, we provide environmental records based on magnetic parameters for the last 3 million years from the Tengger Desert, China, one such marginal arid region. Our results reveal wet-dry cycles at a dominant frequency of 405 kiloyears, with drier intervals corresponding to eccentricity minima. These findings are consistent with previous reconstructions of East Asian summer and North African summer monsoon precipitation variability. Our records emphasize the dominant role of eccentricity in forcing East Asian monsoonal precipitation as well as monsoonal-derived environmental fluctuations experienced in peripheral desert areas. These results challenge the traditional view that high-latitude ice sheets are the primary driver of East Asian monsoon precipitation during the Quaternary based on Chinese loess records.

Echocardiographic markers at diagnosis of persistent pulmonary hypertension of the newborn.

OBJECTIVES: Clinical parameters along with echocardiographic markers are used to interrogate the haemodynamics in persistent pulmonary hypertension of the newborn (PPHN). The aim of this study was to compare different echocardiographic markers in recent cohort of newborn infants with and without PPHN. METHODS: In this retrospective study, common echocardiographic markers were examined in infants>34 weeks' gestation with PPHN (cases) and without PPHN (controls). Infants with congenital heart disease were excluded. Binary regression testing was used to evaluate echocardiographic markers predicting PPHN and death. In addition, diagnostic accuracy testing of echocardiographic markers using ROC was also performed. Intra-observer reliability for echocardiographic markers was examined using coefficient of variation (CoV) and intraclass correlation. RESULTS: Fifty-two infants were studied; 22 (42 %) infants with PPHN had significantly higher oxygen requirement, oxygenation index and ventilation days when compared with controls. Echocardiographic markers such as TR Vmax, S/D TR, PAAT, TAPSE and eccentricity index (EI) were significantly different between cases and controls. Receiver operator characteristics analysis of echocardiographic markers revealed TR Vmax 0.96 (0.9-1.0), S/D TR 0.95 (0.87-1.0) and end systolic EI 0.94 (0.87-1.0). These markers were found to predict death in this cohort of infants. CoV and Intra-observer reliability was good for various echocardiographic markers. CONCLUSIONS: Among the various echocardiographic markers studied, TR Vmax when present along with S/D TR and end systolic EI had good intra-observer reliability and were diagnostic of PPHN and predicted death in this cohort. Future trials could use these markers in studies examining PPHN.

Compound Fault Characteristic Analysis for Fault Diagnosis of a Planetary Gear Train.

The carrier eccentricity error and gear compound faults are most likely to occur simultaneously in an actual planetary gear train (PGT). Various faults and errors are coupled with each other to generate a complex dynamic response, which makes the diagnosis of PGT faults difficult in practice. In order to analyze the joint effect of the error and the compound faults in a PGT, a carrier eccentricity error model is proposed and incorporated into the TVMS model by considering the time-varying center distance, line of action (LOA), meshing angle, and contact ratio. Then, the TVMS of the cracked gear is derived based on the potential energy method. On this basis, the dynamic model of a PGT with both the carrier eccentricity error and compound gear cracks as internal excitations are established. Furthermore, the meshing characteristics and dynamic responses of the PGT are simulated to investigate the compound fault features. A series of experiments are conducted to further analyze the influence of the compound fault on the vibration response. The relevant conclusions can provide a reference for the compound fault diagnosis of a PGT in practice.

Cable Eccentricity Detection Method Based on Magnetic Field.

Amid the rapid advancement of electronic information technology, the need for cable eccentricity measurement in the industry is increasing both in China and across the globe. Current detection methods have several flaws, including high costs, insufficient accuracy, and instability. In this paper, we introduce a magnetic field-based detection method for cable eccentricity that provides high precision and cost-effectiveness. We position three pairs of magnetic field-collection modules in a circular array to gather magnetic flux density information induced by the electrified cable. We apply the law of electromagnetic induction to calculate the cable eccentricity. Our method is non-contact, preserving the cable's integrity. Our method outperforms traditional detection methods, not only in achieving greater accuracy and stability but also in significantly lowering the detection cost. Simulations and experiments show that our method's error rate under specified conditions is 0~4%, with a maximum standard deviation of 0.11, confirming its precision and stability in detecting cable eccentricity. The effectiveness of our method is influenced by two factors: lift-off value and loading current intensity. Our method presents a novel concept and a dependable strategy for the progress of cable eccentricity-detection technology.

Shifts in structural connectome organization in the limbic and sensory systems of patients with episodic migraine.

