Impact of blinking on ocular surface and tear film parameters

Effects of blinking exercises on palpebral fissure height and tear film parameters

PURPOSE

Blinking is an involuntary movement essential for ocular surface health and visual comfort. While blinking exercises in patients with dry eye have been shown to improve symptoms, increase non-invasive tear film breakup time (NIBUT), and decrease incomplete blink rate (IBR), no studies have quantified improvements in eyelid opening. This study evaluated the effects of blinking exercises on palpebral fissure height (PFH), subjective symptoms, and tear film-related parameters.

METHODS

Participants were randomly assigned to a "blinking exercise group" that performed blinking exercises after instilling artificial tear drops five times daily for three days or control group that only used artificial tear drops. Standard Patient Evaluation of Eye Dryness (SPEED) and Visual Analog Scale (VAS) scores were recorded for dryness, eye strain, ocular discomfort, blurred vision, foreign body sensation, dullness, and difficulty in opening the eyelids. The pre- and post-study measurements included lipid layer thickness, PFH, blink interval, IBR, tear meniscus height, NIBUT, fluorescein staining, and fluorescein breakup time (FBUT).

RESULTS

Among 100 participants (28 males, 72 females, mean age 38.4 ± 7.4 years), 52 were in the blinking exercise group and 48 were in the control group. The blinking exercise group showed significant improvements in SPEED (P < 0.001), VAS scores for eye strain and discomfort (P = 0.003, 0.007), enlarged PFH (P < 0.001), prolonged NIBUT and FBUT (P < 0.001), and reduced IBR (P < 0.001) compared to the controls.

CONCLUSIONS

Blinking exercises improved PFH, incomplete blinking, tear film stability, and subjective symptoms in patients with dry eye.

Blinking characteristics analyzed by a deep learning model and the relationship with tear film stability in children with long-term use of orthokeratology

Purpose

Using deep learning model to observe the blinking characteristics and evaluate the changes and their correlation with tear film characteristics in children with long-term use of orthokeratology (ortho-K).

Methods

31 children (58 eyes) who had used ortho-K for more than 1 year and 31 age and gender-matched controls were selected for follow-up in our ophthalmology clinic from 2021/09 to 2023/10 in this retrospective case-control study. Both groups underwent comprehensive ophthalmological examinations, including Ocular Surface Disease Index (OSDI) scoring, Keratograph 5M, and LipiView. A deep learning system based on U-Net and Swim-Transformer was proposed for the observation of blinking characteristics. The frequency of incomplete blinks (IB), complete blinks (CB) and incomplete blinking rate (IBR) within 20 s, as well as the duration of the closing, closed, and opening phases in the blink wave were calculated by our deep learning system. Relative IPH% was proposed and defined as the ratio of the mean of IPH% within 20 s to the maximum value of IPH% to indicate the extent of incomplete blinking. Furthermore, the accuracy, precision, sensitivity, specificity, F1 score of the overall U-Net-Swin-Transformer model, and its consistency with built-in algorithm were evaluated as well. Independent t-test and Mann-Whitney test was used to analyze the blinking patterns and tear film characteristics between the long-term ortho-K wearer group and the control group. Spearman's rank correlation was used to analyze the relationship between blinking patterns and tear film stability.

Results

Our deep learning system demonstrated high performance (accuracy = 98.13%, precision = 96.46%, sensitivity = 98.10%, specificity = 98.10%, F1 score = 0.9727) in the observation of blinking patterns. The OSDI scores, conjunctival redness, lipid layer thickness (LLT), and tear meniscus height did not change significantly between two groups. Notably, the ortho-K group exhibited shorter first (11.75 ± 7.42 s vs. 14.87 ± 7.93 s, p = 0.030) and average non-invasive tear break-up times (NIBUT) (13.67 ± 7.0 s vs. 16.60 ± 7.24 s, p = 0.029) compared to the control group. They demonstrated a higher IB (4.26 ± 2.98 vs. 2.36 ± 2.55, p < 0.001), IBR (0.81 ± 0.28 vs. 0.46 ± 0.39, p < 0.001), relative IPH% (0.3229 ± 0.1539 vs. 0.2233 ± 0.1960, p = 0.004) and prolonged eye-closing phase (0.18 ± 0.08 s vs. 0.15 ± 0.07 s, p = 0.032) and opening phase (0.35 ± 0.12 s vs. 0.28 ± 0.14 s, p = 0.015) compared to controls. In addition, Spearman's correlation analysis revealed a negative correlation between incomplete blinks and NIBUT (for first-NIBUT, r = -0.292, p = 0.004; for avg-NIBUT, r = -0.3512, p < 0.001) in children with long-term use of ortho-K.

Conclusion

The deep learning system based on U-net and Swim-Transformer achieved optimal performance in the observation of blinking characteristics. Children with long-term use of ortho-K presented an increase in the frequency and rate of incomplete blinks and prolonged eye closing phase and opening phase. The increased frequency of incomplete blinks was associated with decreased tear film stability, indicating the importance of monitoring children's blinking patterns as well as tear film status in clinical follow-up.

Blink completeness and rate in dry eye disease: An investigator-masked, prospective registry-based, cross-sectional, prognostic study

PURPOSE

To investigate the prognostic ability of blink rate and the proportion of incomplete blinking to predict dry eye disease diagnosis, as defined by the TFOS DEWS II criteria.

METHODS

A total of 453 community residents (282 females, 171 males; mean ± SD age, 37 ± 19 years) were recruited in an investigator-masked, prospective registry-based, cross-sectional, prognostic study. Dry eye symptomology, tear film quality, and ocular surface characteristics were assessed in a single clinical session, and blink parameters evaluated by an independent masked observer.

RESULTS

Overall, 214 (47 %) participants fulfilled the TFOS DEWS II criteria for dry eye disease. Multivariate regression analysis demonstrated that an increased proportion of incomplete blinking was associated with a higher odds of dry eye disease (odds ratio, 1.12 per 10 % increase; 95 % CI, 1.05-1.19; p < 0.001), with the Youden-optimal prognostic threshold proportion being ≥ 40 % incomplete blinking. Higher levels of incomplete blinking were also associated with poorer dry eye symptomology, tear film stability, corneal and lid margin staining, lipid layer thickness, meibography, and meibum quality (all p ≤ 0.03). No significant associations were detected between blink rate and ocular surface parameters (all p > 0.10).

CONCLUSIONS

The degree of incomplete blinking is a significant predictor of dry eye disease, and the utility of incorporating blink assessment into diagnostic workup algorithms warrants further investigation. The association with meibomian gland dropout, expressed meibum quality, and lipid layer thickness would suggest that incomplete blinking may predispose towards the development of meibomian gland dysfunction.

Meibomian gland alterations in allergic conjunctivitis: insights from a novel quantitative analysis algorithm

Purpose

To investigate the changes in meibomian gland (MG) structure in allergic conjunctivitis (AC) patients using an intelligent quantitative analysis algorithm and to explore the relationship between these changes and clinical parameters.

Methods

A total of 252 eyes from patients with AC and 200 eyes from normal controls were examined. Infrared meibography was performed using the non-contact mode of the Keratograph 5M. MG images were analyzed using a deep learning-based a quantitative analysis algorithm to evaluate gland length, area, dropout ratio, and deformation. Clinical parameters, including tear meniscus height, tear break up time (TBUT), conjunctival hyperemia, and Ocular Surface Disease Index (OSDI) scores, were assessed and correlated with changes in the structure of MG.

Results

The average MG length in AC patients was 4.48 ± 1.04 mm, shorter compared to the control group (4.72 ± 0.94 mm). The average length of the central 5 glands in AC patients was 4.94 ± 1.67 mm, which was also shorter than the control group's central 5 glands (5.38 ± 1.42 mm). Furthermore, the central 5 glands' area in AC patients (1.61 ± 0.64 mm2) was reduced compared to the control group (1.79 ± 0.62 mm2). Tear meniscus height was lower in the allergy group (0.26 ± 0.10 mm) compared to the control group (0.44 ± 0.08 mm) (P < 0.05). The non-invasive first tear film break-up time was shorter in the allergy group (8.65 ± 6.31 s) than in the control group (10.48 ± 2.58 s) (P < 0.05). Conjunctival congestion was higher in the allergy group (1.1 ± 0.52) compared to the control group (0.97 ± 0.30) (P < 0.05). The OSDI score in the allergy group (8.33 ± 7.6) was higher than that in the control group (4.00 ± 0.50) (P < 0.05). Correlation analysis revealed that the gland dropout ratio was positively associated with male gender and negatively associated with age and OSDI scores. Additionally, despite an increased number of MG, tear film stability was not improved.

