BCLA CLEAR presbyopia: Mechanism and optics.

With over a billion adults worldwide currently affected, presbyopia remains a ubiquitous, global problem. Despite over a century of study, the precise mechanism of ocular accommodation and presbyopia progression remains a topic of debate. Accordingly, this narrative review outlines the lenticular and extralenticular components of accommodation together with the impact of age on the accommodative apparatus, neural control of accommodation, models of accommodation, the impact of presbyopia on retinal image quality, and both historic and contemporary theories of presbyopia.

Bilateral Sutureless Application of Human Dehydrated Amniotic Membrane with a Specialised Bandage Contact Lens for Moderate-to-Severe Dry Eye Disease: A Prospective Study with 1-Month Follow-Up.

Purpose: To assess changes in symptoms and ocular surface signs following a bilateral sutureless treatment of dehydrated amniotic membrane (dAM) under a specialised bandage contact lens (sBCL) in patients with moderate-to-severe dry eye disease (DED). Patients and Methods: In this prospective pre-post interventional study, 35 patients diagnosed with moderate-to-severe DED, with an Ocular Surface Disease Index (OSDI) score >30 on current treatment, were enrolled. Assessments were conducted at baseline (day -30), after 30 days run-in with no additional treatment (day 0 - control), and 30 days post sBCL+dAM treatment (day 30 - treatment). Intervention involved two successive bilateral 4-5 day sutureless applications of dAM (17mm diameter, with a 6 mm central aperture, Omnigen® VIEW) under an 18mm sBCL (OmniLenz®). Symptomatology and ocular signs were measured using OSDI, Dry Eye Questionnaire-5 (DEQ-5), Symptom Assessment iN Dry Eye (SANDE), and other ocular surface health indicators including non-invasive breakup time, corneal and conjunctival staining, and lid wiper epitheliopathy length and width (LWE). Results: While symptomatology remained stable during the 30-day no-treatment run-in, 1-month post-dAM treatment, there was a significant reduction in OSDI scores (from 55.8 to 32.3, p<0.001), DEQ-5 (from 14.6 to 10.0, p<0.001), SANDE frequency (from 65.2 to 43.6, p<0.001), and SANDE severity (from 59.8 to 41.1, p<0.001). Additionally, there was a notable decrease in the width of LWE staining, from grade 2 (50-75% of the lid wiper) to grade 1 (25-50% of the lid wiper) (p=0.011). Conclusion: A bilateral 8-10-day treatment duration with dAM applied with sBCL demonstrated a 31 to 42% improvement in symptomatology and a decrease in ocular surface signs of mechanical stress. This innovative bilateral treatment approach offers a promising treatment modality for patients with refractory moderate-to-severe DED.

Digital eye strain and its impact on working adults in the UK and Ireland.

CLINICAL RELEVANCE: Digital eye strain (DES) is a condition encompassing visual and ocular symptoms that may arise due to the prolonged use of digital devices. The 2023 Tear Film Ocular Surface Lifestyle report defined DESas"the development or exacerbation of recurrent ocular symptoms and / or signs related specifically to digital device screen viewing". Studies vary as to the prevalence of DES with some reporting values as low as 10 % and some reporting values over 90 %, however no study has examined the prevalence of DES in the UK or Ireland (UK&I). PURPOSE: To determine the prevalence of DES amongst adults who work with digital devices in UK&I, their symptoms and ameliorative approaches taken by those affected. METHODS: A web-based survey of digital device users was conducted. Adults who used a device for at least 1 h per day for work purposes were eligible to participate. The questionnaire was designed to determine the prevalence of DES, daily device usage, musculoskeletal and ocular symptoms, how they manage their symptoms and eye care history. RESULTS: Based on a Computer Vision Syndrome Questionnaire score ≥ 6, the occurrence of DES was high at 62.6 %. The mean number of hours devices were used for was 9.7 h. Musculoskeletal symptoms were reported by 94.3 % of users and ocular symptoms by 89.5 % with symptoms most likely to occur with those working from home. 8.1 % of respondents considered their symptoms significant enough to affect their work. CONCLUSION: This study provides a valuable insight into DES in digital device users in UK&I and is the first of its kind to be completed. It shows, that while the level of DES is high in device users, at 62.6 %, the actual effect or consequences of it on many does not appear to be significant.

BCLA CLEAR Presbyopia: Evaluation and diagnosis.

