Meibomian glands visibility assessment through a new quantitative method.

PURPOSE: The aim of this study is to develop a new objective semiautomatic method for analysing Meibomian glands visibility quantitatively. METHODS: One hundred twelve healthy volunteers aged between 18 and 90 years (48.29 ± 27.46 years) participated in this study. Infrared meibography was obtained from the right upper eyelid through Oculus Keratograph 5 M. Meibographies were classified into 3 groups: Group 1 = patients with good subjective glands visibility and a gland dropout percentage < 1/3 of the total Meibomian gland area; Group 2 = patients with low subjective glands visibility and a gland dropout < 1/3; and Group 3 = patients with low subjective glands visibility and a gland dropout > 1/3. New metrics based on the visibility of the Meibomian glands were calculated and later compared between groups. Rho Spearman test was used to assess the correlation between each metric, and Meibomian gland dropout percentage with the entire sample and after excluding Group 2. A p value less than 0.05 was defined as statistically significant. RESULTS: Fifty-six subjects were classified in Group 1 (24.48 ± 9.62 years), 19 in Group 2 (69.16 ± 21.30 years) and 37 in Group 3 (73.59 ± 13.70 years). No statistically significant differences were found between Groups 1 and 2 in dropout percentage. All metrics, with the exception of entropy, showed a higher Meibomian gland visibility in Group 1 than in the other two groups. Moderate correlations were statistically significant for all metrics with the exception of entropy. Correlations were higher after excluding Group 2. CONCLUSION: The proposed method is able to assess Meibomian gland visibility in an objective and repeatable way, which might help clinicians enhance Meibomian gland dysfunction diagnosis and follow-up treatment.

Diagnostic Capability of a New Objective Method to Assess Meibomian Gland Visibility.

SIGNIFICANCE: The diagnosis of dry eye disease and meibomian gland dysfunction (MGD) is challenging. Measuring meibomian gland visibility may provide an additional objective method to diagnose MGD. PURPOSE: This study aimed to evaluate the ability of new metrics to better diagnose MGD, based on measuring meibomian gland visibility. METHODS: One hundred twelve healthy volunteers (age, 48.3 ± 27.5 years) were enrolled in this study. Ocular surface parameters were measured using the Oculus Keratograph 5M (Oculus GmbH, Wetzlar). Subjects were classified according to the presence or absence of MGD. New metrics based on the visibility of the meibomian glands were calculated and later compared between groups. The diagnostic ability of ocular surface parameters and gland visibility metrics was studied through receiver operating characteristic curves. Logistic regression was used to obtain the combined receiver operating characteristic curve of the metrics with the best diagnostic ability. RESULTS: Statistically significant differences were found between groups for all ocular surface parameters and new gland visibility metrics, except for the first noninvasive keratograph breakup time and gland expressibility. New gland visibility metrics showed higher sensitivity and specificity than did current single metrics when their diagnostic ability was assessed without any combination. The diagnostic capability increased when gland visibility metrics were incorporated into the logistic regression analysis together with gland dropout percentage, tear meniscus height, dry eye symptoms, and lid margin abnormality score (P < .001). The combination of median pixel intensity of meibography gray values and the aforementioned ocular surface metrics achieved the highest area under the curve (0.99), along with excellent sensitivity (1.00) and specificity (0.93). CONCLUSIONS: New meibomian gland visibility metrics are more powerful to diagnose MGD than current single metrics and can serve as a complementary tool for supporting the diagnosis of MGD.

Repeatability of Non-invasive Keratograph Break-Up Time measurements obtained using Oculus Keratograph 5M.