Conclusion

Through the intelligent quantitative algorithm, we found that AC leads to significant changes in MG structure, particularly affecting gland length and central area.

Eyelid Motion Tracking During Blinking Using High-Speed Imaging and Digital Image Correlation

This study presents a novel technique to measure the motion of the eyelid during blinking. High-speed imaging and digital image correlation (DIC) were employed to monitor the eyelid during blinking in a noninvasive manner. Both spontaneous and reflex blinks were studied. A black liquid eyeliner was used to generate a speckle pattern on the surface of the eyelid. Facet motion captured through a DIC analysis software generated kinematic data for each blink. Calculations using this dataset yielded information on the duration of the blink, eyelid displacements, and peak eyelid velocities. A consistent dataset quantified the difference between blink types and reinforced the repeatability of this DIC analysis method to measure the kinematics of blinking.

Digital Applications for Videoterminal-Associated Dry Eye Disease

Dry eye disease (DED) has become increasingly prevalent in the digital era, largely due to prolonged screen exposure. The excessive use of digital devices contributes to inappropriate blink frequency and dynamics, leading to ocular surface dryness and discomfort. Additionally, digital screen use has broader implications for systemic health, including visual strain, headaches, and disrupted circadian rhythms caused by blue light exposure. Previous studies have shown that prolonged screen time correlates with altered blink frequency and increased symptom severity in DED patients, exacerbating the imbalance in tear film production and evaporation. Blinking dynamics, particularly blink rate and completeness, are crucial in maintaining ocular surface moisture. Incomplete blinking impairs meibomian gland function, reducing lipid secretion, which is essential for preventing tear evaporation. Raising patient awareness through educational material, ergonomic adjustments, and blinking exercises has been shown to mitigate these effects. Digital tools that provide targeted educational interventions can be particularly effective in improving blink dynamics and overall ocular comfort. This study evaluates the efficacy of digital applications in optimizing blinking dynamics and enhancing tear film stability. The findings suggest that these innovations improve patient outcomes by encouraging healthier eye care practices. However, further research is needed to assess their long-term impact across diverse populations.

A pilot study of the impact of repeated blink refrainment on ocular surface temperature and the interblink period

SIGNIFICANCE

This study examines a potential stress test of repeated blink refrainment and its effects on the interblink period and the rate of evaporative ocular surface cooling. Such a test could aid in the study of computer vision syndrome, in which screen users unconsciously delay blinking, leading to onset of symptoms.

PURPOSE

This study aimed to examine the relationship between the length of the maximum achievable interblink time and the rate of ocular surface cooling under stress test conditions of repeated refrainment from blinking for as long as possible.

METHODS

Subjects acclimated to the examination room for 10 minutes before measurement and then were asked to hold the eyes open and refrain from blinking for as long as possible (the maximum blink interval), while ocular surface temperature was recorded using an infrared thermographic video camera. Subjects completed 20 trials with four successive blinks separating each trial.

RESULTS

Fifteen subjects (8 female and 7 male subjects) completed the study. The grand mean ocular surface cooling rate was -0.027°C/s (range, -0.338 to +0.014°C/s). A faster ocular surface cooling rate was significantly related to an exponentially shorter maximum blink interval (p<0.001). An increasing number of trials was related to a clinically insignificant increase in the length of the maximum blink interval overall, and a post hoc analysis revealed subject subgroups for whom the stress test was effective or ineffective.

CONCLUSIONS

The ocular surface evaporatively cools exponentially during periods of blink refrainment. With a subgroup of subjects with initially stable tear films and normal lipid layer thickness, cumulative tear film stress from repeated, longer-term blink refrainment could contribute to tear evaporation and symptoms of computer vision syndrome.

Digital Eye Strain: Updated Perspectives

Purpose

Digital eye strain (DES) is a growing worldwide concern because digital devices are prevalent in both our work and home lives. The purpose of this review was to summarize clinically relevant and evolving key topics related to DES.

Methods

A PubMed.gov search was conducted on or before June 8, 2024. No date restrictions were used during the primary search. The search was aimed at detecting all articles related to DES; thus, the search terms only included "digital eye strain" or "computer vision syndrome".

Results

The two most used, validated DES questionnaires are the Computer Vision Syndrome Questionnaire (CVS-Q) and Computer Vision Symptom Scale (CVSS17). The world-wide prevalence of DES ranges from 8.2% to 100% depending upon the subjects evaluated and the method used to evaluate them. The most common DES symptoms include headache, eye strain, eye redness, eye itching, tearing, photophobia, burning sensation, blurred vision, eye pain, neck and shoulder pain, and eye dryness. Ocular surface symptoms in DES are integrally tied to decreased blink frequency, which causes ocular surface desiccation, increased osmolarity, and dry eye-like symptoms. The most studied DES-specific treatments are improving subjects' environment, artificial tears, blinking exercises, and near work breaks.

Conclusion

DES is a highly prevalent condition that should be regularly screened for in clinic with a validated diagnosis instrument. While there are several treatment options, the community's treatment approach is evolving and primarily focused on treating the visual and dry eye-like symptoms associated with the condition.

Epidemiology and Risk Factors of Dry Eye Disease: Considerations for Clinical Management

Dry eye disease is a multifactorial condition characterised by tear film instability, hyperosmolarity and ocular surface inflammation. Understanding the epidemiology of dry eye disease and recognising both modifiable and non-modifiable risk factors can assist eye care practitioners in assessing, treating, and managing patients with the condition. This review considers current knowledge surrounding its incidence and prevalence, as well as associated demographic, systemic, ocular, and iatrogenic, and lifestyle-related modifiable risk factors. Population-based prevalence estimates vary according to the diagnostic criteria used to define dry eye disease, as well as severity and demographic characteristics of the population. Considering recent data and variable population demographics, conservative prevalence estimates suggest that 10-20% of the population over 40 years of age report moderate to severe symptoms and/or seek treatment for dry eye disease. Individuals with specific non-modifiable demographic risk factors may be at increased risk of developing dry eye disease. Advanced age, female sex and East Asian ethnicity have been identified as key non-modifiable demographic features predisposing individuals to dry eye disease. Systemic conditions that have been associated with an increased risk of dry eye disease include migraine, Sjögren syndrome, connective tissue disorders, mental health disorders, diabetes mellitus and androgen deficiency. Medications that may contribute to this risk include antidepressants, antihistamines, and hormone replacement therapy. Ocular and iatrogenic risk factors of dry eye disease include blepharitis, Demodex infestation, ocular surgery, blink completeness, contact lens wear, and topical ophthalmic medications. A range of modifiable lifestyle factors that can increase the risk of dry eye disease have also been identified, including low humidity environments, digital screen use, quality of sleep, diet, and eye cosmetic wear. Dry eye is a common disease affecting millions globally. Increasing knowledge regarding its associated risk factors can better prepare the eye care practitioner to successfully manage patients with this ocular surface disease.

Dry eye disease as an occupational risk factor in operating room nurses

CLINICAL RELEVANCE

Knowing occupational risks in a multifactorial disease such as dry eye disease is important for disease diagnosis and treatment.

BACKGROUND

Dry eye disease (DED) is a multifactorial disease of the ocular surface characterised by tear film instability, adversely affecting visual function and quality of life. The operating room environment has many risk factors for DED such as air conditioning, constant humidity, constant room temperature, intense lighting, surgical smoke, anaesthetic gases and irritating chemicals, and prolonged mask use. This study investigates the ocular surface findings and blink patterns of operating room nurses at risk of DED.

METHODS

A total of 68 nurses (operating room, n = 34; outpatient clinic, n = 34) were included in this study. The diagnosis of DED was assessed using a questionnaire, best-corrected visual acuity, tear break-up time, corneal fluorescein staining, meibomian gland assessment, Schirmer I test. All the tests were conducted in the same area.

RESULTS

According to the ocular surface disease index, the rate of dry eye symptoms was significantly higher among operating room nurses than among outpatient nurses (70.5% vs 41.1%). Severe dry eye symptoms were more common in the operating room group. The meibomian gland score was higher in the operating room group (29.4% vs 5.9%). The numbers of blinks (30.91 ± 12.81 vs 21.05 ± 7.77) and incomplete blinks (8.76 ± 4.68 vs 5.76 ± 3.20) at rest were higher in operating room nurses.

