Breakup Area Research Articles

Localized Evaporative Cooling Explains Observed Ocular Surface-Temperature Patterns.

We determined interblink corneal surface-temperature decline and tear-film evaporation rates of localized tear breakup cold regions (LCRs) and localized tear unbroken warm regions (LWRs) of the corneal surface, as well as that of the overall average corneal surface. Each subject underwent 4 inter-day visits where the interblink corneal surface-temperature history of the right eye was measured using a FLIR A655sc infrared thermographer. Corneal surface temperature history was analyzed to determine the overall, LCR, and LWR temperature-decline rates. Evaporation rates of LCR and LWR regions were determined from the measured LCR and LWR temperature data using the physical model of Dursch et al. Twenty subjects completed the study. Mean (SD) difference of LCR temperature-decline rate was -0.08 (0.07)°C/s faster than LWR (P < 0.0001). Similarly, evaporation rates of LCR and LWR were statistically different (P < 0.0001). At ambient temperature, mean LCR and LWR evaporation rates were 76% and 27% of pure water evaporation flux, respectively. There was no statistically significant difference between the inter-day measured temperature-decline rates and the interblink starting temperature. Significant differences in corneal temperature-decline rate and evaporation rate between LCR and LWR were quantified using infrared thermography. In agreement with literature, LCRs and LWRs correlate directly with fluorescein break-up areas and unbroken tear areas, respectively. Because lipid-evaporation protection is diminished in breakup areas, higher local evaporation rates and faster local cooling rates occur in LCRs relative to LWRs. Our results confirm this phenomenon clinically for the first time.

Effects of different types of fibrotic remodelling in areas of low voltage on atrial fibrillation dynamics: an in-silico study

Abstract Background Personalized computational models include the effects of personalised anatomy and atrial fibrillation (AF) remodelling in a framework that can be used to investigate patient-specific AF mechanisms and test treatment response, but modelling fibrosis remains an unresolved matter. The interpretation of regions exhibiting low voltage in electroanatomic mapping data at different pacing rates also remain unclear. However, these occurrences are correlated with fibrotic remodelling. We aimed to use patient-specific simulations to investigate the effects of fibrosis type on AF properties by modelling conduction velocity slowing, changes in ionic channels, and replacement fibrosis, incorporated in regions of low voltage identified through omnipolar mapping at different pacing rates. Methods Local activation times (LATs) voltage and geometry data were obtained from patients undergoing ablation for persistent AF. LATs were collected in sinus rhythm with coronary sinus pacing at pacing interval (PIs) of 250ms and 600ms. For a total of 10 cases, personalised anatomical models were constructed for electrophysiology simulations, and analysed using an automated pipeline in python. For conductivity models, areas with peak omnipolar voltage (OV) below 0.5mV were assigned low conduction velocity. To incorporate ionic changes, the ionic properties were altered in fibrotic regions (peak OV &amp;lt; 0.5mV). In the simulations where replacement fibrosis was included through a probabilistic percolation method, percolation was modelled by using random number generator to probabilistically remove elements of low voltage. Pulmonary vein isolation was simulated in each model after 5s of AF, and wavefront propagation patterns were analysed to quantify the number of rotational areas or areas of wavefront break-up in 7 anatomical segments. Results The models with conductivity fibrotic remodelling demonstrated rotational drivers in more than two LA anatomical segments for both CS250ms pacing rate and CS600ms pacing rate across all 10 cases. The anterior wall exhibited the largest degree of rotational activity in 7 out of 10 cases for CS250ms pacing rate and in 9 out of 10 cases for CS600ms pacing rate (Figure A). The combination of percolation and conductivity remodelling also exhibited rotational activity on the anterior wall in 9 out of 10 cases at CS250ms pacing rate, and 7 out of 10 cases for CS600ms pacing rate. For the simulations where replacement fibrosis was included (percolation), both the roof and anterior wall exhibited the largest degree of rotational activity in 5 out of 10 cases at CS250ms pacing rate; while at CS600ms pacing rate, the posterior walled exhibited the majority of rotational activity in 7 cases (Figure B). All fibrosis models containing ionic changes terminated in more than half of the 10 cases for both pacing rates (CS250ms and 600). Conclusion The impact of low voltage on fibrotic remodelling causes complex effects on AF dynamics.

