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).

Nga whakaro hauora Maori o te karu: Maori thoughts and considerations surrounding eye health.

CLINICAL RELEVANCE: Research highlighting Indigenous patient perspectives is essential in the pursuit of understanding and addressing longstanding health inequities. BACKGROUND: Evidence indicates that disparities in ocular health outcomes between Maori and non-Maori are pervasive in the New Zealand health system. Evidence shows the cause of these inequities is often multifactorial; due to factors such as colonisation, ongoing marginalisation, racism, socioeconomic status, poverty and culturally unsafe practice between health professionals and Maori patients. METHODS: This project used kaupapa Maori methodology to identify the perceptions of Maori surrounding ocular healthcare within a Maori context in Aotearoa New Zealand. Three focus groups with Maori community members and three individual interviews with Maori eyecare practitioners were conducted. Participants discussed sub-topics relating to Maori health, ocular health consultations, ocular examination and access to ocular health services in Aotearoa New Zealand. Reflexive thematic analysis was undertaken using NVivo qualitative research software. RESULTS: Five key themes were derived from the data: (1) the importance of effective clinician-patient communication; (2) historical experiences of patients inform their health attitudes; (3) barriers to access are systemic; (4) Maori health is important to Maori and (5) Te Ao Maori, Tikanga and Tapu are significant cultural concepts for Maori. Overall, Maori patients recognise the value of ocular healthcare and the importance of acknowledging Maori models of health within services. CONCLUSION: The key issues Maori patients face within ocular health services resonate strongly with wider concepts intrinsically important to Maori. These are the right to cultural safety within clinical settings, the right to accurate and pertinent communication of information between clinician and patient and the respect of cultural beliefs and acknowledgement of power imbalances within the wider healthcare system. Participant discussions and suggestions raise possible pathways to begin addressing ocular ethnic disparities in healthcare delivery.

Blinking and upper eyelid morphology.

PURPOSE: To explore blinking patterns and sagittal eyelid misalignment in the East Asian eye. METHODS: Forty-four participants (22 females; age 26 ± 5 years; 52% of East Asian ethnicity) were enrolled in this pilot study and subdivided, based on upper eyelid crease presence and extent, into single (n = 10), partial (n = 11) or double (n = 23) eyelid crease groups. Blinking was filmed surreptitiously with high-speed video simultaneously from an inferior temporal and frontal view. Spontaneous blink rate and type (incomplete, almost complete, or complete) were assessed over a 30 s period. Sagittal misalignment of the lids on closure was graded during complete spontaneous blinks, voluntary lid closure and voluntary maximal lid contraction (squeezing). A 0.15 µL drop of lissamine green was placed on the central lower lid margin and the number and type of blinks required to eliminate the drop informed complete palpebral apposition during blinking. RESULTS: Mean ± SD blink rates averaged 16.9 ± 10.5 blinks/minute. The proportion of incomplete blinks was 83 ± 22% in single, 58 ± 35% in partial and 59 ± 30% in double eyelid crease groups. The sagittal misalignment of the lid margins during blinking was limited to approximately one-third of the lid margin width; this was similar for all lid morphologies and blink types. The lissamine green drop was eliminated only by voluntary maximal lid contraction, and was similar in all groups (p = 0.97). CONCLUSIONS: Incomplete blinking and sagittal lid misalignment of the central eyelid margin predominate in habitual blinking, irrespective of lid morphology.

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.

Association between dry eye disease, self-perceived health status, and self-reported psychological stress burden.