CONCLUSION

The occupational risk for DED was high among operating room staff. National and international standards for the prevention and management of DED in personnel involved in health care services are needed.

Potential applications of artificial intelligence in image analysis in cornea diseases: a review

Artificial intelligence (AI) is an emerging field which could make an intelligent healthcare model a reality and has been garnering traction in the field of medicine, with promising results. There have been recent developments in machine learning and/or deep learning algorithms for applications in ophthalmology-primarily for diabetic retinopathy, and age-related macular degeneration. However, AI research in the field of cornea diseases is relatively new. Algorithms have been described to assist clinicians in diagnosis or detection of cornea conditions such as keratoconus, infectious keratitis and dry eye disease. AI may also be used for segmentation and analysis of cornea imaging or tomography as an adjunctive tool. Despite the potential advantages that these new technologies offer, there are challenges that need to be addressed before they can be integrated into clinical practice. In this review, we aim to summarize current literature and provide an update regarding recent advances in AI technologies pertaining to corneal diseases, and its potential future application, in particular pertaining to image analysis.

Comparison of deep learning-assisted blinking analysis system and Lipiview interferometer in dry eye patients: a cross-sectional study

BACKGROUND

Abnormal blinking pattern is associated with ocular surface diseases. However, blink is difficult to analyze due to the rapid movement of eyelids. Deep learning machine (DLM) has been proposed as an optional tool for blinking analysis, but its clinical practicability still needs to be proven. Therefore, the study aims to compare the DLM-assisted Keratograph 5M (K5M) as a novel method with the currently available Lipiview in the clinic and assess whether blinking parameters can be applied in the diagnosis of dry eye disease (DED).

METHODS

Thirty-five DED participants and 35 normal subjects were recruited in this cross-sectional study. DED questionnaire and ocular surface signs were evaluated. Blinking parameters including number of blinks, number of incomplete blinking (IB), and IB rate were collected from the blinking videos recorded by the K5M and Lipiview. Blinking parameters were individually collected from the DLM analyzed K5M videos and Lipiview generated results. The agreement and consistency of blinking parameters were compared between the two devices. The association of blinking parameters to DED symptoms and signs were evaluated via heatmap.

RESULTS

In total, 140 eyes of 70 participants were included in this study. Lipiview presented a higher number of IB and IB rate than those from DLM-assisted K5M (P ≤ 0.006). DLM-assisted K5M captured significant differences in number of blinks, number of IB and IB rate between DED and normal subjects (P ≤ 0.035). In all three parameters, DLM-assisted K5M also showed a better consistency in repeated measurements than Lipiview with higher intraclass correlation coefficients (number of blinks: 0.841 versus 0.665; number of IB: 0.750 versus 0.564; IB rate: 0.633 versus 0.589). More correlations between blinking parameters and DED symptoms and signs were found by DLM-assisted K5M. Moreover, the receiver operating characteristic analysis showed the number of IB from K5M exhibiting the highest area under curve of 0.773.

CONCLUSIONS

DLM-assisted K5M is a useful tool to analyze blinking videos and detect abnormal blinking patterns, especially in distinguishing DED patients from normal subjects. Large sample investigations are therefore warranted to assess its clinical utility before implementation.

The effect of incomplete blinking rate on corneal epithelial remodeling after trans-PRK surgery: a six-month study

Purpose

To evaluate the impact of incomplete blink rate on corneal epithelial thickness after transepithelial photorefractive keratectomy (Trans-PRK) surgery.

Methods

Trans-PRK patients were divided into two groups based on preoperative incomplete blinking rates, namely rates ≤0.5 (41 right eyes, group A) and rates >0.5 (65 right eyes, group B). We used anterior segment optical coherence tomography to measure the corneal epithelial thickness (CET) and lipiview to measure the number of blinks, incomplete blinking rate, and lipid layer thickness (LLT).

Results

In both groups, CET decreased at 1 week and 1 month, and the thicknesses in the IT, T, and ST regions exceeded the preoperative levels. Three months after Trans-PRK, the thickness exceeded the preoperative levels and continued to increase during subsequent follow-ups. The blinking times and LLT in both groups decreased at 1 week and gradually increased but did not return to preoperative levels. Group A maintained an incomplete blinking rate of over 0.5 at all postoperative periods. The incomplete blinking rate of group B remained above 0.5 postoperatively, although there was an improvement compared with preoperative rates. Both groups showed a correlation between changes in CET and incomplete blinking rate. There was a correlation between changes in LLT and the incomplete blinking rate after surgery.

Conclusion

Both groups showed uneven corneal epithelia thickening, which became more pronounced approaching the peripheral areas. In addition, changes in CET after surgery were positively correlated with the incomplete blinking rate in both patient groups. There was a negative correlation between postoperative LLT and incomplete blinking rate.

An Automated Grading System Based on Topological Features for the Evaluation of Corneal Fluorescein Staining in Dry Eye Disease

BACKGROUND

Corneal fluorescein staining is a key biomarker in evaluating dry eye disease. However, subjective scales of corneal fluorescein staining are lacking in consistency and increase the difficulties of an accurate diagnosis for clinicians. This study aimed to propose an automatic machine learning-based method for corneal fluorescein staining evaluation by utilizing prior information about the spatial connection and distribution of the staining region.

METHODS

We proposed an end-to-end automatic machine learning-based classification model that consists of staining region identification, feature signature construction, and machine learning-based classification, which fully scrutinizes the multiscale topological features together with conventional texture and morphological features. The proposed model was evaluated using retrospective data from Beijing Tongren Hospital. Two masked ophthalmologists scored images independently using the Sjögren's International Collaborative Clinical Alliance Ocular Staining Score scale.

RESULTS

A total of 382 images were enrolled in the study. A signature with six topological features, two textural features, and two morphological features was constructed after feature extraction and selection. Support vector machines showed the best classification performance (accuracy: 82.67%, area under the curve: 96.59%) with the designed signature. Meanwhile, topological features contributed more to the classification, compared with other features. According to the distribution and correlation with features and scores, topological features performed better than others.

CONCLUSIONS

An automatic machine learning-based method was advanced for corneal fluorescein staining evaluation. The topological features in presenting the spatial connectivity and distribution of staining regions are essential for an efficient corneal fluorescein staining evaluation. This result implies the clinical application of topological features in dry-eye diagnosis and therapeutic effect evaluation.

Ocular dryness in intensive care: proposal for a new nursing diagnosis

OBJECTIVE

to analyze the concept associated with diagnostic proposition Ocular dryness in adult patients hospitalized in an Intensive Care Unit, identifying its attributes, antecedents and consequences.

METHODS

a methodological study carried out through concept analysis, operationalized by scoping review.

RESULTS

the analysis of 180 studies allowed the identification of two attributes, 32 antecedents and 12 consequences. The attributes were tear film deficiency and ocular signs and/or symptoms. The prevalent antecedents were incomplete eyelid closure (lagophthalmos) and blinking mechanism decrease. Major consequences included conjunctival hyperemia and decreased tear volume.

CONCLUSIONS

this study allowed constructing nursing diagnosis Ocular dryness, part of domain 11, class 2, with 12 defining characteristics, 12 related factors, seven populations at risk and 13 associated conditions. This problem-focused proposal may provide targeted care by promoting early detection and implementing interventions that reduce the risk of ocular damage.

Dry eye disease in astronauts: a narrative review

Long-duration spaceflight can have adverse effects on human health. One of the most common ocular conditions experienced by astronauts is dry eye disease (DED). Symptoms of DED include feelings of eye irritation, eye strain, foreign body sensation and blurred vision. Over 30% of International Space Station expedition crew members reported irritation and foreign body sensation. We reviewed the current literature on the prevalence and mechanisms of DED in astronauts and its potential implications for long-duration spaceflight, including the influence of environmental factors, such as microgravity and fluid shift on tear film physiology in space. DED has negative effects on astronaut performance, which is why there is a need for further research into the pathophysiology and countermeasures. As an in-flight countermeasure, neurostimulation seems to be among the most promising options.