The unique properties of tear film breakup process in patients with nasal unilateral pterygium.

This study found that the unique properties of tear film breakup process in eyes with pterygium, combined with ocular surface parameters, further revealed specific dynamic mechanism. It suggested that the thickness of pterygium was especially valuable in deciding the necessity of surgical management. This study aimed to explore the dynamic mechanism of tear film instability in eyes with pterygium. A paired-eye controlled cross-sectional study was conducted. Seventy-eight patients with nasal pterygium were enrolled. Fluorescein tear film breakup was observed. Several key parameters related to tear film quality were defined and analyzed, including total breakup area (mathematically derived from pixel size using MATLAB), breakup velocity, fluorescein breakup time, breakup location and pattern, tear meniscus height, score of fluorescein corneal staining, and meiboscore. With comparable tear meniscus height, score of fluorescein corneal staining, and meiboscore between paired eyes (p > 0.05), eyes with pterygium had shorter breakup time, larger breakup area, and faster breakup velocity (p < 0.05). In eyes with pterygium, a positive correlation between meiboscore and pterygium parameters including length, thickness, and size was observed (p > 0.001). As the thickness increased, difference of breakup time and area between paired eyes increased (p = 0.02 and 0.046). Eyes with pterygium had more fixed inferonasal breakup location and often presented as dimple break (60%), whereas random break was the most common in contralateral normal eyes (62%). A unique breakup pattern named pterygium-induced local dimple break was found. It displayed as an irregular but vertical line-like shape appearing after lipid layer spreading, which was adjacent to the lower margin of pterygium and presented with unique properties including inferonasal breakup location, local breakup area, shorten breakup time, and faster breakup velocity. Eyes with pterygium showed a unique tear film breakup process and novel breakup pattern named pterygium-induced local dimple break . Dynamic mechanism played a significant role in tear film instability of eyes with pterygium rather than aqueous deficiency and increased evaporation.

Role of initial chirp and dispersion on Airy pulse propagation in an optical single-mode fiber

We study numerically the propagation dynamics of an initially finite-energy chirped Airy pulse in an optical single-mode fiber when the group-velocity dispersion parameter β2 and chirp C have opposite signs. The different chirp parameters of the Airy pulse represent a special spectrum that improves the propagation. For β2C<0, the chirped Airy pulse forms a weak breakup area. We found the change rule of the main lobe and peak intensity with the pulse propagation distance and the position of the breakup area in order to understand the importance of the initial pulse chirp. The impact of chirp and self-phase modulation to the Airy pulse is discussed.

Lithospheric Strength and Rift Migration Controls on Synrift Stratigraphy and Breakup Unconformities at Rifted Margins: Examples From Numerical Models, the Atlantic and South China Sea Margins

AbstractSynrift stratigraphy and the distribution of breakup‐related erosional unconformities vary vastly between passive margins and cannot be explained by classical rifting models. Here we use numerical modeling to predict their spatiotemporal distribution. We show that synrift stratigraphy mimics rift architecture, which is controlled by lithospheric strength. Basinward rift migration during extension produces (1) oceanward younging, syntectonic and posttectonic sequences, (2) rift migration unconformities, RMUs, predating breakup, and (3) a breakup unconformity, BU, that only extends over the outermost margins, since breakup is not linked with a sudden stress drop. With small synrift sedimentation, the RMUs and BU laterally merge to form a margin‐wide unconformity. In symmetric, wide conjugate margins, which arise for weak lithospheres such as the South China Sea, a long phase of distributed deformation with little subsidence results in early synrift sediment over most of the margins. RMUs merge into a single event that marks the subsequent focusing of deformation into a narrow breakup area, which experiences short‐lived intense thinning and subsidence. In asymmetric conjugate margins, lateral rift migration transports shallowly deposited, early synrift sediments from the narrow to the wide, hyperextended margin, leading to a condensed syntectonic sequence and a single BU in the narrow margin and a series of RMUs in the wide one. For very weak lower crusts, lateral rift migration generates large synrift sag basins in the wide margin, as in Angola and Congo margins. Our models resemble the observed margins tectonic diversity and may be used as templates for interpreting their distal, unexplored areas.

