Air Puff Research Articles

Numerical and Experimental Study of the Spatial Stress Distribution on the Cornea Surface During a Non-Contact Tonometry Examination

The determination of biomechanical properties of the cornea by a non-contact tonometry (NCT) examination requires a precise knowledge of the air puff generated in the device, which is applied to the cornea surface. In this study, a method is proposed to identify the resulting stress profile on the surface, which may be used to numerically solve an inverse problem to obtain the material properties. This method is based on an experimental characterization of the air puff created by the Corvis ST in combination with computational fluid dynamic (CFD) simulations, which are adjusted to the experimental data. The identified nozzle inlet pressure of approximately $25 \text {kPa}$ (188.5mmHg) is then used for a numerical influence study of the interaction between the air puff and the cornea deformation. Therefore, eleven cornea deformation states based on measurements are implemented in the CFD model. A more realistic model is also analyzed by the geometrical reproduction of the human face, which is used for a further influence study. The outcomes showed a dependence between the cornea deformation and the pressure as well as the shear stress distribution. However, quantitatively, the shear stress component can be considered of minor importance being approximately one hundred times smaller than the pressure. The examination with consideration of the human face demonstrates that the pressure and shear stress distributions are not rotationally symmetric in measurements on real humans, which indicates the requirement to include more complex stress distributions on the eye. We present the detailed stress distribution on the cornea during a non-contact tonometry examination, which is made accessible for further investigations in the future by analytical nonlinear functions.

Encoding prediction signals during appetitive and aversive Pavlovian conditioning in the primate lateral hypothalamus.

The lateral hypothalamus (LH), which plays a role in homeostatic functions such as appetite regulation, is also linked to arousal and motivational behavior. However, little is known about how these components are encoded in the LH. Thus cynomolgus monkeys were conditioned with two distinct contexts, i.e., an appetitive context with available rewards and an aversive context with predicted air puffs. Different LH neuron groups encoded different degrees of expectation, predictability, and risks of rewards in a specific manner. A nearly equal number of one-third of the recorded LH neurons showed a positive or negative correlation between their response to visual conditioned stimuli (CS) that predicted the probabilistic delivery of rewards (0%, 50%, and 100%) and the associative values. For another one-third of recorded neurons, a nearly equal number showed a positive or negative correlation between their responses to rewards [appetitive unconditioned stimulus (US)] and reward predictability. Some neurons exhibited their highest or lowest trace-period responses in the 50% reward trials. These response modulations were represented independently and overlaid on a consistent excitatory or inhibitory response across the conditioning events. LH neurons also showed consistent responses in the aversive context. However, the responses to aversive conditioning events depending on the air puff value and predictability were less common. The multifaceted modulation of consistent activity related to outcome predictions may reflect motivational and arousal signals. Furthermore, it may underlie the role the LH plays in the integration and relay of signals to cortices for adaptive and goal-directed physiological and behavioral responses to environmental changes. NEW & NOTEWORTHY The lateral hypothalamus (LH) is implicated in motivational and arousal behavior; however, the detailed information carried by single LH neurons remains unclear. We demonstrate that primate LH neurons encode multiple combinations of signals concerning different degrees of expectation, appreciation, and uncertainty of rewards in consistent responses across conditioning events and between different contexts. This multifaceted modulation of activity may underlie the role of the LH as a critical node integrating motivational signals with arousal signals.

PO-125 Fis1 governs normal mitophagy in slow muscle during the low-intensity and long-period exercise

