Meibum Lipidomic Analysis in Evaporative Dry Eye Subjects.

Meibomian Glands (MG) are sebaceous glands responsible for the production of meibum, the main component of the Tear Film Lipid Layer (TFLL). The TFLL facilitates the spread of the tear film over the ocular surface, provides stability and reduces tear evaporation. Alterations in meibum composition lead to different ocular alterations like Meibomian Gland Dysfunction (MGD) and subsequent Evaporative Dry Eye (EDE). The aim of the present study was to investigate the composition and abundance of meibum lipids and their relationship with eyelid margin abnormalities, lipid layer patterns and MG status. The study utilizes a lipidomic approach to identify and quantify lipids in meibum samples using an Elute UHPLC system. This system considered all four dimensions (mass/charge, retention time, ion mobility and intensity) to provide the accurate identification of lipid species. Samples were categorized as healthy or low/no signs of alteration (group 1) or severe signs of alteration or EDE/MGD (group 2). The current investigation found differences in Variable Importance in Projection lipid abundance between both groups for the MGD signs studied. Changes in meibum composition occur and are related to higher scores in eyelid margin hyperaemia, eyelid margin irregularity, MG orifice plugging, MG loss and lipid layer pattern.

Assessing neophyte response to daily disposable silicone hydrogel contact lenses: A randomised clinical trial investigation over one month.

OBJECTIVE: This randomised clinical trial assessed the impact on symptoms, tear film dynamics and ocular surface integrity of daily disposable silicone-hydrogel contact lenses (CLs) over a month, paying special attention to lid wiper epitheliopathy (LWE) and its implications for CL discomfort. METHODS: Neophyte CL wearers (n = 44, 21.09 ± 5.00 years old) were randomly assigned to either the experimental (n = 24) or control group (n = 20). Participants assigned to the experimental group were required to wear daily disposable CLs for 1 month for at least 8 h/day and 6 days/week. All participants were healthy subjects (no history of ocular surgery or active ocular disease) with spherical refractive errors between -8.00 and +5.00 D and cylindrical power <0.75 D. At the baseline and 1-month sessions, the Dry Eye Questionnaire 5 (DEQ-5) was completed, together with the measurement of tear film osmolarity with the TearLab osmometer, tear meniscus height (TMH) and lipid layer pattern (LLP) using a slit-lamp with Tearscope Plus attached, fluorescein break-up time (FBUT), maximum blink interval (MBI), corneal staining with fluorescein under cobalt blue light and LWE with lissamine green under slit lamp and halogen white light. RESULTS: At the baseline session, LWE showed a negative correlation with DEQ-5 (r = -0.37, p = 0.02). Significant differences in FBUT and LWE (p = 0.04) and a positive correlation between LWE and DEQ-5 (r = 0.49, p = 0.007) were observed at 1 month. Intrasession analysis at 1 month showed significant differences between the experimental and control groups in DEQ-5, FBUT and LWE (all p ≤ 0.02). Intersession analysis in the experimental group showed variations in DEQ-5, FBUT and LWE (all p ≤ 0.02) but no significant variation in the control group (all p ≥ 0.11). CONCLUSION: The presence of LWE was significantly correlated with higher symptom values in the DEQ-5. Also, participants in the experimental group presented higher values of LWE after 1 month of CL wear, in comparison with the control group.

A Comprehensive Study on Tear Meniscus Height Inter-Eye Differences in Aqueous Deficient Dry Eye Diagnosis.

(1) Background: Dry eye disease (DED) is a chronic ocular surface condition that requires precise diagnostic tools. The present study aimed to investigate the diagnostic potential of the absolute inter-eye difference (|OD-OS|) in tear meniscus height (TMH) for the detection of the presence of aqueous deficient dry eye (ADDE). (2) Methods: A sample of 260 participants with dry eye complaints underwent ocular surface examinations thorough diagnostic assessments based on the Tear Film and Ocular Surface Society guidelines (TFOS DEWS II). Participants were subsequently categorized as No ADDE and ADDE based on TMH. Statistical analyses to determine the optimal TMH|OD-OS| cut-off value in a randomly selected study group (200 participants) were performed, while a separate validation analysis of the cut-off value obtained in a random cross-validation group (60 participants) was also performed. (3) Results: The significant diagnostic capability of TMH|OD-OS| (area under the curve = 0.719 ± 0.036, p < 0.001) was found. The identified cut-off value of 0.033 mm demonstrated reliable specificity (77.6%) and moderate sensitivity (59.1%). Cross-validation confirmed the cut-off value's association with the TFOS DEWS II diagnostic criterion (Cramer's V = 0.354, p = 0.006). (4) Conclusions: The present study provides evidence for the diagnostic potential of TMH|OD-OS| in identifying ADDE. The identified cut-off value enhances the specificity and offers moderate sensitivity, providing an objective tool for clinical decision making.