Ocular surface analysis and automatic non-invasive assessment of tear film breakup location, extension and progression in patients with glaucoma

BackgroundTear film stability is the key event in ocular surface diseases. The purpose of this study is to evaluate spatial and temporal progression of the tear film breakup using an automatic non-invasive device.MethodsNon-invasive tear breakup time (NITBUT) parameters, such as First NITBUT (F-NITBUT) and Average NITBUT (A-NITBUT), were evaluated in 132 glaucoma and 87 control eyes with the Keratograph 5 M device. Further analysis of this data was used to determine size, location and progression of tear film breakup with automatically identified breakup areas (BUA). The progression from First BUA (F-BUA) to total BUA (T-BUA) was expressed as Dry Area Growth Rate (DAGR). Differences between both groups were analysed using Student t-test for parametric data and Mann-Whitney U test for non-parametric data. Pearson’s correlation coefficient was used to assess the relationship between parametric variables and Spearman in the case of non-parametric variables.ResultsF-NITBUT was 11.43 ± 7.83 s in the control group and 8.17 ± 5.73 in the glaucoma group (P = 0.010). A-NITBUT was 14.04 ± 7.21 and 11.82 ± 6.09 s in control and glaucoma groups, respectively (P = 0.028). F-BUA was higher in the glaucoma group than in the control group (2.73 and 2.28; P = 0.022) and was more frequently located at the centre of the cornea in the glaucoma group (P = 0.039). T-BUA was also higher in the glaucoma group than in the control group (13.24 and 9.76%; P = 0.012) and the DAGR was steeper in the glaucoma group than in the control group (34.38° and 27.15°; P = 0.009).ConclusionsShorter NITBUT values and bigger, more central tear film breakup locations were observed in the glaucoma group than in the control group. The DAGR indicates that tear film rupture is bigger and increases faster in glaucomatous eyes than in normal eyes.

Changes in Corneal Detection Thresholds After Repeated Tear Film Instability.

PurposeTo use a human-based model to study the effects of repeated tear film instability on corneal detection thresholds to cold, mechanical, and chemical stimuli.MethodsTwenty-five subjects participated in three study visits. A computer-controlled Belmonte esthesiometer was used to estimate corneal detection thresholds to cold, mechanical, and chemical stimuli before, after, and 30 minutes following 10 consecutive sustained tear exposure (STARE) trials. Subjects turned a pain knob (0–10) to indicate discomfort during STARE trials. The area of tear breakup and thinning in each trial was analyzed. Symptoms were evaluated by the Current Symptom Questionnaire (CSQ).ResultsThere was a significant time effect on CSQ symptoms during both visits (Friedman test, P < 0.001), with immediately after repeated STARE and 30 minutes later significantly differing from before STARE (Wilcoxon, P < 0.017). Tear breakup occurred in every trial, ranging from 25% to 88% of the exposed corneal area and all subjects indicated discomfort during trials. There was a significant time effect on mechanical thresholds between before STARE mechanical thresholds and 30 minutes later (repeated measures analysis of variance [ANOVA] P < 0.001), but not cold (P = 0.057) or chemical (P = 0. 565) thresholds.ConclusionsIn this study, tear breakup during STARE trials was associated with discomfort, which when repeated, resulted in increased symptoms of ocular discomfort and alterations of mechanical sensory thresholds after 30 minutes. These results suggest that tear film instability, which is thought to occur repeatedly during normal blinking among dry eye patients over the day, can produce neurosensory alterations.

Intense Pulsed Light Therapy for Patients with Meibomian Gland Dysfunction and Ocular Demodex Infestation.

