Air Puff Research Articles

Distribution of IOP measured with an air puff tonometer in a young population

PurposeTo determine the normal range of intraocular pressure (IOP) in the young and its association with certain corneal parameters using a non-contact device. MethodsSubjects were selected from students of Mashhad University of Medical Sciences through stratified sampling. All participants had visual acuity testing, corneal imaging, a comprehensive slit-lamp examination by an ophthalmologist, and IOP measurement using a non-contact air-puff tonometer. ResultsOf the 1280 invitees, 1073 (83.8%) participated, and 1027 were eligible. Mean IOP was 16.38 mmHg [95% confidence interval (CI): 16.22–16.53] in the total sample, 16.14 mmHg (95% CI: 15.84–16.45) in men, and 16.48 mmHg (95% CI: 16.31–16.66) in women. There was a significant IOP difference between myopes and emmetropes (P = 0.031). Based on the multiple linear regression model, IOP associated directly with age and central corneal thickness (CCT), and inversely with corneal diameter, spherical equivalent (SE), and keratoconus. Based on standardized coefficients of the regression model, CCT and SE had the strongest association with IOP. ConclusionsIn the present study, we demonstrated the IOP distribution in a young population using a non-contact method. CCT and SE were strongly associated with IOP.

Introduction of Two Novel Stiffness Parameters and Interpretation of Air Puff–Induced Biomechanical Deformation Parameters With a Dynamic Scheimpflug Analyzer

To investigate two new stiffness parameters and their relationships with the dynamic corneal response (DCR) parameters and compare normal and keratoconic eyes. Stiffness parameters are defined as Resultant Pressure at inward applanation (A1) divided by corneal displacement. Stiffness parameter A1 uses displacement between the undeformed cornea and A1 and stiffness parameter highest concavity (HC) uses displacement from A1 to maximum deflection during HC. The spatial and temporal profiles of the Corvis ST (Oculus Optikgeräte, Wetzlar, Germany) air puff were characterized using hot wire anemometry. An adjusted air pressure impinging on the cornea at A1 (adjAP1) and an algorithm to biomechanically correct intraocular pressure based on finite element modelling (bIOP) were used for Resultant Pressure calculation (adjAP1 - bIOP). Linear regression analyses between DCR parameters and stiffness parameters were performed on a retrospective dataset of 180 keratoconic eyes and 482 normal eyes. DCR parameters from a subset of 158 eyes of 158 patients in each group were matched for bIOP and compared using t tests. A P value of less than .05 was considered statistically significant. All DCR parameters evaluated showed significant differences between normal and keratoconic eyes, except peak distance. Keratoconic eyes had lower stiffness parameter values, thinner pachymetry, shorter applanation lengths, greater absolute values of applanation velocities, earlier A1 times and later second applanation times, greater HC deformation amplitudes and HC deflection amplitudes, and lower HC radius of concave curvature (greater concave curvature). Most DCR parameters showed a significant relationship with both stiffness parameters in both groups. Keratoconic eyes demonstrated less resistance to deformation than normal eyes with similar IOP. The stiffness parameters may be useful in future biomechanical studies as potential biomarkers. [J Refract Surg. 2017;33(4):266-273.].

DualBlink

Increased visual attention, such as during computer use leads to less blinking, which can cause dry eyes—the leading cause of computer vision syndrome. As people spend more time looking at screens on mobile and desktop devices, computer vision syndrome is becoming epidemic in today's population, leading to blurry vision, fatigue, and a reduced quality of life. One way to alleviate dry eyes is increased blinking. In this paper, we present a series of glasses-mounted devices that track the wearer's blink rate and, upon absent blinks, trigger blinks through actuation: light flashes, physical taps, and small puffs of air near the eye. We conducted a user study to evaluate the effectiveness of our devices and found that air puff and physical tap actuations result in a 36% increase in participants’ average blink rate. Air puff thereby struck the best compromise between effective blink actuations and low distraction ratings from participants. In a follow-up study, we found that high intensity, short puffs near the eye were most effective in triggering blinks while receiving only low-rated distraction and invasiveness ratings from participants. We conclude this paper with two miniaturized and self-contained DualBlink prototypes, one integrated into the frame of a pair of glasses and the other one as a clip-on for existing glasses. We believe that DualBlink can serve as an always-available and viable option to treat computer vision syndrome in the future.