Intraocular pressure fluctuations assessment in professional wind instrument players.

CLINICAL RELEVANCE: Due to the long-time that wind musicians spend playing their instruments, it is important to investigate if intraocular pressure could be affected by this activity. BACKGROUND: To assess the intraocular pressure fluctuations and fluctuations affecting factors in professional wind musicians while playing different tones. METHODS: Thirty professional wind musicians (23.0 ± 3.20 years) were recruited from the Professional Music College of A Coruña. A questionnaire about environmental/demographic factors was given to participants. Intraocular pressure was measured four times by ICare IC100 tonometer: before, during low and high-pitched tones, and immediately after stopping playing the wind instrument. RESULTS: Pairwise comparison revealed statistical differences between measurement points (Sidak, all p ≤ 0.019), except between before playing and while playing low-pitched tones (Sidak, p = 1.000). Intraocular pressure increases during high pitch playing and decreases after stopping playing. No significant differences in intraocular pressure fluctuation were reported between physically active (>2 days/week) and non-physically active participants (Unpaired t-test, p = 0.680). All intraocular pressure values were positively correlated (Pearson's correlation, all r ≥ 0.505, p ≤ 0.004). Intraocular pressure fluctuations were negatively correlated with musical playing years (Pearson's correlation, r = - 0.396, p = 0.030). There were no significant correlations among intraocular pressure fluctuation and gender, age, weight, height, or daily time playing (Pearson's correlation, all p ≥ 0.058). CONCLUSION: Professional wind musicians suffer intraocular pressure peaks while playing high-pitched tones; therefore, ocular fundus evaluation and visual campimetry should be performed as routine tests in the visual exam of this population.

Tear film osmolarity variation between weeks in healthy and dry eye disease subjects / Variação semanal da osmolaridade do filme lacrimal em indivíduos saudáveis e com síndrome do olho seco

ABSTRACT Purpose: The possible variability in diagnostic test results is a statistical feature of dry eye disease patients. The clinician should consider tear film variations over time since the timing of tear film measurements is important for proper diagnosis. The purpose of the present study was to analyze the inter-week variation of osmolarity measurement in healthy and dry eye disease participants. Methods: Based on the Dry Eye Workshop II (DEWS-II) diagnostic methodology report criteria, a battery of tests (Ocular Surface Disease Index [OSDI] questionnaire, breakup time, and corneal staining) was administered to rule out the presence of dry eye disease. A total of 40 qualified volunteers were recruited into two groups: with only 20 healthy and 20 dry eye disease participants. The inter-week variation of osmolarity in the two groups was measured using a TearLab osmometer in two sessions one-week apart. The differences between the results were calculated. Results: There were no significant differences in osmolarity between the two sessions for either the healthy (paired t-test; p=0.085) or dry eye disease (paired t-test; p=0.093) participants. Moreover, there was no significant correlation between the means and differences in either session on healthy (Pearson correlation: r=0.020; p=0.935) or dry eye disease (Pearson correlation: r=-0.022; p=0.928) participants. In session 1, there was a significant difference in osmolarity values between groups (unpaired t-test; p=0.001), but no difference was found in session 2 (unpaired t-test; p=0.292). Conclusions: The present study discovered no inter-week variation in the tear film osmolarity of healthy and dry eye disease participants classified based on the DEWS-II criteria.