To observe the clinical changes of meibomian gland dysfunctipn (MGD) and ocular Demodex infestation after intense pulsed light (IPL) treatment to further examine the mechanism of IPL treating patients with MGD and ocular Demodex infestation. The medical records of 25 patients (49 eyes) with MGD treated with IPL, were retrospectively examined to determine outcomes. Associated ocular-surface parameters (ocular surface disease index, OSDI; lipid layer thickness, LLT; noninvasive first breakup time, NIF-BUT; noninvasive average breakup time, NIAvg-BUT; tear film breakup area, TBUA; Schirmer I Test, SIT; corneal fluorescein staining, CFS), eyelid margin abnormalities, meibum quality and expressibility, MG morphological parameters (macrostructure and microstructure), and the number of Demodex infestation were examined before and after treatment. The MG microstructure and the Demodex infestation were examined via in vivo confocal microscopy (IVCM). The results showed that there were statistically significant differences in associated ocular-surface parameters (all P<0.05) before and after IPL treatment, except SIT (P=0.065). Eyelid margin abnormalities, meibum quality and expressibility obviously improved in upper and lower eyelid after IPL treatment (all P<0.0001). MG macrostructure (MG dropouts) decreased in upper (P=0.002) and lower eyelid (P=0.001) after IPL treatment. The nine parameters of MG microstructure in upper and lower eyelid all distinctly improved after IPL treatment (all P<0.0001). The mean number of Demodex mites on the upper lid margin (6.59±7.16 to 3.12±3.81/9 eyelashes) and lower lid margin (2.55±2.11 to 1.29±1.53/9 eyelashes) significantly reduced after IPL treatment (all P<0.0001). The Demodex eradication rate was 20% (8/40) in upper lid margin and 34.15% (14/41) in lower lid margin. These findings indicate that IPL shows great therapeutic potential for patients of MGD and ocular Demodex infestation.

Tear Film Break-Up Time Measurement Using Deep Convolutional Neural Networks for Screening Dry Eye Disease

Tear film instability is one of the major characteristics of dry eye syndrome. However, traditional diagnostic methods, such as the fluorescein tear film break-up time (FTBUT) test, are limited by the subjective interpretation of results. The test needs to manually identify break-up areas in the fluorescent image, thus producing variable diagnosis results. This paper proposes an automatic method to detect the fluorescent tear film break-up area using a deep convolutional neural network (CNN) model and to define its appearance as CNN-BUT. A digital slit-lamp recorded the standard FTBUT measurement for each of 80 study participants. Fifty participants were used to train the CNN model to identify the tear film break-up area, while the remaining 30 were used to validate the proposed CNN-BUT test. Among six normal controls and 24 dry eye patients enrolled in this paper, CNN-BUT was significantly lower in dry eye patients ( ${p} ). The correlation between CNN-BUT and FTBUT was also significant ( ${r} =0.9$ ; ${p} ). Using 5 s as the cutoff value, the CNN-BUT offered acceptable sensitivity and specificity to screen dry eye patients (0.83 and 0.95, respectively). These results indicate that CNN-BUT may be used to evaluate tear film stability and to assess the status of dry eye syndrome automatically.

Effects of xanthan gum on atomization and deposition characteristics in water and Silwet 408 aqueous solution