It is important to be able to measure the range of clear focus in clinical practice to advise on presbyopia correction techniques and to optimise the correction power. Both subjective and objective techniques are necessary: subjective techniques (such as patient reported outcome questionnaires and defocus curves) assess the impact of presbyopia on a patient and how the combination of residual objective accommodation and their natural DoF work for them; objective techniques (such as autorefraction, corneal topography and lens imaging) allow the clinician to understand how well a technique is working optically and whether it is the right choice or how adjustments can be made to optimise performance. Techniques to assess visual performance and adverse effects must be carefully conducted to gain a reliable end-point, considering the target size, contrast and illumination. Objective techniques are generally more reliable, can help to explain unexpected subjective results and imaging can be a powerful communication tool with patients. A clear diagnosis, excluding factors such as binocular vision issues or digital eye strain that can also cause similar symptoms, is critical for the patient to understand and adapt to presbyopia. Some corrective options are more permanent, such as implanted inlays / intraocular lenses or laser refractive surgery, so the optics can be trialled with contact lenses in advance (including differences between the eyes) to better communicate with the patient how the optics will work for them so they can make an informed choice.

BCLA CLEAR Presbyopia: Epidemiology and impact.

The global all-ages prevalence of epidemiologically-measured 'functional' presbyopia was estimated at 24.9% in 2015, affecting 1.8 billion people. This prevalence was projected to stabilise at 24.1% in 2030 due to increasing myopia, but to affect more people (2.1 billion) due to population dynamics. Factors affecting the prevalence of presbyopia include age, geographic location, urban versus rural location, sex, and, to a lesser extent, socioeconomic status, literacy and education, health literacy and inequality. Risk factors for early onset of presbyopia included environmental factors, nutrition, near demands, refractive error, accommodative dysfunction, medications, certain health conditions and sleep. Presbyopia was found to impact on quality-of-life, in particular quality of vision, labour force participation, work productivity and financial burden, mental health, social wellbeing and physical health. Current understanding makes it clear that presbyopia is a very common age-related condition that has significant impacts on both patient-reported outcome measures and economics. However, there are complexities in defining presbyopia for epidemiological and impact studies. Standardisation of definitions will assist future synthesis, pattern analysis and sense-making between studies.

BCLA CLEAR Presbyopia: Definitions.

Presbyopia is often the first sign of ageing experienced by humans. Standardising terminology and adopting it across the BCLA CLEAR Presbyopia reports, improves consistency in the communication of the evidence-based understanding of this universal physiological process. Presbyopia can be functionally and psychologically debilitating, especially for those with poor access to eyecare. Presbyopia was defined as occurring when the physiologically normal age-related reduction in the eye's focusing range reaches a point that, when optimally corrected for far vision, the clarity of vision at near is insufficient to satisfy an individual's requirements. Accommodation is the change in optical power of the eye due to a change in crystalline lens shape and position, whereas pseudo-accommodation is the attainment of functional near vision in an emmetropic or far-corrected eye without changing the refractive power of the eye. Other definitions specific to vision and lenses for presbyopia were also defined. It is recommended that these definitions be consistently adopted in order to standardise future research, clinical evaluations and education.

Psychometric evaluation of the near activity visual questionnaire presbyopia (NAVQ-P) and additional patient-reported outcome items.

BACKGROUND: The Near Visual Acuity Questionnaire Presbyopia (NAVQ-P) is a patient-reported outcome (PRO) measure that was developed in a phakic presbyopia population to assess near vision function impacts. The study refined and explored the psychometric properties and score interpretability of the NAVQ-P and additional PRO items assessing near vision correction independence (NVCI), near vision satisfaction (NVS), and near vision correction preference (NVCP). METHODS: This was a psychometric validation study conducted using PRO data collected as part of a Phase IIb clinical trial (CUN8R44 A2202) consisting of 235 randomized adults with presbyopia from the US, Japan, Australia, and Canada. Data collected at baseline, week 2, and months 1, 2, and 3 during the 3-month trial treatment period were included in the analyses to assess item (question) properties, NAVQ-P dimensionality and scoring, reliability, validity, and score interpretation. RESULTS: Item responses were distributed across the full response scale for most NAVQ-P and additional PRO items. Confirmatory factor analysis supported the pre-defined unidimensional structure and calculation of a NAVQ-P total score as a measure of near vision function. Item deletion informed by item response distributions, dimensionality analyses, item response theory, and previous qualitative findings, including clinical input, supported retention of 14 NAVQ-P items. The 14-item NAVQ-P total score had excellent internal consistency (α = 0.979) and high test-retest reliability (Intraclass Correlation Coefficients > = 0.898). There was good evidence of construct-related validity for all PROs supported by strong correlations with concurrent measures. Excellent results for known-groups validity and ability to detect change analyses were also demonstrated. Anchor-based and distribution-based methods supported interpretation of scores through generation of group-level and within-individual estimates of meaningful change thresholds. A meaningful within-patient change in the range of 8-15-point improvement on the NAVQ-P total score (score range 0-42) was recommended, including a more specific responder definition of 10-point improvement. CONCLUSIONS: The NAVQ-P, NVCI, and NVS are valid and reliable instruments which have the ability to detect change over time. Findings strongly support the use of these measures as outcome assessments in clinical/research studies and in clinical practice in the presbyopia population.