Electrophysiological and laboratory behavioral responses of a leaf beetle pest of elm, Ambrostoma quadriimpressum, to selected plant volatiles and essential oils

AbstractThe leaf beetle Ambrostoma quadriimpressum Motschulsky (Coleoptera: Chrysomelidae) is distributed in China, Siberia, and elsewhere in northeastern Asia. This pest feeds only on buds and leaves of elm trees (Ulmaceae) and inhibits elm trees sprouting, increasing the risk of damage and destruction by other pests. We investigated selected plant compounds that could be used for the development of semiochemical‐based push‐pull methods for the control of this elm pest. Electroantennogram (EAG), Y‐tube olfactometer, and wind tunnel bioassays were conducted to test the electrophysiological and behavioral response of A. quadriimpressum to nine individual volatiles and five essential oils. Individual volatiles and essential oils were selected based on their activity against insects in previous studies. The individual volatiles and essential oils were dissolved in dichloromethane and adsorbed by filter paper. Using a pipette, odor stimuli were delivered as 0.5‐s puffs of air into a continuously humidified air stream in the odor delivery tube at 400 ml per min. Ambrostoma quadriimpressum adults display strong EAG responses to l mol l−1 isoeugenol, (1R)‐(+)‐α‐pinene, 1% pepper oil (derived from the pericarp of Piper chinense Miq.), and peppermint oil [derived from the aerial parts of Mentha haplocalyx (Briq.)] compared to the control. In behavioral assays conducted using a Y‐tube olfactometer and a wind tunnel, adult beetles were attracted by (1R)‐(+)‐α‐pinene but repelled by 0.1% pepper oil. The results provide a basis for the development of a ‘push‐pull’ strategy to manage A. quadriimpressum.

Biomechanical Changes After In Vivo Collagen Cross-Linking With Rose Bengal-Green Light and Riboflavin-UVA.

To compare corneal biomechanical properties after in vivo and ex vivo cross-linking (CXL) using rose bengal-green light (RGX) or riboflavin-UVA (UVX). Corneas of 30 rabbits were treated in vivo by the two CXL modalities monolaterally (Group 1) or bilaterally (Group 2). Rabbits in Group 1 were euthanized 1 month after treatments and in Group 2 two months after treatment. Ex vivo CXL was also performed. Eyes were measured by Scheimpflug air puff corneal deformation imaging (Corvis ST) under constant IOP. Corneal deformation parameters were assessed. Inherent corneal biomechanical properties were estimated using inverse finite element modeling. Peak to peak distance decreased 16% 2 months after RGX, and 4% and 20% 1 and 2 months after UVX, respectively. The equivalent Young's modulus (Eeq) increased relative to the control during the post treatment period for both RGX and UVX. The Eeq increased by factors of 3.4 (RGX) and 1.7 (UVX) 1 month and by factors of 10.7 (RGX) and 7.3 (UVX) 2 months after treatment. However, the Eeq values for ex vivo CXL were much greater than produced in vivo. The ex vivo Eeq was greater than the 1-month in vivo values by factors of 8.1 (RGX) and 9.1 (UVX) and compared with 2 month by factors of 2.5 (RGX) and 2.1 (UVX). These results indicate that corneal stiffness increases after CXL, and further increases as a function of time after both RGX and UVX. Also, while biomechanical properties determined after ex vivo CXL are indicative of corneal stiffening, they may not provide entirely accurate information about the responses to CXL in vivo.