In order to investigate the effects of viscosity on spray formation and utilization of pesticide, different concentrations of xanthan gum (XG) were added into water and 0.1% Silwet 408 aqueous solution. Droplet size, relative span (RS), fan angle, length of breakup and maximum retention (Rm) were measured with the LU120-02 nozzle spraying under the pressure of 0.3 MPa. The dynamic spreading of the different solutions on maize leaves was tested using a 5 μL micro-injector. The results showed: VMD, RS, length of breakup and Rm went up as the increasing of XG concentration in the range of 0-0.5% with the same solution, while the fan angle of nozzle and spreading area on maize leaf showed the opposite tendency. Silwet 408 could reduce the surface tension of liquid, which could alter the dominant mode of spray formation and lead to earlier sheet breakup, especially in low viscosity solutions. Under the same concentration of XG the addition of Silwet 408 could reduce the RS of drop size spectrum but has no effect on VMD or fan angle. In water solution, there was no difference with different concentrations of XG in the spreading time on maize leaf. Besides, in the 0.1% Silwet 408 aqueous solution, the spraying time and area were several-fold of that in water with same XG concentration. Moreover, with the same XG concentration, the smaller surface tension liquid indicated lower Rm, and the difference was magnified as the concentration increases. This work has demonstrated that initial spray characteristics such as droplet size and RS, fan angle, length of breakup, Rm and spreading area can vary depending on the viscosity of spray liquids. Therefore, by transforming the viscosity of the spray liquid to adjust the droplet spectrum to reduce drift, increasing the Rm and spreading area to improve liquid utilization and reduce the usage of pesticides. Keywords: atomization, xanthan gum, spray, droplet size, breakup length, dynamic spreading DOI: 10.25165/j.ijabe.20181103.3802 Citation: Wang S L, He X K, Song J L, Wang S S, Jia X M, Ling Y. Effects of xanthan gum on atomization and deposition characteristics in water and Silwet 408 aqueous solution. Int J Agric & Biol Eng, 2018; 11(3): 29–34.

동일 재질의 투명 및 써클콘택트렌즈 착용 시 정상안과 건성안의 눈물막 안정성 차이

목적: 본 연구에서는 동일재질의 투명 및 써클소프트콘택트렌즈(써클렌즈)를 정상안과 건성안에 착용시켰을 때 착용시간 경과에 따른 눈물막 안정성의 차이를 분석하고자 하였다. 방법: 연구대상자를 눈물량에 따라 정상안과 건성안으로 분류한 후 hilafilcon B 재질과 nelfilcon A 재질의 투명 및 써클렌즈를 각각 착용시키고, 렌즈 착용 30분 후, 6시간 후에 비침입성 눈물막 파괴시간, 렌즈중심안정위치, 눈물막깨짐 시작부위를 측정하여 눈물막 안정성의 변화를 알아보였다. 결과: 정상안과 건성안 모두 투명 및 써클콘택트렌즈 착용 시 착용시간경과에 따라 눈물막파괴시간은 통계적으로 유의한 감소를 보였다. 눈물막깨짐 시작 비율은 두 렌즈 모두 투명렌즈보다 써클렌즈의 주변부에서 높았고, 정상안보다는 건성안의 주변부에서 높게 나타났다. Hilafilcon B 재질보다는 nelfilcon A 재질 렌즈의 주변부에서 눈물막깨짐 시작 비율이 높았으나 착용시간경과에 따른 변화는 서로 다른 양상으로 나타났다. 한편, hilafilcon B 재질의 써클렌즈 착용 시 단위면적 당 눈물막깨짐 개수는 모두 주변부에서 많게 나타났던 반면, nelfilcon A 재질 써클렌즈의 경우는 착용시간 경과에 따라 중심부에서의 수가 증가하였다. 또한, 렌즈중심안정위치는 착용시간 경과에 따라 두 재질 모두 써클렌즈에 비해 투명렌즈가 동공중심 가까이에 존재하였으나 정상안에 비해 건성안의 중심이탈이 크게 나타났다. 결론: 본 연구결과 렌즈착용시간이 경과함에 따라 착색공정을 거친 써클렌즈 뿐만 아니라 투명렌즈도 눈물막에 미치는 영향이 달라질 수 있으며, 렌즈재질에 따라 눈물막 안정성에 영향을 주는 요인 또한 달라짐을 알 수 있었다. 따라서 투명 및 써클렌즈를 착용하고자 할 때에는 착용자의 일일착용시간이나 착용기간 등과 같은 사용습관에 따라 렌즈의 착색공법/염료 뿐만 아니라 렌즈 재질 또한 고려하여 적절한 렌즈를 선택하여야 할 것이다. Purpose: The aim of this study was to analyze the difference in tear film stability according to the wearing time when wearing clear and circle soft contact lens(circle lens) made of same material. Methods: The clear and circle contact lenses of hilafilcon B and nelfilcon A materials were respectively applied on the subjects classified as normal and dry eyes depending on their tear volume, and their tear film stability was investigated by measuring the non-invasive tear film break-up times, lens centration and the first appearing area of tear breakup after 30 mins and 6 hrs of lens wearing. Results: Non-invasive tear film breakup time significantly reduced with increase of the wearing time for normal and dry eyes when wearing clear and circle contact lenses. The starting ratio of tear film break-up was higher at the peripheral area of clear and circle lenses in all two different materials, and higher at the peripheral area of dry eyes than normal eyes. Starting ratio of tear film break-up was higher at the peripheral area of nelfilcon A lenses compared with hilafilcon B lenses, however, its change with the increase of wearing time showed a different aspect. The number of tear film break-up per unit area when wearing circle lenses of nelfilcon A increased at the central area with the wearing time while its number was higher at the peripheral area when wearing circle lenses of hilafilcon B. The centration of clear lenses made of two materials was closer to pupil compared to circle lenses with the increase of wearing time, however, a larger decentration was shown in dry eyes compared with normal eyes. Conclusions: The research revealed that an effect on tear film stability may be changed by clear lenses as well as circle lenses with coloring process according to the increase of wearing time, and the factors affecting on tear film stability may also vary depending on lens materials. Thus, the appropriate lenses should be selected by the consideration of lens material as well as coloring method/dyes according to the wearers' habit such as daily wearing time and wearing period when trying to wear clear and circle lenses.