Objective Mitochondrial dynamics include mitochondrial fusion and mitochondrial fission. It has long been widely recognized that Fis1 plays a role in mitochondrial fission in mammals. However, the finding of Dr. Youle’s team suggests that Fis1 may play an important role in mediating normal mitophagy. Both of mitochondrial dynamics and mitophagy are closely related to skeletal muscle homeostasis. Therefore, in this study, Fis1 was specifically knocked out in skeletal muscle in vivo, looking forward to: 1) investigating the relationship between Fis1 and mitochondrial morphology, mitophagy in mouse skeletal muscle. 2) The mechanism of Fis1 in mitochondrial quality in skeletal muscle under exercise stress. So as to we can clarify the molecular mechanism of Fis1 in mediating mitochondrial quality in skeletal muscle, but also expect to provide more theoretical basis for skeletal muscle health and exercise adaptation.
 Methods We constructed conditional skeletal muscle Fis1 knockout mice (C57BL/6) and littermate control mice through Cre / Loxp technique. The mice were free feeding, drinking and activity during the teat, we only selected male mice for all of the tests. And the genotypes were Fis1FL / FL MCK-Cre + (Fis1KO) and Fis1FL / FL MCK-Cre – (WT). First, we performed endurance test on 10 WT and 10 Fis1KO mice (32-40 weeks, n = 10), then dissected quadriceps, gastrocnemius and soleus (n=4-5) quickly and rapidly frozen in liquid nitrogen, then stored at -80 ° C freezer for testing Fis1 and OXPHOS expression (Western-blot). On the other hand, we selected WT and Fis1KO mice (n=3) to prepare EM samples, so as to observe mitochondrial morphology and muscle ultrastructure. Skeletal muscle (n=3-4) was snap-frozen in isopentane cooled with liquid nitrogen for HE, NADH staining, and observing GFP-LC3 (mitophagy).
 Base on the exploration of loss of Fis1 without stress, we adopted endurance exhaustive exercise on WT (WT EEE) and Fis1KO mice (Fis1KO EEE) (n=3-4). Mice were acclimated to and trained on a 10o uphill treadmill. Mice were acclimated to and trained on a 10o uphill treadmill (Columbus Instruments) for 2 days. On day 3, mice were subjected to a single bout of running starting at the speed of 10m/min. Forty minutes later, the treadmill speed was increased at a rate of 1m/min every 10 min for a total of 30 min, and then increased at the rate of 1m/min every 5 min until mice were exhausted. Exhaustion was defined as the point at which mice spent more than 5 s on the electric shocker without attempting to resume running even if we used short air puffs and tail tickles with bristle brush. We dissected soleus and gastrocnemius to observe muscle ultrastructure and mitophagy through EM and confocal microscope respectively (same methods as before). At the same time, we used immune-EM to observe autophagosome morphology and LC3 distribution.
 Results Behavior test on specific knock out skeletal muscle Fis1 mice model
 We found that loss of Fis1 induced significantly lower performance in treadmill endurance tests than controls (P <0.001).
 The effect of loss of Fis1 on mitochondrial morphology and function
 In soleus, knocking out Fis1 caused mitochondrial hyperfusion (mitochondrial size was significantly increased, P = 0.01). In addition, we found more swollen mitochondria in Fis1 knock-out gastrocnemius.
 On the other hand, compared with the control mice, lack of Fis1 significantly reduced the protein expression of Complex I, Complex II and Complex IV in soleus (P <0.01). As same as before, we also found a significant increase GFP-LC3 (P <0.01) in Fis1KO soleus.
 3) Changes of muscle ultrastructure and mitophagy after endurance exhaustive exercise (EEE)
 First, comparing with the control group, swollen sarcoplasmic reticulum (skeletal muscle endoplasmic reticulum (ER)) and extremely swollen terminal cisternae (TC) were found in Fis1KO soleus and gastrocnemius respectively after endurance exhaustive exercise.
 We found a significant accumulation of GFP-LC3 (P <0.0001) in Fis1KO soleus compared to the control. However, GFP-LC3 signal still increased (P <0.001) in Fis1KO soleus after exercise compared with that in soleus before exercise. Moreover, we observed a lot of large and irregular autophagosomes appeared in Fis1KO soleus after EEE through immune electron microscope.
 Conclusions 1) Loss of Fis1 causes a certain degree of mitochondrial hyperfusion, increases mitophagy and significantly decreases mitochondrial function in slow muscle. However, losing Fis1 does not cause obvious alteration on quick muscle and synthetic muscle. Therefore, the absence of Fis1 has a significant effect on mitochondria-rich muscle.
 2) Mitochondrial-ER interactions may be involved in the connection of endoplasmic reticulum swelling after endurance exhaustive exercise.
 3) Endurance exercise with oxidative phosphorylation aggravate the increase and abnormality of mitophagy caused by the loss of Fis1 in slow muscle, suggesting that Fis1 governs normal mitophagy in slow muscle during the low-intensity and long-period exercise. This phenomenon may be related to the worse performance in treadmill endurance test of Fis1 KO mice.

