A Fully Automatic Estimation of Tear Meniscus Height Using Artificial Intelligence

Purpose

Accurate quantification measurement of tear meniscus is vital for the precise diagnosis of dry eye. In current clinical practice, the measurement of tear meniscus height (TMH) relies on doctors' manual operation. This study aims to propose a novel automatic artificial intelligence (AI) system to evaluate TMH.

Methods

A total of 510 photographs obtained by the oculus camera were labeled. Three thousand and five hundred images were finally attained by data enhancement to train the neural network model parameters, and 60 were used to evaluate the model performance in segmenting the cornea and tear meniscus region. One hundred images were used to test generalization ability of the model. We modified a segmentation model of the cornea and the tear meniscus based on the UNet-like network. The output of the segmentation model is followed by a calculation module that calculates and reports the TMH.

Results

Compared with ground truth (GT) manually labeled by clinicians, our modified model achieved a Dice Similarity Coefficient (DSC) and Intersection over union (Iou) of 0.99/0.98 in the corneal segmentation task and 0.92/0.86 for the detection of tear meniscus on the validation set, respectively. On the test set, the TMH automatically measured by our AI system strongly correlates with the results manually calculated by the ophthalmologists.

Conclusions

We developed a fully automated and reliable AI system to obtain TMH. After large-scale clinical testing, our method could be used for dry eye screening in clinical practice.

Lower tear meniscus height measured by optical coherence tomography in children

INTRODUCTION

While optical coherence tomography (OCT) measurements of the lower tear meniscus height (LTMH) have been reported in adults, here we obtained LTMH measurements through Fourier Domain OCT in healthy children and compared these with values obtained in healthy adults.

METHODS

Participants were children 7-17 years of age and a control group of adults 20-40 years of age. Inclusion criteria were no abnormal eye conditions or the use of contact lenses. Candidates who fulfilled the TFOS DEWS II criteria for dry eye disease (DED) were excluded. All subjects underwent LTMH measurement (OCT Spectralis) and tests for non-invasive tear break-up time and ocular surface staining. Participants also completed the ocular surface disease index questionnaire.

RESULTS

A total of 86 children and 27 adults were included. Mean LTMH values in the children and adult groups were 217.40 ± 71.40 μm and 225.0 ± 54.86 μm, respectively; p = 0.53. However, 59.3% of the children had an LTMH ≤210 μm suggestive of DED, compared with only 33.3% of adults (p = 0.02). For the children, no significant differences in LTMH were observed with sex or for those more or less than 12 years of age.

CONCLUSIONS

Optical coherence tomography-derived LTMH measurements were obtained in healthy children. While values were similar in children and adults, a greater proportion of children had an LTMH compatible with a diagnosis of DED. More studies in different paediatric populations are required to establish a complete set of normative LTMH measurements.

Accuracy of a New Noninvasive Automatic Ocular Surface Analyzer for the Diagnosis of Dry Eye Disease-Two-Gate Design Using Healthy Controls

PURPOSE

The purpose of this study was to assess the diagnostic performance of measurements from a new noninvasive, automated ocular surface analyzer (IDRA) in the diagnosis of dry eye disease (DED).

METHODS

We prospectively identified patients with and without DED using best practice methods. Subsequently, all participants underwent IDRA analysis, consisting of 5 components: noninvasive tear film break-up time, tear meniscus height, lipid layer interferometry, eye blink quality, and infrared meibography. The manufacturer provides cutoff values for a pathologic result for each of these components. Using a stepwise augmentation multivariate logistic regression model, we identified the components with the strongest association for the presence of DED. For the 3 components with the strongest association (interferometry, tear meniscus, and infrared meibography), we calculated the probability of DED.

RESULTS

We enrolled 40 patients (80 eyes) with DED (mean age 60.5 years; women 78.3%) and 35 healthy subjects (70 eyes, mean age 31.1 years; women 21.7%). The IDRA had an area under the curve of 0.868 (95% confidence interval: 0.809-0.927) to detect DED. A normal (≥80) interferometry combined with a normal (>0.22) tear meniscus and a normal (≤40) infrared meibography was associated with an estimated probability of 18% for the presence of DED, whereas the estimated probability of DED was as high as 96% when all 3 findings were pathologic.