Migraine is a complex neurological condition characterized by recurrent headaches, which is often accompanied by various neurological symptoms. Magnetic resonance imaging (MRI) is a powerful tool for investigating whole-brain connectivity patterns; however, systematic assessment of structural connectome organization has rarely been performed. In the present study, we aimed to examine the changes in structural connectivity in patients with episodic migraines using diffusion MRI. First, we computed structural connectivity using diffusion MRI tractography, after which we applied dimensionality reduction techniques to the structural connectivity and generated three low-dimensional eigenvectors. We subsequently calculated the manifold eccentricity, defined as the Euclidean distance between each data point and the center of the data in the manifold space. We then compared the manifold eccentricity between patients with migraines and healthy controls, revealing significant between-group differences in the orbitofrontal cortex, temporal pole, and sensory/motor regions. Between-group differences in subcortico-cortical connectivity further revealed significant changes in the amygdala, accumbens, and caudate nuclei. Finally, supervised machine learning effectively classified patients with migraines and healthy controls using cortical and subcortical structural connectivity features, highlighting the importance of the orbitofrontal and sensory cortices, in addition to the caudate, in distinguishing between the groups. Our findings confirmed that episodic migraine is related to the structural connectome changes in the limbic and sensory systems, suggesting its potential utility as a diagnostic marker for migraine.

'Eccentricity', by DH Tuke (1892).

An astronomical concept up to the eighteenth century, 'eccentricity' started to be used to refer to behaviours considered as odd, strange, rare, extravagant, etc. Once reified into a personality trait, it gained explanatory power. This not only increased its popularity but also facilitated its links with psychopathology and neuropsychology, and, via the shared concept of madness, with the notions of genius and creativity. This Classic Text describes the process whereby Alienism (Psychiatry) medicalized eccentricity. To this day, the latter remains firmly attached to 'psychoticism' and to some personality disorders.

Exploration of the synergistic role of cortical thickness asymmetry ("Trabecular Eccentricity" concept) in reducing fracture risk in the human femoral neck and a control bone (Artiodactyl Calcaneus).

The mechanobiology of the human femoral neck is a focus of research for many reasons including studies that aim to curb age-related bone loss that contributes to a near-exponential rate of hip fractures. Many believe that the femoral neck is often loaded in rather simple bending, which causes net tension stress in the upper (superior) femoral neck and net compression stress in its inferior aspect ("T/C paradigm"). This T/C loading regime lacks in vivo proof. The "C/C paradigm" is a plausible alternative simplified load history that is characterized by a gradient of net compression across the entire femoral neck; action of the gluteus medius and external rotators of the hip are important in this context. It is unclear which paradigm is at play in natural loading due to lack of in vivo bone strain data and deficiencies in understanding mechanisms and manifestations of bone adaptation in tension vs. compression. For these reasons, studies of the femoral neck would benefit from being compared to a 'control bone' that has been proven, by strain data, to be habitually loaded in bending. The artiodactyl (sheep and deer) calcaneus model has been shown to be a very suitable control in this context. However, the application of this control in understanding the load history of the femoral neck has only been attempted in two prior studies, which did not examine the interplay between cortical and trabecular bone, or potential load-sharing influences of tendons and ligaments. Our first goal is to compare fracture risk factors of the femoral neck in both paradigms. Our second goal is to compare and contrast the deer calcaneus to the human femoral neck in terms of fracture risk factors in the T/C paradigm (the C/C paradigm is not applicable in the artiodactyl calcaneus due to its highly constrained loading). Our third goal explores interplay between dorsal/compression and plantar/tension regions of the deer calcaneus and the load-sharing roles of a nearby ligament and tendon, with insights for translation to the femoral neck. These goals were achieved by employing the analytical model of Fox and Keaveny (J. Theoretical Biology 2001, 2003) that estimates fracture risk factors of the femoral neck. This model focuses on biomechanical advantages of the asymmetric distribution of cortical bone in the direction of habitual loading. The cortical thickness asymmetry of the femoral neck (thin superior cortex, thick inferior cortex) reflects the superior-inferior placement of trabecular bone (i.e., "trabecular eccentricity," TE). TE helps the femoral neck adapt to typical stresses and strains through load-sharing between superior and inferior cortices. Our goals were evaluated in the context of TE. Results showed the C/C paradigm has lower risk factors for the superior cortex and for the overall femoral neck, which is clinically relevant. TE analyses of the deer calcaneus revealed important synergism in load-sharing between the plantar/tension cortex and adjacent ligament/tendon, which challenges conventional understanding of how this control bone achieves functional adaptation. Comparisons with the control bone also exposed important deficiencies in current understanding of human femoral neck loading and its potential histocompositional adaptations.

Foveal to peripheral extrapolation of facial emotion.

