Repeatability of tear meniscus evaluation using spectral-domain Cirrus® HD-OCT and time-domain Visante® OCT

Reliability of Tear Meniscus Height Measurements in Contact Lens Wearers and Its Relationship With Discomfort Symptoms

OBJECTIVES

To evaluate the reliability and agreement of tear meniscus height (TMH) measurements performed with a corneal analyzer and optical coherence tomography (OCT) technology in contact lens (CL) wearers and its correlation with contact lens discomfort symptoms.

METHODS

Asymptomatic and symptomatic CL wearers classified through the Contact Lens Dry Eye Questionnaire-8 were evaluated with the Corneal Analyzer (Topcon CA-800) and OCT technology (Topcon 3D OCT-2000). The repeatability and intraclass correlation coefficient (ICC) were calculated. The agreement between devices was calculated using the Bland-Altman method. The relationship between TMH measurements and the Contact Lens Dry Eye Questionnaire-8 and Contact Lens Discomfort Index scores was assessed through the Spearman correlation coefficient.

RESULTS

Seventy-nine asymptomatic and 42 symptomatic CL wearers aged 34.24±12.50 years were enrolled. The repeatability values obtained for the CA-800 were 0.07 mm in all cases, and the ICC was 0.93 for the whole sample. The CA-800 provided significantly ( P <0.01) higher TMH values than the OCT for the whole sample (0.22±0.08 vs. 0.17±0.06 mm). A weak indirect correlation (ρ=-0.22) between the OCT TMH measurement and Contact Lens Discomfort Index scores was found ( P ≤0.04).

CONCLUSION

The CA-800 provides reliable TMH measurements during CL wear; however, they might not be interchangeable with OCT ones. Tear meniscus height measurements might be useful as a complementary sign to detect CL discomfort, but it cannot be used alone as a diagnostic tool.

Ocular surface parameters repeatability and agreement -A comparison between Keratograph 5M and IDRA

PURPOSE

To evaluate the repeatability and agreement in dry eye measurements using Oculus Keratograph 5M (K5M) and SBM Sistemi IDRA (IDRA).

METHODS

A total of 108 participants were enrolled and 108 eyes were evaluated. Tear meniscus height (TMH) and first and average non-invasive break-up time (NIBUT) were measured using the K5M and IDRA (order randomly assigned). TMH was measured using the built-in caliper tool while NIBUT was computed by the automatic algorithm of the instruments.

RESULTS

The Bland Altman plots analysis showed a good agreement between the two instruments for TMH (95 % Limits of Agreement (LoA), -0.17 to 0.16), but not the first NIBUT (95 % LoA, -8.13 to 14.79) and average NIBUT (95 % LoA, -7.89 to 10.32). The values of the first and average NIBUT measured using IDRA were significantly shorter than in K5M (difference = median (IQR) -2.75 (-6.48- -0.28)s, p < 0.001 and difference = median (IQR) -1.65 (-3.97-1.89)s, p = 0.008 respectively). The TMH (p = 0.037) and NIBUT average (p = 0.033) measured by K5M, as well as the TMH (p = 0.040) measured by IDRA, exhibited unstable measurements across the three measurement times. The remaining parameters exhibited stability with three repeated measurements.

CONCLUSION

The NIBUT measurements are not interchangeable between IDRA and K5M, while the TMH was little difference between the two instruments. It is important to exercise caution when using different ocular surface analyzers to minimize errors in comparing multiple measurements.

Surgical outcomes of endoscopic dacryocystorhinostomy for eyes with nasolacrimal duct obstruction via tear meniscus height evaluation

PURPOSE

To evaluate the association of tear meniscus height (TMH) with clinical outcomes of patients who underwent endonasal dacryocystorhinostomy.

METHODS

We recruited 304 patients from two institutes. The TMH was measured using anterior segment optical coherence tomography before surgery. All patients underwent endoscopic DCR with lacrimal intubation stent insertion. The lacrimal stent was removed 2 months after surgery. The TMH was measured at 2 months and 12 months after surgery. Improvements in epiphora were assessed using a visual analogue scale (range, 0-2). Recurrence was determined based on lacrimal irrigation and endoscopic evaluation results.