CONCLUSIONS

The results of IDRA showed a positive concordance with routine clinical diagnostic tests. The new analyzer is an easy-to-access diagnostic tool to rule out the presence of DED in the extramural setting and to guide a timely DED treatment.

Changes in Tear Meniscus Analysis of Children Who Have Type 1 Diabetes Mellitus, With and Without Vitamin D Deficiency

PURPOSE

The aim of this study was to quantitatively evaluate dry eye test parameters of pediatric patients with and without vitamin D deficiency (VDD) in type 1 diabetes mellitus.

METHODS

In this prospective cross-sectional study, the Ocular Surface Disease Index, Schirmer test, tear film breakup time, corneal staining score, and anterior segment optical coherence tomography were used to determine the dry eye test parameters of pediatric patients with type 1 diabetes mellitus (T1-DMPs) (group 1) and a healthy pediatric control group (group 2). Group 1 was divided into 2 subgroups based on their vitamin D status: group 1a, who had a VDD, and group 1b, who had vitamin D levels that were within the normal range.

RESULTS

This study compared 90 eyes of 90 pediatric T1-DMPs with 80 eyes of 80 healthy controls. The demographic characteristics of the groups were similar ( P > 0.05). The tear film breakup time, Schirmer test, corneal staining score, and values of the tear meniscus height and area were observed to have been lower in the patients in group 1a than the healthy pediatric control group, at P < 0.001. The same parameters were statistically significantly lower in the patients in group 1a when compared with group 1b ( P < 0.05 for both).

CONCLUSIONS

The tear measurements of the pediatric T1-DMPs were lower than those in the healthy pediatric control group. The accompanying VDD made this situation more pronounced.

Changes in Tear Meniscus Analysis After Ptosis Procedure and Upper Blepharoplasty

INTRODUCTION

To quantitatively evaluate dry eye test and tear measurements following oculoplastic surgery.

METHODS

This comparative prospective clinical study comprised three groups of adult patients: the 1) blepharoplasty group: those with dermatochalasis; and 2) the blepharoplasty + Muller's muscle-conjunctival resection and 3) blepharoplasty + anterior levator resection groups: those with dermatochalasis and ptosis showing significant improvement after 10% phenylephrine administration. Ocular Surface Disease Index, tear film break-up time, corneal staining, and Schirmer test values were recorded. Tear meniscus area and height were measured using anterior segment-optical coherence tomography.

RESULTS

This study comprised 56 patients (18 males, 38 females). The blepharoplasty group included 40 eyes of 20 patients. The blepharoplasty + MMCR group included 21 eyes of 16 patients. The blepharoplasty + ALR group included 30 eyes of 20 patients. No significant differences resulted between the preoperative and postoperative dry eye test and tear measurements in the blepharoplasty group (P> 0.005/for all). Significant increases were seen in the corneal staining, TMH, TMA, and Schirmer test values were significantly decreased compared to those postoperatively in the blepharoplasty + MMCR group (P= 0.018, P< 0.001, P= 0.033 and P= 0.030, respectively). In the blepharoplasty + ALR group, the TMH and TMA were significantly decreased (P= 0.031, P= 0.036).

CONCLUSION

No changes resulted in dry eye tests following blepharoplasty in patients without dry eye symptoms. Changes were more pronounced following ptosis surgery, especially MMCR. Patients should be carefully examined for dry eye and treated during follow-up.

LEVEL OF EVIDENCE IV

This journal requires that authors assign a level of evidence to each article. For a full description of these evidence-based medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

The Role of Different Tear Volume Detection Methods in the Evaluation and Diagnosis of Mild Dry Eye Disease

Purpose

To compare the diagnostic power of strip meniscometry (SM), Schirmer test (ST), and tear meniscus (TM) in mild dry eye disease (DED) and to evaluate the association with DED-related parameters.

Methods

Forty left eyes with mild DED and 40 left eyes of control participants were investigated. All participants underwent a comprehensive ocular surface examination, including the Ocular Surface Disease Index (OSDI), fluorescein tear film break-up time (FTBUT), ocular surface staining grades, meiboscores, and tear film volume examinations, including SM, ST, tear meniscus height (TMH), and tear meniscus cross-sectional area (TMA) measurements, respectively, by optical coherence tomography (OCT) and Keratograph 5M (K5M). The correlation between these parameters was evaluated, and the receiver operating characteristic (ROC) curve was used to verify the diagnostic power by the area under the curve (AUC).