RESUMO Objetivo: A possível variabilidade nos resultados de testes diagnósticos é uma característica estatística dos pacientes com síndrome do olho seco. O médico deve considerar as variações do filme lacrimal ao longo do tempo, pois o momento em que o filme lacrimal é medido pode ser crítico para o diagnóstico adequado. O objetivo deste estudo foi analisar a variação semanal da osmolaridade do filme lacrimal em participantes saudáveis e em outros com síndrome do olho seco. Métodos: Com base nos critérios da metodologia de diagnóstico do relatório da Dry Eye Workshop II (DEWSII), foi aplicada uma bateria de testes (questionário do índice de doença da superfície ocular [OSDI], tempo de ruptura do filme lacrimal e coloração da córnea) para descartar a presença de síndrome do olho seco. Um total de 40 voluntários qualificados foi recrutado e distribuído em dois grupos de 20 participantes saudáveis e 20 participantes com síndrome do olho seco. A variação da osmolaridade entre semanas foi medida com um osmômetro TearLab em duas sessões com uma semana de intervalo nos dois grupos. As diferenças entre os resultados foram então calculadas. Resultados: Não foram encontradas diferenças significativas na osmolaridade entre as medidas obtidas nas duas sessões, nem no grupo de participantes saudáveis (teste de t pareado; p=0,085), nem no de participantes com síndrome do olho seco (teste de t pareado; p=0,093). Não foi detectada nenhuma correlação significativa entre as médias e diferenças entre as duas sessões entre participantes saudáveis (correlação de Pearson: r=0,020, p=0,935) e aqueles com síndrome do olho seco (correlação Pearson: r=-0,022, p=0,928). Foi encontrada uma diferença significativa nos valores de osmolaridade entre os dois grupos na primeira sessão (teste de t não pareado; p=0,001), mas nenhuma diferença foi encontrada na segunda sessão (teste de t não pareado; p=0,292). Conclusões: O presente estudo não encontrou variação entre semanas consecutivas na osmolaridade do filme lacrimal em participantes saudáveis e com síndrome do olho seco, classificados com base nos critérios do DEWSII.

Lenstar LS900 vs EchoScan US-800: comparison between optical and ultrasound biometry with and without contact lenses and its relationship with other biometric parameters.

BACKGROUND: Due to the increasing use of contact lenses (CL) and the interest in ocular and body size relationships, this study aimed to compare measurements from two biometers (contact ultrasonic EchoScan US-800 and non-contact optical Lenstar LS900) with and without CL and to explore the relationship between ocular and body biometric parameters. DESIGN AND METHODS: This cross-sectional study measured ocular biometry using two biometers along with their body height and right foot length in 50 participants. Differences between biometry data from the two devices were compared and correlations between ocular and body biometric values were analyzed. RESULTS: All parameters showed interbiometric differences (p ≤ 0.030), except crystalline lens thickness during CL wear (p = 0.159). Comparing measurements with and without CL, differences were observed in axial length (p < 0.001), vitreous length measured by optical biometer (p = 0.016), and anterior chamber depth by ultrasonic biometer (p < 0.016). Lens thickness remained unaffected (p ≥ 0.190). Body height and foot length were correlated with anterior chamber depth, vitreous length, and axial length (p ≤ 0.019, r ≥ 0.330). Most biometric parameters were correlated among them using both devices (p ≤ 0.037, r ≥ 0.296). CONCLUSIONS: These biometers are not interchangeable and CL affects measurements. Body height and foot length correlate with ocular dimensions, and most ocular biometric values correlate positively.

Meibomian gland secretion quality association with ocular parameters in university students during COVID- 19 restrictions.

PURPOSE: To determine if the Meibomian Gland (MG) secretion quality is associated with symptoms of ocular discomfort, hours of Video Display Terminals (VDT) use, eyelid margin abnormalities, conjunctival hyperemia, and Meibomian Gland Loss Area (MGLA) in a sample of university students. METHODS: An online survey that included an Ocular Surface Disease Index (OSDI) questionnaire and an extra question about hours of VDT use recruited an initial sample of 183 participants. Only 120 participants that fulfilled the inclusion criteria were scheduled for a battery of ocular surface and MG specific exam. The tests include: 1) meibometry, 2) slit lamp exploration of eyelid margin abnormalities (irregularity, hyperemia and MG orifices plugging), MG secretion quality and conjunctival hyperemia, and 3) Meibography. RESULTS: Significant positive correlations between the MG secretion quality and eyelid margin hyperemia, MG orifices plugging, MGLA, nasal conjunctival hyperemia, and temporal conjunctival hyperemia (Spearman Rho; all r>0.186, p<0.042) were found. Multivariate regression found association between OSDI with hours of VDT use (B=0.316, p=0.007), and eyelid hyperemia (B=0.434, p≤ 0.001). A statistical association between MG secretion quality and eyelid margin hyperemia, MG orifices plugging, MGLA and conjunctival hyperemia (Fisher's exact; all p<0.039) were found. Multivariate regression found association between MG secretion quality with MG orifices plugging (B=0.295, p=0.004) and meibometry (B=-0.001, p=0.029). CONCLUSION: Participants with higher values in MG secretion quality have higher values in eyelid margin hyperemia, MG plugging, MGLA, and conjunctival hyperemia. No direct relationship between MG secretion quality and hours of VDT use or OSDI were found.