Impact of diurnal IOP variations on the dynamic corneal hysteresis measured with air-puff swept-source OCT

The deformation amplitudes measured with air-puff OCT are sensitive to both (intraocular pressure) IOP and biomechanical properties of the cornea. Analysis of the amplitudes of corneal deformation is challenging due to interrelation of IOP and corneal biomechanics. In this study, we used natural diurnal IOP fluctuations to investigate corneal deformations in a number of subjects whose eyes were measured multiple times during a day. The results of analysis, based on corneal hysteresis, revealed a corneal hysteresis parameter, which remains constant during a day for each individual eye. We hypothesize that above-mentioned metric might correlate with biomechanical properties of the cornea without influence of IOP. Full Text: PDF ReferencesMeek KM, Tuft SJ, Huang Y, Gill PS, Hayes S, Newton RH, Bron AJ, "Changes in Collagen Orientation and Distribution in Keratoconus Corneas", Invest Ophthalmol Vis Sci, 2005. 46(6): p. 1948-56. CrossRef Zimmermann DR, Fisher RW, Winterhalter KH, Witmer R, Vaughan L, "Comparative studies of collagens in normal and keratoconus corneas", Exp Eye Res, 1988. 46(3): p. 431-42. CrossRef Andreassen TT, Simonsen AH, and Oxlund H, "Biomechanical properties of keratoconus and normal corneas", Experimental Eye Research, 1980. 31(4): p. 435-441. CrossRef Heijl A, Leske MC, Bengtsson B, Hyman L, Bengtsson B, Hussein M, "Reduction of Intraocular Pressure and Glaucoma Progression", Arch Ophthalmol, 2002. 120(10): p. 1268-79. CrossRef Chauhan BC and Drance SM, "The influence of intraocular pressure on visual field damage in patients with normal-tension and high-tension glaucoma", Investigative Ophthalmology & Visual Science, 1990. 31(11): p. 2367-2372. DirectLink Gelaw Y, "The impact of central corneal thickness on intraocular pressure among Ethiopian glaucoma patients: a cross-sectional study", BMC Ophthalmology, 2012. 12(1): p. 58. CrossRef Doughty MJ and Zaman ML, "Human Corneal Thickness and Its Impact on Intraocular Pressure Measures: A Review and Meta-analysis Approach", Surv Ophthalmol, 2000. 44(5): p. 367-408. CrossRef Liu J, and Roberts CJ, "Influence of corneal biomechanical properties on intraocular pressure measurement: Quantitative analysis", J Cataract Refract Surg, 2005. 31(1): p. 146-55. CrossRef Ehlers N, Hansen FK, and Aasved H, "Biometric Correlations of Corneal Thickness", Acta Ophthalmol (Copenh), 1975. 53(4): p. 652-9. CrossRef Harada Y, Hirose N, Tawara A, "The Influence of Central Corneal Thickness and Corneal Curvature Radius on The Intraocular Pressure as Measured By Different Tonometers: Noncontact and Goldmann Applanation Tonometers", J Glaucoma, 2008. 17(8): p. 619-25. CrossRef Alonso-Caneiro D, Karnowski K, Kaluzny BJ, Kowalczyk A, Wojtkowski M, "Assessment of corneal dynamics with high-speed swept source Optical Coherence Tomography combined with an air puff system", Optics Express, 2011. 19(15): p. 14188-14199. CrossRef Dorronsoro C, Pascual D, Perez-Merino P, Kling S and Marcos S, "Dynamic OCT measurement of corneal deformation by an air puff in normal and cross-linked corneas", Biomedical Optics Express, 2012. 3(3): p. 473-487. CrossRef Karnowski K, Kaluzny BJ, Szkulmowski M, Gora M, Wojtkowski M, "Corneal topography with high-speed swept source OCT in clinical examination", Biomedical Optics Express, 2011. 2(9): p. 2709-2720. CrossRef A. N. S. Institute, "American National Standard for Safe use of Lasers," (American National Standards Institute, Orlando, FL, 2000) DirectLink David R, Zangwill L, Briscoe D, Dagan M, Yagev R, Yassur Y, "Diurnal intraocular pressure variations: an analysis of 690 diurnal curves", Br J Ophthamlom, 1992, 76(5): p. 280-282 CrossRef Maczynska E, Karnowski K, Szulzycki K, Malinowska M, Dolezyczek H, Cichanski A, Wojtkowski M, Kaluzny BJ, Grulkowski I, Journal of Biophotonics (to be published).