Results

All tear film volume examinations significantly correlated with DED parameters. Among them, the most relevant factor to OSDI scores and FTBUT was SM. In addition, SM (AUC = 0.992), TMH-OCT (AUC = 0.978), and TMA-OCT (AUC = 0.960) showed better diagnostic power than ST (AUC = 0.650) in DED, in which the cutoff value of SM was 3.5 mm (sensitivity, 97.5%; specificity, 95.0%).

Conclusions

Compared with ST, SM and TM parameters obtained by OCT were more relevant to ocular surface parameters and can provide a more valuable approach to discriminate mild DED from control participants.

Translational Relevance

This study made a comprehensive comparison of the existing tear volume detection methods and provided a basis for the clinical selection of appropriate detection methods and the diagnosis of mild DED.

Influence of Sodium Hyaluronate Concentration in Tear Meniscus Height: 10-min Dynamic Profile After Single Instillation

PURPOSE

To assess the height, area, and density of tear meniscus throughout 10 min after instillation of sodium hyaluronate (SH) of equal molecular weight at two different concentrations.

METHODS

Thirty-four eyes from 17 patients were enrolled in this longitudinal, nonrandomized, interventional and contralateral eye study. Tear meniscus height (TMH), corneal meniscus junction (CMJ), lower-lid meniscus junction (LLMJ), and tear meniscus area (TMA) images were obtained with the anterior segment module of the deep range imaging ocular coherence tomography ([DRI-OCT] Triton Swept-Source). Tear meniscus density (TMD) was calculated using the image processing and analysis software by Java (ImageJ program). Sodium hyaluronate artificial tears at 0.1% and 0.2% concentrations were instilled into all right and left eyes, respectively.

RESULTS

Patients' mean age was 61.05±11.43 years. Tear meniscus height, CMJ, LLMJ, and TMA measured at 1-, 5-, 7- and 10-min postinstillation of 0.1% SH proved significant differences among them (P<0.05). Sodium hyaluronate 0.2% instillation obtained similar findings, although no significant differences were found between 1- and 3-min postinstillation measurements (P>0.05). Fewer differences were found in TMD 0.2% SH group due to a lower baseline densitometry compared to the 0.1% group.

CONCLUSION

0.2% sodium hyaluronate achieved better TMH and TMA in 1 and 3 min after instillation than 0.1% concentration. However, there were no statistically significant differences between 0.1% and 0.2% sodium hyaluronate throughout a ten-minute longitudinal profile measurement using DRI-OCT.

Anwendungsmöglichkeiten der optischen Kohärenztomographie beim trockenen Auge

Durch die stetige Weiterentwicklung und Verbesserung der Technik hat die optische Kohärenztomographie (OCT) in den letzten Jahren neue Möglichkeiten zur Beurteilung der Strukturen des vorderen Augenabschnittes eröffnet. Aufgrund der Darstellung kleinster Strukturen, wie beispielsweise des Tränenfilms, nimmt die OCT in der Diagnostik und Verlaufsbeurteilung des trockenen Auges eine immer wichtigere Rolle ein. Der vorliegende Beitrag gibt einen Überblick über die derzeitigen Einsatzmöglichkeiten der OCT beim trockenen Auge.

A Review of Imaging Biomarkers of the Ocular Surface

A biomarker is a "characteristic that is measured as an indicator of normal biological processes, pathogenic processes, or responses to an exposure or intervention, including therapeutic interventions." Recently, calls for biomarkers for ocular surface diseases have increased, and advancements in imaging technologies have aided in allowing imaging biomarkers to serve as a potential solution for this need. This review focuses on the state of imaging biomarkers for ocular surface diseases, specifically non-invasive tear break-up time (NIBUT), tear meniscus measurement and corneal epithelial thickness with anterior segment optical coherence tomography (OCT), meibomian gland morphology with infrared meibography and in vivo confocal microscopy (IVCM), ocular redness with grading scales, and cellular corneal immune cells and nerve assessment by IVCM. Extensive literature review was performed for analytical and clinical validation that currently exists for potential imaging biomarkers. Our summary suggests that the reported analytical and clinical validation state for potential imaging biomarkers is broad, with some having good to excellent intra- and intergrader agreement to date. Examples of these include NIBUT for dry eye disease, ocular redness grading scales, and detection of corneal immune cells by IVCM for grading and monitoring inflammation. Further examples are nerve assessment by IVCM for monitoring severity of diabetes mellitus and neurotrophic keratitis, and corneal epithelial thickness assessment with anterior segment OCT for the diagnosis of early keratoconus. However, additional analytical validation for these biomarkers is required before clinical application as a biomarker.