Assessment of visual function using mobile Apps.

With the advances in smartphone and tablet screens, as well as their processing power and software, mobile apps have been developed reporting to assess visual function. This review assessed those mobile apps that have been evaluated in the scientific literature to measure visual acuity, reading metrics, contrast sensitivity, stereoacuity, colour vision and visual fields; these constitute just a small percentage of the total number of mobile apps reporting to measure these metrics available for tablets and smartphones. In general, research suggests that most of the mobile apps evaluated can accurately mimic most traditionally paper-based tests of visual function, benefitting from more even illumination from the backlit screen and aspects such as multiple tests and versions (to minimise memorisation) being available on the same equipment. Some also utilise the in-built device sensors to monitor aspects such as working distance and screen tilt. As the consequences of incorrectly recording visual function and using this to inform clinical management are serious, clinicians must check on the validity of a mobile app before adopting it as part of clinical practice.

Optimising subjective grading of corneal staining in Sjögren's syndrome dry eye disease.

AIM: To assess whether smaller increment and regionalised subjective grading improves the repeatability of corneal fluorescein staining assessment, and to determine the neurological approach adopted for subjective grading by practitioners. METHODS: Experienced eye-care practitioners (n = 28, aged 45 ± 12 years), graded 20 full corneal staining images of patients with mild to severe Sjögren's syndrome with the Oxford grading scheme (both in 0.5 and 1.0 increments, globally and in 5 regions), expanded National Eye Institute (NEI) and SICCA Ocular Staining Score (OSS) grading scales in randomised order. This was repeated after 7-10 days. The digital images were also analysed objectively to determine staining dots, area, intensity and location (using ImageJ) for comparison. RESULTS: The Oxford grading scheme was similar with whole and half unit grading (2.77vs2.81,p = 0.145), but the variability was reduced (0.14vs0.12,p < 0.001). Regional grade was lower (p < 0.001) and more variable (p < 0.001) than global image grading (1.86 ± 0.44 for whole increment grading and 1.90 ± 0.39 for half unit increments). The correlation with global grading was high for both whole (r = 0.928,p < 0.001) and half increment (r = 0.934,p < 0.001) grading. Average grading across participants was associated with particle number and vertical position, with 74.4-80.4% of the linear variance accounted for by the digital image analysis. CONCLUSIONS: Using half unit increments with the Oxford grading scheme improve its sensitivity and repeatability in recording corneal staining. Regional grading doesn't give a comparable score and increased variability. The key neurally extracted features in assigning a subjective staining grade by clinicians were identified as the number of discrete staining locations (particles) and how close to the vertical centre was their spread, across all three scales.

Utility of artificial intelligence-based large language models in ophthalmic care.

PURPOSE: With the introduction of ChatGPT, artificial intelligence (AI)-based large language models (LLMs) are rapidly becoming popular within the scientific community. They use natural language processing to generate human-like responses to queries. However, the application of LLMs and comparison of the abilities among different LLMs with their human counterparts in ophthalmic care remain under-reported. RECENT FINDINGS: Hitherto, studies in eye care have demonstrated the utility of ChatGPT in generating patient information, clinical diagnosis and passing ophthalmology question-based examinations, among others. LLMs' performance (median accuracy, %) is influenced by factors such as the iteration, prompts utilised and the domain. Human expert (86%) demonstrated the highest proficiency in disease diagnosis, while ChatGPT-4 outperformed others in ophthalmology examinations (75.9%), symptom triaging (98%) and providing information and answering questions (84.6%). LLMs exhibited superior performance in general ophthalmology but reduced accuracy in ophthalmic subspecialties. Although AI-based LLMs like ChatGPT are deemed more efficient than their human counterparts, these AIs are constrained by their nonspecific and outdated training, no access to current knowledge, generation of plausible-sounding 'fake' responses or hallucinations, inability to process images, lack of critical literature analysis and ethical and copyright issues. A comprehensive evaluation of recently published studies is crucial to deepen understanding of LLMs and the potential of these AI-based LLMs. SUMMARY: Ophthalmic care professionals should undertake a conservative approach when using AI, as human judgement remains essential for clinical decision-making and monitoring the accuracy of information. This review identified the ophthalmic applications and potential usages which need further exploration. With the advancement of LLMs, setting standards for benchmarking and promoting best practices is crucial. Potential clinical deployment requires the evaluation of these LLMs to move away from artificial settings, delve into clinical trials and determine their usefulness in the real world.