Clinical relevance: Dry eye disease is a common chronic ocular condition, which is acknowledged to have adverse impacts on quality of life and work productivity.Background: The wide-reaching impacts of dry eye disease on mental health and quality of life have received growing attention in recent years. The purpose of this study was therefore to investigate the relationship between dry eye disease, self-perceived health status, and self-reported psychological stress burden.Methods: Three hundred and twelve community residents (178 females, 134 males; mean ± SD age, 38 ± 21 years) with no major systemic, ophthalmic, or psychiatric conditions (other than dry eye disease), were recruited in a cross-sectional study. Self-perceived health status and self-reported psychological stress burden were assessed, and dry eye symptomology, ocular surface characteristics, and tear film quality were evaluated for each participant within a single clinical session, in accordance with the global consensus recommendations of the Tear Film and Ocular Surface Society Dry Eye Workshop II reports.Results: Multivariate regression analysis, adjusted for age, sex, ethnicity, and contact lens wear, demonstrated that improved self-perceived health status was associated with decreased odds of dry eye disease, aqueous tear deficiency and meibomian gland dysfunction (all p < 0.05). Increased self-reported psychological stress burden was positively associated with dry eye disease, aqueous tear deficiency and meibomian gland dysfunction (all p ≤ 0.01).Conclusion: Dry eye disease is associated with poorer self-perceived health status and greater self-reported psychological stress burden. The findings of this study highlight the wide-reaching impacts of dry eye disease, and the importance of minimising the impacts of the condition with optimised management and actioning inter-disciplinary referral for affected patients where necessary.

Modifiable lifestyle risk factors for dry eye disease.

PURPOSE: To examine the association between modifiable lifestyle factors and dry eye disease. METHODS: Three hundred and twenty-two community residents (186 females, 136 males; mean ± SD age, 41 ± 22 years) with no major systemic or ophthalmic conditions (other than dry eye disease) were recruited in a cross-sectional study. A lifestyle factor questionnaire was administered, and dry eye symptomology, ocular surface characteristics, and tear film quality were evaluated for each participant within a single clinical session, in accordance with the global consensus recommendations of the TFOS DEWS II reports. RESULTS: A total of 111 (34 %) participants fulfilled the TFOS DEWS II diagnostic criteria for dry eye disease. Multivariate regression analysis demonstrated that advancing age, female sex, East Asian ethnicity, and increased digital screen exposure time were positive risk factors for dry eye disease (all p < 0.05), while increased caffeine consumption was a protective factor (p = 0.04). CONCLUSIONS: Increased digital screen exposure time and reduced caffeine consumption were modifiable lifestyle factors associated with higher odds of dry eye disease. These findings might contribute to informing the design of future prospective research investigating the efficacy of preventative intervention and risk factor modification strategies.

Developing evidence-based guidance for the treatment of dry eye disease with artificial tear supplements: A six-month multicentre, double-masked randomised controlled trial.

PURPOSE: To assess the six-month therapeutic profiles of lipid and non-lipid-based artificial tear supplements in managing dry eye disease (DED). METHODS: Ninety-nine participants fulfilling the TFOS DEWS II diagnostic criteria for DED (64% females; mean ± SD age, 44 ± 16 years) were enrolled in a prospective, multicentre, double-masked, parallel group, randomised controlled trial. Participants instilled lipid-based nanoemulsion drops or non-lipid-based aqueous drops for six months, at least four times daily. Symptomology, tear film and ocular surface characteristics were assessed at Days 0, 30, 60, 90, 120, 150 and 180. RESULTS: Sustained reductions in OSDI, DEQ-5, and SANDE symptom scores from baseline were observed from Day 30 onwards in both groups (all p < 0.05) and decreased superior lid wiper epitheliopathy grades from Day 60 onwards (all p ≤ 0.01). Improvements in non-invasive tear film breakup time, and sodium fluorescein and lissamine green staining scores followed from Day 120 onwards in both groups (all p < 0.05). Tear lipid layer grades increased from Day 90 onwards only with the lipid-based drops, and with significantly greater improvement in those with suboptimal lipid layer thickness at baseline (grade ≤3; p = 0.02). By Day 180, 19% of participants no longer fulfilled the diagnostic criteria for DED. CONCLUSIONS: Over a six-month treatment period, improvements in dry eye symptomology preceded tear film and ocular surface changes with regular use of both lipid and non-lipid-based artificial tear supplements. Both formulations addressed most mild-to-moderate forms of aqueous deficient and evaporative DED, while evaporative cases benefitted preferentially from lipid-based supplementation. This represents a first step towards mapping DED therapeutic strategies according to disease subtype and severity.

Therapeutic potential of castor oil in managing blepharitis, meibomian gland dysfunction and dry eye.