Novel Approaches for Imaging-Based Diagnosis of Ocular Surface Disease

Imaging has become indispensable in the diagnosis and management of diseases in the posterior part of the eye. In recent years, imaging techniques for the anterior segment are also gaining importance and are nowadays routinely used in clinical practice. Ocular surface disease is often synonymous with dry eye disease, but also refers to other conditions of the ocular surface, such as Meibomian gland dysfunction or keratitis and conjunctivitis with different underlying causes, i.e., allergies or infections. Therefore, correct differential diagnosis and treatment of ocular surface diseases is crucial, for which imaging can be a helpful tool. A variety of imaging techniques have been introduced to study the ocular surface, such as anterior segment optical coherence tomography, in vivo confocal microscopy, or non-contact meibography. The present review provides an overview on how these techniques can be used in the diagnosis and management of ocular surface disease and compares them to clinical standard methods such as slit lamp examination or staining of the cornea or conjunctiva. Although being more cost-intensive in the short term, in the long term, the use of ocular imaging can lead to more individualized diagnoses and treatment decisions, which in turn are beneficial for affected patients as well as for the healthcare system. In addition, imaging is more objective and provides good documentation, leading to an improvement in patient follow-up and education.

Fourier-Domain OCT Imaging of the Ocular Surface and Tear Film Dynamics: A Review of the State of the Art and an Integrative Model of the Tear Behavior During the Inter-Blink Period and Visual Fixation

In the last few decades, the ocular surface and the tear film have been noninvasively investigated in vivo, in a three-dimensional, high resolution, and real-time mode, by optical coherence tomography (OCT). Recently, OCT technology has made great strides in improving the acquisition speed and image resolution, thus increasing its impact in daily clinical practice and in the research setting. All these results have been achieved because of a transition from traditional time-domain (TD) to Fourier-domain (FD) technology. FD-OCT devices include a spectrometer in the receiver that analyzes the spectrum of reflected light on the retina or ocular surface and transforms it into information about the depth of the structures according to the Fourier principle. In this review, we summarize and provide the state-of-the-art in FD-OCT imaging of the ocular surface system, addressing specific aspects such as tear film dynamics and epithelial changes under physiologic and pathologic conditions. A theory on the dynamic nature of the tear film has been developed to explain the variations within the individual compartments. Moreover, an integrative model of tear film behavior during the inter-blink period and visual fixation is proposed.

TMIS: a new image-based software application for the measurement of tear meniscus height

PURPOSE

To present a new automated image recognition software for the measurement of tear meniscus height (TMH) and investigate its correlation and efficacy compared with an open-source software (NIH ImageJ) and manual evaluation.

METHODS

A total of 520 slit lamp photographs, among which 276 were in ×16 magnification and 244 were ×40 magnified, captured from 138 eyes of 69 healthy subjects were assessed for TMH by the new automated Tear Meniscus Identification Software (TMIS), ImageJ and human graders. Images processing of TMIS included filtration, recognition and measurement of slit lamp photographs under certain algorithm, which output two measurement patterns, TMIS_{M ax} and TMIS_{M ean} . TMH measured by ImageJ software, considered as the reference value, was conducted by a masked observer while four masked ophthalmologists performed the manual evaluation.

RESULTS

In both magnifications, TMH measured by TMIS_{M ean} showed similar values with ImageJ while manual evaluation demonstrated underestimated results, and a strong correlation was detected between TMIS and ImageJ. In ×16 magnified photographs, manually obtained TMH revealed a higher correlation with ImageJ, whereas a notably stronger correlation of TMIS with ImageJ was observed in ×40 photographs. Correspondingly, the accuracy for both TMIS_{M ax} and TMIS_{M ean} appeared to be lower than most doctors in ×16 slit lamp images, in contrast to a better precision of TMIS_{M ean} in ×40 ones.