Peripheral vision is characterized by poor resolution. Recent evidence from brightness perception suggests that missing information is filled out with information at fixation. Here we show a novel filling-out mechanism: when participants are presented with a crowd of faces, the perceived emotion of faces in peripheral vision is biased towards the emotion of the face at fixation. This mechanism is particularly important in social situations where people often need to perceive the overall mood of a crowd. Some faces in the crowd are more likely to catch people's attention and be looked at directly, while others are only seen peripherally. Our findings suggest that the perceived emotion of these peripheral faces, and the overall perceived mood of the crowd, is biased by the emotions of the faces that people look at directly.

Differences in eccentricity for sound-induced flash illusion in four visual fields.

A sound-induced flash illusion (SiFI) is a multisensory illusion dominated by auditory stimuli, in which the individual perceives that the number of visual flashes is equal to the number of auditory stimuli when visual flashes are presented along with an unequal number of auditory stimuli. Although the mechanisms underlying fission and fusion illusions have been documented, there is not yet a consensus on how they vary according to the different eccentricities. In the present study, by incorporating the classic SiFI paradigm into four different eccentricities, we aimed to investigate whether the SiFI varies under the different eccentricities. The results showed that the fission illusion varied significantly across the four eccentricities, with the perifovea (7°) and peripheral (11°) illusions being greater than the fovea and parafovea (3°) illusions. In contrast, the fusion illusion did not vary significantly across the four eccentricities. Our findings revealed that SiFI was affected by different visual fields and that there were differences between the fission and the fusion illusions. Furthermore, by examining the SiFI of eccentricity across visual fields, this study also suggests that bottom-up factors affect the SiFI.

Effects of cortical distance on the Ebbinghaus and Delboeuf illusions.

The Ebbinghaus and Delboeuf illusions affect the perceived size of a target circle depending on the size and proximity of circular inducers or a ring. Converging evidence suggests that these illusions are driven by interactions between contours mediated by their cortical distance in primary visual cortex. We tested the effect of cortical distance on these illusions using two methods: First, we manipulated retinal distance between target and inducers in a two-interval forced choice design, finding that targets appeared larger with a closer surround. Next, we predicted that targets presented peripherally should appear larger due to cortical magnification. Hence, we tested the illusion strength when positioning the stimuli at various eccentricities, with results supporting this hypothesis. We calculated estimated cortical distances between illusion elements in each experiment and used these estimates to compare the relationship between cortical distance and illusion strength across our experiments. In a final experiment, we modified the Delboeuf illusion to test whether the influence of the inducers/annuli in this illusion is influenced by an inhibitory surround. We found evidence that an additional outer ring makes targets appear smaller compared to a single-ring condition, suggesting that near and distal contours have antagonistic effects on perceived target size.

Nut Geometry Inspection Using Improved Hough Line and Circle Methods.

Nuts are the cornerstone of human industrial construction, especially A-grade nuts that can only be used in power plants, precision instruments, aircraft, and rockets. However, the traditional nuts inspection method is to manually operate the measuring instrument for conducting an inspection, so the quality of the A-grade nut cannot be guaranteed. In this work, a machine vision-based inspection system was proposed, which performs a real-time geometric inspection of the nuts before and after tapping on the production line. In order to automatically screen out A-Grade nuts on the production line, there are 7 inspections within this proposed nut inspection system. The measurements of parallel, opposite side length, straightness, radius, roundness, concentricity, and eccentricity were proposed. To shorten the overall detection time regarding nut production, the program needed to be accurate and uncomplicated. By modifying the Hough line and Hough circle, the algorithm became faster and more suitable for nut detection. The optimized Hough line and Hough circle can be used for all measures in the testing process.

Comparative Study of Planar Octahedron Molecular Structure via Eccentric Invariants.

A branch of graph theory that makes use of a molecular graph is called chemical graph theory. Chemical graph theory is used to depict a chemical molecule. A graph is connected if there is an edge between every pair of vertices. A topological index is a numerical value related to the chemical structure that claims to show a relationship between chemical structure and various physicochemical attributes, chemical reactivity, or, you could say, biological activity. In this article, we examined the topological properties of a planar octahedron network of m dimensions and computed the total eccentricity, average eccentricity, Zagreb eccentricity, geometric arithmetic eccentricity, and atom bond connectivity eccentricity indices, which are used to determine the distance between the vertices of a planar octahedron network.

Bruno Schulz's 1930 article "The Hereditary Relationships of Old-Age Paranoid Psychosis".