RESULTS

All patients experienced improvements in subjective symptoms 2 months after surgery. The mean TMH also decreased significantly compared with that before surgery. During the follow-up period, four patients experienced recurrence. The mean TMH 12 months after surgery was significantly lower than that before surgery. The rate of change in the TMH was significantly associated with the use of a dacryoendoscope during sheath-guided lacrimal stent intubation at all time points. Of the 251 patients who were followed up at 12 months after surgery, three reported recurrences, and 17 reported mild improvement of epiphora. The rate of change in the TMH was significantly associated with epiphora improvement. Height was also associated with epiphora improvement.

CONCLUSIONS

Endoscopic DCR is an acceptable surgical procedure for managing nasolacrimal duct obstruction. Sheath-guided lacrimal stent intubation using a dacryoendoscope resulted in a greater reduction in postoperative TMH compared to the blind insertion technique, which may lead to favorable clinical outcomes.

Intraobserver Repeatability Assessment of the S390L Firefly WDR Slitlamp in Patients With Dry Eye Disease: Objective, Automated, and Noninvasive Measures

OBJECTIVES

To assess the intraobserver repeatability of automated, objective, and noninvasive measures obtained with the S390L Firefly WDR slitlamp.

METHODS

This cross-sectional study included 50 eyes of patients with dry eye disease with a mean age of 55.06±12.96 years. Three consecutively repeated measures of the following variables were obtained: first noninvasive break-up time (F-NIBUT), average noninvasive break-up time (A-NIBUT), tear meniscus height, tear meniscus area (TMA), nasal ciliary hyperemia (NCIH), temporal ciliary hyperemia (TCIH), nasal conjunctival hyperemia (NCOH), temporal conjunctival hyperemia (TCOH), upper loss area meibomian gland (U-LAMG), lower loss area meibomian gland (L-LAMG), upper meibomian gland dysfunction grade (U-MGD grade), and lower meibomian gland dysfunction grade (L-MGD grade). Intraobserver repeatability was estimated with coefficient of variation (CoV), intrasubject standard deviation (SD) (S w ), and Bland-Altman plots.

RESULTS

All variables showed no statistically significant differences in the repeated-measures analysis except for L-MGD grade ( P =0.045). F-NIBUT and A-NIBUT obtained the highest CoV with an average value of 0.48±0.41 [0.02-1.00] and 0.34±0.25 [0.02-1.00], respectively. The remaining variables showed CoVs between 0.04±0.11 [0.00-0.43] and 0.18±0.16 [0.00-0.75]. A-NIBUT, TMA, NCOH, and L-LAMG obtained an S w of 2.78s, 0.21 mm 2 , <0.001, and 4.11%, respectively. Bland-Altman plots showed a high level of agreement between pairs of repeated measures.

CONCLUSION

The S390L Firefly WDR slitlamp has moderate intraobserver repeatability for F-NIBUT and A-NIBUT, which suggests that F-NIBUT and A-NIBUT are tests with high variability. The remaining variables show satisfactory intraobserver repeatability.

Efficacy of pyridostigmine (Mestinon) in the relief of patients with epiphora

BACKGROUND

Although the mechanism is not clear, the inability of the orbicularis oculi muscle, especially the deeper segment (Horner muscle), is thought to be responsible in epiphora. This study evaluates the effect of the anticholinergic drug pyridostigmine (Mestinon) in patients with patent but dysfunctional lacrimal drainage system.