The multifactorial pathogenesis and interrelationship of blepharitis, meibomian gland dysfunction and dry eye disease poses challenges to any therapeutic approach. Current treatments are mostly palliative, with success limited by perceived inefficacy and poor patient compliance. Castor oil, a natural derivative of the Ricinus communis plant, is widely used as an emollient in cosmetics and personal care products, drug delivery systems and wound dressings. Castor oil is deemed safe and tolerable, with strong anti-microbial, anti-inflammatory, anti-nociceptive, analgesic, antioxidant, wound healing and vaso-constrictive properties. Its main constituent, ricinoleic acid, has a bipolar molecular structure that promotes the formation of esters, amides and polymers. These can supplement deficient physiological tear film lipids, enabling enhanced lipid spreading characteristics and reducing aqueous tear evaporation. Studies reveal that castor oil applied topically to the ocular surface has a prolonged residence time, facilitating increased tear film lipid layer thickness, stability, improved ocular surface staining and symptoms. This review summarises the properties, current uses of, and therapeutic potential of castor oil in managing ocular surface disease. The biochemical, medicinal actions of castor oil are explored from the perspective of ocular surface pathology, and include microbial and demodectic over-colonisation, inflammatory and oxidative processes, as well as clinical signs and symptoms of dryness and discomfort.

Randomized trial of topical periocular castor oil treatment for blepharitis.

PURPOSE: To evaluate the effects of topical castor oil application to the eyelids on ocular surface and tear film parameters in patients with blepharitis. METHODS: Twenty-six participants (14 females, 12 males; mean ± SD age, 38 ± 21 years) with clinical signs of blepharitis were enrolled in a prospective, investigator-masked, randomized, paired-eye trial. A 100% cold pressed castor oil formulation (Lotus Garden Botanicals, Biddeford, ME, USA) was applied to the eyelids of one eye (randomized), twice daily for 4 weeks. Ocular surface characteristics, symptoms, and tear film parameters were assessed at baseline and day 28. RESULTS: Baseline measurements did not differ between treated and control eyes (all p > 0.05). A significant reduction in OSDI symptomology score was observed following the four-week treatment period (p = 0.001). Clinical improvements in eyelid margin thickening, telangiectasia, eyelash matting, madarosis, cylindrical dandruff, and lid wiper epitheliopathy were limited to treated eyes (all p < 0.01), while greater decreases in staphylococcal and seborrheic eyelash crusting were observed in treated than control eyes (both p < 0.05). No adverse events were reported during the treatment period. CONCLUSION: Topical castor oil application effected significant improvements in ocular surface signs and symptoms in patients with blepharitis. The favourable therapeutic profile would suggest that castor oil demonstrates promise as a potential treatment for blepharitis, and support the conduct of further efficacy trials with longer follow up. TRIAL REGISTRATION NUMBER: ACTRN12618000856213.

Ageing and the natural history of dry eye disease: A prospective registry-based cross-sectional study.

PURPOSE: To investigate the impact of ageing on ocular surface parameters, and empirically determine optimal prognostic cut-off ages for clinical markers of dry eye disease, aqueous tear deficiency, and meibomian gland dysfunction. METHODS: A total of 1331 community residents (785 females, 546 males; mean ± SD age, 38 ± 19 years) were recruited in a prospective registry-based cross-sectional study. Dry eye symptomology, ocular surface characteristics, and tear film quality were evaluated for each participant within a single clinical session, in accordance with the global consensus recommendations of the TFOS DEWS II reports. RESULTS: Multivariate regression analysis demonstrated positive associations between ageing and clinical markers of dry eye disease (all p ≤ 0.001). The Youden-optimal prognostic cut-off ages for signs of meibomian gland dysfunction occurred during the third decade of life (24-29 years); the optimal predictive ages for lid wiper epitheliopathy, tear film instability, hyperosmolarity, and dry eye symptoms occurred during the fourth decade of life (31-38 years); while the optimal prognostic thresholds for signs of aqueous tear deficiency and ocular surface staining occurred in the fifth and sixth decades of life (46-52 years). CONCLUSIONS: Advancing age is a significant risk factor for dry eye disease, which represents a growing public health concern with the ageing population worldwide. Signs of meibomian gland dysfunction appeared earlier in the natural history of disease progression, and the brief delay prior to the development of other clinical dry eye signs might represent a window of opportunity for preventative interventions in the young adult age group.