CONCLUSION

The new software displayed high accuracy and efficacy in ×40 magnification and TMIS_{M ean} pattern, suggesting the possibility of this automated TMH measurement platform to be a valid tool in dry eye screening and follow-up practice.

Automated Measurement of Tear Meniscus Height with the Kowa DR-1α Tear Interferometer in Both Healthy Subjects and Dry Eye Patients

Purpose

To develop and assess a method for quantitation of lower tear meniscus height (TMH) with the Kowa DR-1α tear interferometer.

Methods

Sixty-nine eyes of 49 men and 20 women (36 healthy volunteers, 33 patients with aqueous-deficient dry eye [ADDE]; mean age ± SD, 50.0 ± 14.0 years) were enrolled. TMH of each subject was measured by two observers both with DR-1α and newly developed software and with anterior-segment swept-source optical coherence tomography (SS-OCT). Intraoperator repeatability and interoperator and intersession reproducibility of measurements were assessed based on the within-subject SD (Sw), coefficient of variation (CV), and intraclass correlation coefficient (ICC). Agreement between the two devices was assessed by regression and Bland-Altman analysis.

Results

The CV for system repeatability of DR-1α was <2.0%. The CV for intraoperator repeatability and interoperator and intersession reproducibility for DR-1α measurements was ≤9.6%, ≤4.5%, and ≤4.4% in healthy subjects, respectively, and ≤16.8%, ≤9.8%, and ≤10.3% in ADDE patients. All corresponding ICC values were ≥0.87 in healthy subjects and ≥0.48 in ADDE patients. Bland-Altman plots indicated a high level of agreement between the two devices. Schirmer test value was significantly correlated with interferometric TMH in both healthy subjects (β = 0.59, P < 0.001) and ADDE patients (β = 0.47, P = 0.017).

Conclusions

Tear interferometry allows measurement of TMH as reliably as does SS-OCT. DR-1α may inform not only the diagnosis of dry eye disease but also identification of disease subtype.

Intraocular light scatter in patients on topical intraocular pressure-lowering medication

PURPOSE:

To quantify ocular light scattering in patients under treatment with intraocular pressure-lowering eye-drops.

METHODS:

In this prospective, observational, cross-sectional case series study, 160 eyes of 160 patients with primary open angle glaucoma or primary ocular hypertension were consecutively recruited from our Glaucoma Department over 7 months. In total, 46 eyes of 46 healthy volunteers matched for age and sex served as the control group. The variables recorded in a single visit were as follows: drug and number of drops per day, treatment duration, OXFORD corneal staining grade, lower tear meniscus height as measured by spectral domain optical coherence tomography, ocular redness and non-invasive tear breakup time measured with the Oculus Keratograph 5M, ocular surface disease index questionnaire score and objective scatter index through a double-pass technique (Optical Analysis System II).

RESULTS:

Objective scatter index was higher in the patient group (3.1, interquartile range = 1.8-5.47) than in the control group (1.95; interquartile range = 0.7-5; p = 0.017). In a multiple linear regression model, non-invasive tear breakup time was identified as the most influential variable on light scatter (mean ratio = -1.015; p = 0.003; 95% confidence interval = -1.025 to -1.005). No correlation with objective scatter index was observed for number of daily eye-drops, preservative concentration or treatment duration.

CONCLUSION:

Participants on anti-glaucoma medication showed a significantly higher objective scatter index than control group individuals. In the treated patient group, a lower non-invasive tear breakup time was associated with a higher objective scatter index. This suggests that lubricating eye-drops to improve tear breakup time could also improve vision quality in these patients by diminishing light scattering.

Ocular Surface Disease in Patients under Topical Treatment for Glaucoma

Purpose

To examine the relationship between ocular surface disease (OSD) and topical antiglaucoma therapy.

Methods

A total of 211 eyes of 211 patients with open-angle glaucoma or ocular hypertension on topical medication were recruited over 10 months. Controls were 51 eyes of 51 healthy age- and sex-matched volunteers. In each patient, we recorded the intraocular pressure-lowering eyedrops used, the number of medications used, and daily and cumulative preservative concentrations (PC). Main outcome measures were fluorescein corneal staining score (Oxford scale), lower tear meniscus height (LTMH) (spectral-domain optical coherence tomography), noninvasive tear film breakup time (NI-TBUT) (Oculus Keratograph 5M), and OSD symptom questionnaire index (OSDI).