Validation of periodic fMRI signals in response to wearable tactile stimulation

To map cortical representations of the body, we recently developed a wearable technology for automatic tactile stimulation in human functional magnetic resonance imaging (fMRI) experiments. In a two-condition block design experiment, air puffs were delivered to the face and hands periodically. Surface-based regions of interest (S-ROIs) were initially identified by thresholding a linear statistical measure of signal-to-noise ratio of periodic response. Across subjects, S-ROIs were found in the frontal, primary sensorimotor, posterior parietal, insular, temporal, cingulate, and occipital cortices. To validate and differentiate these S-ROIs, we develop a measure of temporal stability of response based on the assumption that a periodic stimulation evokes stable (low-variance) periodic fMRI signals throughout the entire scan. Toward this end, we apply time-frequency analysis to fMRI time series and use circular statistics to characterize the distribution of phase angles for data selection. We then assess the temporal variability of a periodic signal by measuring the path length of its trajectory in the complex plane. Both within and outside the primary sensorimotor cortex, S-ROIs with high temporal variability and deviant phase angles are rejected. A surface-based probabilistic group-average map is constructed for spatial screening of S-ROIs with low to moderate temporal variability in non-sensorimotor regions. Areas commonly activated across subjects are also summarized in the group-average map. In summary, this study demonstrates that analyzing temporal characteristics of the entire fMRI time series is essential for second-level selection and interpretation of S-ROIs initially defined by an overall linear statistical measure.

The reference frame of the tilt aftereffect measured by differential Pavlovian conditioning

We used a differential Pavlovian conditioning paradigm to measure tilt aftereffect (TAE) strength. Gabor patches, rotated clockwise and anticlockwise, were used as conditioned stimuli (CSs), one of which (CS+) was followed by the unconditioned stimulus (UCS), whereas the other (CS−) appeared alone. The UCS was an air puff delivered to the left eye. In addition to the CS+ and CS−, the vertical test patch was also presented for the clockwise and anticlockwise adapters. The vertical patch was not followed by the UCS. After participants acquired differential conditioning, eyeblink conditioned responses (CRs) were observed for the vertical patch when it appeared to be tilted in the same direction as the CS+ owing to the TAE. The effect was observed not only when the adapter and test stimuli were presented in the same retinotopic position but also when they were presented in the same spatiotopic position, although spatiotopic TAE was weak—it occurred approximately half as often as the full effect. Furthermore, spatiotopic TAE decayed as the time after saccades increased, but did not decay as the time before saccades increased. These results suggest that the time before the performance of saccadic eye movements is needed to compute the spatiotopic representation.

Effects of forced movements on learning: Findings from a choice reaction time task in rats

To investigate how motor sensation facilitates learning, we used a sensory–motor association task to determine whether the sensation induced by forced movements contributes to performance improvements in rats. The rats were trained to respond to a tactile stimulus (an air puff) by releasing a lever pressed by the stimulated (compatible condition) or nonstimulated (incompatible condition) forepaw. When error rates fell below 15%, the compatibility condition was changed (reversal learning). An error trial was followed by a lever activation trial in which a lever on the correct or the incorrect response side was automatically elevated at a preset time of 120, 220, 320, or 420 ms after tactile stimulation. This lever activation induced forepaw movement similar to that in a voluntary lever release response, and also induced body movement that occasionally caused elevation of the other forepaw. The effects of lever activation may have produced a sensation similar to that of voluntary lever release by the forepaw on the nonactivated lever. We found that the performance improvement rate was increased by the lever activation procedure on the incorrect response side (i.e., with the nonactivated lever on the correct response side). Furthermore, the performance improvement rate changed depending on the timing of lever activation: Facilitative effects were largest with lever activation on the incorrect response side at 320 ms after tactile stimulation, whereas hindering effects were largest for lever activation on the correct response side at 220 ms after tactile stimulation. These findings suggest that forced movements, which provide tactile and proprioceptive stimulation, affect sensory–motor associative learning in a time-dependent manner.

Estimation of the Corneal Young's Modulus In Vivo Based on a Fluid-Filled Spherical-Shell Model with Scheimpflug Imaging.