PURPOSE: The aim of this study is to assess the intraexaminer repeatability of Non-invasive Keratograph Break-Up Time (NIKBUT) obtained using the Oculus Keratograph 5M (K5M), given its relevance as a homeostasis marker in Dry Eye Disease (DED). METHODS: In total, 80 healthy volunteers aged between 30 and 89 years participated. Measurements were classified according to age, sex and the presence or not of DED. Repeatability was evaluated by the calculation of within-subject standard deviation (Sw), coefficient of repeatability (CoR) and coefficient of variation (CoV). Moreover, the Passing-Bablok regression method was applied. RESULTS: Sw, CoR and CoV coefficients showed low repeatability in all groups with values between 3.57 and 7.14; 9.90 and 19.79; and 51.90 and 65.49, for each coefficient, respectively. No statistically significant differences were found in the NIKBUT measurements between healthy and DED patients (p = 0.188). Groups with more DED risk had better repeatability. Passing-Bablok regression also confirmed a lack of agreement between the maximum and minimum NIKBUT measurement. CONCLUSION: NIKBUT measurement has low intraexaminer repeatability even when considering sex, age and DED diagnosis. Nevertheless, not only is this low repeatability due to the device, but also it is largely due to the intrinsic variability of the tear film.

Response of the Aging Eye to First Day of Modern Material Contact Lens Wear.

OBJECTIVES: To investigate the ocular surface of an aged population wearing a daily disposable contact lens (CL) over their 1st day of wear. METHODS: Forty eyes from 40 presbyopic subjects were fitted a daily CL (Delefilcon A). Tear osmolarity, tear meniscus area (TMA), and ocular surface aberrations (total higher-order root mean square [RMS]) were assessed at baseline (t0), at 20 min (t1) and after 8 hr (t2) of wear. Fluorescein corneal and conjunctival staining and tear breakup time (TBUT) were performed at t0 and t2. RESULTS: No statistically significant changes were found between t0, t1, and t2 for TMA and between t0 and t2 for fluorescein corneal and conjunctival staining. Tear breakup time worsened by the end of the day from 10.4±0.4 sec t0 to 9.0±0.3 sec t2 (P<0.05). Osmolarity showed significant changes between t0 306.9±2.3 mOsm/L and t1 312.4±2.4 mOsmol/L (P=0.02) but returned to baseline values at 8 hr (310.40±2.26 mOsm/L; P=0.09). Total higher-order RMS showed significant changes between t0 0.38±0.02 µm and t1 0.61±0.04 µm (P≤0.001) and between t0 and t2 0.64±0.41 µm (P≤0.001). CONCLUSIONS: Delefilcon A may induce measures changes (osmolarity and TBUT values) in a presbyopic population; however, TMA and vital staining were maintained at the baseline level over the day.

Repeatability assessment of anterior segment biometric measurements under accommodative and nonaccommodative conditions using an anterior segment OCT.

PURPOSE: As accommodation is a dynamic process changing anterior ocular structures, we aim to compare the repeatability between the biometric measurements taken with and without accommodation. METHODS: Thirty healthy right eyes were measured in a baseline and an accommodative state using Visante-OCT. Three repeated measurements were taken to obtain central corneal thickness (CCT), anterior chamber depth (ACD), angle-to-angle distance (ATA), iridocorneal angles (IA), and crystalline lens thickness (LT). Repeatability was evaluated by the calculation of coefficient of repeatability (CoR), coefficient of variation (CoV), and intraclass correlation coefficient (ICC). In addition, the Passing-Bablok regression method was applied. RESULTS: For the nonaccommodative state, the CoR for CCT, ACD, ATA, and LT was 20.02 µm, 0.09 mm, 0.25 mm, and 0.12 mm respectively. The CoR for CCT, ACD, ATA, and LT in the 6D-accommodative state was 20.85 µm, 0.08 mm, 0.26 mm, and 0.14 mm respectively. IA had similar results for both states; the CoR ranged between 3 and 4°, CoV was less than 4%, and the ICC was between 0.984-0.988. There were no significant differences between the three repeated measurements for any measurement. CONCLUSIONS: Visante-OCT provides good repeatability for anterior segment measurements for both accommodative and nonaccommodative states.

Risk Factors for Myopia: A Review.

Due to the myopia prevalence increase worldwide, this study aims to establish the most relevant risk factors associated with its development and progression. A review search was carried out using PubMed, Web of Science, and Scopus databases to identify the main myopia risk factors. The inclusion criteria for the articles were those related to the topic, carried out in subjects from 5 to 30 years, published between January 2000 and May 2023, in English, and with the full text available. Myopia etiology has proven to be associated with both genetic and environmental factors as well as with gene-environment interaction. The risk of developing myopia increases in children with myopic parents (one parent ×2 times, two parents ×5 times). Regarding environmental factors, education is the main risk factor correlated with myopia prevalence increase. Further, several studies found that shorter distance (<30 cm) and longer time spent (>30 min) for near work increase the risk of myopia. Meanwhile, increased outdoor activity (>40 min/day) has been shown to be a key factor in reducing myopia incidence. In conclusion, the interventional strategy suggested so far to reduce myopia incidence is an increase in time outdoors and a reduction in the time spent performing near-work tasks.