Prophylactic action of lipid and non-lipid tear supplements in adverse environmental conditions: A randomised crossover trial.

PURPOSE: To evaluate the prophylactic benefits of lipid-based and non-lipid-based artificial tear lubricants, in dry eye disease, after adverse environmental exposure. METHODS: Twenty-eight participants with dry eye disease were recruited in a prospective, double-masked, randomised crossover trial. On separate days, participants were randomised to receive a single application of a lipid-containing tear supplement (Systane Complete) to one eye, and a non-lipid containing eye drop (Systane Ultra) to the contralateral eye. Participants were then exposed to a previously validated simulated adverse environment. Symptoms, non-invasive tear film breakup time, lipid layer grade, and tear meniscus height were assessed at three time points; baseline, following eye drop instillation, and after exposure to the adverse environment. RESULTS: Both treatments effected improvements in symptoms and non-invasive tear film stability following instillation (all p < 0.05), although an improvement in lipid layer quality was limited to the lipid-containing nano-emulsion tear supplement (p = 0.003). Although protective effects were conferred by both treatments following exposure to the simulated adverse environment, more favourable symptomology scores, non-invasive tear film stability, and lipid layer quality were observed in the lipid-containing tear supplement group (all p < 0.05). No significant changes were observed in tear meniscus height in both treatment groups (all p > 0.05). CONCLUSIONS: Both the lipid and non-lipid-based artificial tear supplement demonstrated prophylactic benefits in a simulated adverse environment. However, the ability to preserve tear film quality and reduce dry eye symptomology was greater with the lipid-containing eye drop. TRIAL REGISTRATION NUMBER: ACTRN12619000361101.

Ocular Demodex: a systematic review of the clinical literature.

PURPOSE: There is increasing clinical and research interest in the potential contribution of Demodex to ocular surface disease. The aim of this systematic review was to summarise and synthesise current clinical evidence relating to the aetiology, diagnosis and treatment of ocular Demodex. RECENT FINDINGS: A comprehensive literature search was performed in OVID Medline, OVID Embase, and clinical trial registries, for studies published between 1990 and August 2019, examining Demodex on the ocular surface. The review included primary clinical research studies and systematic reviews of primary clinical research studies, where Demodex was considered in the context of the ocular surface and/or adnexa. Studies were categorised using the National Health and Medical Research Council evidence hierarchy. Risk of bias assessment was performed using validated tools for studies categorised as providing Level I or II evidence. A total of 87 studies were eligible for inclusion, including two systematic reviews. Most studies (60%) were observational, describing the prevalence of ocular Demodex in different clinical populations. There was a high degree of variability in the epidemiological data derived from cross-sectional aetiology studies. There was mostly consistent evidence to support an association between ocular Demodex and chronic blepharitis. Seven diagnostic test-accuracy studies were identified, which considered a range of techniques, including slit lamp examination for cylindrical eyelash collarettes and/or eyelash manipulation techniques, light microscopic evaluation of epilated eyelashes and in vivo confocal microscopy. There is currently no accepted gold-standard diagnostic method for ocular Demodex. For intervention studies, there was one systematic review, 11 published randomised trials, six trial registry entries, and nine case series. Despite a number of recent trials, the appropriate treatment regimen for ocular Demodex (including the optimal criteria and timing of an intervention) is not clearly established. CONCLUSIONS: This comprehensive narrative synthesis has captured the landscape of clinical evidence relating to the prevalence, aetiology, diagnosis and treatment of ocular Demodex. There remain opportunities to enhance understanding of its role in ocular surface disease, best diagnostic approaches and optimal treatment protocols.

Systemic risk factors of dry eye disease subtypes: A New Zealand cross-sectional study.