Current intraocular pressure (IOP) measurement using air puff could be erroneous without applying proper corrections. Although noncontact tonometry is not considered to be accurate, it is still popularly used by eye clinics. It is thus necessary to extract the correct information from their results. This study proposes a practical approach to correctly measure IOP in vivo. By embedding a new model-based correction to the Corvis® ST, we can extract the corneal Young's modulus from the patient data. This Young's modulus can be used to correct the IOP readings. The tests were applied to 536 right eyes of 536 healthy subjects (228 male and 308 female) between March of 2012 and April of 2016. The tests were applied to patients at the Department of Ophthalmology, National Taiwan University Hospital and the Hung-Chuo Eye Clinics. The statistical analysis showed that the value for the Young's modulus was independent of all the other parameters collected from the Corvis ST, including the corneal thickness and the intraocular pressure. Therefore, it is important to independently measure the Young's modulus instead of depending on the correlation with the other parameters. This study adds the methodology of measuring corneal stiffness in vivo for ophthalmologists' reference in diagnosis.

Meditation on a Red Seed as Transformation, and: Sisters of the Raging Millennium at a Hundred Years, and: On the Levitation of Beautiful Objects

Meditation on a Red Seed as Transformation, and: Sisters of the Raging Millennium at a Hundred Years, and: On the Levitation of Beautiful Objects Karen An-hwei Lee (bio) Meditation on a Red Seed as Transformation for the sculptor and landscape architect, Isamu Noguchi (1904–1988) Dear Isamu— Nayantara refused your love in the end,red seed of resilience in the magnified shapeof biomorphism, halved core of perfume—sequoia or balsain a transformation of millennial living.Or a giant melon seed, half-shaved with a steel wire,one nervous fiber beveled on the right.Isamu Noguchi Garden Museum in Long Island City,a sculpture called Red Seed, 1928— Aromatic as a sandalwood treeof circassian seeds. Tears of betel-nut juice.Roasted watermelon seeds dyed for the new year, pods of red wax in the galleria. Auburn-soaked heartwood more roan than russetriding to the horizon on the flanks of wild mustangs. [End Page 39] Sisters of the Raging Millennium at a Hundred Years Sisters of a raging millennium, if we survive a hundred years,let us grill a thousand mackerelsfor dinner, skin on. No urgency to scour the charcoal racks.Fork the arugula with no olives,nurse no grudges. Synthesize rosebushes in factories.Hem floor-length, mulberry-silknightshifts if it pleases the years to grow an inch of our bonesso late in life. Never too darkto iron a bias cut or whistle at a finch, if so. Let usextinguish sins candidly.Forgive a loved one’s trespasses as inflation,drone-wars, and the unrequitedflameout. Yes, let us pray the seasshall be kind enough to yieldglobal wealth to us. [End Page 40] Yes, sisters, pleasewipe a century’s blood off our bodiesgently, without spurs of narcissism,a thousand-fold sprungmillennial vanities. On the Levitation of Beautiful Objects For those millennials who desire one, I offer a parable. Once upon a lifetime, in my turbulent years as a weather system, I was a typhoon named Karen. If I whirled my spiral rainbands in the north, my rotation would’ve shifted to the right. In reality, the Coriolis effect deflected my movement in the southern hemisphere. A corrective footnote in meteorological history, for the record— I made landfall as a tropical storm, not a hurricane by the Isla de la Juventud, the Isle of Youth. On this archipelago, I alighted on an isle,kissed the gangly mangrove shores,upset ferries, hydrofoils, yachts. While serenity blew a puff of air—a glaucoma test in my solo eye—I roared no to sea ports and unreeled an archive of 35mm film, no to fashion institutes, no to civil engineering, no to female pelvic exams, no to forced sterilization, no to acid vibes of the bay, absolutely no to war, a decolonial no to imperialism. A thousand megawatts powering a million offshore turbines, I tossed a love note into my namesake storm— Dear brazen fury of juventud, I lost strength while summoning the beauty of the unanchored, not the lost. Pure verticality and relentless [End Page 41] power, as the world’s rudest tambourine, I dragged my inclemency over palmetto groves, fishing piers, and utility lines. Beloved denizens of the archipelago, so very anthropocentric in scope, you failed to see I was only levitating beautiful objects. [End Page 42] Karen An-hwei Lee Karen An-hwei Lee is the author of the poetry collections Phyla of Joy (Tupelo), Ardor (Tupelo), In Medias Res (Sarabande), and a novel, Sonata in K (Ellipsis). Currently, Lee lives in San Diego, where she serves in the university administration at Point Loma Nazarene University. Copyright © 2017 University of Nebraska Press