MATERIAL AND METHODS

Twenty patients with bilateral epiphora (mean age:60.78 ± 6.49 yrs) were included in this study. Patients with a patent lacrimal irrigation test based on persistent and symptomatic epiphora, wiping >10 times daily or continuous tearing and grade 4-5 epiphora according to Munk scale, showing neuropathic involvement in the orbicularis oculi muscle by the quantitative motor unit potential (MUP) analysis method were evaluated prospectively. Fluorescein dye disappearance test (a semi-quantitative assessment of delayed tear outflow) together with a Schirmer test reading were performed in order to detect dry eye. The patients were evaluated for tear meniscus measurements by anterior segment optical coherence topography (OCT) and non-invasive tear break-up time (NI-BUT) was measured by Oculus Keratograph 5 M. Those with a NI-BUT value above 10 s, without eyelid laxity, previous ocular surgery or ocular surface disease, or nasolacrimal duct obstruction, and who agreed to use the drug were included in the study. Each subject underwent OCT measurements of the lower tear meniscus of both eyes before and 15 mins after taking Mestinon (1 × 60 mg tablet). Upon measurement of the positive effect of the drug on tear meniscus height (TMH), the patients were asked to continue this regime daily for 1 month and then evaluated for relief in their epiphora complaints and any systemic drug side effects.

RESULTS

A total of 20 patients (40 eyes) with bilateral epiphora were included in the study. All eyes had grade 4 Munk-score epiphora, Schirmer's test was within the normal range in all eyes (mean, 14 ± 4 mm), and patent lacrimal irrigation test. The lower mean TMH reductions 15 min after Mestinon in the right and left eyes were 135.41 ± 85.47 and 55.44 ± 61.56 mm, respectively, a statistically significant decrease in both eyes (p = 0.001, p < 0.01). The mean tear meniscus area (TMA) in the right and left eyes was 131.83 ± 68.27 mm² and 62.72 ± 50.57 mm², respectively; 15 mins after administration of Mestinon, the mean TMA in the right and left eyes was 77.27 ± 48.34 and 59.18 ± 44.74 mm², respectively (p = 0.001, p < 0.01). The mean decreases of 54.56 ± 39.34 mm² in the right eye area and 3.53 ± 42.32 mm² in the left eye area were statistically significant (p = 0.041, p < 0.05).

CONCLUSION

Symptomatic relief for epiphora cannot be achieved with known treatment options due to lacrimal pump dysfunction. We found that pyridostigmine (Mestinon) provided relief in patients' complaints of epiphora consistent with a significant reduction in TMH levels.

Lacrimal Gland Insufficiency in Aqueous Deficiency Dry Eye Disease: Recent Advances in Pathogenesis, Diagnosis, and Treatment

BACKGROUND

Aqueous deficiency dry eye disease is a chronic and potentially sight-threatening condition, that occurs due to the dysfunction of the lacrimal glands. The aim of this review was to describe the various recent developments in the understanding, diagnosis and treatment of lacrimal gland insufficiency in aqueous deficiency dry eye disease.

METHODS

A MEDLINE database search using PubMed was performed using the keywords: "dry eye disease/syndrome", "aqueous deficient/deficiency dry eye disease", "lacrimal gland" and "Sjogren's syndrome". After scanning through 750 relevant abstracts, 73 eligible articles published in the English language from 2016 to 2021 were included in the review.

RESULTS

Histopathological and ultrastructural studies have revealed new insights into the pathogenesis of cicatrising conjunctivitis-induced aqueous deficiency, where the lacrimal gland acini remain uninvolved and retain their secretory property, while significant ultrastructural changes in the gland have been observed. Recent advances in diagnosis include the techniques of direct clinical assessment of the lacrimal gland morphology and secretion, tear film osmolarity, tear film lysozyme and lactoferrin levels, tear film interferometry and lacrimal gland confocal microscopy. Developments in the treatment of aqueous deficiency dry eye disease, apart from the nanoparticle-based tear substitutes, include secretagogues like diquafosol tetrasodium and rebamipide, anti-inflammatory topical agents like nanomicellar form of cyclosporine and lifitegrast, scleral contact lenses, neurostimulation, and acupuncture for increasing the amount of tear production, minor salivary gland transplantation, faecal microbial transplantation, lacrimal gland regeneration and mesenchymal stem cell therapy.

CONCLUSIONS

Significant advances in the understanding, diagnosis and management of lacrimal gland insufficiency and its role in aqueous deficiency dry eye disease have taken place within the second half of the last decade. Of which, translational breakthroughs in terms of newer drug formulations and regenerative medicine are most promising.

