Browsing by Author "Ngo, William"

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    Development of an in vitro eye model to better represent in vivo physiological conditions
    (University of Waterloo, 2021-06-23) Chan, Vivian; Jones, Lyndon; Ngo, William
    Purpose The purpose of this thesis was to optimize a novel in vitro blink model, the OcuBlink, to best mimic the physiological characteristics of the human eye. By improving this in vitro model, the results from in vitro studies using this model can be more representative of in vivo studies. Methods The first experimental chapter of this thesis, Chapter 3, explores the results of active lysozyme deposition on contact lenses using the blink model. An ex vivo active lysozyme deposition study was referenced to determine the ideal flow rate for the blink model. These parameters were used to determine the active lysozyme deposition data for several other lens materials. The blink model was directly compared to a simple vial at 8 hours of incubation to show the difference between the two in vitro models. The experiments in Chapter 3 led to several developmental improvements to the blink model design. Chapter 4 explores the changes to the blink model from its initial design through different iterations to incorporate a heated system to simulate ocular temperatures. Chapter 5 uses the new blink model improvements to study contact lens dehydration. The effect of incubation temperature, incubation solution, and in vitro model design were explored. The comparison between the vial system and the blink model showed a difference in water content patterns over time. Results With ex vivo data as a reference, the blink model was able to replicate the active lysozyme deposition data on etafilcon A lenses. The parameters of the blink model were used to determine active lysozyme deposition on other contact lenses. This study provided the expected range for ex vivo active lysozyme deposition for these lens materials as this data was not available in the literature at the time of the study. The comparison of the in vitro models showed that contact lens material plays a large role in active lysozyme deposition patterns over time. The different iterations of the blink model show how different materials and designs can improve and progress in vitro testing of ocular studies. The most significant addition to the blink model was the incorporation of a heated element to allow studies to be conducted at ocular temperatures. The improved blink model showed a decrease in water content for all lenses for an increase in incubation temperature. The incubation solution did not have an effect on water content for most tested lenses, however, lens material played a major role. All lenses decreased in water content after the first hour of incubation. With the blink model, lenses showed a recovery in water content over 16 hours, however the lenses showed a plateau effect in a simple vial model. The recovery in water content on the blink model has not been seen on other in vitro or in vivo studies to date and will need further testing to better understand the phenomenon. Conclusion Although the data has yet to be validated with in vivo data, this thesis shows that the blink model has promise as a predictive tool for in vivo studies. The advanced in vitro blink model can be adjusted per study as required to fulfil experimental requirements. The ultimate goal of the blink model is to produce results that are more representative of in vivo data compared to more simplistic in vitro models while minimizing the cost and time of animal models and clinical trials where appropriate.
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    Efficacy of a new nanoemulsion artificial tear in dry eye disease management: Study protocol for a prospective cohort study
    (Public Library of Science (PLOS), 2025) Liao, Xulin; Guo, Biyue; Bian, Jingfang; Li, Peter H.; Tse, Jimmy S. H.; Ngo, William; Zhou, Lei; Lam, Thomas
    Background Dry eye disease (DED) is a complex ocular disorder with a significant prevalence worldwide, especially in the Asian population. This study aimed to investigate changes in dry eye symptoms and signs following regular use of a new nanoemulsion eye drop, Systane COMPLETE Multi-Dose Preservative-Free (MDPF), in patients with mild to moderate DED in the Asian population. Methods and design This is a prospective cohort study (ClinicalTrials.gov identifier: NCT06188260) that aims to recruit approximately 40 patients from the Asian population suffering from mild to moderate DED. Mild to moderate DED is defined according to the Tear Film and Ocular Surface Society (TFOS) Dry Eye Workshop (DEWS) II diagnostic criteria, including an Ocular Surface Disease Index (OSDI) score between 13-32, and with at least one of the following positive signs: corneal staining, Non-Invasive Tear Breakup Time (NITBUT), or osmolarity. The proposed follow-up period is 3 months. Patients undergo three assessments: baseline before using the eye drops, and follow-up visits after 2 weeks and 3 months regular use of the eye drops (four times daily). The primary outcome is the change in the OSDI score at 2 weeks. Discussion The results examine the dry eye symptoms before and after using the new nanoemulsion eye drop, Systane COMPLETE MDPF, in a cohort of mild to moderate DED sufferers. The findings may provide new treatment options for dry eye sufferers with significant clinical implications.