PURPOSE: To evaluate systemic risk factors of dry eye disease, aqueous tear deficiency, and meibomian gland dysfunction. METHODS: Three hundred and seventy-two community residents (222 females, 150 males; mean ± SD age, 39 ± 22 years) were recruited in a cross-sectional study. Past medical history, dry eye symptomology, ocular surface characteristics, and tear film quality were evaluated for each participant within a single clinical session. The diagnosis of dry eye disease, aqueous tear deficiency, and meibomian gland dysfunction were based on the global consensus recommendations of the Tear Film and Ocular Surface Society's Dry Eye Workshop II (TFOS DEWS II) and International Workshop on Meibomian Gland Dysfunction. RESULTS: Overall, 109 (29%) participants fulfilled the TFOS DEWS II criteria for dry eye disease, 42 (11%) had aqueous tear deficiency, and 95 (26%) had meibomian gland dysfunction. Multivariate logistic regression analysis demonstrated that systemic rheumatologic disease and antidepressant medication were independently associated with aqueous tear deficiency (both p < 0.05). Significant risk factors for meibomian gland dysfunction included age, East Asian ethnicity, migraine headaches, thyroid disease, and oral contraceptive therapy (all p ≤ 0.01). CONCLUSIONS: Both etiological subtypes of dry eye disease were associated with a number of systemic risk factors. These findings would support routine systemic inquiry of dry eye disease and associated systemic conditions and medications, in order to facilitate opportunistic screening and timely inter-disciplinary referral where necessary.

Cytomorphological assessment of the lid margin in relation to symptoms, contact lens wear and lid wiper epitheliopathy.

PURPOSE: Lid wiper epitheliopathy (LWE) is insufficiently understood from a cytological perspective. This study explored the relationship between lid margin cytomorphology, LWE, contact lens wear, and lens-related symptoms. METHODS: Habitual, symptomatic (n = 20) and asymptomatic (n = 20) soft, rigid gas permeable (n = 18) and non-contact lens wearers (n = 19) were enrolled. LWE was graded using lissamine green and the Korb scale. Subjective symptoms were assessed using the Ocular Surface Disease Index and the Contact Lens Dryness Evaluation Questionnaire. Impression cytology samples obtained from the central upper and lower lid margins of both eyes stained histologically to highlight keratinization and imaged using high-resolution microscopy. A masked investigator digitally delimited and measured the average sagittal width of the lid wiper conjunctiva and mucocutaneous junction using ImageJ. RESULTS: The upper lid wiper conjunctiva measured 424 ± 171 µm, 404 ± 75, 667 ± 219 and 266 ± 64 in asymptomatic soft, symptomatic soft, rigid and non-contact lens wearers, respectively. The corresponding lower lid wiper conjunctivae measured 141 ± 57 µm, 232 ± 150, 519 ± 212 and 225 ± 102, which was significantly narrower than that of the upper eyelid in most cases (p < 0.05). Symptoms were not associated with lid margin changes; however, rigid lens wear and clinical LWE were associated with histologically enlarged lid wiper conjunctival areas and increased keratinization. CONCLUSION: A novel, exploratory account of histological measures of LWE and cytomorphological change associated with contact lens wear suggests mechanical or frictional cellular insult is occurring at the lid wiper conjunctiva.

Improved Demodex diagnosis in the clinical setting using a novel in situ technique.

PURPOSE: To compare existing and novel diagnostic techniques for confirming ocular Demodex infestation and to recommend the most reliable method for routine use by eye care practitioners, based on yield and clinical applicability. METHODS: Fifteen participants with a prior Demodex blepharitis diagnosis or featuring typical cylindrical dandruff (CD) collarettes, and seven healthy controls were enrolled. Demodex presence was assessed using five techniques, applied consecutively, on a minimum of two different eyelashes on each eyelid of every participant, for each test, in situ: 1. using fine-point forceps and 25-40x biomicroscopy magnification, by eyelash rotation as proposed by Mastrota (ROT); 2. by removing cylindrical dandruff and exposing the eyelash insertion point at the lid margin (CDR); and 3. by laterally tensioning the eyelash (LET) following CDR. The typical appearance of cigar-shaped mite tails protruding from each assessed eyelash follicle was observed, and mite tails counted and averaged per participant for each assessment technique. 4. Lash epilation, and mite presence evaluated using bright-field microscopy at 10-40x magnification (EPI). 5. Finally, eyelash follicles were imaged using in vivo confocal microscopy (IVCM) and the images visually inspected for mite presence. RESULTS: In the Demodex group, the highest numbers of mites/eyelash were identified by LET (3.8 ± 1.4), versus CDR (2.4 ± 1.6) and ROT (1.1 ± 1.2), alone (all p < 0.002). An average of 1.0 ± 0.8 mites/lash was identified by EPI. IVCM failed to offer unequivocal evidence of Demodex presence even in confimed cases. CONCLUSIONS: A novel technique for the clinical diagnosis and grading of Demodex in situ is described. By removing cylindrical dandruff and applying static, lateral tension to the eyelash without epilation, large numbers of mites are visible at the exposed eyelash follicle. The proposed method is convenient and clinically applicable, requiring only forceps and 25-40x biomicroscope magnification, and allowing rapid, efficient evaluation of large numbers of eyelashes.