Multisensory and Motor Representations in Rat Oral Somatosensory Cortex

In mammals, a complex array of oral sensors assess the taste, temperature and haptic properties of food. Although the representation of taste has been extensively studied in the gustatory cortex, it is unclear how the somatosensory cortex encodes information about the properties of oral stimuli. Moreover, it is poorly understood how different oral sensory modalities are integrated and how sensory responses are translated into oral motor actions. To investigate whether oral somatosensory cortex processes food-related sensations and movements, we performed in vivo whole-cell recordings and motor mapping experiments in rats. Neurons in oral somatosensory cortex showed robust post-synaptic and sparse action potential responses to air puffs. Membrane potential showed that cold water evoked larger responses than room temperature or hot water. Most neurons showed no clear tuning of responses to bitter, sweet and neutral gustatory stimuli. Finally, motor mapping experiments with histological verification revealed an initiation of movements related to food consumption behavior, such as jaw opening and tongue protrusions. We conclude that somatosensory cortex: (i) provides a representation of the temperature of oral stimuli, (ii) does not systematically encode taste information and (iii) influences orofacial movements related to food consummatory behavior.

Concurrent aero-tactile stimulation does not bias perception of VOT for non-initial stops

Previous work has established that puffs of air applied to the skin and timed with listening tasks bias the perception of voicing in onset stops by naive listeners (Gick and Derrick, 2009; Goldenberg et al., 2015). While the primary cue for the voicing contrast in stops is VOT (Lisker and Abramson, 1964), in English aspiration typically functions as a cue foot initially. This study tests the effect of air puffs on perception of voicing for English stops in a non-foot-initial context (“apa/aba”) using VOT continua. Goldenberg et al. (2015) have shown that listeners are sensitive to aero-tactile effects only when these are congruent with the expected contrast (i.e., in VOT but not vowel quality distinctions). Since VOT is generally non-contrastive for English stops that are not foot-initial, air puffs were not expected to affect perception in the current case, and indeed, of 22 participants (11 females; mean age 34.2) tested, 20 showed no effect. Comparison of this null result to the significant bias observed in the earlier (foot-initial context) study extends the finding that, for aero-tactile stimulation to bias perception, the cues must be consistent with those expected in production of the perceived sounds.

Classical Short-Delay Eyeblink Conditioning in One-Year-Old Children.

Classical eyeblink conditioning (EBC) refers to the learned association between a conditioned stimulus (an auditory tone) and an unconditioned stimulus (a puff of air to the cornea). Eyeblink conditioning is often used experimentally to detect abnormalities in cerebellar-dependent learning and memory that underlies this type of associative learning. While experiments in adults and older children are relatively simple to administer using commercial equipment, eyeblink conditioning in infants is more challenging due to their poor compliance, which makes correct positioning of the equipment difficult. To achieve conditioning in one-year-old infants, a custom-made or an adapted commercial system can be used to deliver the air puff to the infant's cornea. The main challenge lies in successfully detecting and classifying the behavioral responses. We report that automated blink detection methods are unreliable in this population, and that conditioning experiments should be analyzed using frame-by-frame analysis of supplementary video camera recordings. This method can be applied to study developmental changes in eyeblink conditioning and to examine whether this paradigm can detect children with neurological disorders.

Visual-aerotactile perception and congenital hearing loss

Previous research on multimodal speech perception with hearing-impaired individuals focused on audiovisual integration with mixed results. Cochlear-implant users integrate audiovisual cues better than perceivers with normal hearing when perceiving congruent [Rouger et al. 2007, PNAS, 104(17), 7295–7300] but not incongruent cross-modal cues [Rouger et al. 2008, Brain Research 1188, 87–99), leading to the suggestion that early auditory exposure is required for typical speech integration processes to develop (Schorr 2005, PNAS, 102(51), 18748–18750). If a deficit of one modality does indeed lead to a deficit in multimodal processing, then hard of hearing perceivers should show different patterns of integration in other modality pairings. The current study builds on research showing that gentle puffs of air on the skin can push individuals with normal hearing to perceive silent bilabial articulations as aspirated. We report on a visual-aerotactile perception task comparing individuals with congenital hearing loss to those with normal hearing. Results indicate that aerotactile information facilitated identification of /pa/ for all participants (p < 0.001) and we found no significant difference between the two groups (normal hearing and congenital hearing loss). This suggests that typical multi-modal speech perception does not require access to all modalities from birth. [Funded by NIH.]Previous research on multimodal speech perception with hearing-impaired individuals focused on audiovisual integration with mixed results. Cochlear-implant users integrate audiovisual cues better than perceivers with normal hearing when perceiving congruent [Rouger et al. 2007, PNAS, 104(17), 7295–7300] but not incongruent cross-modal cues [Rouger et al. 2008, Brain Research 1188, 87–99), leading to the suggestion that early auditory exposure is required for typical speech integration processes to develop (Schorr 2005, PNAS, 102(51), 18748–18750). If a deficit of one modality does indeed lead to a deficit in multimodal processing, then hard of hearing perceivers should show different patterns of integration in other modality pairings. The current study builds on research showing that gentle puffs of air on the skin can push individuals with normal hearing to perceive silent bilabial articulations as aspirated. We report on a visual-aerotactile perception task comparing individuals with congenital hearing ...