Application of Keratograph and Fourier-Domain Optical Coherence Tomography in Measurements of Tear Meniscus Height

To compare the interoperator repeatability of tear meniscus height (TMH) measurements obtained with a keratograph and Fourier-domain optical coherence tomography (FD-OCT) and to assess the agreement between the methods.Forty-seven eyes with DED and 41 healthy eyes were analyzed using the Schirmer test I and tear breakup time test (TBUT). The TMH was measured three times with each device. The repeatability of measurements was assessed by within-subject standard deviation (Sw), repeatability (2.77 Sw), coefficient of variation (CoV) and intraclass correlation coefficient (ICC). Efficacy in detecting DED was evaluated in terms of the area under the curve (AUC). The TMHs obtained with the keratograph were 0.03 mm lower than those obtained with FD-OCT in both groups (p < 0.001 for the DED group and p = 0.0143 for the control group, respectively). The intraexaminerICCs of the keratographic TMH were 0.789 and 0.817 for the DED and control groups, respectively, and those of the FD-OCT TMH were 0.859 and 0.845, respectively. Although a close correlation was found between the TMHs measured with the keratograph and FD-OCT by the Spearman analysis in both groups (both p < 0.001), poor agreement between the devices was shown in both groups using a Bland−Altman plot. The AUCs of the keratography and FD-OCT results were 0.971 (p < 0.001) and 0.923 (p < 0.001), respectively. Both devices had excellent diagnostic accuracy in differentiating normal patients from DED patients. FD-OCT TMH measurements were more reliable than the keratograph data in the DED group. Agreement between the devices was poor in both groups.

AS-OCT and Ocular Hygrometer as Innovative Tools in Dry Eye Disease Diagnosis

Dry eye disease (DED) is one of the conditions that most commonly leads patients to visit an ophthalmologist. Fast and accurate diagnosis relieves patient discomfort and spares them from long-term effects on the ocular surface. Many tests used in the diagnosis of DED may be considered subjective as they rely on an experienced observer for image interpretation, resulting in variations in diagnosis. On one hand, the non-contact nature of the anterior segment optical coherence tomography (AS-OCT) device and its rapid image acquisition enable the measurement of the tear meniscus parameter without reflex tearing. On the other hand, an ocular hygrometer allows a rapid, safe, but also efficient, analysis and is associated with low costs and the repeatability of the procedure.

Evaluation of tear meniscus height using different clinical methods

Clinical relevance: The height of the tear meniscus (TMH) is a generally accepted method to evaluate tear film volume, especially in dry eye diagnoses and management.Background: The purpose of this study was to evaluate the ability of different methods to measure tear meniscus height accurately and repeatably.Methods: Lower TMH of 20 volunteers (26.8 ± 5.6 years) was measured by two observers (OI and OII) using optical coherence tomography (OCT), slitlamp microscope image analysis, and with a reticule at low (8x) and high (32x) magnification. TMH was also evaluated by both observers by comparing TMH to thickness of the lid margin (lid-ratio; grade 0: TMH 1/2 lid margin thickness; grade 1: 1/3; grade 2: 1/4; grade 3: 1/5; grade 4: 1/6) and to the number of eyelashes fitting in the tear meniscus. Differences between observers were analysed by paired-t-test. Differences between OCT-TMH and other methods were analysed by ANOVA, and inter-observer repeatability by intra-class-correlation-coefficient (ICC). The ability to predict OCT-TMH was calculated by receiver operative characteristic (ROC) curve analysis.Results: There was no significant difference between OI and OII in all methods except of the eyelash-count-method (p = 0.008). For OI, TMH measured using a reticule at 8x (0.20 ± 0.05 mm) was significantly lower than OCT-TMH (0.24 ± 0.07 mm) (p = 0.032) but not at 32x (0.22 ± 0.01 mm; p = 0.435). TMH evaluated by the image software of the slitlamp (0.20 ± 0.05 mm) was significantly lower than OCT-TMH (p = 0.022). The lid-ratio-method and eyelash-count-method resulted in grades of 2.35 ± 1.22 and 2.85 ± 0.81, respectively. ROC analyses showed that only the 8x and the 32x magnification method could discriminate between normal and abnormal OCT-TMH. OCT had the best repeatability (ICC = 0.88; p < 0.001) followed by reticule using 32x magnification (ICC = 0.70; p = 0.004).Conclusion: The most reliable method to measure TMH was OCT followed by slitlamp using a reticule. TMH cannot be reliably evaluated by comparing it against lid margin thickness or number of eyelashes.