2022 Glenn A. Fry Award lecture: Enhancing clinical assessment for improved ophthalmic management.

ABSTRACT: Detailed clinical assessment is critical to allow sensitive evaluation of the eye and its management. As technology advances, these assessment techniques can be adapted and refined to improve the detection of pathological changes of ocular tissue and their impact on visual function. Enhancements in optical medical devices including spectacle, contact, and intraocular lenses have allowed for a better understanding of the mechanism and amelioration of presbyopia and myopia control. Advancements in imaging technology have enabled improved quantification of the tear film and ocular surface, informing diagnosis and treatment strategies. Miniaturized electronics, large processing power, and in-built sensors in smartphones and tablets capacitate more portable assessment tools for clinicians, facilitate self-monitoring and treatment compliance, and aid communication with patients. This article gives an overview of how technology has been used in many areas of eye care to improve assessments and treatment and provides a snapshot of some of my studies validating and using technology to inform better evidence-based patient management.

Using big data to understand interest in myopia.

SIGNIFICANCE: Popularity of publicly searched myopia terminologies is reported, for example, myopia control over myopia management and myopia over nearsighted or shortsighted. Insights are also provided for searches on specific myopia control interventions. The findings offer an evidence-based starting point for public messaging and communications by clinicians, policymakers, and other industry leaders. PURPOSE: Public understanding of myopia can be difficult to ascertain for clinicians. Although small-scale studies provide valuable snapshots of data, findings tend to be population-specific and thus difficult to extrapolate to global audiences. In this study, big data were used to provide a more comprehensive depiction of global market interest in myopia. METHODS: Google Trends data were used to analyze searches relating to myopia between January 2004 and August 2023. Data extracted were related to use of the terms myopia control and myopia management, with further searches executed for common myopia control interventions: orthokeratology, contact lenses, atropine, and glasses. Analysis into the search interest of other refractive error states, hyperopia and astigmatism, was also undertaken along with alternative terms that may be used to describe myopia. Where relevant, search trends were considered worldwide, by country, and over time. RESULTS: Myopia was a more popular search term than common layman alternatives such as nearsighted or shortsighted. Myopia control was found to be more popular than myopia management, and of the specific myopia interventions, atropine was most popular. Compared with astigmatism and hyperopia, relative search volumes were greatest for myopia, on average accounting for approximately 50% of the relative search volume at the country level. CONCLUSIONS: The differences identified in both popularity of myopia-related search terms and specific interventions may provide the basis for improvements in public messaging and facilitate patient-practitioner communication.

Dry eye disease in the young: A narrative review.

Dry eye disease (DED), a multifactorial ocular disease that significantly impacts quality of life, is most commonly reported in adults. This review describes the prevalence, risk factors, diagnosis and management of DED in children. A literature search, conducted from January 2000-December 2022, identified 54 relevant publications. Using similar diagnostic criteria to those reported in adults, namely standardized questionnaires and evaluation of tear film homeostatic signs, the prevalence of DED in children ranged from 5.5% to 23.1 %. There was limited evidence for the influence of ethnicity in children, however some studies reported an effect of sex in older children. Factors independently associated with DED included digital device use, duration of digital device use, outdoor time and urban living, Rates of DED were higher in children with ocular allergy and underlying systemic diseases. Compared with similar studies in adults, the prevalence of a prior DED diagnosis or a diagnosis based on signs and symptoms was lower in children, but symptoms were commonly reported. Treatment options were similar to those in adults, including lifestyle modifications, blinking, management of lid disease and unpreserved lubricants in mild disease with escalating treatment with severity. Management requires careful exploration of symptoms, medical history and the diagnosis and management of ocular comorbidities such as allergy and anterior blepharitis. Appropriately powered population-based studies are required to understand the prevalence of and risk factors for DED in children. Development of age-appropriate thresholds for signs and symptoms of DED would support better diagnosis of disease and understanding of natural history.