In the 1899 6th edition of his influential textbook, Kraepelin proposed a diagnostic category of "Old-Age Paranoid Psychosis." In this 1930 article, Bruno Schulz studied the morbid risk (MR) of several disorders and traits in the parents, siblings, offspring, and nieces/nephews of 51 probands with "Old-Age Paranoid Psychosis." His results permitted an evaluation of the validity of Kraepelin's category of Old-Age Paranoid Psychosis, in particular, whether it was a form of psychosis resulting from "senile changes" or late-onset schizophrenia. The MR of schizophrenia in these four groups of relatives varied from 0 to 2.4% with 3 of 4 somewhat higher than population expectations but much lower than parallel results in relatives of schizophrenics. By contrast, the rates of eccentricity in these relatives were uniformly elevated over population rates, sometimes approaching those seen in relatives of schizophrenics. Schulz concluded, from his study, that Old-Age Paranoid Psychosis was a distinct disorder not closely related to schizophrenia. However, he suggested that a family history and/or a premorbid trait of eccentricity increases the risk of developing a paranoid psychosis in old age, particularly when associated with physical or mental decline. He was uncertain about whether the trait of eccentricity he found in this study was very similar or distinct from that observed in excess in relatives of schizophrenics. This study was the first, to the best of our knowledge, to use a family study design explicitly to address a nosologic question-in this case the familial relationship between Old-Age Paranoid Psychosis and schizophrenia.

The central-peripheral dichotomy and metacontrast masking.

According to the central-peripheral dichotomy (CPD), feedback from higher to lower cortical areas along the visual pathway to aid recognition is weaker in the more peripheral visual field. Metacontrast masking is predominantly a reduced visibility of a brief target by a brief and spatially adjacent mask when the mask succeeds rather than precedes or coincides with the target. If this masking works mainly by interfering with the feedback mechanisms for target recognition, then, by the CPD, this masking should be weaker at more peripheral visual locations. We extended the metacontrast masking at fovea by Enns and Di Lollo to visual field eccentricities 1∘, 3∘, and 9∘. Relative to the target's onset, the mask appeared at a stimulus onset asynchrony (SOA) of -50, 0, 50, 92, or 142 milliseconds (ms). Enlarged stimuli were used for larger eccentricities to equalize target discrimination performance across eccentricities as best as possible for zero SOA and when SOA was too long for substantial masking. At each eccentricity, the masking was weakest at 0 or -50 ms SOA, strongest at 50 ms SOA, and weakened with larger (positive) SOAs. Consistent with the CPD, larger eccentricities presented weaker maskings at all nonzero, and particularly the positive, SOAs.

Prediction of anterior ocular surface sagittal heights using Placido-based corneal topography in healthy eyes.

PURPOSE: To investigate the validity of Placido-based corneal topography parameters to predict corneoscleral sagittal heights measured by Fourier-based profilometry at various diameters. METHODS: Minimal (Minsag ), maximal (Maxsag ) sagittal height, toricity (Maxsag - Minsag ) and axis of the flattest meridian (Minsag ) of 36 subjects (mean age 25.4 SD ± 3.2 years; 21 female) were measured using the Eye Surface Profiler and analysed for diameters (chord length) of 8 to 16 mm (in 2-mm intervals). Furthermore, corneal central radii, corneal astigmatism, eccentricity and diameter were measured using the Keratograph 5 M. RESULTS: Using multiple linear regression analysis, the best equation for predicting the sagittal heights for 8 mm (r2  = 0.95), and 10 mm (r2  = 0.93) diameters included corneal central radii and eccentricity. The best equation for predicting sagittal heights for 12 mm (r2  = 0.86), 14 mm (r2  = 0.78) and 16 mm (r2  = 0.65) diameters included corneal central radii, eccentricity and corneal diameter. Corneal astigmatism was significantly correlated with sagittal height toricity for 8 and 10 mm diameters (r2  = 0.50 and 0.29; p < 0.01), while no correlation was observed for 12, 14 and 16 mm diameters (p = 0.18 to p = 0.76). The axis of the flattest corneal meridian measured by Placido-based topography was significantly correlated with the axis of the flattest meridian measured by Fourier-based profilometry for 8, 10 and 12 mm diameters (r2  = 0.17 to 0.44; p < 0.05), while there was no correlation for 14 and 16 mm diameters (p = 0.48 and p = 0.75). For a typical soft contact lens diameter of 14 mm, 78% of the variance could be determined with a corneal topographer and 68% with keratometry and corneal diameter measurement. CONCLUSIONS: The combination of corneal central radii, eccentricity and corneal diameter measured by Placido-based topography is a valid predictor of the corneoscleral sagittal height in healthy eyes. Scleral toricity and axis of the flattest meridian seem to be independent from Placido-based corneal parameters and requires additional measuring tools.