Interexaminer Reproducibility of Optical Coherence Tomography for Measuring the Tear Film Meniscus

Application of optical coherence tomography and keratograph in the measurements of lower lid margin thickness

PURPOSE

This study aims to investigate the applicability of lower lid margin thickness (LLMT) measurements in adults with and without meibomian gland dysfunction (MGD) by optical coherence tomography (OCT) and keratograph.

METHODS

This is a cross-sectional, observational study. A hundred and eight volunteers aged 20 to 79, including 68 MGD patients and 40 normal subjects, were recruited. Using OCT and keratograph to measure the LLMT from the posterior lash line to anterior edge or outer edge of the tear meniscus was separately performed two times by the same person.

RESULTS

The mean age of normal and MGD subjects was 50.5 ± 14.2 years and 55.8 ± 15.5 years, respectively. The LLMT with OCT and keratograph in MGD patients was significantly greater than that in normal subjects (1.06 ± 0.27 and 1.03 ± 0.25 mm vs. 0.90 ± 0.20 and 0.86 ± 0.16 mm, respectively). In both normal and MGD subjects, the tear meniscus height and LLMT with OCT were both greater than that with keratograph (P < 0.05), and intraclass correlation coefficient (ICC) demonstrated a good agreement in the LLMT measurements between two devices (ICC = 0.83 and 0.79, respectively). Additionally, the LLMT in MGD patients was appeared to be positively correlated with meiboscore (rs = 0.37, P = 0.002).

CONCLUSIONS

The OCT and keratograph were two reliable tools in the LLMT measurements, which may have potential applications for diagnosis and evaluation of MGD. Furthermore, we found that the LLMT measured by OCT was greater than that measured by keratograph.

The effect of topical steroids and non-steroidal anti inflammatory drugs on epiphora of unknown cause: Optical coherence tomography study

PURPOSE

The aim of this study is to evaluate using topical non-steroidal antiinflammatory and low-potency steroid drugs for the treatment of epiphora without an underlying cause using anterior segment-optical coherence tomography (AS-OCT) and Munk epiphora grading system.

METHODS

Thirty patients with epiphora who had no underlying cause were evaluated prospectively.A detailed ophthalmological examination, tear meniscus height on slit-lamp, fluorescein tear break-up time, schirmer test, lisamin green conjonctival staining, lacrimal syringing of the upper and lower canaliculus were done in all patients. The patients with contact lens wear,punctal stenosis, lacrimal system disorders, dry eye disease, eyelid malpositions, pterygium, conjunctivochalasis, conjunctivitis, blepharitis, ocular infection, and corneal disease, used topical anti-glaucomatous drugs were excluded. All patients were treated with a combination of topical low-potency drug (loteprednol etabonate 0.5%) twice daily for ten days and topical non-steroidal anti-inflammatory drug (nepafenac 0.3%)once a day for 1 month. Before and after the medical treatment protocol, tear meniscus area (TMA) and tear meniscus height (TMH) were measured by AS-OCT and patients were asked to subjectively rate their epiphora according to the Munk epiphora grading system. The effectiveness of treatment were evaluated by AS-OCT measurements and the Munk epiphora grading system.

RESULTS

Fourteen males and sixteen females were included. The mean age at presentation was 60.1 ± 7.35 years and duration of symptoms was 10.03 ± 5.08 months. The mean duration of follow-up was 8.7 ± 3.2 months. Munk epiphora grading system was significantly decreased from 2.5 to 1.6 after treatment (p: 0.004). TMH and TMA were significantly decreased on AS-OCT (TMH:402 vs 309 µm, p:0.001, TMA:0.797 vs 0.347 mm², p = 0.006).Six of thirty patients subjectively reported that their symptoms had not improved but TMH and TMA were significantly decreased on AS-OCT.

CONCLUSIONS

The combined use of topical non-steroidal anti-inflammatory and low-potency steroid drops may be a good option in patients with epiphora who does not have an underlying cause.

Correlation of Measures From the OCULUS Keratograph and Clinical Assessments of Dry Eye Disease in the Dry Eye Assessment and Management Study

PURPOSE

The purpose of this study was to compare objective, noninvasive assessments of tear function using the OCULUS Keratograph with the corresponding clinical assessments [tear break-up time (TBUT), Schirmer test, and bulbar erythema] among patients with moderate-to-severe dry eye disease.

METHODS

Participants in the Dry Eye Assessment and Management study at centers having an OCULUS Keratograph were assessed using standardized procedures. Associations between the assessments from the Keratograph [noninvasive keratograph break-up time (NIKBUT), tear meniscus height (TMH), and bulbar redness (BR)] and clinical examination (TBUT, Schirmer test, and bulbar erythema) and between these test results and Ocular Surface Disease Index (OSDI) scores were summarized with Spearman correlation coefficients (r s ); 95% confidence intervals (95% CI) accounted for intereye correlation.