Analysis of the Differences in Ocular Surface Damage and Inflammatory Signs between Healthy and Evaporative Dry Eye Participants.

OBJECTIVE: Distinguish between EDE severity levels by analysing the MGLA, conjunctival hyperemia and corneal staining. METHODS: One hundred participants were recruited based on OSDI, TO, TFBUT, TMH, and LLP to be categorised as healthy (Group 1) or EDE (Group 2). Group 2 was divided into Group 2A (mild symptoms), 2B (moderate), and 2C (severe). MGLA, conjunctival hyperemia, and corneal staining were measured. RESULTS:  Positive correlation between MGLA, conjunctival hyperemia, and corneal staining were found (all r ≥ 0.221, p ≤ 0.027). Significant differences were found: MGLA between Group 1 vs. 2C and 2C vs. 2A or 2B; conjunctival hyperemia between Group 1 vs. 2A, 2B or 2C; corneal staining between Group 1 vs. 2B or 2C and 2A vs. 2B or 2C (all p ≤ 0.049). CONCLUSION: Severe EDE participants have higher MGLA, conjunctival hyperemia, and corneal staining values than healthy, mild, or moderate EDE participants.

A cross-sectional study of non-modifiable and modifiable risk factors of dry eye disease states.

PURPOSE: The present study aimed to determine the relationship of non-modifiable (rheumatoid arthritis, thyroid diseases, and arterial hypertension) and modifiable risk factors (diuretics, antidepressants, or anxiolytics tranquilizers) with the different Dry Eye Disease (DED) diagnostics in a sample adjusted by antihistamines intake. METHODS: A total of 400 participants were included in a cross-sectional study. Before a dry eye examination, participants completed an online self-administered OSDI questionnaire with six additional questions about possible DED risk factors. The Tear Film and Ocular Surface Society Dry Eye Workshop II (TFOS DEWS-II) diagnostic criteria of DED was used. Based on signs and/or symptoms, participants were divided into 4 groups: No DED, Pre-clinical DED, Predisposition to DED and DED. Since the symptom scores would have been altered by the use of antihistamines, the analysis of each outcome was adjusted for this factor, where those participants were assumed to be symptomatic. RESULTS: Multivariable logistic regression found thyroid disease as a possible risk factor for DED (OR 4.53, 95 % CI 1.04-19.73; Fisher's exact, p = 0.044; Cramers V = 0.140, p = 0.024). No association was found between the studied parameters and Pre-clinical DED (Fisher's exact, all p ≥ 0.398; Cramers V, all p ≥ 0.242) or Predisposition to DED (Fisher's exact, all p ≥ 0.065; Cramers V, all p ≥ 0.031). CONCLUSION: Participants with thyroid disease were more likely to develop DED, therefore, thyroid disease could be a risk factor for DED.

Changes of symptomatology, tear film and ocular surface integrity one week during Somofilcon-A and Omafilcon-A lens wear.