Keratometry Agreement Between Two Swept-Source OCT Devices in Healthy and Post-refractive Surgery Eyes.

PURPOSE: To evaluate the keratometry agreement between two swept-source devices for healthy and post-refractive surgery eyes and compare them. METHODS: One hundred volunteers between 20 and 55 years of age were recruited for this study including both healthy and post-refractive surgery eyes. Three consecutive measurements of simulated keratometry (Sim K), posterior keratometry (PK), and total keratometry (TK) were obtained with the IOLMaster 700 and Anterion. The agreement was assessed through the Bland-Altman method. Limits of agreement (LoA) were calculated as mean difference ±1.96·SD and it represents the 95% of the differences between devices. RESULTS: For both groups, Sim K measurements exhibited a mean difference close to 0 and within a range of ±0.30 and ±0.36 diopters (D) for the control and post-refractive surgery groups, respectively. Meanwhile, the IOLMaster 700 provided flatter PK values (0.30 D on average) for both groups. In general, the post-refractive surgery group exhibited slightly greater mean differences and wider 95% LoA than the control group for Sim K and PK. Steeper TK values were obtained by the IOLMaster in both groups (control = 0.50 D and post-refractive surgery = 0.75 D). TK differences between devices were significantly greater in the post-refractive surgery group (ranging from 0.38 to 1.14 D) compared to the control group (ranging from 0.15 to 0.85 D). CONCLUSIONS: The IOLMaster 700 and Anterion are not interchangeable for TK measurements and eyes that had corneal refractive surgery even decreased the agreement between devices. Differences between devices for Sim K and PK measurements should be clinically judged, particularly in eyes with previous corneal surgery. [J Refract Surg. 2023;39(5):347-353.].

An Emerging Method to Assess Tear Film Spread and Dynamics as Possible Tear Film Homeostasis Markers.

Purpose: This study aims to assess the performance of an analysis method to measure in vivo the movement speed of tear film particles post-blink as a measure of tear film spreading.Materials and methods: Ocular surface parameters and the recording of tear film particles' spreading post-blink were assessed in eighty-one healthy volunteers (43.7 ± 27.0 years) using Keratograph 5 M. The developed software automatically decomposed the video into frames to manually track particles' position for 1.75 seconds after a blink. The following tear film-dynamic metrics were automatically calculated: mean, median, maximum, and minimum particles' speed at different times after blinking and time for particle speed to decrease to <1.20 mm/second. Repeatability of each tear film-dynamic metric and its correlations with ocular surface signs and symptoms were analyzed. Binomial logistic regression was performed to assess the predictability of new metrics to ocular parameters.Results: Repeatability tended to be lower just after blinking (variability of 12.24%), whereas the metrics from 0.5 s onwards had acceptable repeatability (variability below 10%). Tear film-dynamic metrics correlated positively with Non-Invasive Break-Up Time (NIKBUT) while negatively with meibomian gland drop-out. Binomial logistic regression analysis revealed that tear film-dynamic metrics were able to predict NIKBUT. Nevertheless, no statistically significant association was found with gland drop-out. This means that higher particle speed is related to larger NIKBUT. The metric "time for particle speed to decrease to <1.20 mm/second" can be considered the best metric to assess the quality of the tear film, since it was more strongly correlated with NIKBUT (r = 0.42, p = .004), it was more strongly associated in the binomial logistic regression analysis with NIKBUT and showed good repeatability (variability = 5.49%).Conclusions: Tear film-dynamic metrics are emerging homeostasis parameters for assessing indirectly the tear film quality in natural conditions with acceptable repeatability.

Evaluation of Physiological Parameters on Discomfort Glare Thresholds Using LUMIZ 100 Tool.