Thermographic evaluation of tear film break-up time to study tear film stability

Tear film instability is one of the major characteristics of dry eye syndrome. However, traditional diagnostic method like fluorescein tear film break-up time (FTBUT) test is limited by its invasiveness, the necessity to use fluorescein sodium and thus variable result. In this study, we proposed a noninvasive method to demonstrate thermal break-up area (Thermal BUA) by thermography, and defined its appearance as thermal break-up time (Thermal BUT). Among 31 normal controls and 42 dry eye patients enrolled in this study, Thermal BUT was significantly lower in dry eye patients (P < 0.001). Further, dry eye patients showed faster increase in Thermal BUA. The correlation between Thermal BUT and FTBUT was also significant (r = 0.56; P < 0.001) in dry eye patients. Using 4 s as the cut-off value, Thermal BUT had high sensitivity and specificity to screen dry eye patients (0.80 and 0.89, respectively). These results indicate that thermography can be used to evaluate tear film stability and assessing the status of dry eye syndrome.

Computational approach for tear film assessment based on break-up dynamics

Dry eye syndrome is a common disorder of the tear film which affects a remarkable percentage of the population, impacting on quality of life. The study of the tear film stability is essential for the dry eye characterisation. The Break-Up Time (BUT) is a clinical test which computes the time the first tear film break-up appears. Besides the time, break-up properties can be related to specific aspects of the tear film that could affect dry eye severity. This work describes a fully automatic methodology to compute the BUT measurement and evaluate the dynamics of break-up areas. This methodology has been tested on a data set consisting of 18 tear film videos, achieving similar results to the manual annotations marked by the experts. This analysis provides useful additional information for the tear film assessment.

An evaluation of Retaine™ ophthalmic emulsion in the management of tear film stability and ocular surface staining in patients diagnosed with dry eye.