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.

Imaging Biomarkers for Dry Eye Disease

The clinical, scientific, economic, and regulatory impact of validated biomarkers and surrogate endpoints has the potential to revolutionize the approach to ocular surface diseases. At present, there is a growing interest in developing biomarkers for dry eye disease, and other ocular surface disorders and imaging are of the most promising approaches to this issue. Among the several and constantly evolving imaging technologies, some tools that are aimed to assess tear film stability and volume, meibomian gland morphology and function, and ocular surface microanatomy are now supported by a good body of evidence. To date, clinical trials on ocular surface diseases have slowly started incorporating imaging biomarkers for disease diagnosis and stratification and as surrogate endpoints. Major efforts are still needed, mainly aimed to improve automatic acquisition and quantitative analysis, standardization (standard operating procedures, normative databases etc.), and validation of imaging biomarkers.

Objective Imaging Diagnostics for Dry Eye Disease

Traditional diagnostic tests for dry eye disease (DED), such as fluorescein tear film break-up time and the Schirmer test, are often associated with poor reproducibility and reliability, which make the diagnosis, follow-up, and management of the disease challenging. Advances in ocular imaging technology enables objective and reproducible measurement of changes in the ocular surface, tear film, and optical quality associated with DED. In this review, the authors will discuss the application of various imaging techniques, such as, noninvasive tear break-up time, anterior segment optical coherence tomography, in vivo confocal microscopy, meibography, interferometry, aberrometry, thermometry, and tear film imager in DED. Many studies have shown these devices to correlate with clinical symptoms and signs of DED, suggesting the potential of these imaging modalities as alternative tests for diagnosis and monitoring of the condition.

Ocular Clinical Signs and Diagnostic Tests Most Compatible With Keratoconjunctivitis Sicca: A Latent Class Approach

PURPOSE

To evaluate the ocular signs and tests for keratoconjunctivitis sicca (KCS) in the absence of a gold standard.

METHODS

Cross-sectional study of participants from the Sjögren's International Collaborative Clinical Alliance (SICCA) registry. Participants had oral/ocular/rheumatologic examinations, blood/saliva samples collected, and salivary gland biopsy. Latent class analysis (LCA) identified clusters of patients based on 3 to 4 predictor variables relating to signs or tests of KCS. The resulting model-based "gold standard" classification formed the basis for estimated sensitivity and specificity associated with these predictors.

RESULTS

A total of 3514 participants were enrolled into SICCA, with 52.9% classified as SS. LCA revealed a best-fit model with 2 groups. For the gold standard-positive group, an abnormal tear breakup time, ocular staining score (OSS), and Schirmer I had a sensitivity of 99.5%, 91.0%, and 47.4%, respectively. For the gold standard-negative group, an abnormal tear breakup time, OSS, and Schirmer I had a specificity of 32.0%, 84.0%, and 88.5%, respectively. OSS components (fluorescein and lissamine staining), exhibited a sensitivity of 82.6% and 90.5%, respectively, in the gold standard-positive group, whereas these signs in the gold standard-negative group had a specificity of 88.8% and 73.0%, respectively.

CONCLUSIONS

OSS and its components (fluorescein and lissamine staining) differentiated 2 groups from each other better than other KCS parameters and had relatively high sensitivity and specificity.

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.