RESULTS

Among 288 patients (576 eyes), the mean (standard deviation) age was 56.6 (13.8) years, 78.1% were female, and the mean baseline OSDI score was 44.3 (14.0). The mean was 2.9 (1.5) seconds for TBUT and 8.2 (5.7) seconds for NIKBUT (their correlation r s = 0.18, 95% CI = 0.09-0.28). The mean was 10.6 (7.6) mm for the Schirmer test and 0.3 (0.2) mm for TMH (r s = 0.15, 95% CI = 0.04-0.25). The median clinical grade redness was mild, and the mean BR score was 1.1 (0.5) (r s = 0.25, 95% CI = 0.15-0.35). Correlation between results of each of the 6 tests and OSDI scores was low (r s from -0.07 to 0.05).

CONCLUSIONS

In the Dry Eye Assessment and Management study, NIKBUT, TMH, and BR were weakly correlated with their clinical counterparts. No measurements were correlated with the OSDI score.

Bony nasolacrimal duct size and outcomes of nasolacrimal silicone intubation for incomplete primary acquired nasolacrimal duct obstruction

Purpose

To investigate the association between the bony nasolacrimal duct (NLD) size and outcomes of nasolacrimal silicone intubation for incomplete primary acquired nasolacrimal duct obstruction (PANDO).

Methods

Patients who underwent silicone intubation for incomplete PANDO and had undergone facial computed tomography (CT) were included. Surgical success was judged by both epiphora improvement and normalized tear meniscus height (TMH; < 300 μm) on anterior segment optical coherence tomography at 3 months after tube removal. The area, major axis diameter, and minor axis diameter of the elliptic bony NLD sections were measured in 1.0 mm-thick axial CT images. These bony NLD sizes were analyzed for associations with surgical success and TMH normalization.

Results

Eighty-one eyes of 48 patients were investigated. The smallest area and the smallest minor axis diameter were significantly larger in the success group (49 eyes), compared with those in the failure group (median smallest minor axis diameter: 4.7 mm vs. 3.8 mm, P = 0.008, Mann–Whitney U test). There was also a tendency for the TMH normalization rate to significantly increase as the smallest area and the smallest minor axis diameter increased (P = 0.028 and 0.037, respectively, Fisher’s 2 × 4 tests). Under multivariable logistic regression analysis using generalized estimating equation, a larger smallest minor axis diameter was associated with success of the nasolacrimal silicone intubation (odds ratio: 2.481, 95% confidence interval: 1.143–5.384).

Conclusion

Surgical success of the nasolacrimal silicone intubation in incomplete PANDO is associated with a larger smallest minor axis diameter of the bony NLD. This finding will help understand the pathophysiology of surgical failure after nasolacrimal silicone intubation.

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.

Outcome Measures to Assess Dry Eye Severity: A Review

Outcome measures used to assess efficacy of dry eye therapeutics have not been consistently applied in clinical settings, nor have they been shown to correlate with functional outcomes. We propose that corneal staining, a clinically meaningful dry eye parameter, should be used as a standard objective outcome measure across all clinical trials evaluating dry eye treatments. We justify this based on evidence regarding its relationship to vision and vision related quality-of-life. In addition, corneal staining has been shown to correlate with ocular surface inflammation, a well elucidated aspect of dry eye pathophysiology and an active area in therapeutics research. No one outcome measure explored herein correlates perfectly to this heterogenous disease. However, there is mounting evidence showing the correlation between corneal staining and functional visual indices. We hope that future clinical trials will standardize corneal staining as a measure to determine the efficacy of interventions and justify their clinical utility.

Objective assessment of eyelid position and tear meniscus in facial nerve palsy

PURPOSE

To evaluate lower lid position and tear meniscus in peripheral idiopathic facial nerve palsy (FNP).

METHODS

A prospective study enrolled patients with peripheral idiopathic FNP and epiphora. Data were collected on patient demographics, House-Brackmann (HB) scale, digital photographs of the face, and tear meniscus at the 1st, 30, and 90 day after onset of FNP. Marginal reflex distance to the upper (MRD1) and lower eyelid (MRD2) were evaluated using ImageJ software. Anterior segment optical coherence tomography (OCT) was performed to measure the tear menis- cus. P< .05 was considered statistically significant.

RESULTS

Sixteen patients were evaluated. The HB scale at presentation was grade III in six patients (37.5%). At 90 day, nine patients (56.25%) were grade I-normal. Three (18.7%) had upper lid retraction, three (18.7%) upper eyelid asymmetry and 7 (43.75%), lower eyelid retraction. The difference between MRD2-FNP with MRD2-healthy side was 0.51 ± 1.9 mm at the 1st visit, decreasing to 0.09 ± 1.47 mm at 90 days (P= .877). Tear meniscus measurements were significantly higher in FNP at the 1st visit (P= .001). The decrease in MRD2 was statistically correlated with the reduction of the tear meniscus area (TMA) (r = 0.67; P= .007) at 90 days. No correlation was found between HB and TMA. There is a difference in TMA between age groups at the 1st day(p= .009). Eldest group had higher HB scales.