PURPOSE: Clinicians play a key role in prescribing contact lenses that best suited for fitting which materials had an impact on ocular surface parameters. The present study aimed to evaluate the impact on symptomatology, tear film dynamics and ocular surface integrity of a silicone-hydrogel (Somofilcon-A) and a hydrogel (Omafilcon-A) lens before and after wearing for one week in contact lens neophyte participants. METHODS: A Somofilcon-A and Omafilcon-A were randomly fitted to one or other the eye on an initial group of 28 participants. Subjects were scheduled for three sessions: basal session previous fitting, second session after 4-wear hours, and final session after 7-wear days for up to 10 h. In each session, CLDEQ-8, tear meniscus height and hyperemia with and without lenses, as well as lipid layer thickness and corneal/conjunctival staining without lenses were assessed. Values were compared between lenses and sessions. RESULTS: In intrasession comparison, there were no differences in any parameter between materials on any session with or without lenses (all p≥0.176), except on the conjunctival staining where values obtained during Somofilcon-A wear (all p ≤ 0.006). In intersession analysis, CLDEQ-8 score, tear meniscus height and lipid layer thickness showed a statistical difference during both materials wear (all p ≤ 0.009), while conjunctival hyperemia does not (p = 0.237); corneal staining showed differences during Omafilcon-A wear (p = 0.037), contrary to conjunctival staining which showed differences only during Somofilcon-A wear (p < 0.001). CONCLUSION: Contact lenses wear had an impact on ocular parameters that have some specific influences of the material on which lenses were manufactured.

Validation of a New Software Application for Tear Breakup Measurement.

SIGNIFICANCE: Tear film instability has been recognized as one key mechanism on dry eye disease. There is a need for new instruments, methods, or protocols to improve the repeatability and reproducibility of the tear film stability to facilitate its clinical evaluation use as a rapid and reliable primary diagnostic test. PURPOSE: The present pilot study aimed to validate a method to automatically measure the tear film breakup time (BUT). METHODS: A total of 264 videos of BUT were randomly selected among the clinical history of subjects attending the optometry clinic. Videos were stored in a backup server through a secure file transfer protocol and analyzed by three different examiners: two masked observers (subjective evaluation) and a third investigator using the automatic software application (objective evaluation). Subjective evaluation was conducted only once on an online software designed for this protocol where videos were presented in random masked order. Automatic evaluation based on color and texture analysis was performed by (1) automatic localization of sequences of interest in the video, (2) extraction of the region of interest within each frame, and (3) automatic BUT measurement from evolution curves in the region of interest as time elapsed from the beginning of the sequence of interest until the curve exceeds a threshold. RESULTS: Substantial correlation was observed among the examiners (intraclass correlation coefficient, 0.752). There was a statistical difference between observer 1 and 2 evaluations (t test, P < .001), whereas data provided by the software showed no significant differences from those of the observers (t test, P ≥ .26). Similar results to the whole data set analysis were obtained when the sample was reassessed only considering mean BUT values ≤15 seconds. CONCLUSIONS: The present pilot study showed acceptable clinical results for the software application designed to objectively measure the BUT.

Osmolality and pH of commercially available contact lens care solutions and eye drops.

PURPOSE: The physical properties of contact lens care solutions and Eye Drops (ED) may affect initial comfort and dry eye symptomatology in contact lens wearers, although these properties are not always provided by manufacturers. The present study aimed to measure and compare the osmolality and pH of commercially available contact lens care solutions and ED. METHODS: Forty-four solutions were tested (17 lens care solutions and 27 ED) and classified by the presence and/or combination of the viscosity/lubrication-enhancing ingredients. Solution osmolality was obtained with the Fiske 110 osmometer and pH was measured with a micro-pH 2000. Each measurement was taken ten times, following the manufacturer's instructions, while controlling for room temperature and humidity. Differences between the values of the physical properties of the solutions were analysed by type and viscosity/lubrication-enhancing agent subclassification. RESULTS: Osmolality ranged from 192.6 ± 2.17 to 364.6 ± 2.88 mOsm/Kg, while pH ranged from 6.35 [6.35-6.26] to 7.99 [7.99-8.00]. A significant difference in the osmolality and pH values of contact lens care solutions and ED was found when classified by type or viscosity/lubrication-enhancing agent (ANOVA and Kruskal-Wallis respectively, both p < 0.001). CONCLUSIONS: The physical properties of some contact lens care solutions and ED are not readily available. The osmolality and pH values of various commercially available lens care solutions and ED vary significantly both by type and viscosity/lubrication-enhancing ingredients.