Results

Compared to controls, significantly higher OSDI (median [interquartile range] 10.24 [4.54-18.94] vs 2.5 [0-12.5]; p<0.001) and corneal staining (≥1: 64.93% vs 32.61%; p<0.001) scores were recorded in the medication group. The NI-TBUT and LTMH failed to vary between the groups (p>0.05). A higher daily PC was associated with a lower LTMH (R −0.142; p = 0.043). In the medication group, multivariate analysis identified correlations between benzalkonium chloride (BAK) (odds ratio [OR] 1.56) and BAK plus polyquaternium-containing drops (OR 5.09) or higher OSDI (OR 1.06) and abnormal corneal staining test results and between older age (mean ratio [MR] 1.05), longer treatment duration (MR 1.02), or corneal staining presence (MR 1.22) and a higher OSDI score.

Conclusions

Ocular surface disease was more prevalent in the medication group. The main factors impacting OSD were drops with preservatives, longer treatment duration, and older age.

Assessment of the Tear Meniscus by Strip Meniscometry and Keratograph in Patients With Dry Eye Disease According to the Presence of Meibomian Gland Dysfunction

PURPOSE

We aimed to compare the tear meniscus measurements using strip meniscometry (SM) and Keratograph5M (K5M) between 3 subtypes of dry eye disease patient groups, classified according to the presence of meibomian gland dysfunction (MGD), and normal subjects.

METHODS

We enrolled 145 eyes from 145 subjects and measured the tear meniscus using SM and K5M, tear film breakup time, ocular surface staining, and ocular surface disease index; the Schirmer test; and examined lid margins and meibomian glands. Correlation of tear meniscus parameters with other parameters and efficacy of the 2 measurements were evaluated.

RESULTS

The SM and K5M results were significantly lower in the non-Sjögren syndrome aqueous-deficient dry eye (non-SS ADDE) with and without MGD groups than in the MGD-only group and normal subjects. The SM or K5M results correlated with each other and with other ocular surface parameters. The area under the curve (AUC) of the SM and K5M results was 0.637 (P = 0.012) and 0.610 (P = 0.042), respectively. Except for the MGD group, the AUC of the SM and K5M results were 0.721 (P < 0.001) and 0.694 (P = 0.001), respectively. The AUC of SM and K5M were 0.947 (P < 0.001) and 0.784 (P = 0.002), differentiating non-SS ADDE-only patients from those with normal eyes.

CONCLUSIONS

Tear meniscus measurements using SM and K5M can compensate for detection of aqueous-deficient components of dry eye. These results should be interpreted according to the presence or absence of MGD.

Lower Tear Meniscus Measurements Using a New Anterior Segment Swept-Source Optical Coherence Tomography and Agreement With Fourier-Domain Optical Coherence Tomography

PURPOSE

To assess intraobserver repeatability and interobserver and intersession reproducibility of lower tear meniscus height (LTMH) measurements obtained using a new anterior segment swept-source optical coherence tomography (SS-OCT) device. Agreement with Fourier-domain (FD) OCT (Spectralis) was also examined.

METHODS

In an observational cross-sectional study, one eye of 29 healthy subjects was randomly imaged with both devices at our center. Two examiners then randomly measured the LTMH using the software's calipers. To assess intraobserver repeatability and interobserver and intersession reproducibility, within-subject standard deviation (Sw), test-retest repeatability, coefficients of variation (CoV), and intraclass correlation coefficients (ICCs) were calculated. Agreement between both devices was also determined in Bland-Altman plots.

RESULTS

Mean LTMHs for SS-OCT and FD-OCT were 276.6 ± 87.6 and 280.3 ± 80 μm, respectively. Using the SS-OCT device, intraobserver CoV, interobserver CoV, and intersession CoV were found to be ≥16.9%, ≤7.2%, and ≤11.5%, respectively. ICCs for these parameters were ≤88%, ≥97%, and ≥94%, respectively. Bland-Altman analysis indicated poor agreement between SS-OCT and FD-OCT, and the correlation was low (CoV 34.5%, ICC 0.36).

CONCLUSIONS

SS-OCT LTMH measurements showed excellent interobserver and intersession repeatability along with good intraobserver reproducibility. Agreement between the devices was poor.