Impression Cytology of the Lid Wiper Area.

Few reports on the cellular anatomy of the lid wiper (LW) area of the inner eyelid exist and only one report makes use of cytological methods. The optimization of a method of collecting, staining and imaging cells from the LW region using impression cytology (IC) is described in this study. Cells are collected from the inner surface of the upper eyelid of human subjects using hydrophilic polytetrafluoroethylene (PTFE) membranes, and stained with cytological dyes to reveal the presence of goblet cells, mucins, cell nuclei and various degrees of pre- and para-keratinization. Immunocytochemical dyes show cell esterase activity and compromised cell membranes by the use of a confocal scanning laser microscope. Up to 100 microscopic digital images are captured for each sample and stitched into a high-resolution, large scale image of the entire IC span. We demonstrate a higher sensitivity of IC than reported before, appropriate for identifying cellular morphologies and metabolic activity in the LW area. To our knowledge, this is the first time this selection of fluorescent dyes was used to image LW IC membranes. This protocol will be effective in future studies to reveal undocumented details of the LW area, such as assessing cellular particularities of contact lens wearers or patients with dry eye or lid wiper epitheliopathy.

Tear exchange and contact lenses: a review / Intercambio de lágrima y lentes de contacto: revisión

Tear exchange beneath a contact lens facilitates ongoing fluid replenishment between the ocular surface and the lens. This exchange is considerably lower during the wear of soft lenses compared with rigid lenses. As a result, the accumulation of tear film debris and metabolic by-products between the cornea and a soft contact lens increases, potentially leading to complications. Lens design innovations have been proposed, but no substantial improvement in soft lens tear exchange has been reported. Researchers have determined post-lens tear exchange using several methods, notably fluorophotometry. However, due to technological limitations, little remains known about tear hydrodynamics around the lens and, to-date, true tear exchange with contact lenses has not been shown. Further knowledge regarding tear exchange could be vital in aiding better contact lens design, with the prospect of alleviating certain adverse ocular responses. This article reviews the literature to-date on the significance, implications and measurement of tear exchange with contact lenses (AU)

El intercambio de lágrima bajo las lentes de contacto facilita la reposición continua de fluido entre la superficie ocular y las lentes. Dicho intercambio es considerablemente menor con el uso de lentes blandas en lugar de rígidas. Como resultado, se incrementa la acumulación de desechos de la película de lágrimas y los sub-productos metabólicos entre la córnea y las lentes de contacto blandas, lo que conlleva complicaciones potenciales. Se han propuesto innovaciones en el diseño de las lentes, pero no se ha reportado ninguna mejora sustancial en lo referente al intercambio de lágrima con las lentes de contacto blandas. Los investigadores han determinado el intercambio de lágrimas tras el uso de lentes utilizando diversos métodos, principalmente la fluorofotometría. Sin embargo, debido a las limitaciones técnicas, se conoce poco acerca de la hidrodinámica relacionada con las lentes y, hasta la fecha, no se ha mostrado un intercambio de lágrima substancial con lentes de contacto. El conocimiento adicional sobre el intercambio de lágrima podría resultar esencial para ayudar a diseñar lentes de contacto mejoradas, con la perspectiva de aliviar ciertas respuestas oculares adversas. Este artículo revisa la literatura hasta la fecha acerca de la importancia, implicaciones y medición del intercambio de lágrima con lentes de contacto (AU)