Topical ivermectin 1.0% cream in the treatment of ocular demodicosis.

PURPOSE: Ocular demodicosis can cause debilitating ocular surface disease. As ivermectin is effective at reducing Demodex proliferation in rosacea, this study investigated the efficacy of topical ivermectin 1.0% cream in treating ocular demodicosis. METHODS: This retrospective single-centre clinical practice chart analysis involved the off-label treatment of patients who had ocular demodicosis with topical ivermectin 1.0 % cream (Soolantra, Galderma Ltd, UK) applied nightly to the lid margins of both eyes for 3 months. Ocular surface health was assessed at baseline when the treatment was prescribed and followed up at 3 and 12 months after baseline. Slit lamp biomicroscopy was used to take digital images of the upper eyelid lashes. Manual image analysis with ImageJ was conducted by a masked assessor to quantify signs of ocular demodicosis including the number of lashes with collarettes, with visible Demodex tails and with follicle pouting. RESULTS: Data from a total of 75 patients with ocular demodicosis were analysed for this study (mean age 66.6 ± 13.9 years, 44 female). The numbers of lashes with collarettes (Median [Interquartile range]: 8 [4-13] at baseline to 0 [0-2] at the final visit, p < 0.001) and lashes with follicle pouting (3 [1-5] at baseline to 0 [0-1.8] at the final visit, p < 0.001) decreased with treatment. Any sign of lashes with visible tails was eliminated by the final visit (p < 0.007). Fluorescein staining severity score also improved, particularly from baseline (1 [0-2]) to the second visit (0 [0-1], p < 0.001). CONCLUSIONS: The findings of this study show evidence for the efficacy of a 3-month course of topical ivermectin 1.0% cream in treating ocular demodicosis as indicated by reduction in collarettes, follicle pouting and visible Demodex tails. More research is warranted to improve the diagnosis, management and monitoring of this condition which is often overlooked or misdiagnosed.

Strategies and attitudes on the management of myopia in clinical practice in Spain - 2022 update.

OBJECTIVE: This study analyses strategies and attitudes on myopia management reported by eye care practitioners (ECP) from Spain in 2022. METHODS: A questionnaire was distributed to ECPs worldwide via the internet through professional associations. The questionnaire was distributed by email to all registered Spanish optician-optometrists. Questions examined awareness of increasing myopia prevalence; perceived efficacy; uptake of available approaches; and reasons preventing further uptake of specific approaches. RESULTS: Of 3,107 practitioners who participated in the study, 380 were Spanish ECPs. Using a 10-point scale, Spanish practitioners reported less concern about increasing pediatric myopia (8.3 ± 1.6) compared to ECP's worldwide (8.5 ± 1.9) (p < 0.001), but similar level of clinical activity in myopia control (7.8 ± 2.3 vs. 7.5 ± 2.5, respectively) (p > 0.05); however, around half of all prescribed treatments were single-vision distance spectacles/contact lenses both in Spain and in most regions, with Spanish practitioners prescribing less single-vision spectacles than African and Asian (p < 0.001), but more than Australasian practitioners (p = 0.04). No significant differences were found between Spain and the other regions in the perceived efficacy of combined therapy, orthokeratology, and outdoor time (p > 0.05), with the former being perceived as the most effective myopia control method followed by orthokeratology. No significant differences were found between Spain and the world's average in factors preventing the prescription of myopia control approaches (p > 0.05). Spanish practitioners reported that embracing myopia management has a positive, but lower impact on customer loyalty, practice revenue and job satisfaction compared with the other regions (all p < 0.001). CONCLUSIONS: Myopia control is increasing, although around half of practitioners still prescribe single-vision distance spectacles/contact lenses to young/progressive myopes. Combined therapy followed by orthokeratology were perceived as the most effective treatments. Embracing myopia management improved patient loyalty and job satisfaction.

Myopia management algorithm. Annexe to the article titled Update and guidance on management of myopia. European Society of Ophthalmology in cooperation with International Myopia Institute.