To study the effects of central corneal thickness, axial length, and anterior chamber depth on intraocular pressure

Purpose: The aim of the research project is to study the effects of central corneal thickness (CCT), axial length (AL), and anterior chamber (ACD) depth on intraocular pressure (IOP). Study Period: It was a cross-sectional study and was conducted from February 2015 to June 2015. Methodology: A total of 100 participants of varying age groups were selected from Qassim University clinics who had clinically normal corneas and then were divided into different groups based on their ages. All the participants had no evidence of any ocular disease and both eyes were examined in each participant. Anterior chamber depth (ACD) and CCT were measured with Pentacam (OCULUS). IOP was measured with air puff tonometer. AL was measured by A-scan ultrasonography. Results: Two hundred eyes of one hundred participants were examined. The ages of the participants ranged between 18 and 30 years. Mean age was 23.94 years with ± 2.994 standard deviations The number of emmetropes, myopes, and hypermetropes was 50, 19, and 31, respectively. The mean corneal thickness in the right eye was 541.64 μm (±34.80) and in the left eye, it was 543.46 μm (±33.65). IOP was found to increase with increased CCT and it was statistically significant (P

Bulbar conjunctival microvascular responses in dry eye

PurposeConjunctival microvascular responses may be a surrogate metric of efferent neural pathway function innervating the ocular surface as changes in blood flow occur within seconds after a stimulus. As somatosensory dysfunction may partially underlie dry eye (DE), in this study we evaluate whether bulbar conjunctival microvascular alterations correlate with various aspects of DE. MethodsFifty-six DE patients were prospectively recruited from a Veterans Affairs ophthalmology clinic over an 11-month period. DE symptoms and ocular pain were assessed along with DE signs. A novel functional slit lamp biomicroscope (FSLB) was used to image the temporal bulbar conjunctiva from the right eye before and after central corneal stimulation with an air puff. Blood flow velocities were measured and noninvasive microvascular perfusion maps (nMPMs) were created. ResultsThe bulbar blood flow velocity was 0.50 ± 0.15 mm/s at baseline and increased to 0.55 ± 0.17 mm/s after stimulation (P < 0.001); the average change in velocity was 0.05 ± 0.09. nMPMs values and venule diameter, on the other hand, did not significantly increase after stimulation (1.64 ± 0.004 at baseline, 1.65 ± 0.04 after stimulation, P = 0.22 and 22.13 ± 1.84 μm at baseline, 22.21 ± 2.04 μm after stimulation, P = 0.73, respectively). Baseline blood flow velocity positively associated with Schirmer scores (r = 0.40, P = 0.002). Those with higher self-rated wind hyperalgesia demonstrated less change in blood flow velocity (r = −0.268, P = 0.046) after air stimulation on the central cornea. ConclusionConjunctival blood flow velocity, but not vessel diameter or complexity, increases after wind stimuli. Baseline flow positively correlated with Schirmer scores while change in flow negatively correlated with self-reported wind hyperalgesia.

A new kind of wireless mouse

Scientists typically control the behavior of a lab mouse by enticing it with food or repelling it with puffs of air. When I gathered with my colleagues in a Stanford University lab, however, we had a more direct way: We took command of its brain with a shining light. Implanted in that mouse's brain was a device about the size of a peppercorn. When we used our wireless power system to switch it on, the device glowed with a blue light that activated genetically engineered brain cells in the premotor cortex, which sends signals to the muscles. We watched in amazement as the mouse stopped its random motions and began to run in neat circles around the cage.

Functional role of airflow-sensing hairs on the bat wing

Bat wings are adaptive airfoils that enable demanding flight maneuvers. The bat wing is sparsely covered with sensory hairs, and wing-hair removal results in reduced flight maneuverability. Here, we report for the first time single-neuron responses recorded from primary somatosensory cortex to airflow stimulation that varied in amplitude, duration, and direction. The neurons show high sensitivity to the directionality of airflow and might act as stall detectors.