A single-center, open-label study consisting of two visits over the course of approximately 2 weeks was conducted to evaluate the efficacy of Retaine™ ophthalmic emulsion in improving the signs and symptoms of dry eye. Forty-two subjects were enrolled and received 1–2 drops twice daily of Retaine™ beginning at the first visit (day 1) and ending at the second visit. Subjects were instructed to complete a symptomatology diary twice daily prior to drop instillation through the morning of the second visit. Ocular sign and symptom assessments, visual acuity procedures, and comfort assessments were conducted during both visits. A statistically significant reduction was observed in mean breakup area on the second visit between the predose time and the postdose time (P=0.026). On the second visit, subjects had significantly less corneal fluorescein staining in the superior (P=0.002), central (P=0.017), corneal sum (P=0.011), and all ocular regions combined (P=0.038) than on the first visit. On the second visit, statistically significant reductions in dryness (P<0.001), grittiness (P=0.0217), ocular discomfort (P=0.0017), and all symptoms (P<0.001) were also seen as measured by the Ora Calibra™ Ocular Discomfort and 4-Symptom Questionnaire (0–5 scale). Subjects reported a statistically significant improvement in their abilities to work with a computer at night (P=0.044). Mean drop comfort scores ranged from 1.29–1.81 on the Ora Calibra™ 0–10 Drop Comfort Scale, on which 0 is very comfortable and 10 is very uncomfortable. Retaine™ demonstrates promising results as a novel artificial tear option for individuals suffering from dry eye. The unique mechanism of action of Retaine™ provides enhanced comfort and improves the quality of life of dry eye subjects while reducing the ocular signs of dry eye.

Effect of initial frequency chirp on Airy pulse propagation in an optical fiber

We study both analytically and numerically the propagation dynamics of an initially chirped Airy pulse in an optical fiber. It is found that the linear propagation of an initially chirped Airy pulse depends considerably on whether the second-order dispersion parameter β(2) and chirp C have the same or opposite signs. For β(2)C<0, the chirped Airy pulse first undergoes an initial compression phase, then reaches a breakup area as depending on the values of C, and then experiences a lossy inversion transformation such that it continues to propagate with an opposite acceleration. The chirped Airy pulse is always dispersed during propagation in the case of β(2)C>0. The impact of truncation coefficient and Kerr nonlinearity on the chirped Airy pulse propagation is also disclosed separately.

Direct observation and validation of fluorescein tear film break-up patterns by using a dual thermal-fluorescent imaging system.

The fluorescein tear film break-up test is a common tear film stability test for dry eye diagnosis. This test requires applying fluorescein sodium drops to a tear film to observe the tear film break-up. However, this test is limited by using the fluorescein sodium drops, which can induce reflex tearing and reduce the reliability of the diagnosis results. This paper proposes that tear film evaporation accelerates on the fluorescein tear film break-up area (FTBA), resulting in a lower temperature area (LTA) on the tear film. A dual modality system was established to capture the thermal and fluorescent image of fluorescein-stain tear films for 48 participants. Observations showed that the LTA and FTBA were highly correlated in their location (r = 0.82) and size (r = 0.91). This is first study to show that the FTBA and LTA are essentially the same region. This study demonstrated the feasibility of using the noncontact thermograph method to evaluate tear film stability without using a fluorescein sodium drop.

Noninvasive Keratograph assessment of tear film break-up time and location in patients with age-related cataracts and dry eye syndrome

To investigate tear-film break-up time and spatial distribution via noninvasive Keratograph 4 in patients with cataracts and dry eye syndrome (DES). Noninvasive first break-up time (NIKf-BUT) and average break-up time (NIKav-BUT) were evaluated via Keratograph 4 in patients with age-related cataracts and DES. The location and size of tear break regions were recorded and the distribution of first break-up areas was summarized. Patients also underwent conventional break-up time assessments (TBUT test and Schirmer's test). A total of 43 left and 43 right eyes were examined. There was no significant difference between TBUT and NIKav-BUT. NIKf-BUT was significantly shorter than TBUT. Both NIKf-BUT and NIKav-BUT correlated positively with TBUT. In both the left and right eye, the most common first break-up areas were the peripheral domain of the inferior precorneal surface and the central domain of the superior portion. The Keratograph 4 appears to provide an effective noninvasive method for assessing tear film, enabling effective preoperative evaluation of tear film break-up regularity, informing the location of the incision and reducing the probability of postoperative DES.