Classical Short-Delay Eyeblink Conditioning in One-Year-Old Children

Classical eyeblink conditioning (EBC) refers to the learned association between a conditioned stimulus (an auditory tone) and an unconditioned stimulus (a puff of air to the cornea). Eyeblink conditioning is often used experimentally to detect abnormalities in cerebellar-dependent learning and memory that underlies this type of associative learning. While experiments in adults and older children are relatively simple to administer using commercial equipment, eyeblink conditioning in infants is more challenging due to their poor compliance, which makes correct positioning of the equipment difficult. To achieve conditioning in one-year-old infants, a custom-made or an adapted commercial system can be used to deliver the air puff to the infant's cornea. The main challenge lies in successfully detecting and classifying the behavioral responses. We report that automated blink detection methods are unreliable in this population, and that conditioning experiments should be analyzed using frame-by-frame analysis of supplementary video camera recordings. This method can be applied to study developmental changes in eyeblink conditioning and to examine whether this paradigm can detect children with neurological disorders.

Examining affective structure in chickens: valence, intensity, persistence and generalization measured using a Conditioned Place Preference Test

When measuring animals’ valenced behavioural responses to stimuli, the Conditioned Place Preference (CPP) test goes a step further than many approach-based and avoidance-based tests by establishing whether a learned preference for, or aversion to, the location in which the stimulus was encountered can be generated. We designed a novel, four-chambered CPP test to extend the capability of the usual CPP paradigm to provide information on four key features of animals’ affective responses: valence, scale, persistence and generalization. Using this test, we investigated the affective responses of domestic chickens (Gallus gallus domesticus) to four potentially aversive stimuli: 1. Puffs of air; 2. Sight of (robotic) snake; 3. Sprays of water; 4. Sound of conspecific alarm calls. We found conditioned avoidance of locations associated with the air puffs and water sprays (Friedman’s χ2(3) = 13.323 p > .005; χ2(3) = 14.235 p > .005), but not with the snake and alarm calls. The scale of the learned avoidance was similar for the air puff and water spray stimuli, but persistence and generalization differed. We conclude that the four chambered CPP test can have a valuable role to play in making multi-feature measurements of stimulus-generated affective responses, and we highlight the value of such measurements for improving our understanding of the structure of affect in chickens and other animals.

Socially-mediated arousal and contagion within domestic chick broods

Emotional contagion – an underpinning valenced feature of empathy – is made up of simpler, potentially dissociable social processes which can include socially-mediated arousal and behavioural/physiological contagion. Previous studies of emotional contagion have often conflated these processes rather than examining their independent contribution to empathic response. We measured socially-mediated arousal and contagion in 9-week old domestic chicks (n = 19 broods), who were unrelated but raised together from hatching. Pairs of observer chicks were exposed to two conditions in a counterbalanced order: air puff to conspecifics (AP) (during which an air puff was applied to three conspecifics at 30 s intervals) and control with noise of air puff (C) (during which the air puff was directed away from the apparatus at 30 s intervals). Behaviour and surface eye temperature of subjects and observers were measured throughout a 10-min pre-treatment and 10-min treatment period. Subjects and observers responded to AP with increased freezing, and reduced preening and ground pecking. Subjects and observers also showed reduced surface eye temperature - indicative of stress-induced hyperthermia. Subject-Observer behaviour was highly correlated within broods during both C and AP conditions, but with higher overall synchrony during AP. We demonstrate the co-occurrence of socially-mediated behavioural and physiological arousal and contagion; component features of emotional contagion.