Dry eye disease and blinking behaviors: A narrative review of methodologies for measuring blink dynamics and inducing blink response

Dry eye disease (DED) is a leading cause of ophthalmology clinical encounters with prevalence ranging from 8.7% to 64% in various populations. Blinking is an endogenous process to refresh the tear film, clear debris and maintain quality vision. Altered blinking behavior is a common feature of DED and is implicated in the pathology of the disease. However, lack of a comprehensive review on the relationship between altered blinking behavior and DED is notable in the literature. Blinking behavior may be an effect of DED due to an unstable tear film sensitizing a motor response or be its cause due to destabilization of the tear film in conditions such as benign essential blepharospasm. In this comprehensive review, we summarize the current models and theories of tear film dynamics and blinking behavior to better understand their connection to DED and introduce contemporary technologies and measurement tools used in the evaluation and induction of blinking behavior. We also describe future directions of research to better understand the relationship between DED and blinking and explore therapies that address the abnormal blinking component of DED.

High-resolution structural and functional retinal imaging in the awake behaving mouse

The laboratory mouse has provided tremendous insight to the underpinnings of mammalian central nervous system physiology. In recent years, it has become possible to image single neurons, glia and vascular cells in vivo by using head-fixed preparations combined with cranial windows to study local networks of activity in the living brain. Such approaches have also succeeded without the use of general anesthesia providing insights to the natural behaviors of the central nervous system. However, the same has not yet been developed for the eye, which is constantly in motion. Here we characterize a novel head-fixed preparation that enables high-resolution adaptive optics retinal imaging at the single-cell level in awake-behaving mice. We reveal three new functional attributes of the normal eye that are overlooked by anesthesia: 1) High-frequency, low-amplitude eye motion of the mouse that is only present in the awake state 2) Single-cell blood flow in the mouse retina is reduced under anesthesia and 3) Mouse retinae thicken in response to ketamine/xylazine anesthesia. Here we show key benefits of the awake-behaving preparation that enables study of retinal physiology without anesthesia to study the normal retinal physiology in the mouse.

Prevalence and associated factors for self-reported symptoms of dry eye among Thai school children during the COVID-19 outbreak

PURPOSE

COVID-19 pandemic caused an increase in digital screen time, which seemed to increase the prevalence of dry eye symptoms among the population with abnormally high digital screen usage hours. However, there are no reports of dry eye symptoms in school children with high digital usage hours. Therefore, the present study aimed to assess the prevalence of dry eye symptoms and evaluate the associated factors among school children aged 12 to 18 years during the COVID-19 outbreak.

METHODS

Multistage cluster sampling was applied, and six sections of online questionnaires were distributed to selected respondents in November 2021. The odds ratio (OR) with confidence intervals (CIs) for the factors was calculated using binary logistic regression. All statistical significance was determined at p < 0.05.

RESULTS

The findings revealed that 62.5% of 603 students showed symptoms of dry eye (DEQ-5 score ≥ 6). Significant associated factors included being female (adjusted OR (aOR) 1.54; 95% CIs 1.05-2.25), higher-grade student (aOR 1.77; 95% CIs 1.23-2.57), digital screen time use (6 to < 12 hours: aOR 2.00; 95% CIs 1.12-3.57, ≥12 hours: aOR 2.54; 95% CIs 1.39-4.76), and perceived stress (aOR 1.12; 95% CIs 1.08-1.16). The Thai-Perceived Stress Scale-10 scores were positively correlated with the scores on the 5-item dry eye questionnaire (Spearman's r = 0.38, p-value < 0.01).

CONCLUSION

A high prevalence of dry eye symptoms might be common among school children during the COVID-19 outbreak. Significant risk factors include being female, being a higher-grade level student, prolonged use of digital screens, and perceived stress. However, contact lens use, smoking, and the most common digital device usage patterns were not found to be contributing factors.

Simultaneous real-time analysis of tear film optical quality dynamics and functional visual acuity in dry eye disease

BACKGROUND

To assess the effect of tear film instability in dry eye disease (DED) by measuring visual performance and tear film optical quality in a simultaneous real-time analysis system.

METHODS

Thirty-seven DED participants and 20 normal controls were recruited. A simultaneous real-time analysis system was developed by adding a functional visual acuity (FVA) channel to a double-pass system. Repeated measurements of FVA and objective scatter index (OSI) were performed simultaneously with this system under blink suppression condition for 20 s. Patient-reported symptoms was evaluated using the Ocular Surface Disease Index (OSDI) questionnaire. Mean FVA, mean OSI, and visual acuity break-up time were defined. The OSI maintenance ratio was calculated as an evaluation index to assess the difference between dynamic OSI changes and baseline OSI. The visual maintenance ratio was also calculated in the same way.

RESULTS

Moderate correlations were noted between mean OSI and FVA-related parameters (mean FVA, visual maintenance ratio, visual acuity break-up time: 0.53, - 0.56, - 0.53, respectively, P < 0.01 for all). Moderate to high correlations were noted between OSI maintenance ratio and FVA-related parameters (mean FVA, visual maintenance ratio, visual acuity break-up time: - 0.62, 0.71, 0.64, respectively, all P < 0.01). The metrics derived from the simultaneous real-time analysis system were moderately correlated with the patient-reported symptoms and the visual acuity break-up time possessed the highest correlation coefficients with OSDI total, ocular symptoms, and vision-related function (- 0.64, - 0.63, - 0.62, respectively, P < 0.01). The OSI-maintenance ratio alone appeared to exhibit the best performance of the metrics for the detection of DED with sensitivity of 95.0% and specificity of 83.8% and the combinations of FVA parameters and OSI parameters were valid and can further improve the discriminating abilities.

CONCLUSIONS

OSI-related metrics were found to be potential indicators for assessing and diagnosing DED which correlated with both subjective visual performance and patient-reported symptoms; the FVA-related metrics were quantifiable indicators for evaluating visual acuity decline in DED.

TRIAL REGISTRATION NUMBER

Chinese Clinical Trial Registry, ChiCTR2100051650. Registered 29 September 2021, https://www.chictr.org.cn/showproj.aspx?proj=134612.

Features and influences on the normal tear evaporation rate

Tear evaporation is a normal physiological phenomenon that has an important role in regulating blink activity and tear production. An altered tear evaporation rate (TER) is a defining characteristic of evaporative dry eye disease (DED), and the measurement of tear evaporation is a useful clinical test for diagnosis. Reported values for a normal TER cover a broad range, which may be due to the influence of ocular, environmental, and systemic factors. For improved disease diagnosis, a fuller understanding of the normal TER range is essential. This paper reports on a literature review of the current knowledge of these normal influences on TER.

TFOS Lifestyle: Impact of the digital environment on the ocular surface

Eye strain when performing tasks reliant on a digital environment can cause discomfort, affecting productivity and quality of life. Digital eye strain (the preferred terminology) was defined as "the development or exacerbation of recurrent ocular symptoms and/or signs related specifically to digital device screen viewing". Digital eye strain prevalence of up to 97% has been reported, due to no previously agreed definition/diagnostic criteria and limitations of current questionnaires which fail to differentiate such symptoms from those arising from non-digital tasks. Objective signs such as blink rate or critical flicker frequency changes are not 'diagnostic' of digital eye strain nor validated as sensitive. The mechanisms attributed to ocular surface disease exacerbation are mainly reduced blink rate and completeness, partial/uncorrected refractive error and/or underlying binocular vision anomalies, together with the cognitive demand of the task and differences in position, size, brightness and glare compared to an equivalent non-digital task. In general, interventions are not well established; patients experiencing digital eye strain should be provided with a full refractive correction for the appropriate working distances. Improving blinking, optimizing the work environment and encouraging regular breaks may help. Based on current, best evidence, blue-light blocking interventions do not appear to be an effective management strategy. More and larger clinical trials are needed to assess artificial tear effectiveness for relieving digital eye strain, particularly comparing different constituents; a systematic review within the report identified use of secretagogues and warm compress/humidity goggles/ambient humidifiers as promising strategies, along with nutritional supplementation (such as omega-3 fatty acid supplementation and berry extracts).

Effects of cataract surgery on blinking

PURPOSE

To assess the effects of cataract surgery on the spontaneous blinking pattern and blinking kinematics.

SETTING

FISABIO Oftalmología Médica Eye Hospital, Valencia, Spain.

DESIGN

Observational descriptive clinical study.