Differential contribution of hypertonic electrolytes to corneal epithelial dysfunction

The surface of the eye is covered by a protective tear film consisting of an aqueous-mucus layer and a superficial lipid layer, which are vital for light refraction and protection of vision. The aqueous component of the tear film contains electrolytes and a large variety of proteins, peptides and glycoproteins secreted by the lacrimal and meibomian glands, and apical cells of the corneal and conjunctival epithelia (Ohashi, Y. et al., 2006; Ruiz-Ederra, J. et al., 2009). Maintenance of a precise osmotic gradient of electrolytes between the tear film and the ocular surface epithelia is of paramount importance in regulating cell function and homeostasis. An imbalance of electrolytes is a hallmark of many pathologies, including dry eye, a disease affecting between 6 and 43 million people in the United States alone (Gilbard, J.P., 1994; Pflugfelder, S.C., 2011).

Validation and verification of the OPI 2.0 System

PurposeThe Ocular Protection Index (OPI) 2.0 System was developed to evaluate ocular surface protection under a natural blink pattern and normal visual conditions. The OPI 2.0 System implements fully automated software algorithms which provide a real-time measurement of corneal exposure (breakup area) for each interblink interval during a 1-minute video. Utilizing this method, the mean breakup area (MBA) and OPI 2.0 (MBA/interblink interval) were calculated and analyzed. The purpose of this study was to verify and validate the OPI 2.0 System for its ability to distinguish between dry eye and normal subjects, and to accurately identify breakup area.MethodsIn order to verify and validate the OPI 2.0 System, a series of artificial images and a series of still image frames captured during an actual clinical session using fluorescein staining videography were analyzed. Finally, a clinical validation process was completed to determine the effectiveness and clinical relevance of the OPI 2.0 System to differentiate between dry eye and normal subjects.ResultsSoftware analysis verification conducted in a set of artificially constructed images and in actual videos both saw minimal error rates. MBA and OPI 2.0 calculations were able to distinguish between the qualifying eyes of dry eye and normal subjects in a statistically significant fashion (P < 0.001 for both outcomes). As expected, dry eye subjects had a higher MBA and OPI 2.0 than normal subjects (0.232, dry eye; 0.040, normal and 0.039, dry eye; 0.006, normal, respectively). Results for the worst eyes and all qualifying analyses based on staining, forced-stare tear film breakup time, and MBA were numerically similar.ConclusionThe OPI 2.0 System accurately identifies the degree of breakup area on the cornea and represents an efficient, clinically relevant measurement of the pathophysiology of the ocular surface.

A single-center study evaluating the effect of the controlled adverse environment (CAE(SM)) model on tear film stability.

PurposeTo investigate use of an improved ocular tear film analysis protocol (OPI 2.0) in the Controlled Adverse Environment (CAESM) model of dry eye disease, and to examine the utility of new metrics in the identification of subpopulations of dry eye patients.MethodsThirty-three dry eye subjects completed a single-center, single-visit, pilot CAE study. The primary endpoint was mean break-up area (MBA) as assessed by the OPI 2.0 system. Secondary endpoints included corneal fluorescein staining, tear film break-up time, and OPI 2.0 system measurements. Subjects were also asked to rate their ocular discomfort throughout the CAE. Dry eye endpoints were measured at baseline, immediately following a 90-minute CAE exposure, and again 30 minutes after exposure.ResultsThe post-CAE measurements of MBA showed a statistically significant decrease from the baseline measurements. The decrease was relatively specific to those patients with moderate to severe dry eye, as measured by baseline MBA. Secondary endpoints including palpebral fissure size, corneal staining, and redness, also showed significant changes when pre- and post-CAE measurements were compared. A correlation analysis identified specific associations between MBA, blink rate, and palpebral fissure size. Comparison of MBA responses allowed us to identify subpopulations of subjects who exhibited different compensatory mechanisms in response to CAE challenge. Of note, none of the measures of tear film break-up time showed statistically significant changes or correlations in pre-, versus post-CAE measures.ConclusionThis pilot study confirms that the tear film metric MBA can detect changes in the ocular surface induced by a CAE, and that these changes are correlated with other, established measures of dry eye disease. The observed decrease in MBA following CAE exposure demonstrates that compensatory mechanisms are initiated during the CAE exposure, and that this compensation may provide the means to identify and characterize clinically relevant subpopulations of dry eye patients.