CONCLUSION

Quantitative evaluation of eyelid position and tear meniscus are effective to document the evolution of FNP and can serve as a clue of orbicularis recovery.

Measurement of the Lower Lid Margin Thickness by Oculus Keratograph

OBJECTIVES

To investigate the lower lid margin thickness (LLMT) from the posterior lash line to the anterior edge of tear meniscus with Oculus Keratograph 4 (K4).

METHODS

This was a prospective, single-center, observational study. A total of 90 volunteers aged 18 to 79 years with no ocular diseases were included in this study. The LLMT of 90 subjects was measured twice by the same person with K4. To determine the reliability of K4, measuring the LLMT of 30 normal subjects was separately performed by two operators.

RESULTS

The LLMT measurements with K4 between two operators demonstrated a good reproducibility (0.94±0.18 vs. 0.96±0.16 mm; intraclass correlation coefficient=0.88; P=0.18). The mean age of 90 volunteers (42 men and 48 women) was 45.5±14.1 years. The LLMT was 0.95±0.17 mm, which was a significant positive correlation with age (rs=0.57; P<0.001). In addition, there was no significant difference in the LLMT between genders (0.97±0.16 vs. 0.93±0.18 mm; P=0.32).

CONCLUSIONS

We found that K4 was a reliable tool in the LLMT measurements, and the LLMT seemed to be closely related to age but not to gender.

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.

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.

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.

Effect of different lubricant eye gels on tear film thickness as measured with ultrahigh-resolution optical coherence tomography

PURPOSE

To compare the effect of a single drop of different lubricant eye gels on tear film thickness (TFT) as measured with ultrahigh-resolution optical coherence tomography (UHR-OCT) in patients with mild-to-moderate dry eye disease (DED).

METHODS

The study followed a randomized, single-masked, observer-blinded parallel group design. Patients received a single dose of either unpreserved trehalose 3% + hyaluronic acid 0.15% (TH), hyaluronic acid 0.2% (HA) or polyethylene glycol 0.4% + propylene glycol 0.3% (PP) eye drops. In total, 60 patients were included and TFT was measured using a custom-built UHR-OCT system.

RESULTS

The mean TFT at baseline was 3.5 ± 0.7 μm. There was a significant difference in the time-course of TFT between the three groups (p = 0.001 between groups). Ten minutes after instillation, TFT increased by 155.8 ± 86.6%, 65.7 ± 71.5% and 33.4 ± 19.6% in the PP, TH and HA group, respectively (p < 0.001 between groups). Thirty minutes after instillation, the effect of all three different agents on TFT was comparable. Sixty and 120 min after administration, a significant increase in TFT was only seen for the TH group, but not for the other products (60 min: p < 0.021 between groups; 120 min: p < 0.037 between groups).

CONCLUSION

In conclusion, we observed differences in TFT after administration of the lubricant gels. Ten minutes after instillation, a pronounced increase in TFT was observed in all groups. As compared to the other products, the combination of trehalose 3% + hyaluronic acid 0.15% offers a significantly longer increase in TFT indicating for a longer residence time.

The Growing Need for Validated Biomarkers and Endpoints for Dry Eye Clinical Research

Purpose

Biomarkers with minimally invasive and reproducible objective metrics provide the key to future paradigm shifts in understanding of the underlying causes of dry eye disease (DED) and approaches to treatment of DED. We review biomarkers and their validity in providing objective metrics for DED clinical research and patient care.

Methods

The English-language literature in PubMed primarily over the last decade was surveyed for studies related to identification of biomarkers of DED: (1) inflammation, (2) point-of-care, (3) ocular imaging, and (4) genetics. Relevant studies in each group were individually evaluated for (1) methodological and analytical details, (2) data and concordance with other similar studies, and (3) potential to serve as validated biomarkers with objective metrics.

Results

Significant work has been done to identify biomarkers for DED clinical trials and for patient care. Interstudy variation among studies dealing with the same biomarker type was high. This could be attributed to biologic variations and/or differences in processing, and data analysis. Correlation with other signs and symptoms of DED was not always clear or present.

Conclusions

Many of the biomarkers reviewed show the potential to serve as validated and objective metrics for clinical research and patient care in DED. Interstudy variation for a given biomarker emphasizes the need for detailed reporting of study methodology, including information on subject characteristics, quality control, processing, and analysis methods to optimize development of nonsubjective metrics. Biomarker development offers a rich opportunity to significantly move forward clinical research and patient care in DED.