METHOD

Patients with senile cataract were evaluated before (visit 1) and at 1 month (visit 2) and 3 months (visit 3) after undergoing phacoemulsification cataract surgery. The blinking of patients was recorded for 90 seconds using an eye-tracking device. Blinks were analyzed by means of image analysis to obtain a noninvasive detailed description of blinking including blink rate, number of complete and incomplete blinks, percentage of incomplete blinks, and kinematic parameters, including amplitude, closing, contact, opening, and total durations and closing and opening speeds.

RESULTS

50 patients were included in this study. The blink rate was significantly smaller at visit 3 compared with baseline ( P = .03) and visit 2 ( P = .001). Likewise, the number of complete blinks was significantly smaller, and the percentage of incomplete blinks was significantly higher at 3 months postoperatively compared with baseline ( P = .02 and P = .01, respectively), although no differences were observed at 1 month postoperatively ( P > .05). Conversely, no differences in the number of incomplete blinks or any kinematic parameter were observed between visits ( P = .12).

CONCLUSIONS

Cataract surgery significantly altered the blinking pattern at 3 months postoperatively, although kinematic parameters remained unvaried. Clinicians should be aware of potential alterations in blinking after phacoemulsification cataract surgery and the implications this may have on the ocular surface of patients.

Prevalence of Dry Eye Symptoms and Associated Risk Factors among University Students in Poland

Aim: The aim of the study was to demonstrate the prevalence and risk factors of dry eye symptoms (DES) among university students in Poland. Material and methods: A cross-sectional study survey was conducted among 312 Polish university students. The questionnaire consisted of the Ocular Surface Disease Index (OSDI), the 5-Item Dry Eye Questionnaire (DEQ-5) and questions regarding medical history and risk factors. Results: According to the OSDI, more than half of respondents (57.1%) have symptoms of ocular surface disease. Time spent using electronic devices is correlated with scores gathered in both OSDI and DEQ-5 (p < 0.001). There is a statistically significant dependence between psychotropics (p = 0.002), glucocorticosteroids usage (p = 0.026), the presence of depression (p < 0.001), diabetes (p = 0.01) or allergy (p = 0.008) and dry eye symptoms proved in both questionnaires. Respondents with refractive errors and those living in metropolitan areas have a statistically higher symptom intensity(p < 0.022). Stress felt by students is associated with higher DES risk. No correlation between DES and smoking habits was observed. The history of SARS-CoV-2 infection was associated with the severity of DES (p = 0.036). Conclusion: Pathogenesis of DES is multifactorial and its severity depends on several factors, both genetic and environmental. Its prevalence among the young population is underestimated. Determining risk factors will enable the implementation of appropriate prophylaxis and early diagnosis.

Influence of video display terminal use and meibomian gland dysfunction on the ocular surface and tear neuromediators

OBJECTIVE

To evaluate the effects of video display terminal (VDT) work and meibomian gland dysfunction (MGD) on ocular surface parameters, tear cytokine and substance P (SP) levels, and their association with dry eye disease (DED).

METHODS

This cross-sectional study included 60 patients with evaporative DED and 20 healthy individuals. The DED patients were divided into three groups according to daily VDT work time and presence of MGD. The ocular surface and tear film were assessed using the Ocular Surface Disease Index questionnaire (OSDI), tear film break-up time (TBUT), ocular surface staining, Schirmer II test, and corneal sensitivity. MGD was evaluated with meibography. Corneal nerve alterations were evaluated using in vivo confocal microscopy (IVCM). The tear levels of 30 cytokines and SP were examined.

RESULTS

Compared to controls, DED patients had higher OSDI score (p < 0.001), increased corneal staining with fluorescein and lissamine green (p = 0.046, p = 0,038), and lower TBUT (p < 0.001). Tear interleukin-6 levels were higher in DED patients, while tear SP levels did not differ between the groups (p = 0.265). VDT work time showed a weak positive correlation with OSDI (r = 0.274, p = 0.014) and SP level (r = 0.284, p = 0.011).

CONCLUSION

The results of this study show that VDT use and MGD have an adverse effect on the ocular surface. It was also observed that the combination of VDT use and MGD did not significantly increase the ocular surface disease, but longer VDT exposure may be associated with more complaints of ocular discomfort.

Neurostimulation for dry eye disease

PURPOSE OF REVIEW

To review the neuroanatomy and physiology of the basal and reflex tearing and present the available and developing therapies using the concept of neurostimulation in dry eye disease (DED).

RECENT FINDINGS

The most prevalent current DED treatments seek to supplement low tear volume and tear components or reduce inflammation. Neurostimulation is a unique approach gaining momentum in recent years, geared toward increasing the production of all basal tear components by stimulating the nerves responsible for producing the various tear components. The neuroanatomy of the lacrimal unit provides several possible access points to stimulate tear production through two arms of the sensory trigeminal nerves. Modes of stimulation include chemical or energy in electrical or magnetic form. Research thus far has shown that neurostimulation can achieve lacrimal, goblet cell, and meibomian gland stimulation. Subjectively it improves symptoms of DED. Clinically, neurostimulation has improved the signs and symptoms of DED by increasing basal tear production and tear volume.

SUMMARY

Neurostimulation using electrical, mechanical, or chemical means is a novel concept to increase tear production and was demonstrated to be an effective, safe, and well-tolerated method for managing DED.

Alterations in the ocular surface and tear film following keratoplasty

The purpose of this study was to evaluate any alterations in the tear film and ocular surface beyond the early postoperative period following penetrating keratoplasty (PK) and deep anterior lamellar keratoplasty (DALK). This cross-sectional, contralateral-eye study compared ocular surface and tear film parameters of eyes with a previous PK or DALK in one eye and no prior surgery in the contralateral eye. Overall, 14 (87.5%) participants underwent PK, and 2 (12.5%) underwent DALK using a mechanical dissection. The median time from surgery was 3.4 years (range 1.5 to 38.7 years). The indication for unilateral keratoplasty was keratoconus in 15 (94%) participants, and corneal scarring in 1 (6%) eye, secondary to microbial keratitis. Operated eyes exhibited poorer non-invasive tear film breakup time, lower corneal sensitivity, lower sub-basal nerve density and more severe fluorescein staining scores than unoperated fellow eyes (all Q < 0.05). There were no significant differences in tear film lipid layer quality, tear meniscus height, conjunctival hyperaemia, lissamine green staining score, or meibography grade between operated and fellow eyes (all Q ≥ 0.20). Higher corneal esthesiometry threshold (lower corneal sensitivity) was correlated with shorter non-invasive tear film breakup time (Spearman’s rho =  − 0.361, p = 0.04) and increased fluorescein staining score (Spearman’s rho = 0.417, p = 0.02). Keratoplasty can induce persistent changes in the ocular surface and tear film, including: increased fluorescein staining, decreased tear film breakup time, decreased corneal sub-basal nerve plexus density, and reduced corneal sensitivity.

Study to the Effect of Involutional Blepharoptosis Surgery Using Objective and Subjective Parameters

Background  We investigate the effect of involutional blepharoptosis (IB) surgery based on dry eye symptoms by analysis using objective and subjective measures.

Methods  We recorded various parameters from patients that underwent levator advancement surgery for IB, totaling 125 eyes (total 65 patients, 5 unilateral, 60 bilateral). Subjective assessment comprised a questionnaire on dry eye-related quality of life score (DEQS), a summary score calculated from DEQS, and six-grade evaluation, the patient's own measure of eye comfort. Objective assessment comprised marginal-reflex distance-1 (MRD-1), measurement of tear film breakup time, and superficial keratopathy (SPK) existence by slit lamp microscope.

Results  Subjective assessments showed that IB patients had improvement of dry eye symptoms and eye comfort when surgery increased MRD-1. On the other hand, objective assessments showed that the presence of SPK is suspected when the postoperative MRD-1 level is 3 mm or higher.

Conclusion  IB surgery must not only increase MRD-1 value, but also to perform maintenance of the appropriate ocular surface condition. From our parameters, we suggest postoperative MRD-1 value should be maintained at < 3 mm to safe and effective of IB surgery.