Inter-eye osmolarity differences in patients with symptomatic and non-symptomatic dry eyes / Diferenças de osmolaridade entre olhos de pacientes com olhos secos sintomáticos e não sintomáticos

ABSTRACT Purpose: To analyze whether inter-eye osmo larity differences were related to dry eye symptomatology. Methods: A total of 135 participants were randomly recruited from those who visited in the Optometry Clinic of the Optometry Faculty (Universidade de Santiago de Compostela). In a single scheduled session after the recruitment, Ocular Surface Disease Index was filled out following the standard instructions and TearLab measurements were made in both the participants' eyes (10-15 min lapse). Osmolarity values were compared between the right and left eyes and the absolute inter-ocular difference (-OD-OS-) correlated with the Ocular Surface Disease Index score for the whole sample. Based on the Ocular Surface Disease Index score, the sample was divided into four symptomatic subgroups, and differences in the -OD-OS- values were calculated. Results: The whole sample showed a statistically significant inter-eye osmolarity difference (p=0.025; -OD-OS- = 9.2 ± 9.3 mOsm/l) and the correlation between Ocular Surface Disease Index and -OD-OS- (r=0.369; p<0.001). A statistically significant difference was found in the -OD-OS- value between symptomatic subgroups (Kruskal-Wallis, p=0.003). Mann-Whitney U test showed a significant difference between asymptomatic vs. moderate (p=0.006) vs. severe symp tomatic patients (p=0.001) and between mild vs. severe symptomatic patients (p=0.045), whereas no difference on -OD-OS- was found between participants with contiguous symptomatic subgroups (all p³0.174). Conclusion: Tear film inter-eye osmolarity differences are significantly higher in severe dry eye disease symptoms.

RESUMO Objetivo: Analisar se as diferenças entre osmolaridade entre os olhos foram relacionadas à sintomatologia do olho seco. Métodos: Um total de 135 participantes foram recrutados aleatoriamente entre os indivíduos da Clínica de Optometria da Faculdade de Optometria (Universidade de Santiago de Compostela). Em uma única sessão agendada após o recrutamento, o Índice de Doenças da Superfície Ocular foi preenchido seguindo as instruções padrão e as mensurações do TearLab foram feitas em ambos os olhos dos participantes (lapso de 10 a 15 min). Os valores de osmolaridade foram com parados entre os olhos direito e o esquerdo e a diferença absoluta ocular (-OD-OS-) correlacionada com a pontuação do Índice de Doença da Superfície Ocular para toda a amostra. Com base na pontuação do Índice de Doença da Superfície Ocular, a amostra foi dividida em quatro subgrupos sintomáticos, e as diferenças nos -OD-OS- os valores foram calcula dos. Resultados: A amostra total mostrou uma diferença de osmolarida de entre os olhos estatisticamente significativa (p=0,025; -OD-OS- = 9,2 ± 9,3 mOsm/l) e a correlação entre o Índice de Doença da Superfície Ocular e -OD-OS- (r=0,369; p<0,001). Diferença estatisticamente significativa foi encontrada no valor -OD-OS- entre os subgrupos sintomáticos (Kruskal-Wallis, p=0,003). O teste U de Mann-Whitney mostrou uma diferença significativa entre pacientes assintomáticos versus moderados (p=0,006) versus sintomáticos graves (p=0,001) e entre pacientes sinto máticos leves e graves (p=0,045), enquanto que nenhuma di ferença de -OD-OS- foi encontrada entre os participantes de subgrupos sintomáticos contíguos (todos p³0,174). Conclusão: As diferenças entre osmolaridade inter-ocular do filme lacrimal são significativamente maiores nos sintomas graves da doença do olho seco.

Inter-eye osmolarity differences in patients with symptomatic and non-symptomatic dry eyes.