Purpose: To assess the links between discomfort glare sensitivity and physiological factors such as eye biometry, refraction, skin phototype, age, and gender among a large sample of healthy human subjects. Methods: A total of 489 participants who were 20 to 70 years old (241 men, 248 women) underwent discomfort glare threshold measurements via the LUMIZ 100. Eye biometry and optical quality were measured using a Zeiss IOLMaster 700 biometer and i.Profiler aberrometer. Iris color, skin tone, age, gender, eyeglasses use, chronotype, fatigue level, self-evaluation of light sensitivity, and time spent outdoors were determined. Statistical analysis was carried out using nonparametric Mann-Whitney and Kruskal-Wallis tests for categorical data and correlation coefficients for numerical data. Results: The female subgroup had lower discomfort thresholds than the males (P < 0.001). There was no effect of age group, ametropia, eye biometry, iris color, skin tones, chronotype, or fatigue level on discomfort thresholds. Discomfort thresholds were related to self-assessment of light sensitivity, sunglasses ownership, and frequency of use (P < 0.001). Conclusions: Exploration of easily measurable physiological parameters and questionnaire failed to provide reliable indicators of individual light sensitivity to discomfort glare. Translational Relevance: Light sensitivity is highly subjective and variable across the population. Patients frequently complain about light bothering their daily lives. Accessible physiological factors and questionnaires are unable to predict discomfort levels due to glare. The LUMIZ 100 provides a reliable, rapid, and safe way to determine light discomfort thresholds in order to better manage light sensitivity in clinical care.

Performance of a new device for the clinical determination of light discomfort.

PURPOSE: To assess the performance of a new device for the clinical determination of light discomfort on a large sample of healthy human subjects. METHODS: A total of 489 subjects ranging from 20 to 70 years old (241 men, 248 women) were evaluated with the LUMIZ™ 100 to determine light discomfort. Repeatability was assessed by means of within-subject standard deviation, coefficient of variation (CoV), and intraclass correlation coefficient (ICC). Repeated measures ANOVA, Kruskal-Wallis, and correlation analysis were applied to test for differences between repeated measures, and effect of age on reliability. RESULTS: Discomfort thresholds obtained are well distributed across the light intensity range available (25 to 10211 lux). Intrasession ICCs are higher than 0.849 for all thresholds, and 85% of CoV are below 10%. Thresholds obtained in the first set of measurements are highly correlated with the median of three sets (r2 > 0.8). Intersession, 64% of CoV are below 10%. Age does not affect discomfort thresholds (p = 0.30), nor affect reliability (variance on CoV, p = 0.368). CONCLUSIONS: The new device provides good intrasession repeatability for the clinical determination of light discomfort thresholds, although variance is slightly greater between sessions. The system is useful for the clinical determination of light discomfort.

Anterior Segment Biometry and Their Correlation with Corneal Biomechanics in Caucasian Children.

PURPOSE: To assess the relationship between the corneal biomechanical parameters and the anterior segment parameters in Caucasian children. METHODS: This study included 293 eyes from 293 healthy children aged between 6 and 17 years. Corneal hysteresis (CH) and corneal resistance factor (CRF) were evaluated with the Ocular Response Analyzer, axial length (AL) with IOLMaster and the anterior segment with Pentacam. Anterior segment parameters obtained were the following: central corneal thickness (CCT), corneal volume (CV), anterior chamber depth (ACD), anterior chamber volume (ACV) and mean anterior and posterior keratometry. Two multiple linear regression models were constructed to assess the association between CH and CRF with anterior segment parameters. A value of p < 0.05 was taken as the criterion for statistical significance in all analyses. RESULTS: The mean CH and CRF were 12.12 ± 1.71 and 12.30 ± 1.89 mmHg, respectively. Multiple linear regression revealed that CH and CRF were associated negatively with AL in both models, and positively with CCT and CV in the first and second model, respectively. Meanwhile ACD, ACV or mean keratometry did not correlated with CH and CRF. Moreover, when CCT was in the model, it explained more variability for both CH (22.1%) and CRF (30.9%) than when CV was included (16.2% for CH and 16.5% for CRF). CONCLUSIONS: CH and CRF were correlated positively with CCT and CV, and negatively with AL in healthy Caucasian children. Moreover, corneal parameters were the most contributory variables to CH and CRF changes.