The impact of contact lenses on meibomian gland morphology

Despite years of experience with contact lenses, controversy remains as to whether contact lenses adversely impact the meibomian glands (MG). This review summarizes the present body of evidence, showing that contact lens wear is associated with alterations in MG morphology (up to 80% higher gland atrophy compared to non-wearers) and qualitative changes in MG secretion. Key factors such as duration of contact lens wear, contact lens type (e.g., soft vs. rigid), edge design, and material modulus of elasticity are discussed in relation to the extent of MG morphological changes, the quality of MG secretion and other ocular surface parameters. Longitudinal studies of sufficient statistical power are needed to better understand how contact lens wear affects the MG, risk factors, and the clinical sequelae of these changes.

Pillar tarsoconjunctival flap: An alternative approach for the management of refractory corneal ulcer

PURPOSE

To report the effectiveness of the surgical procedure of the tarsoconjunctival flap (FTC) in patients with severe ocular surface impairment refractory to previous conventional treatments.

METHODS

A retrospective, noncomparative, consecutive case series.

RESULTS

Pillar tarsoconjunctival flap (PTCF) was performed in eight eyes of eight patients. Three patients had neurotrophic corneal ulcer (NCU), three had exposure keratopathy and two had corneal melting. Seven of them had satisfactory postoperative results, showing total corneal re-epithelialization that lasted throughout the postoperative follow-up (mean 10.33 ± 2.65 months [SD], range 6 to 12 months). Mean time for the re-epithelization was 11.28 ± 8.97 days [SD] (range 4 to 30 days).

CONCLUSION

This study suggest PTCF is a valid alternative to tarsorrhaphy in cases of persistent epithelial defect (PED) or NCU resistant to conventional treatments. Notwithstanding, prospective comparative trials comparing PTFC with conventional and/or novel therapies in PED or NCU are needed to corroborate these findings.

Impact of Incomplete Blinking Analyzed Using a Deep Learning Model With the Keratograph 5M in Dry Eye Disease

Purpose

To establish a deep learning model (DLM) for blink analysis, and investigate whether blink video frame sampling rate influences the accuracy of analysis.

Methods

This case-controlled study recruited 50 dry eye disease (DED) participants and 50 normal subjects. Blink videos recorded by a Keratograph 5M, symptom questionnaires, and ocular surface assessments were collected. After processing the blink images as datasets, further training and evaluation of DLM was performed. Blink videos of 30 frames per second (FPS) under white light, eight FPS extracted from white light videos, and eight FPS under infrared light were processed by DLM to generate blink profiles, allowing comparison of blink parameters, and their association with DED symptoms and signs.

Results

The blink parameters based on 30 FPS video presented higher sensitivity and accuracy than those based on eight FPS. The average relative interpalpebral height (IPH), the frequency and proportion of incomplete blinking (IB) were much higher in DED participants than in normal controls (P < 0.001). The IB frequency was closely associated with DED symptoms and signs (|R| ≥ 0.195, P ≤ 0.048), as was IB proportion and the average IPH (R ≥ 0.202, P ≤ 0.042).

Conclusions

DLM is a powerful tool for analyzing blink videos with high accuracy and sensitivity, and a frame rate ≥ 30 FPS is recommended. The IB frequency is indicative of DED.

Translational Relevance

The system of DLM-based blink analysis is of great potential for the assessment of IB and diagnosis of DED.

Regenerative therapy for the Cornea

The cornea is the outmost layer of the eye, unique in its transparency and strength. The cornea not only transmits the light essential for vision, also refracts light, giving focus to images. Each of the three layers of the cornea has properties essential for the function of vision. Although the epithelium can often recover from injury quickly by cell division, loss of limbal stem cells can cause severe corneal surface abnormalities leading to corneal blindness. Disruption of the stromal extracellular matrix and loss of cells determining this structure, the keratocytes, leads to corneal opacity. Corneal endothelium is the inner part of the cornea without self-renewal capacity. It is very important to maintain corneal dehydration and transparency. Permanent damage to the corneal stroma or endothelium can be effectively treated by corneal transplantation; however, there are drawbacks to this procedure, including a shortage of donors, the need for continuing treatment to prevent rejection, and limits to the survival of the graft, averaging 10-20 years. There exists a need for new strategies to promote regeneration of the stromal structure and restore vision. This review highlights critical contributions in regenerative medicine with the aim of corneal reconstruction after injury or disease. These approaches include corneal stromal stem cells, corneal limbal stem cells, embryonic stem cells, and other adult stem cells, as well as induced pluripotent stem cells. Stem cell-derived trophic factors in the forms of secretomes or exosomes for corneal regeneration are also discussed. Corneal sensory nerve regeneration promoting corneal transparency is discussed. This article provides description of the up-to-date options for corneal regeneration and presents exciting possible avenues for future studies toward clinical applications for corneal regeneration.

Assessment of Eyelid Pressure Using a Novel Pressure Measurement Device in Patients With Moderate-to-Severe Dry Eye Disease

Objective

To assess a novel eyelid pressure measurement device and study the relationship between eyelid pressure and ocular surface parameters of moderate-to-severe dry eye disease (DED).

Methods

The present study included 70 eyes of 35 moderate-to-severe DED patients. All subjects were subjected to the following examinations for DED assessment: Ocular Surface Disease Index (OSDI) questionnaire, tear meniscus height (TMH), lipid layer thickness (LLT), number of partial blink (PB), total blink (TB) and partial blink rate (PBR), fluorescein tear breakup time (FBUT), corneal fluorescein staining (CFS), lid margin abnormality, meibum expression assessment (meibum score), meibomian gland dropout (MGd) and Schirmer I test. Pressure of the upper eyelid was measured thrice with the novel pressure measurement device. Repeatability of the device was evaluated by intraclass correlation coefficient (ICC). Safety of the device was evaluated by observing ocular adverse reactions of each subject prior to measurement, at day 1 and day 7 following measurement. Correlations between eyelid pressure and ocular surface parameters of moderate-to-severe DED were analyzed by using Pearson correlation coefficient and Kendall's tau-b correlation coefficient.

Results

ICC of the measurement results in our study was 0.86. There was no abnormality presenting in all subjects recorded prior to measurement, 1 and 7 days following measurement. The eyelid pressure was significantly correlated with PBR (r = 0.286, P = 0.016), FBUT (r = −0.331, P = 0.005), CFS (r = 0.528, P = 0.000), lid margin abnormality (r = 0.408, P = 0.011) and MGd (r = 0.226, P = 0.016) in moderate-to-severe DED patients, but not significantly correlated with OSDI score (r = 0.016, P = 0.912), TMH (r = −0.002, P = 0.988), meibum score (r = −0.196, P = 0.317), LLT (r = 0.114, P = 0.346), PB (r = 0.116, P = 0.338), TB (r = 0.074, P = 0.544), meibum score (r = −0.196, P = 0.317) and Schirmer I test (r = 0.028, P = 0.821).

Conclusion

The novel pressure measurement device exhibited good repeatability and safety in measuring eyelid pressure. Significant correlations were noted between the eyelid pressure and PBR, FBUT, CFS, lid margin abnormality and MGd in moderate-to-severe DED. The measurement of eyelid pressure combined with ocular surface parameters may be valuable for the assessment of DED.

Evaluation of Tear Evaporation Rate in Patients with Diabetes Using a Hand-Held Evaporimeter

Diabetes is a very common disease and is considered a risk factor for many diseases such as dry eye. The aim of the current work was to evaluate the tear evaporation rate (TER) in patients with diabetes using a hand-held evaporimeter. This observational, case–control and non-randomized study included 30 male patients with diabetes (17 controlled and 13 uncontrolled) with a mean ± standard deviation (SD) of 33.1 ± 7.9 years. An age-matched (18–43 years; 32.2 ± 6.5 years) control group consisting of 30 male subjects was also enrolled for comparison. Subjects with thyroid gland disorder, a high body mass index, high blood cholesterol, or thalassemia, contact lens wearers, and smokers were excluded. The TER was measured after the completion of the ocular surface disease index (OSDI) by each participant. The OSDI and TER median scores were significantly (Wilcoxon test, p < 0.05) higher in patients with diabetes (median (interquartile range; IQR) = 12.0 (8.3) and 46.4 (36.7) g/m2h, respectively) compared to the subjects within the control group (5.6 (7.0) and 15.1 (11.9) g/m2h, respectively). The median scores for the OSDI and TER measurements were significantly (Wilcoxon test, p < 0.05) higher among uncontrolled diabetes patients (13.0 (11.5) and 53.4 (14.2) g/m2h, respectively) compared to those obtained for patients with controlled diabetes (11.0 (8.0) and 27.3 (32.6) g/m2h, respectively). The tear evaporation rate in patients with diabetes was significantly higher compared to those obtained in subjects without diabetes. Uncontrolled diabetes patients have a higher tear evaporation rate compared to controlled diabetes patients. Therefore, diabetes can lead to eye dryness, since these patients possibly suffer excessive tear evaporation.