Diagnosis of Dry Eye by Tear Meniscus Measurements Using Anterior Segment Swept Source Optical Coherence Tomography

To evaluate the diagnostic power of tear meniscus measurements using anterior segment swept source optical coherence tomography (SS-OCT) for dry eye and suspected dry eye. Fifty subjects (27 men and 23 women; mean age 43.3 ± 13.7 years), comprising 26 eyes of 26 healthy subjects and 24 eyes of 24 patients with dry eye or suspected dry eye according to Japanese diagnostic criteria, were enrolled at The University of Tokyo Graduate School of Medicine. Subjects underwent SS-OCT, and the central upper and lower tear meniscus heights (TMHs) and areas (TMAs) and the lower tear meniscus volume (TMV) were examined. Intergrader variability and interimage variability, calculated using the pooled coefficient of variation and intraclass correlation coefficient, were used to assess repeatability of measurements in the dry eye group. To diagnose dry eye using tear meniscus measurements by SS-OCT, sensitivity, specificity, and cutoff values of optical coherence tomography (OCT) measurements were determined using receiver operating characteristic analysis. The TMH, TMA, and TMV measured by OCT were significantly lower in the dry eye group than in the control group (P < 0.001). Cutoff values of the lower TMH, TMA, and TMV were 191 μm, 12,360 μm, and 0.0473 mm, respectively. Intergrader repeatability and interimage repeatability, measured as the intraclass correlation coefficient, were >80% for all tear meniscus parameters, with acceptable repeatability. Significant correlations between tear meniscus measurements by OCT and vital staining scores, Schirmer test values, and tear film breakup time were observed (P < 0.05). SS-OCT is a noninvasive and practical method for quantitative evaluation of tear fluid and has the potential for detecting dry eye and suspected dry eye.

The Effects of Increasing Ocular Surface Stimulation on Blinking and Tear Secretion

PURPOSE

To investigate the effect of varying levels of ocular surface stimulation on the timing and amplitude of the blink and tear secretion.

METHODS

Following instillation of fluorescein dye, increasing levels of air flow were directed toward the central corneas of 10 healthy subjects. Interblink interval (IBI), tear meniscus height (TMH), and fluorescence intensity were measured simultaneously. Because blinking can obscure changes in TMH, we developed novel measures of tear secretion by calculating tear meniscus fluorescein concentration (TMFC) from intensity using a mathematical model. The change of TMH and TMFC over trials and the slope of the TMFC within each IBI (IBI-TTR) were further calculated.

RESULTS

The mean IBI was decreased by 8.08 ± 8.54 seconds from baseline to maximum air stimulation. The TMH increase was highly variable (0.41 ± 0.39 mm) among subjects, compared to the fluorescence tear turnover metrics: decrease in TMFC of 2.84 ± 0.98 natural logarithm or ln(%) and IBI-TTR of 0.065 ± 0.032 ln(%)/sec. Ocular surface stimulation was highly correlated with the TMFC and IBI-TTR, but less so with TMH (Pearson's r = 0.71, 0.69, and 0.40, P < 0.01, respectively). Blinking and tearing were significantly correlated with each other (Pearson's r = 0.56, P < 0.01), but tearing lagged behind by an average of 6.54 ± 4.07 seconds.

CONCLUSIONS

Blinking and tearing share a common origin with sensory stimulation at the ocular surface. Both showed a dose-response increase with surface stimulation and were correlated with each other. These methods can potentially be used to understand alterations in ocular surface sensory function and associated protective responses in dry eye and other disorders of the ocular surface.

Intra-observer and inter-observer repeatability of ocular surface interferometer in measuring lipid layer thickness

Background

Tear lipid morphology is important for normal tear function. Recently, there have been clinical studies using interferometry to assess lipid layer thickness (LLT). The aim of the study is to examine the repeatability of a commercially available interferometer.

Methods

Two observers measured LLT in twenty Asian subjects (20 eyes) using an interferometer (LipiView® ocular surface interferometer, TearScience Inc, Morrisville, NC). Dry eye symptoms, tear break up time (TBUT) and corneal fluorescein staining were also prospectively evaluated.