Video-based data acquisition system for use in eye blink classical conditioning procedures in sheep.

Pavlovian eye blink conditioning (EBC) has been extensively studied in humans and laboratory animals, providing one of the best-understood models of learning in neuroscience. EBC has been especially useful in translational studies of cerebellar and hippocampal function. We recently reported a novel extension of EBC procedures for use in sheep, and now describe new advances in a digital video-based system. The system delivers paired presentations of conditioned stimuli (CSs; a tone) and unconditioned stimuli (USs; an air puff to the eye), or CS-alone "unpaired" trials. This system tracks the linear distance between the eyelids to identify blinks occurring as either unconditioned (URs) or conditioned (CRs) responses, to a resolution of 5 ms. A separate software application (Eye Blink Reviewer) is used to review and autoscore the trial CRs and URs, on the basis of a set of predetermined rules, permitting an operator to confirm (or rescore, if needed) the autoscore results, thereby providing quality control for accuracy of scoring. Learning curves may then be quantified in terms of the frequencies of CRs over sessions, both on trials with paired CS-US presentations and on CS-alone trials. The latency to CR onset, latency to CR peak, and occurrence of URs are also obtained. As we demonstrated in two example cases, this video-based system provides efficient automated means to conduct EBC in sheep and can facilitate fully powered studies with multigroup designs that involve paired and unpaired training. This can help extend new studies in sheep, a species well suited for translational studies of neurodevelopmental disorders resulting from gestational exposure to drugs, toxins, or intrauterine distress.

Visual-tactile integration in speech perception: Evidence for modality neutral speech primitives.

Audio-visual [McGurk and MacDonald (1976). Nature 264, 746-748] and audio-tactile [Gick and Derrick (2009). Nature 462(7272), 502-504] speech stimuli enhance speech perception over audio stimuli alone. In addition, multimodal speech stimuli form an asymmetric window of integration that is consistent with the relative speeds of the various signals [Munhall, Gribble, Sacco, and Ward (1996). Percept. Psychophys. 58(3), 351-362; Gick, Ikegami, and Derrick (2010). J. Acoust. Soc. Am. 128(5), EL342-EL346]. In this experiment, participants were presented video of faces producing /pa/ and /ba/ syllables, both alone and with air puffs occurring synchronously and at different timings up to 300 ms before and after the stop release. Perceivers were asked to identify the syllable they perceived, and were more likely to respond that they perceived /pa/ when air puffs were present, with asymmetrical preference for puffs following the video signal-consistent with the relative speeds of visual and air puff signals. The results demonstrate that visual-tactile integration of speech perception occurs much as it does with audio-visual and audio-tactile stimuli. This finding contributes to the understanding of multimodal speech perception, lending support to the idea that speech is not perceived as an audio signal that is supplemented by information from other modes, but rather that primitives of speech perception are, in principle, modality neutral.

Air-puff induced vocalizations: A novel approach to detecting negative affective state following concussion in rats

BackgroundNegative emotional states resulting from concussion are of increasing concern. In the current study, we developed a model to investigate negative affect following concussion in the projectile concussive impact (PCI) model. High frequency ultrasonic vocalizations (22kHz USVs) are associated with negative affective stimuli in rats. Changes in negative affective state were examined following PCI using a mild air-puff stimulus to elicit 22kHz USVs. New methodForty-eight hours post-injury, animals were placed into a clean acrylic box lined with bedding. A 5min baseline recording was followed by 15 air puffs (55psi) spaced 15s apart aimed at the upper back and neck. ResultsInjured animals produced on average 153.5±55.13 more vocalizations than shams, vocalizing on average 4min longer than shams. Additionally, concussed animals vocalized to fewer air-puffs, exhibiting a 1.5 fold lower threshold for the expression of negative affect. Comparison with existing methodsStudies currently used to test negative affective states following concussion in animals, such as the elevated plus maze and forced swim task have, as of yet, been unsuccessful in demonstrating injury effects in the PCI model. While the air-puff test has been applied in other fields, to our knowledge it has not been utilized to study traumatic brain injury. ConclusionThe current study demonstrates that the air-puff vocalization test may be a valuable tool in assessing negative mood states following concussion in rat models and may be used to evaluate novel therapies following brain injury for the treatment of mood dysfunction.