Mean Tear-Film Lipid Layer Thickness and Video Display Terminal Time as Risk Factors for Abnormal Blinking in Children

Objective: To explore the risk factors for abnormal blinking in children and the role of the tear-film lipid layer thickness (LLT) as a function of duration of video display terminal (VDT) use in children. Methods: Children attending the Optometry Clinic of Xinhua Hospital affiliated with Shanghai Jiao Tong University were recruited for the study between June 2019 and June 2020. Time spent viewing a VDT (VDTt) over the previous 6 months was recorded. Incomplete blinking (IB) and blinking rate were measured over a 10 s period using the Lipiview^® interferometer (Tear Science, Morrisville, NC, USA), and participants were allocated into groups with normal blinking (NBG, blink rate < 20 blinks/min) and abnormal blinking (ABG, blink rate ≥ 20 blinks/min). T-test, chi-square test and Mann-Whitney U-test were used to compare the differences in tear film (TF) stability indexes and meibomian gland function indexes between the two groups. Binary logistic analysis was used to analyze the risk factors for abnormal blinking and protective factors related to children's use of VDT, and receiver operating characteristic (ROC) curve analysis was also conducted. Results: A total of 167 children were included, with no statistically significant differences in age or sex between the two groups. According to the t-test, VDTt was significantly higher in ABG than NBG, while TF stability indices including tear break up time, LLT and the height of the tear meniscus, were significantly higher in NBG than ABG (P < 0.001). The results also showed better meibomian gland function in NBG than ABG (P < 0.05). Binary logistic analysis showed that VDTt is an important risk factor for abnormal blinking, and the average of LLT (AVG) was found to be an important protective factor for children using a VDT for long periods, with a cut-off value of 1.5 h and 57.5 nm, respectively. ROC curve analysis showed that the area under the curve value of VDTt and AVG was 0.833 and 0.969, respectively (P < 0.001). Conclusion: In children, VDTt is an important risk factor for abnormal blinking, and the AVG is an important protective factor for children using VDT for long periods.

Effect of ocular demodicosis on the stability of the tear film and the tear break up time

The aim of the study was to analyze the correlation between the presence of Demodex mites in the hair follicles of patients' eyelashes and the stability and break up time of the tear film assessed with the Non-Invasive Tear Break Up Times (NIBUT) method. 319 patients were included in the study (195 women, 124 men). The patients were divided into two groups: those with Demodex infestation and without visible symptoms of eyelid or eye surface diseases, and asymptomatic non-infested patients. The NIBUT analysis was performed with a 5 M keratograph (oculus). Non-invasive tests were performed to identify the first and mean values of the tear break up time. The first and mean tear break up time in the Demodex-infested group was lower than in the non-infested subjects. The difference was a highly statistically significant. There was a significant correlation with the age of the patients for the first break up time. The first break up time in both eyes decreased with the age of the Demodex-infested and non-infested patients. The NIBUT analyses indicate the impact of Demodex mites on the tear film stability. This may suggest possible association of demodicosis with dry eye syndrome.

Video display terminal use and other risk factors for abnormal blinking in children: gender differences

OBJECTIVE

To explore the risk factors for abnormal blinking in children and compare these between boys and girls.

METHODS

Children attending the Children's Optometry Clinic between June 2019 and June 2020 were recruited for the study. The time they had spent viewing video displays (VDTt) over the past 6 months was recorded. Incomplete blinking (IB) and blinking rate were measured and all participants were allocated to groups based on their blink rate (<20 times/min = normal blinking group, NBG; ≥20 times/min = abnormal blinking group, ABG). Tear film (TF) stability was also evaluated. The corresponding statistical methods are used to analyze the data.

RESULTS

A total of 87 boys and 80 girls were enrolled in the study. No significant difference in age was found between the 2 groups. There was a significant difference in TF stability between the two groups (P<0.05). According to binary logistic analysis, VDTt and ocular protection index (OPI) are important risk factors for abnormal blinking, with cut-off values of 1.75 hours and 1.014 respectively in boys; and 1.25 hours and 1.770 respectively in girls. The average of lipid layer thickness was an important protective factor for children using VDT for long periods, with a cut-off value of 58.5 nm in boys and 53.5nm in girls.

CONCLUSION

Risk factors for abnormal blinking in both boys and girls include VDTt and OPI.

Extended screen time and dry eye in youth

PURPOSE

Extended screen time amongst youth is a pervasive global phenomenon, with wide-ranging implications for health and quality of life. Dry eye disease is increasingly reported as emerging in paediatric populations and is associated with modified blinking behaviour during extended screen time. This study sought to evaluate spontaneous blink rates, dry eye symptomology and screen use habits of young extended screen time users.

METHODS

Attendees of a gaming convention in Auckland, NZ, completed a self-directed iPad-based survey on personal screen use habits and ocular symptoms using the 5-item Dry Eye Questionnaire (DEQ-5) and the Symptom Assessment in Dry Eye (SANDE) questionnaire. Blink rate was covertly and concomitantly recorded using the front-facing iPad camera and quantified by automated software. A validated, self-assessment blink test was administered as a proxy for tear film stability measurements.

RESULTS

A total of 456 respondents (mean age ± SD: 24 ± 10 years, range: 13 - 75, 38% female) reported an average weekly screen time of 43.7 ± 24.4 h. DEQ-5 and SANDE scores were 10 ± 3 and 34 ± 19; 90% of respondents qualified as symptomatic for dry eye disease (DEQ-5 ≥ 6). Blink test results suggested a tear film stability < 10 s in 24% of cases. Poorer symptomology correlated with increased screen use, elevated blink rates and reduced proxy tear film stability (r = 0.15 to 0.22, all p < 0.01).

CONCLUSION

Extended screen time in a young population was associated with blinking behaviour and symptomology consistent with patients with dry eye. Implementing routine clinical screening, educational interventions, and developing official guidance on safe screen use may help prevent an accelerated degradation of ocular surface health and quality of life in young people.

Intraocular Scattering, Blinking Rate, and Tear Film Osmolarity After Exposure to Environmental Stress

Purpose

Dry environments, such as those in offices or aircraft cabins, can potentially generate ocular discomfort and alter the tear film. We compare light scatter, blinking rate, and tear osmolarity in young and older subjects after exposure to low humidity using a controlled environmental chamber.

Methods

Two groups of healthy subjects were recruited; younger (N = 13, 27 ± 6 years) and older (N = 23, 71 ± 7 years). Measurements were carried out before and after 90-minute exposure to low relative humidity (5%) and constant temperature (23 degrees). Ocular light scatter was measured using a double-pass instrument (OQAS, Visiometrics, Spain). Blinking rate was monitored using an infrared video camera. Tear osmolarity was measured using the TearLab system (Escondido, CA, USA).

Results

Ocular light scatter increased by a factor of 10% after exposure to low humidity in the older group (P = 0.03) but did not change significantly in the younger group. Blinking rate increased significantly (40% more blinks) in both groups but there was no difference between the groups. No significant differences in osmolarity were shown between two age groups or as result of environmental stress.

Conclusions

Exposure to dry environment increased light scatter in older subjects. Although more blinks were triggered in both younger and older groups to prevent corneal dehydration, there was no difference between the groups. Blink rate and osmolarity are not associated with the difference in light scatter.

Translational Relevance

Our work approaches a clinical care problem using basic research methods (measuring ocular scatter and blink ratio).

Quantitative evaluation of lipid layer thickness and blinking in children with allergic conjunctivitis

Purpose

To quantitatively evaluate the lipid layer thickness (LLT) and blinking in children with or without allergic conjunctivitis (AC), and to compare those between the different types of AC.

Methods

For this case–control study, 81 children with symptomatic AC with an average age of 9.62 ± 2.67 years were enrolled and subdivided according to the subtypes of AC, including seasonal/perennial allergic conjunctivitis group and vernal keratoconjunctivitis (VKC)/atopic keratoconjunctivitis (AKC) group. Another 82 age-matched healthy children were enrolled as control group. All subjects underwent routine eye examination and measurements of LLT, the number of incomplete or total blinking, partial blinking rate by the LipiView interferometer over a 10-s period. Other ocular surface assessment included fluorescein tear breakup time (TBUT), lower tear meniscus height, meibomian gland loss (MGL), meibum expressibility and quality.