Deep learning segmentation for optical coherence tomography measurements of the lower tear meniscus

The tear meniscus contains most of the tear fluid and therefore is a good indicator for the state of the tear film. Previously, we used a custom-built optical coherence tomography (OCT) system to study the lower tear meniscus by automatically segmenting the image data with a thresholding-based segmentation algorithm (TBSA). In this report, we investigate whether the results of this image segmentation algorithm are suitable to train a neural network in order to obtain similar or better segmentation results with shorter processing times. Considering the class imbalance problem, we compare two approaches, one directly segmenting the tear meniscus (DSA), the other first localizing the region of interest and then segmenting within the higher resolution image section (LSA). A total of 6658 images labeled by the TBSA were used to train deep convolutional neural networks with supervised learning. Five-fold cross-validation reveals a sensitivity of 96.36% and 96.43%, a specificity of 99.98% and 99.86% and a Jaccard index of 93.24% and 93.16% for the DSA and LSA, respectively. Average segmentation times are up to 228 times faster than the TBSA. Additionally, we report the behavior of the DSA and LSA in cases challenging for the TBSA and further test the applicability to measurements acquired with a commercially available OCT system. The application of deep learning for the segmentation of the tear meniscus provides a powerful tool for the assessment of the tear film, supporting studies for the investigation of the pathophysiology of dry eye-related diseases.

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.

Automatic assessment of tear film and tear meniscus parameters in healthy subjects using ultrahigh-resolution optical coherence tomography

Many different parameters exist for the investigation of tear film dynamics. We present a new tear meniscus segmentation algorithm which automatically extracts tear meniscus area (TMA), height (TMH), depth (TMD) and radius (TMR) from UHR-OCT measurements and apply it to a data set including repeated measurements from ten healthy subjects. Mean values and standard deviations are 0.0174 ± 0.007 mm², 0.272 ± 0.069 mm, 0.191 ± 0.049 mm and 0.309 ± 0.123 mm for TMA, TMH, TMD and TMR, respectively. A significant correlation was found between all respective tear meniscus parameter pairs (all p < 0.001, all Pearson's r ≥ 0.657). Challenges, limitations and potential improvements related to the data acquisition and the algorithm itself are discussed. The automatic segmentation of tear meniscus measurements acquired with UHR-OCT might help in a clinical setting to further understand the tear film and related medical conditions like dry eye disease.

Advances in dry eye imaging: the present and beyond

New advances in imaging allow objective measurements for dry eye as well as define new parameters that cannot be measured by clinical assessment alone. A combination of these modalities provides unprecedented information on the static and dynamic properties of the structural and functional parameters in this multifactorial disease. A literature search was conducted to include studies investigating the use of imaging techniques in dry eye disease. This review describes the application of non-invasive tear breakup time, optical coherence tomography, meibomian gland imaging, interferometry, in vivo confocal microscopy, thermography and optical quality assessment for this condition.

Usability and reproducibility of tear meniscus values generated via swept-source optical coherence tomography and the slit lamp with a graticule method

Purpose

To investigate the usability and the reproducibility of the tear meniscus values via swept-source optical coherence tomography (SS-OCT) and the conventional slit lamp microscope method with a graticule.

Methods

The right eye was examined in 90 healthy adult subjects who were grouped according to age (group 1: 20–39 years; group 2: 40–59 years; group 3: ≥60 years). The tear meniscus height (TMH) and tear meniscus area were measured using SS-OCT and TMH by the slit lamp microscope method. The reproducibility of each method was calculated using intraclass correlation coefficients (ICCs) in additionally enrolled 30 healthy young subjects. We also evaluated TMH at 3 mm from the corneal center in both temporal and nasal directions using SS-OCT.

Results

The mean of the TMH values measured by SS-OCT was significantly higher than those measured by the slit lamp method (328 vs. 212 μm, P < 0.001, respectively). High reproducibility was observed for each method (ICC > 0.75 for both). No statistically significant differences were found in TMH among the age groups using both SS-OCT and slit lamp methods (P = 0.985, 0.380, respectively). TMH values at both sides of the corneal center were significantly smaller than those at the corneal center (P < 0.0001).

Conclusions

TMH values obtained by the slit lamp method were lower than those obtained by SS-OCT. However, both methods yielded highly reproducible TMH measurements, suggesting that they are clinically useful. Tear meniscus values did not vary by age but by measurement points in our cohort.