Repeatability assessment of biometric measurements with different refractive states and age using a swept-source biometer.

BACKGROUND: We aim to assess if refractive error or age may influence the repeatability of measurements using a swept-source biometer. METHODS: A total of 61 subjects were evaluated with IOLMaster 700 acquiring measurements of axial length (AL), central corneal thickness (CCT), white-to-white distance (WTW), anterior aqueous depth (AQD), lens thickness (LT), and keratometry (K) readings. Repeatability was evaluated classifying the sample according to the refractive state and age by the calculation of the within-subject standard deviation (Sw), coefficient of repeatability, and intraclass correlation coefficient. RESULTS: Very similar Sw was acquired among groups for AL, CCT, and WTW. Differences found for AQD, LT, keratometry and astigmatism among refractive and age groups were not clinically significant. Refractive groups obtained a Sw for AQD between 0.016 and 0.026, while for LT was between 0.023 and 0.029 mm. Besides, Sw showed values from 0.014 to 0.029 mm for keratometry. Age groups obtained a Sw of 0.025 and 0.016 mm for AQD, and 0.029 and 0.018 mm for LT, respectively. Sw was 0.019 vs 0.018 mm for K1, 0.014 vs 0.031 mm for K2. CONCLUSIONS: IOLMaster 700 showed good repeatability for biometric and keratometric parameters in eyes classified according to their refractive error or age.

Agreement of white-to-white measurements with the IOLMaster 700, Atlas 9000, and Sirius systems.

BACKGROUND: Current advances in ocular surgery require the evaluation of differences in automated white-to-white (WTW) measurements between systems. We aim to analyze three different commonly used devices in clinical practice: the IOLMaster 700, the Atlas 9000, and the Sirius. METHODS: Ninety right eyes of ninety healthy subjects were included. Measurements of WTW distances were taken with each device for all subjects in the same session and by the same observer. Statistical comparison was carried out by means of the rANOVA procedure and the Bonferroni post-hoc test. In addition, the Bland-Altman analysis was applied in order to perform pairwise comparisons. RESULTS: Average WTW values obtained by the IOLMaster 700, the Atlas 9000, and the Sirius devices were 12.18 ± 0.40-mm, 12.32 ± 0.37-mm and 11.90 ± 0.37-mm, respectively. There were statistically significant differences in all pairwise comparisons. Mean differences revealed that the Atlas 9000 provided the highest WTW values, followed by the IOLMaster 700 values and finally by the Sirius results, which had the lowest values. The limits of agreement obtained in all pairwise comparisons were wide, with a range between 0.64 and 0.75 mm. CONCLUSIONS: According to our results, these three devices should not be used interchangeably for WTW diameter measurements during the clinical practice.

Repeatability of whole-cornea measurements using an anterior segment imaging device based on OCT and Placido-disk.

BACKGROUND: Current advances in refractive surgery require high accuracy of corneal measurements. We aim to evaluate the repeatability of topographic measurements using an integrated Placido disk - OCT device. METHODS: Thirty right eyes of thirty healthy and young subjects were included. The topographic parameters of simulated keratometry, asphericity, minimum pachymetry, white-to-white distance, spherical aberration and corneal elevation were studied. Three measurements were taken by the same observer using the Visante omni device. The coefficient of repeatability (CoR), coefficient of variation (CoV) and intraclass correlation coefficient (ICC) were calculated to assess the repeatability. The Bland-Altman graphical method was also applied. RESULTS: No significant differences between repeated measurements were found. The mean difference for simulated keratometry was between 0.01 and 0.02 D. For asphericity was -0.01 ± 0.02, and for minimum pachymetry, spherical aberration and WTW was equal or less than 0.02 mm. The mean differences for corneal elevation, in millimeters and diopters, were between 0.00 and 0.01. Overall, most topographic parameters had a CoV less than 0.4%, a CoR less than 0.3 and an ICC higher than 0.98. CONCLUSIONS: The Visante omni device provides good repeatability for topographical measurements of simulated keratometry, asphericity, pachymetry, spherical aberration and corneal elevation.