Results

Pediatric patients with AC had significant thinner LLT, shorter TBUT, decreased total blinking but increased partial blinking rate, especially in those with VKC/AKC (all P < 0.05). A significant deterioration of meibomian gland parameters was observed in AC group when compared with control subjects, demonstrated by severe upper and lower MGL, lid margin abnormalities, decreased meibum expressibility, and abnormal meibum quality, all of which were worse in the severe type of AC (all P < 0.05). Thinner LLT was significantly correlated with decreased TBUT (β = 3.666, P < 0.001) and severity of upper MGL (β =  − 7.701, P = 0.002).

Conclusion

Decreased LLT and blinking disorders in pediatric patients with AC may contribute to lipid layer deficiency in the long run, which should be considered and appropriately diagnosed for a more precise treatment.

Demographic and lifestyle risk factors of dry eye disease subtypes: A cross-sectional study

PURPOSE

To evaluate demographic and lifestyle factors associated with aqueous deficient and evaporative dry eye disease.

METHODS

A total of 1125 general public visitors (707 females, mean ± SD age, 33 ± 21, range 5-90 years) at the Royal Society Summer Science Exhibition were recruited in a cross-sectional study. A demographic and lifestyle factor questionnaire was administered, and dry eye symptomology (DEQ-5 score), ocular surface characteristics (conjunctival hyperaemia, and infrared meibography), and tear film parameters (tear meniscus height, non-invasive breakup time, and lipid layer grade) were evaluated for the left eye of each participant within a single session. The diagnostic criteria for dry eye disease subtypes were adapted from the rapid non-invasive dry eye assessment algorithm.

RESULTS

Overall, 428 (38%) participants fulfilled the diagnostic criteria for dry eye disease, 161 (14%) with aqueous deficient dry eye disease, and 339 (30%) with evaporative dry eye disease. Multivariate logistic regression demonstrated that advancing age, female sex, reduced sleep duration, higher psychological stress, and poorer self-perceived health status were independently associated with aqueous deficient dry eye disease (all p < 0.05). Significant risk factors for evaporative dry eye disease included advancing age, East and South Asian ethnicity, contact lens wear, increased digital device screen exposure, higher psychological stress, and poorer self-perceived health status (all p < 0.05).

CONCLUSIONS

Both subtypes of dry eye disease were associated with several unique and shared demographic and lifestyle factors. The findings of this study could inform future research design investigating the utility of targeted screening and risk factor modification for the prevention and management of dry eye disease.

Effects on the Ocular Surface from Reading on Different Smartphone Screens: A Prospective Randomized Controlled Study

The purpose of this study was to investigate the influence of smartphone reading on the ocular surface and to compare the various effects of different screens and light conditions on the ocular surface. One hundred nineteen volunteers were randomly divided into: light + organic light-emitting diode (OLED), light + electronic ink (eINK), dark + OLED, and dark + eINK. Ocular surface examinations, including noninvasive break-up time (NIBUT), noninvasive keratograph tear meniscus height (NIKTMH), ocular redness, fluorescein break-up time (FBUT), corneal fluorescein staining, meibomian gland assessment, Schirmer I Test, and blinking frequency, were performed before and after a reading task. Symptoms were evaluated using the Ocular Surface Disease Index (OSDI) and Computer Vision Syndrome Questionnaire (CVS-Q). NIBUT and FBUT were decreased statistically significantly after participants read on an OLED screen for 2 hours compared with the baseline in light and dark environments, whereas no statistically significant decrease was observed on an eINK screen. NIKTMH was statistically significantly decreased after reading on an OLED screen in light and dark settings, and the eINK screen had a lesser effect on NIKTMH. An obvious increase in the ocular redness, OSDI and CVS-Q scores was observed after reading on an OLED screen, whereas the eINK screen had a lesser effect on these indicators. Blink rate increased gradually in OLED subgroups during the reading task, whereas no statistically significant difference was observed in the eINK subgroups. Our research suggested that reading on an OLED screen can cause ocular surface disorder and obvious subjective discomfort, whereas reading on an eINK screen can minimize ocular surface disorder in both dark and light environments.

Production of the Cytokine VEGF-A by CD4+ T and Myeloid Cells Disrupts the Corneal Nerve Landscape and Promotes Herpes Stromal Keratitis

Herpes simplex virus type 1 (HSV-1)-infected corneas can develop a blinding immunoinflammatory condition called herpes stromal keratitis (HSK), which involves the loss of corneal sensitivity due to retraction of sensory nerves and subsequent hyperinnervation with sympathetic nerves. Increased concentrations of the cytokine VEGF-A in the cornea are associated with HSK severity. Here, we examined the impact of VEGF-A on neurologic changes that underly HSK using a mouse model of HSV-1 corneal infection. Both CD4⁺ T cells and myeloid cells produced pathogenic levels of VEGF-A within HSV-1-infected corneas, and CD4⁺ cell depletion promoted reinnervation of HSK corneas with sensory nerves. In vitro, VEGF-A from infected corneas repressed sensory nerve growth and promoted sympathetic nerve growth. Neutralizing VEGF-A in vivo using bevacizumab inhibited sympathetic innervation, promoted sensory nerve regeneration, and alleviated disease. Thus, VEGF-A can shape the sensory and sympathetic nerve landscape within the cornea, with implications for the treatment of blinding corneal disease.

Blink-sensing glasses: A flexible iontronic sensing wearable for continuous blink monitoring

Blink reflex has long been considered closely related to physiological states, from which abundant information on ocular health and activities can be revealed. In this study, a smart glasses wearable has been developed, incorporating a flexible and sensitive pressure sensor, to monitor blink patterns by continuously detecting ocular muscular movements, referred to as blink-sensing glasses. By applying the emerging flexible iontronic sensing (FITS) sensor with the sensitivity of 340 pF/mmHg, the skin pressure variations induced by movements of the orbicularis oculi muscles can be monitored in real time. The blink-sensing glasses can successfully capture blink patterns with a high accuracy of 96.3% and have been used to differentiate the blink features from both dry-eye subjects and healthy controls. This device can be potentially used as a new clinical and research monitoring tool for continuous eye blink analysis, while providing patients with high comfortableness in long-term ambulatory and home settings.

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Blink-sensing glasses can capture blink patterns with clinical-grade high accuracy

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A FITS sensor is applied to monitor the blink by detecting the muscle movement

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Blink-sensing glasses can be of potential use to prognose the dry eye

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The glasses are a continuous detection manner with immunity to ambient lights

Inter-week variation of meibometry and tear break-up time in healthy subjects

CLINICAL RELEVANCE

Variation with time in the tear film parameters should be considered by the clinician since the time when measurements are made can influence proper diagnosis.

BACKGROUND

A hallmark of dry eye is an unstable tear film associated with variability in objective daily measures. The purpose of the present study was to evaluate the inter-week repeatability of meibometry, break-up time (BUT) and maximum blink interval (MBI) in healthy subjects.

METHODS

Forty healthy subjects were recruited for the study. Meibometry, BUT and MBI were performed twice in two sessions, one-week apart. Meibum from the lower eyelid was collected and quantified with the Meibometer MB550. Five meibomian curves were generated by tape and each peak value was averaged as a mean value per session. BUT and MBI were determined three times after fluorescein instillation and recorded by a DV-3 camera attached to the slit lamp. BUT and MBI videos were analysed by a second masked observer. Both BUT and MBI values were calculated by averaging the two most similar measurements of the three evaluated.

RESULTS

No statistical difference between inter-week sessions was obtained for the meibometry (p > 0.340; Wilcoxon test), BUT (p > 0.326; Wilcoxon test) and MBI values (p ≥ 0.248; Wilcoxon test). Inter-week differences were low for BUT and MBI when time intervals were no longer than 15 seconds (both p ≥ 0.586; Wilcoxon test). A correlation between BUT and MBI was found (r ≥ 0.668, p < 0.001; Spearman Rho), while a no statistical correlation was obtained between meibometry results and BUT or MBI (all p ≥ 0.194; Spearman Rho).

CONCLUSION

Meibum secretion and the tear film stability present good intersession repeatability, and are stable along with sessions in healthy patients.