PURPOSE: To analyze whether inter-eye osmo larity differences were related to dry eye symptomatology. METHODS: A total of 135 participants were randomly recruited from those who visited in the Optometry Clinic of the Optometry Faculty (Universidade de Santiago de Compostela). In a single scheduled session after the recruitment, Ocular Surface Disease Index was filled out following the standard instructions and TearLab measurements were made in both the participants' eyes (10-15 min lapse). Osmolarity values were compared between the right and left eyes and the absolute inter-ocular difference (|OD-OS|) correlated with the Ocular Surface Disease Index score for the whole sample. Based on the Ocular Surface Disease Index score, the sample was divided into four symptomatic subgroups, and differences in the |OD-OS| values were calculated. RESULTS: The whole sample showed a statistically significant inter-eye osmolarity difference (p=0.025; |OD-OS| = 9.2 ± 9.3 mOsm/l) and the correlation between Ocular Surface Disease Index and |OD-OS| (r=0.369; p<0.001). A statistically significant difference was found in the |OD-OS| value between symptomatic subgroups (Kruskal-Wallis, p=0.003). Mann-Whitney U test showed a significant difference between asymptomatic vs. moderate (p=0.006) vs. severe symp tomatic patients (p=0.001) and between mild vs. severe symptomatic patients (p=0.045), whereas no difference on |OD-OS| was found between participants with contiguous symptomatic subgroups (all p³0.174). CONCLUSION: Tear film inter-eye osmolarity differences are significantly higher in severe dry eye disease symptoms.

Reproducibility in measuring tear samples using a freezing point depression osmometer.

BACKGROUND: Hyperosmolarity of tear fluid has been recognised as a common feature of all types of dry eye disease. This study was designed to assess the inter-session reproducibility of a freezing point depression osmometer (Fiske 110) as the most common and precise way of measuring osmolality, by using two different volumes of tear samples on healthy subjects, and to determine the possible applications of this device in tear film research and clinical practice. METHODS: Measurements were made by using the Fiske 110 osmometer under two different tear sample volumes (4 µl and 2 µl). In both cases, samples were diluted in purified water to obtain the 20 µl required by the device to perform the measurement (1:4 and 1:9 dilutions, respectively). Inter-session reproducibility was determined in two groups of 40 healthy subjects, in two sessions, one week apart. In each group, one of the two different tear sample volumes was used to determine the reproducibility of each technique. RESULTS: No significant differences were detected between the measurements obtained in the two sessions using the 4 µl (paired t-test, p = 0.772; mean difference ± SD = -0.85 ± 18.77 mOsm/L; 95 per cent limits of agreement [LoAs] = -37.64/+35.94) or the 2 µl volume sample (paired t-test, p = 0.054; mean difference ± SD = 9.27 ± 29.44 mOsm/L; 95 per cent LoAs = -48.43/+66.97). CONCLUSIONS: Whereas both techniques show an acceptable inter-session reproducibility, the bias range with the present protocol was higher using the 2 µl tear sample volume than the 4 µl one. Therefore, it seems that the diluted 4 µl sample was the only dilution that could be acceptable for use in routine clinical practice for tear film analysis.

iDEAS: A web-based system for dry eye assessment.

BACKGROUND AND OBJECTIVES: Dry eye disease is a public health problem, whose multifactorial etiology challenges clinicians and researchers making necessary the collaboration between different experts and centers. The evaluation of the interference patterns observed in the tear film lipid layer is a common clinical test used for dry eye diagnosis. However, it is a time-consuming task with a high degree of intra- as well as inter-observer variability, which makes the use of a computer-based analysis system highly desirable. This work introduces iDEAS (Dry Eye Assessment System), a web-based application to support dry eye diagnosis. METHODS: iDEAS provides a framework for eye care experts to collaboratively work using image-based services in a distributed environment. It is composed of three main components: the web client for user interaction, the web application server for request processing, and the service module for image analysis. Specifically, this manuscript presents two automatic services: tear film classification, which classifies an image into one interference pattern; and tear film map, which illustrates the distribution of the patterns over the entire tear film. RESULTS: iDEAS has been evaluated by specialists from different institutions to test its performance. Both services have been evaluated in terms of a set of performance metrics using the annotations of different experts. Note that the processing time of both services has been also measured for efficiency purposes. CONCLUSIONS: iDEAS is a web-based application which provides a fast, reliable environment for dry eye assessment. The system allows practitioners to share images, clinical information and automatic assessments between remote computers. Additionally, it save time for experts, diminish the inter-expert variability and can be used in both clinical and research settings.

Interobserver variability of an open-source software for tear meniscus height measurement.