Results

Data for 20 participants are presented for either right or left eye (randomly selected). The mean LLT ± standard deviation of these participants was 53.53 ± 14.59 nm. When a single observer repeated the imaging on the same day, the coefficient of repeatability was 16 nm and the 95 % limits of agreement were between −11 nm and 18 nm. When a different observer repeated the scan, the coefficient of repeatability was 13 nm and limits of agreement were −9 nm and 16 nm. LLT was not significantly associated with TBUT, presence of any corneal staining in any corneal zones, or symptomatic status.

Conclusion

With the repeatability of measurements being known, the significance of LLT changes measured by this interferometer may be better interpreted. In this small Asian study, the LLT was lower than previously reported studies.

Fourier-domain optical coherence tomography for monitoring the lower tear meniscus in dry eye after acupuncture treatment

Dry eye is highly prevalent and has a significant impact on quality of life. Acupuncture was found to be effective to treat dry eye. However, little was known about the effect of acupuncture on different subtypes of dry eye. The objective of this study was to investigate the applicability of tear meniscus assessment by Fourier-domain optical coherence tomography in the evaluation of acupuncture treatment response in dry eye patients and to explore the effect of acupuncture on different subtypes of dry eye compared with artificial tear treatment. A total of 108 dry eye patients were randomized into acupuncture or artificial tear group. Each group was divided into three subgroups including lipid tear deficiency (LTD), Sjögren syndrome dry eye (SSDE), and non-Sjögren syndrome dry eye (Non-SSDE) for data analysis. After 4-week treatment, the low tear meniscus parameters including tear meniscus height (TMH), tear meniscus depth (TMD), and tear meniscus area (TMA) in the acupuncture group increased significantly for the LTD and Non-SSDE subgroups compared with both the baseline and the control groups (all P values < 0.05), but not for the SSDE. Acupuncture provided a measurable improvement of the tear meniscus dimensions for the Non-SSDE and LTD patients, but not for the SSDE patients.

Tear meniscus evaluation by anterior segment swept-source optical coherence tomography

PURPOSE

To investigate the repeatability of tear meniscus measurements using anterior segment swept-source optical coherence tomography (OCT) and the relationship of tear meniscus measurements with tear film breakup time and Schirmer test results.

DESIGN

Prospective, observational, cross-sectional study.

METHODS

We enrolled 26 healthy subjects (26 eyes; 20 men and 6 women; mean age, 36.5 ± 6.8 years) at the University of Tokyo School of Medicine, Tokyo, Japan, in this study. Examinations were conducted in the following sequence: anterior segment vertical raster scans by swept-source OCT, tear film breakup time, and Schirmer test. Each subject underwent OCT measurements twice by the same grader, and the central upper and lower tear menisci height and area and the lower tear meniscus volume were examined. Each OCT image was evaluated by 2 masked graders using the software calipers.

RESULTS

The average upper and lower tear meniscus heights were 231 ± 78 μm and 256 ± 57 μm, respectively, and the average upper and lower tear meniscus areas were 18 829 ± 7823 μm(2) and 21 903 ± 8173 μm(2), respectively. The average tear meniscus volume was 0.1327 ± 0.051 mm(3). The intergrader intraclass correlations for all the parameters were more than 95%. The OCT tear meniscus measurements and the Schirmer test scores were correlated significantly (P < .05, Spearman nonparametric correlation analysis). However, tear film breakup time was not correlated significantly with any of the parameters of tear menisci (P > .05).

CONCLUSIONS

Anterior segment swept-source OCT is a noninvasive and practical method that can be used for quantitative evaluation of tear fluid.

Effect of airflow exposure on the tear meniscus

Purpose. To compare the effect of airflow exposure on the tear meniscus and blink frequency in normal and evaporative dry eye subjects. Methods. In 9 normal subjects and 9 short tear breakup time (SBUT) dry eye subjects, lower tear meniscus height (TMH) and area (TMA) and blink frequency were measured with anterior segment optical coherence tomography (OCT) before and after 5 minutes of airflow exposure (1.5 ± 0.5 m/s). Results. In SBUT dry eyes, both TMH and TMA decreased significantly (P = 0.027, P = 0.027) with a significant increase of blink frequency after airflow exposure, while significant increase in TMA was found in normal eyes. Conclusion. Measurement of the tear meniscus with anterior segment OCT seems to be useful as a noninvasive and objective method for evaluating the effect of airflow on tear film.