Sensorimotor Integration and Amplification of Reflexive Whisking by Well-Timed Spiking in the Cerebellar Corticonuclear Circuit

To test how cerebellar crus I/II Purkinje cells and their targets in the lateral cerebellar nuclei (CbN) integrate sensory and motor-related inputs and contribute to reflexive movements, we recorded extracellularly in awake, head-fixed mice during non-contact whisking. Ipsilateral or contralateral air puffs elicited changes in population Purkinje simple spike rates that matched whisking kinematics (∼1Hz/1° protraction). Responses remained relatively unaffected when ipsilateral sensory feedback was removed by lidocaine but were reduced by optogenetically inhibiting the reticular nuclei. Optogenetically silencing cerebellar output suppressed movements. During puff-evoked whisks, both Purkinje and CbN cells generated well-timed spikes in sequential 2- to 4-ms windows at response onset, such that they alternately elevated their firing rates just before protraction. With spontaneous whisks, which were smaller than puff-evoked whisks, well-timed spikes were absent and CbN cells were inhibited. Thus, sensory input can facilitate millisecond-scale, well-timed spiking in Purkinje and CbN cells and amplify reflexive whisker movements.

Comparison of Measurement of Intraocular Pressure between Goldmann Applanation Tonometer and Non-Contact Air Puff Tonometer

Objective: To compare measurement of intraocular pressure between Goldmann Applanation Tonometer and Non-Contact Air Puff Tonometer. Study Design: Clinical Observational Study. Place and Duration of Study: This study was carried out at Out Patient Department of Ophthalmology, Khairpur Medical College Hospital, Khairpur Mir�s from January 2017 to March 2017. Methodology: In this Clinical Observational Study, intra ocular pressures of 400 eyes of 200 patients, Male 125 (250 eyes) and Female 75 (150 eyes) with age ranging from 20 to 70 years, were measured by Goldmann Applanation Tonometer (GAT) and Non-Contact Air Puff Tonometer (APT), results and differences were noted. Results: The mean IOP was 16mmHg (SD = 6 mmHg) measured by APT and 13mmHg (SD = 3 mmHg) measured by GAT. The calculated difference between APT and GAT was 3 � 2.5 mmHg. Pressure taken by APT was slight high (i.e. around 3 mmHg). Conclusion: Air Puff tonometry gives slightly higher results (about 3mmHg) but is safe and easy than Goldmann Applanation tonometer. There is no fear of spread of infection and can be used easily in mass screening programs. Key Words: Goldmann Applanation Tonometer, Air-Puff non-contact Tonometer, Intraocular pressure, Glaucoma.

Comparison of Dynamic Contour Tonometry and Non-contact Tonometry in Older Patients Presenting with Headache or Vision Loss.

Background:Dynamic Contour Tonometry (DCT) is touted to be the most accurate tonometer for Intraocular Pressure (IOP) measurement. Non-Contact “air puff” Tonometry (NCT) may be the most commonly used tonometer for screening of IOP. Elevated IOP is important to exclude in patients presenting with headache or vision loss.Objective:To determine the agreement between DCT and NCT.Methods:The IOP of adult patients 50 years of age or older presenting with headache or vision loss for possible temporal artery biopsy were prospectively recorded. NCT and DCT measurements were obtained within thirty minutes. The right eye IOP measurements were compared with paired t-test, and Bland- Altman plot analysis. The left eye IOP measurements were subsequently analyzed for confirmation of results.Results:There were 106 subjects with complete right eye data, and 104 subjects with complete left eye data. The average age was 72 years, and 70% were female. The NCT IOP was on average 3.9 mm Hg lower in the right eye, and 3.5 mm Hg lower in the left eye compared with DCT. (p<.001) In the right eye the Bland-Altman analysis showed the 95% agreement interval between the two tonometers was -2.5 to 10.4 mmHg and in the left eye -3.0 to 9.9 mmHg.Conclusion:The IOP from NCT and DCT should not be used interchangeably because their level of disagreement includes clinically important discrepancies of up to 10 mm Hg.

Intraocular pressure and its normal range adjusted for ocular and systemic parameters. The Beijing Eye Study 2011.