Material Properties from Air Puff Corneal Deformation by Numerical Simulations on Model Corneas

ObjectiveTo validate a new method for reconstructing corneal biomechanical properties from air puff corneal deformation images using hydrogel polymer model corneas and porcine corneas.MethodsAir puff deformation imaging was performed on model eyes with artificial corneas made out of three different hydrogel materials with three different thicknesses and on porcine eyes, at constant intraocular pressure of 15 mmHg. The cornea air puff deformation was modeled using finite elements, and hyperelastic material parameters were determined through inverse modeling, minimizing the difference between the simulated and the measured central deformation amplitude and central-peripheral deformation ratio parameters. Uniaxial tensile tests were performed on the model cornea materials as well as on corneal strips, and the results were compared to stress-strain simulations assuming the reconstructed material parameters.ResultsThe measured and simulated spatial and temporal profiles of the air puff deformation tests were in good agreement (< 7% average discrepancy). The simulated stress-strain curves of the studied hydrogel corneal materials fitted well the experimental stress-strain curves from uniaxial extensiometry, particularly in the 0–0.4 range. Equivalent Young´s moduli of the reconstructed material properties from air-puff were 0.31, 0.58 and 0.48 MPa for the three polymer materials respectively which differed < 1% from those obtained from extensiometry. The simulations of the same material but different thickness resulted in similar reconstructed material properties. The air-puff reconstructed average equivalent Young´s modulus of the porcine corneas was 1.3 MPa, within 18% of that obtained from extensiometry.ConclusionsAir puff corneal deformation imaging with inverse finite element modeling can retrieve material properties of model hydrogel polymer corneas and real corneas, which are in good correspondence with those obtained from uniaxial extensiometry, suggesting that this is a promising technique to retrieve quantitative corneal biomechanical properties.

Neonatal eyelid conditioning during sleep.

Using an eyelid conditioning paradigm modeled after that developed by Little, Lipsitt, and Rovee-Collier (1984), Fifer et al. (2010) demonstrated that newborn infants learn during sleep. This study examined the role of sleep state in neonatal learning. We recorded electroencephalogram (EEG), respiratory, and cardiovascular activity from sleeping full term newborn infants during delay eyelid conditioning. In the experimental group (n = 21), a tone was paired with an air puff to the eye. Consistent with Fifer et al. (2010), newborn infants reliably learned during sleep. The experimental group more than doubled EMR rates to a tone alone, while a control group (n = 17) presented with unpaired tones and puffs maintained low EMR rates. Infant learners were more likely to produce a conditioned EMR during quiet sleep compared to active sleep. Understanding the influence of sleep state on conditioned responses will inform the potential use of eyelid conditioning for early screening.

Development, validation and application of a device to measure e-cigarette users' puffing topography.

With the rapidly rising popularity and substantial evolution of electronic cigarettes (e-cigarettes) in the past 5–6 years, how these devices are used by vapers and consumers’ exposure to aerosol emissions need to be understood. We used puffing topography to measure directly product use. We adapted a cigarette puffing topography device for use with e-cigarettes. We performed validation using air and e-cigarette aerosol under multiple regimes. Consumer puffing topography was measured for 60 vapers provided with rechargeable “cig-a-like” or larger button-activated e-cigarettes, to use ad-libitum in two sessions. Under all regimes, air puff volumes were within 1 mL of the target and aerosol volumes within 5 mL for all device types, serving to validate the device. Vapers’ mean puff durations (2.0 s and 2.2 s) were similar with both types of e-cigarette, but mean puff volumes (52.2 mL and 83.0 mL) and mean inter-puff intervals (23.2 s and 29.3 s) differed significantly. The differing data show that product characteristics influence puffing topography and, therefore, the results obtained from a given e-cigarette might not read across to other products. Understanding the factors that affect puffing topography will be important for standardising testing protocols for e-cigarette emissions.