The validity of point of care tear film osmometers in the diagnosis of dry eye.

PURPOSE: To determine the repeatability of TearLab and I-PEN osmometers in vivo and their accuracy in vitro. DESIGN: Prospective, single-visit study. METHODS: The tear osmolarity of 28 participants was evaluated with TearLab and I-PEN on two occasions in random order, over a 2-h period. Both eyes were measured in a randomised order. Coefficients of repeatability (CoR) were determined for each device, together with the bias and limits of agreement between them. For the in vitro experiment, the osmolarity was measured by both osmometers in five solutions (290, 297, 342, 338 and 383 mOsm/L) at two different temperatures (22 and 37°C) with a total of four consecutive measures. RESULTS: The CoRs for the TearLab and I-PEN in the right and left eyes were 26.2, 21.3, 33.6 and 28.3 mOsm/L, respectively. Across the first and second repeats, TearLab showed consistency of diagnosis for 50% of participants with 29% as dry eye positive, while I-PEN indicated 68% consistency of diagnosis with 57% dry eye positive. The instruments agreed on the diagnosis in 46.5% of cases. In vitro comparison showed that the average measurement errors for TearLab and I-PEN were -10 ± 13 and 31 ± 39 mOsm/L at 22°C, and 4 ± 13 and 20 ± 51 mOsm/L at 37°C. CONCLUSIONS: In vitro, both instruments showed reasonable accuracy and repeatability at mid-range osmolarities, but repeatability generally declined at higher and lower levels. While TearLab accuracy remained consistent across the osmolarity range, measurement errors for I-PEN noticeably increased outside the mid-range. In vivo, both instruments displayed poor repeatability. This casts doubt on the value of utilising either instrument to establish osmolarity as a factor in the diagnosis of dry-eye, according to currently recommended diagnostic guidelines (TFOS DEWS II), if only a single measurement is taken from each eye.

The effect of airtightness required in building energy conservation regulations on indoor and outdoor originated pollutants.

The contradiction of indoor air quality (IAQ) and energy conservation by isolating the indoor environment from the outdoor through airtightness is one of the challenges of the building sector. The key issue is, what are the optimum airtightness limits that can ensure IAQ in naturally ventilated buildings, taking into account the paradoxical effect of house leakages on the infiltration of outdoor pollutants and accumulation of indoor-generated pollutants? For this purpose, the effect of different levels of airtightness required in energy-compliant, low-energy, and very low-energy buildings on the concentration of two pollutants with outdoor and indoor origin, PM2.5 and formaldehyde, respectively, were studied. This study used a multizone model, CONTAM(W), which was validated using measured data to study the distribution of selected pollutants in a typical relatively old dwelling, to investigate the situation in Iran. Subsequently, we conducted simulations based on different combinations of scenarios for airtightness, user behavior, source strength, and meteorological parameters. The results showed that increasing the airtightness from the baseline scenario (ACH50 = 11.11/h) to 3, 1.5, and 0.75 in closed window conditions reduced the PM2.5 by 15%, 38%, and 58%, respectively, and elevated formaldehyde by 23%, 77%, and 169%, correspondingly. Under normal outdoor PM2.5 pollution, indoor formaldehyde levels exceeded the permissible limit only in closed window conditions, and IAQ remained acceptable in other scenarios. However, there is no indication that IAQ can be ensured by any degree of airtightness under severe outdoor air pollution, demanding specific solutions, such as those proposed in this work.

Dry eye disease: an (in)convenient truth.

The salient rise of chronic disease from the mid-twentieth century threatens to overwhelm public health systems in an increasing number of countries and is now considered an epidemic. Dry eye disease is an underappreciated disorder that bears all the hallmarks of chronic disease. Preventative health care seeks improved and sustainable patient engagement in the self-management of health to limit the progress and extent of chronic disease. Anthropogenic environments engendering lifestyles and behaviours that can be detrimental to human health, can be considered as direct or indirect threats to successful preventative health strategies. Chronic disease can be viewed as the result of physiological responses of the human body to the modern environment. The quest for an increasingly convenient, global, and disease-free lifestyle is ironically threatening to undo the gains in health and quality of life made over the last one hundred years. Considering dry eye disease as an anthropogenic chronic disease, contributions of diet (food and beverages consumed) and nutrition (extending to relationships with self, community, and nature) to development of dry eye disease are explored in this review. Evidence of environmental and behavioural instigators of chronic disease with an emphasis on production, disbursement, and preservation of food, is presented. Furthermore, evidence of traditional food practices that offer resistance to the development of chronic systemic inflammatory disorders are reviewed as an exemplar of potential strategies that can be put into practice by individuals and communities to reinstate a balanced life, community and planet.

The Impact of Probiotics and Prebiotics on Dry Eye Disease Signs and Symptoms.