Myopia is becoming increasingly common in young generations all over the world, and it is predicted to become the most common cause of blindness and visual impairment in later life in the near future. Because myopia can cause serious complications and vision loss, it is critical to create and prescribe effective myopia treatment solutions that can help prevent or delay the onset and progression of myopia. The scientific understanding of myopia's causes, genetic background, environmental conditions, and various management techniques, including therapies to prevent or postpone its development and slow its progression, is rapidly expanding. However, some significant information gaps exist on this subject, making it difficult to develop an effective intervention plan. As with the creation of this present algorithm, a compromise is to work on best practices and reach consensus among a wide number of specialists. The quick rise in information regarding myopia management may be difficult for the busy eye care provider, but it necessitates a continuing need to evaluate new research and implement it into daily practice. To assist eye care providers in developing these strategies, an algorithm has been proposed that covers all aspects of myopia mitigation and management. The algorithm aims to provide practical assistance in choosing and developing an effective myopia management strategy tailored to the individual child. It incorporates the latest research findings and covers a wide range of modalities, from primary, secondary, and tertiary myopia prevention to interventions that reduce the progression of myopia.

After-effect on tear film quality and quantity of reading on laptop computer screen versus hardcopy.

CLINICAL RELEVANCE: Electronic displays, including laptops, tablets, and smartphones, have dramatically altered the way information is accessed and become significant factors in human daily life. They interfere with the blink rate and increase dry eye symptoms, which lead to more discomfort compared to hard copy while reading. BACKGROUND: Digital eye strain occurs when an individual suffers from symptoms, or they are exacerbated, while performing a task requiring digital screen viewing. This study assessed the tear film status immediately following reading on a laptop computer screen versus an identical hard copy. METHODS: Thirty young adults with normal ocular health and reporting no significant symptoms of dry eye (ocular surface disease index (OSDI) score < 13 and non-invasive tear break-up time (NITBUT) > 10 seconds) read a text as hard copy and on a laptop computer screen for 30 min on separate days in a random sequence in a controlled reading experimental condition. The texts were matched in size and contrast and presented at a viewing distance of 40 cm. The NITBUT and strip meniscometry tube tests were administered at baseline and after reading in both conditions. RESULTS: The median baseline NITBUT decreased from 13.0 s to 10.0 s (P < 0.001) after hardcopy reading and to 7.0 (P < 0.001) after reading from a laptop computer screen, with a significant difference between the task medium (P = 0.001). The baseline strip meniscometry tube results decreased from 6.7 mm to 5.0 mm (P < 0.001) after hardcopy reading and to 5.0 mm (P < 0.001) after reading from a laptop computer screen, but there was no significant difference with the task medium (P = 0.085). CONCLUSION: Reading in both conditions led to tear film instability in terms of the tear film quality and quantity. Additionally, the computer screen has a greater impact on the TBUT compared to hardcopy reading, while these two reading mediums had a similar effect on the tear volume.

Human Tear Protein Analysis Using a Quantitative Microfluidic System: A Pilot Study.

OBJECTIVES: Human tears have the potential to be used as biomarkers to aid in the diagnosis and management of dry eye disease (DED). This prospective, controlled pilot study aimed to investigate the hypothesis that a panel of tear protein profiles can be detected and are repeatable when analyzed using a miniaturized quantitative microfluidic system. METHODS: Ten participants were recruited following institutional ethics committee approval. Participants attended two visits 1 week apart when the following measurements were taken in a sequence: tear meniscus height, noninvasive breakup time, ocular redness, tear collection, and corneal and conjunctival staining. Basal tears (>4 µL) were collected using glass microcapillary tubes. Tears were processed to analyze a panel of proteins (14-230 kDa) following the manufacturer's guidelines using a miniaturized quantitative microfluidic system (Protein 230 LabChip with Agilent 2100 Bioanalyzer). Demographics of the clinical measurements and a comparison of the panel of identified proteins and their repeatability were made. RESULTS: Mean age of the participants was 20.8±1.6 years, nine were females, three fulfilled the TFOS DEWS-II diagnostic criteria for DED. The total protein concentration across participants was 6.72±3.56 mg/mL. Several proteins (lysozyme C, lipocalin 1, IgA light chain, zinc-α2-glycoprotein, albumin, and lactoferrin) were identified at both visits for seven or more participants. There were no significant differences ( P >0.05) in individual protein concentrations between the two visits. A high correlation was found between the two visits for all proteins where correlation coefficient ranged between 0.63 and 0.98 ( P <0.05). CONCLUSION: The protein profiles measured by the quantitative microfluidic system are repeatable, thus validating quantitative microfluidic system as a reliable method for investigating a panel of tear proteins. This method is quick, affordable, requires only 4 µL of tear, and is relatively easy method to perform that can be incorporated in a clinical setting. Further studies in larger clinical setting may be beneficial exploring the usability of this method in various patient groups.