Overview

DED is an unmet medical need - a chronic pain syndrome associated with variable vision that affects quality of life, is common with advancing age, interferes with the comfortable use of contact lenses, and can diminish results of eye surgeries, such as cataract extraction, LASIK, and glaucoma procedures. It is a worldwide medical challenge with a prevalence rate ranging from 8% to 50%. Many clinicians and researchers across the globe are searching for better answers to understand the mechanisms related to the development and chronicity of DED. Though there have been many clinical trials for DED, few new treatments have emerged over the last decade. Biomarkers may provide the needed breakthrough to propel our understanding of DED to the next level and the potential to realize our goal of truly personalized medicine based on scientific evidence. Clinical trials and research on DED have suffered from the lack of validated biomarkers and less than objective and reproducible endpoints. Current work on biomarkers has provided the groundwork to move forward. This review highlights primarily ocular biomarkers that have been investigated for use in DED, discusses the methodologic outcomes in providing objective metrics for clinical research, and suggests recommendations for further work.

Anterior Segment Biometry Changes with Cycloplegia in Myopic Adults

PURPOSE

To determine the effect of cycloplegia on corneal thickness, corneal curvature, anterior chamber depth (ACD), angle-to-angle (ATA) and white-to-white (WTW) distances, and axial length (AL).

METHODS

Changes in corneal thickness, corneal curvature, ACD, ATA and WTW distances, and AL with and without cycloplegia were analyzed in 31 eyes of 31 young myopic adults, aged 26.4 ± 3.0 years. Pentacam was used to measure the corneal thickness, corneal volume, and corneal curvatures. Visante optical coherent tomography (OCT) measured corneal thickness, ATA distance, ACD, and pupil size. The AL and WTW distance were measured using IOLMaster.

RESULTS

Cycloplegia induced significant flattening of corneal curvatures (p = 0.019, 0.001, and 0.003 for anterior sagittal, posterior tangential, and posterior sagittal curvatures, respectively). The difference in the posterior corneal curvature was greater in corneas with steeper posterior curvatures. Cycloplegia also induced significant deepening of ACD (0.08 ± 0.06, p < 0.001) and widening of both WTW (0.42 ± 0.43, p < 0.001) and ATA (0.08 ± 0.17, p = 0.015) distances. The cycloplegia-related increase in the ATA distance correlated negatively with AL (r = -0.361, p = 0.046), whereas the cycloplegia-related increase in WTW distance correlated weakly with the increase in ACD (r = 0.347, p = 0.056) but not with AL. The AL did not change with cycloplegia. Pentacam measured a slightly thicker cornea than OCT (p = 0.002). Both Pentacam and OCT detected a significant increase in corneal thickness of 4 μm, which could be attributed to reflex tearing, after cycloplegia.

CONCLUSIONS

Cycloplegia resulted in deeper ACD, greater ATA distance, and flatter corneal curvatures. Surgeons should be aware of these cycloplegia-related alterations for more accurate phakic/functional intraocular lens selection and better refraction results.

Comparison of Tear Meniscus Height Measurements Obtained With the Keratograph and Fourier Domain Optical Coherence Tomography in Dry Eye

PURPOSE

To study the repeatability and reproducibility of tear meniscus height (TMH) measurements obtained with a keratograph and Fourier domain optical coherence tomography (FD-OCT) and to assess their agreement in patients with dry eye.

METHODS

Sixty-four eyes with dry eye were analyzed by the Schirmer test, tear breakup time test, and fluorescein corneal staining. The TMH was measured 3 times using both devices by 2 different examiners. The repeatability and reproducibility of measurements were assessed by within-subject standard deviation (Sw), repeatability (2.77 Sw), coefficient of variation (CoV), and intraclass correlation coefficient.

RESULTS

The TMH measured with the keratograph and FD-OCT was 0.232 ± 0.074 mm and 0.308 ± 0.129 mm, respectively (P < 0.01). A close correlation was found between the TMH measured with the keratograph and FD-OCT (r = 0.343). There was a negative correlation between the mean TMH and differences in the TMH measured with the keratograph and FD-OCT (r = 0.359). Both measurements correlated with the Schirmer test score, tear breakup time, and corneal staining score with P < 0.01. Intraexaminer CoV, 2.77 Sw, and intraclass correlation coefficient of the TMH were <6.5%, <0.059 mm, and >0.986, respectively, and interexaminer CoV and 2.77 Sw were 5.58% and 0.039 mm, respectively.

CONCLUSIONS

Although the TMH measured with the keratograph tended to be lower than that measured with FD-OCT, the TMH measured with the keratograph closely correlated with the TMH measured with FD-OCT and conventional tests and had good repeatability and reliability.