Dry eye is considered an inflammatory disease. Gut microbiota are important in the regulation of low-grade chronic inflammation, including in the eye. Probiotics and prebiotics are increasingly used to regulate chronic-disease-associated gut dysbiosis. Therefore, this double-masked, randomized controlled clinical trial aimed to explore the potential of oral probiotics and prebiotics in the management of dry eye disease. In total, 41 participants with dry eye received probiotic and prebiotic supplements (treatment group, n = 23) or respective placebos (control group, n = 18) for 4 months. Dry eye symptoms and signs were evaluated using the Ocular Surface Disease Index (OSDI), Dry Eye Questionnaire 5, osmolarity, non-invasive keratograph break-up time (NIKBUT), ocular surface staining, tear meniscus height (TMH), lipid layer thickness, and conjunctival redness. After 4 months, the average OSDI score of the treatment group was significantly better compared to that of the controls (16.8 ± 5.9 vs. 23.4 ± 7.4; p < 0.001). The NIKBUT and TMH did not change significantly with treatment (p = 0.31 and p = 0.84) but reduced significantly for controls on average by −5.5 ± 1.0 secs (p = 0.03) and 0.2 ± 0.1 mm (p = 0.02). These data suggest that probiotics and prebiotics might be effective in the management of dry eye disease.

Reproducibility and Reliability of Subbasal Corneal Nerve Parameters of the Inferior Whorl in the Neurotoxic and Healthy Cornea.

PURPOSE: The aim of this study was to investigate the reliability of subbasal corneal nerve plexus parameters of the inferior whorl compared with the central cornea with in vivo corneal confocal microscopy and to investigate the impact of inferior whorl pattern complexity on reproducibility. METHODS: Subbasal corneal nerves of healthy controls (n = 10) and patients with chemotherapy-induced peripheral neuropathy (n = 10) were imaged with a laser scanning confocal microscope. Two masked, experienced observers and the original image taker were tasked with selecting representative images of the central cornea and inferior whorl for each participant. This was conducted on 2 occasions 1 week apart. Corneal nerve fiber length (CNFL) and fractal dimension (CNFrD) [central cornea: CNFL and CNFrD; inferior whorl region: inferior whorl length (IWL) and inferior whorl fractal dimension (IWFrD)] were analyzed. Intraclass correlation coefficient (ICC) was analyzed for interobserver and intraobserver reliability. Inferior whorl complexity was classified according to the ease of identification of the center point of convergence. RESULTS: Interobserver ICC was 0.992 for CNFL, 0.994 for CNFrD, 0.980 for IWL, and 0.954 for IWFrD. When analyzed by inferior whorl complexity, the interobserver reliability was similar for simple (0.987 for IWL; 0.960 for IWFrD) and complex patterns (0.967 for IWL; 0.949 for IWFrD). However, intraobserver ICC were reduced for complex (IWL 0.841-0.970; IWFrD 0.830-0.955) compared with simple patterns (IWL 0.931-0.970; IWFrD 0.921-0.969). CONCLUSIONS: Although the overall interobserver reliability was excellent for the central corneal and inferior whorl parameters, there was lower intraobserver reliability for the inferior whorl parameters for complex morphological patterns. To improve reliability, more sophisticated wide-field imaging of the inferior whorl may be needed.

Corneal dendritic cells and the subbasal nerve plexus following neurotoxic treatment with oxaliplatin or paclitaxel.

Immune cell infiltration has been implicated in neurotoxic chemotherapy for cancer treatment. However, our understanding of immune processes is still incomplete and current methods of observing immune cells are time consuming or invasive. Corneal dendritic cells are potent antigen-presenting cells and can be imaged with in-vivo corneal confocal microscopy. Corneal dendritic cell densities and nerve parameters in patients treated with neurotoxic chemotherapy were investigated. Patients treated for cancer with oxaliplatin (n = 39) or paclitaxel (n = 48), 3 to 24 months prior to assessment were recruited along with 40 healthy controls. Immature (ImDC), mature (MDC) and total dendritic cell densities (TotalDC), and corneal nerve parameters were analyzed from in-vivo corneal confocal microscopy images. ImDC was increased in the oxaliplatin group (Median, Md = 22.7 cells/mm2) compared to healthy controls (Md = 10.1 cells/mm2, p = 0.001), but not in the paclitaxel group (Md = 10.6 cells/mm2). ImDC was also associated with higher oxaliplatin cumulative dose (r = 0.33, p = 0.04) and treatment cycles (r = 0.40, p = 0.01). There was no significant difference in MDC between the three groups (p > 0.05). Corneal nerve parameters were reduced in both oxaliplatin and paclitaxel groups compared to healthy controls (p < 0.05). There is evidence of elevation of corneal ImDC in oxaliplatin-treated patients. Further investigation is required to explore this potential link through longitudinal studies and animal or laboratory-based immunohistochemical research.

The Case for a More Holistic Approach to Dry Eye Disease: Is It Time to Move beyond Antibiotics?

Dry eye disease (DED) is one of the most frequent presentations to optometrists with over 16 million US adults (6.8% of adult population) diagnosed as having this disorder. The majority of associated marketed products offer relief from symptomatology but do not address aetiology. DED harbours many distinguishing features of a chronic inflammatory disorder. The recent explosion in human microbiome research has sparked interest in the ocular microbiome and its role in the preservation and extension of ocular surface health and in the contribution of the gut microbiome to chronic systemic inflammation and associated "Western life-style" diseases. With a significant lack of success for many patients using currently available DED treatments, in this era of the microbiome, we are interested in exploring potential novel therapies that aim to reconstitute healthy bacterial communities both locally and distally (in the gut) as a treatment for DED. Although this direction of investigation is in its infancy, burgeoning interest makes such a review timely. This paper considers a number of studies into the use functional foods and associated products to ameliorate dry eye.