PurposeTo examine the distribution of intraocular pressure (IOP) in a normal population and the associations of IOP with other ocular and systemic parameters.MethodsOut of 3468 participants of the population-based cross-sectional Beijing Eye Study 2011 we selected those individuals without glaucomatous optic neuropathy. The study particpants underwent a detailed ophthalmologic and systemic examination. IOP was measured by air puff non-contact tonometry.ResultsThe study included 3135 eyes of 3135 participants with a mean age of 64.1 ± 9.6 years (mean ± standard deviation). The mean IOP was 14.7 ± 2.8 mmHg. The 95% percentile and 97.5% percentile of the IOP distribution decreased from 20 mmHg / 21 mmHg in individuals aged 40 to 54 years to 18 mmHg / 19 mmHg in individuals aged ≥80 years. In multivariable analysis, higher IOP was associated with the systemic parameters of younger age (P<0.001), higher blood concentration of glucose (P = 0.03) and triglycerides (P<0.001), higher diastolic blood pressure (P<0.001), higher pulse rate (P = 0.003) and higher quantity of alcohol consumption (P = 0.004), and with the ocular parameters of larger central corneal thickness (P<0.001), more myopic refractive error (P = 0.01) and steeper anterior corneal curvature radius (P = 0.006). IOP decreased significantly by 0.50 mmHg and 0.76 mmHg for each increase in age by 10 years and each increase in corneal curvature radius by 1.0 mm, respectively. The range of the mean ± 2 standard deviations of the IOP adjusted for the parameters of the multivariable model was 9.0 to 18.1 mmHg versus 9.2–20.2 mmHg for the unadjusted IOP. In the age group of 50 to 55 years, the age-adjusted IOP range (mean ± 2 standard deviations) was 9 to 18 mmHg, and in the age group of ≥75 years, it was 8 to 18 mmHg.ConclusionsIOP physiologically depends on a multitude of systemic and ocular factors including age and blood pressure. These physiological associations of the IOP may be taken into account in the definition of the normal range of the IOP.

Open Source Tools for Temporally Controlled Rodent Behavior Suitable for Electrophysiology and Optogenetic Manipulations.

Understanding how the brain controls behavior requires observing and manipulating neural activity in awake behaving animals. Neuronal firing is timed at millisecond precision. Therefore, to decipher temporal coding, it is necessary to monitor and control animal behavior at the same level of temporal accuracy. However, it is technically challenging to deliver sensory stimuli and reinforcers as well as to read the behavioral responses they elicit with millisecond precision. Presently available commercial systems often excel in specific aspects of behavior control, but they do not provide a customizable environment allowing flexible experimental design while maintaining high standards for temporal control necessary for interpreting neuronal activity. Moreover, delay measurements of stimulus and reinforcement delivery are largely unavailable. We combined microcontroller-based behavior control with a sound delivery system for playing complex acoustic stimuli, fast solenoid valves for precisely timed reinforcement delivery and a custom-built sound attenuated chamber using high-end industrial insulation materials. Together this setup provides a physical environment to train head-fixed animals, enables calibrated sound stimuli and precisely timed fluid and air puff presentation as reinforcers. We provide latency measurements for stimulus and reinforcement delivery and an algorithm to perform such measurements on other behavior control systems. Combined with electrophysiology and optogenetic manipulations, the millisecond timing accuracy will help interpret temporally precise neural signals and behavioral changes. Additionally, since software and hardware provided here can be readily customized to achieve a large variety of paradigms, these solutions enable an unusually flexible design of rodent behavioral experiments.

Custom air puff-derived biomechanical variables in a refractive surgery screening setting: Study from 2 centers

To assess the ability of air puff-derived biomechanical variables to predict surgeon-perceived candidacy for laser insitu keratomileusis (LASIK). Cole Eye Institute, Cleveland Clinic, Cleveland, Ohio, and Emory Eye Institute, Emory University, Atlanta, Georgia, USA. Retrospective case series. Data were collected from refractive surgery screening examinations by 2 surgeons at 2 centers. Disqualified cases (19 eyes and 28 eyes from each surgeon) were judged not to be candidates based on available data including standard variables from the Ocular Response Analyzer. Controls consisted of LASIK candidates (n=26 and 23). Three custom biomechanical variables not available during screening were calculated and compared by group and surgeon. The hysteresis loop area was significantly different between disqualified cases and controls for both surgeons (Surgeon 1: controls, 121.50±25.38 [SD], disqualified, 107.62±18.50, P=.04; Surgeon 2: controls, 135.89±22.47, disqualified, 106.11±16.40, P<.001). The area under the curves of the receiver operating characteristics and the cutoff values were statistically significant for the concavity minimum and hysteresis loop area for Surgeon 1 and for all variables except concavity minimum for Surgeon 2. The hysteresis loop area had the highest odds ratio (Surgeon 1, 4.48, Surgeon 2, 20.00). Adjusted R2 in best-subsets regressions were 40.2% for Surgeon 1 and 62.9% for Surgeon2. The hysteresis loop area was predictive of which patients were disqualified for LASIK at different sites. Certain measures of the corneal dynamic response to an air puff might serve as correlates to clinically perceived ectasia risk.

Ocular manifestation in Marfan syndrome: corneal biomechanical properties relate to increased systemic score points.