PURPOSE: Different values of the lower tear meniscus height (TMH) can be obtained depending on the method and technique of measurement employed. The aim of this study was to analyse the interobserver variability of a method for measuring TMH by using an open source software. MATERIAL AND METHODS: On a group of 176 subjects, two videos of the central lower tear meniscus, first under slit-lamp illumination and ten minutes later under Tearscope illumination, were generated by a digital camera attached to a slit-lamp. Images were extracted from each video by a masked observer. Two further observers measured in a masked and randomized order the TMH in each illumination method by using an open source software based on Java (NIH ImageJ). TMH was measured from the lower lid to the upper limit of the tear meniscus for both slit-lamp (TMH-SL) and Tearscope (TMH-Tc) illumination methods. Subsequently, in different order, observers assigned a four-grading and a healthy/abnormal subjective classification to each central meniscus. RESULTS: No significant differences were found between the TMH measurements obtained by both investigators in slit-lamp or Tearscope image datasets (t-test; both p≥0.136). When comparing TMH measurements stratified by grade, only interobserver significant differences were observed for grades 3 and 4 with silt-lamp (t-test; both p≤0.009). Significant differences on TMH results between subjective subgroups were observed for both illumination techniques (ANOVA, all p≤0.045). CONCLUSION: This study showed a useful tool to objectively measure TMH by photography.

Accuracy of a Freezing Point Depression Technique Osmometer.

PURPOSE: The purpose of this study was to examine the precision and accuracy of the Fiske 110 Osmolarity System under different protocols to determine the possible applications of this device in tear film research and clinical practice. METHODS: Three separate studies were performed. In the first, Fiske 110 measurements were made on undiluted and diluted (1:1, 1:4, and 1:9 dilutions) standard samples of different osmolarity values: 50, 290, and 850 mOsm/kg and 297 and 338 mOsm/L. In the second study, measurements were made on different types of contact lens care solutions. Finally, in an agreement study, measurements were made in two sets of 60 subjects to compare TearLab versus Fiske 110 (using both 2- and 4-µL tear sample). RESULTS: Although osmolarity measurements for undiluted solutions differed statistically from reference standard values, all biases were in the tolerance range proposed by the manufacturer except for the 850-mOsm/kg solution. No significant differences from reference osmolarity values were observed for the 1:1 and 1:4 diluted 297- and 338-mOsm/L H2O solutions, respectively, although all diluted solutions showed a possible bias out of the range provided. Osmolarities for the soft contact lens solutions fell within the range 293 to 309 mOsm/kg with the exception of Opti-Free Express (225 mOsm/kg). In the agreement study, significant differences were observed between measurements obtained using the TearLab and both Fiske 110 procedures, although the Fiske 110 (4 µL) procedure was closer to the TearLab than the Fiske (2 µL) procedure. CONCLUSIONS: For undiluted solutions, the Fiske 110 shows good performance, making it a useful device for osmolarity measurements in lens care solutions or eye drops. A worse performance was observed for more diluted standard solution samples. When testing diluted samples, performance was acceptable for osmolarity values close to tear values.

Correlation between tear osmolarity and tear meniscus.

PURPOSE: To examine the relationship between tear meniscus height (TMH) and subjective meniscus grading (subjective tear meniscus [TM]) with tear osmolarity. METHODS: Tear osmolarity measurements (using TearLab) and digital images of the TM were obtained in 177 consecutive patients undergoing an eye examination at our optometry clinic (Universidad de Santiago de Compostela, Spain) who fulfilled the study's inclusion criteria. Participants were also administered the McMonnies and Ocular Surface Disease Index questionnaires for the detection of dry eye disease. The lower TM was videotaped by a digital camera attached to a slit lamp in its central portion without fluorescein instillation. After the study, a masked observer extracted an image from each video and measured the TMH using open source software (NIH ImageJ). Subsequently, the masked observer subjectively graded the appearance of each meniscus. For statistical analysis, subjects were stratified by age and by dry eye symptoms as indicated by their scores in the two questionnaires. RESULTS: In the whole study population, a significant relationship was observed between osmolarity and TMH (r = -0.41, p < 0.001) and osmolarity and subjective TM (r = 0.35, p < 0.001). A cluster analysis revealed similar correlations when subjects were stratified by age or dry eye symptoms, these correlations being more pronounced in older and more symptomatic subjects. Objective TMH measurements and subjective meniscus quality were also correlated (r = -0.75, p < 0.001). CONCLUSIONS: Osmolarity and both objective TMH measurements and subjective interpretation of the meniscus showed high correlation, especially in older symptomatic subjects.