To evaluate corneal deformation to an air puff as a new noninvasive tool to document disease status in Marfan syndrome (MFS) METHODS: Prospective observational cohort study. We included patients diagnosed with MFS who had their routine cardiovascular follow-up and applied the revised Ghent nosology to define two subgroups according to a high (≥ 7) and a low (< 7 points) systemic score. Dynamic Scheimpflug-based biomechanical analyses (CorvisST® [CST; Oculus GmbH]) were performed. The main outcome measure was the displacement of the corneal apex as given by the parameters highest concavity (HC; in ms), peak distance (PD; in mm), and highest concavity deformation amplitude (DA; mm). Forty-three eyes of 43 individuals (19 female, 24 male; mean age 42.0 ± 12.0years, range 18-67years) diagnosed with MFS were included. Applying the Ghent criteria, 21 patients had an advanced systemic score of ≥ 7, and 22 had score points < 7. There were no differences in age or sex between both groups. In contrast, HC was faster (P = 0.004), and PD (P < 0.001) was longer in those individuals with systemic score ≥ 7; maximum DA did not result in a statistically significant difference between the groups (P = 0.250). In vivo noninvasive biomechanical analyses with CST offer a new, non-invasive method to identify pathologic corneal deformation responses in adults with MFS. In the future, corneal deformation to an air puff could thus assist early identification of patients with high Ghent score as an adjunct to existing diagnostic tests.

Somatotopic Organization and Temporal Characteristics of Cerebrocortical Excitation in Response to Nasal Mucosa Stimulation With and Without an Odor in the Rat: An Optical Imaging Study

Nasal mucosa has roles in warming and humidifying inspired air and is highly sensitive to mechanical stimuli. Moreover, the upper part of the nasal mucosa expresses olfactory receptors processing olfactory information. Although the somatosensory map of the face in the primary (S1) and secondary (S2) somatosensory cortices is clearly documented, the map of the nasal mucosa and the effect of odors on their activities are largely unknown. This study aimed to identify the cortical regions in S1 and their temporal features in response to somatosensory stimulation of the nasal mucosa using an optical imaging technique in urethane-anesthetized rats. An air puff application response to nasal mucosa first occurred in a part of contralateral S1 and subsequently, spread toward the rostrally and ventrally adjacent sites. Upper pharynx stimulation initially activated this rostrally expanded site and the excitatory propagation from the initially activated region toward ventral region likely represented S2. Signal intensity and activated area increased dependent on air pressure. Nasal tip stimulation initially excited S1 region caudally adjacent to that of nasal mucosa. Moreover, the amplitude of S1 excitation was similar between air puff stimulation with and without an odor, amyl acetate. In contrast to contralateral S1, air puff stimulation with the odor showed a faint optical signal increase in the ipsilateral piriform cortex. These results suggest that somatosensory information from the nasal mucosa and skin, and upper pharynx are processed in spatially continuous regions of S1, and interaction between somatosensory and olfactory systems is relatively small in contralateral S1.

Spatiotemporal integration of looming visual and tactile stimuli near the face.

Real‐world objects approaching or passing by an observer often generate visual, auditory, and tactile signals with different onsets and durations. Prompt detection and avoidance of an impending threat depend on precise binding of looming signals across modalities. Here we constructed a multisensory apparatus to study the spatiotemporal integration of looming visual and tactile stimuli near the face. In a psychophysical experiment, subjects assessed the subjective synchrony between a looming ball and an air puff delivered to the same side of the face with a varying temporal offset. Multisensory stimuli with similar onset times were perceived as completely out of sync and assessed with the lowest subjective synchrony index (SSI). Across subjects, the SSI peaked at an offset between 800 and 1,000 ms, where the multisensory stimuli were perceived as optimally in sync. In an fMRI experiment, tactile, visual, tactile‐visual out‐of‐sync (TVoS), and tactile‐visual in‐sync (TViS) stimuli were delivered to either side of the face in randomized events. Group‐average statistical responses to different stimuli were compared within each surface‐based region of interest (sROI) outlined on the cortical surface. Most sROIs showed a preference for contralateral stimuli and higher responses to multisensory than unisensory stimuli. In several bilateral sROIs, particularly the human MT+ complex and V6A, responses to spatially aligned multisensory stimuli (TVoS) were further enhanced when the stimuli were in‐sync (TViS), as expressed by TVoS < TViS. This study demonstrates the perceptual and neural mechanisms of multisensory integration near the face, which has potential applications in the development of multisensory entertainment systems and media.