Purpose: To locate protein sorption on the surface and inside the matrix of soft contact lens materials and intraocular lenses (IOL). Methods: The proteins albumin and lysozyme were investigated as they are highly abundant in blood serum and tears, respectively. Proteins were conjugated with organic fluorescent probes and using confocal laser scanning microscopy (CLSM) the sorption profile to contact lenses and IOL could be determined. Radiolabeled protein was used for quantification purposes. • Albumin sorption to etafilcon A and lotrafilcon B was determined (Chapter 3) • Different fluorescent probes were used for conjugation and the impact on albumin sorption behaviour was investigated (Chapter 4) • Lysozyme sorption to nine different pHEMA-based and silicone hydrogel contact lenses was determined using two fluorescent probes (Chapter 5) • The efficiency of protein removal from contact lenses using contact lens care regimens was investigated (Chapter 6) • Albumin sorption to IOL materials was quantified and imaged using a modified CLSM technique (Chapter 7) Results: Albumin and lysozyme sorption profiles differed between materials, and were influenced by the fluorescent probes used for conjugation. After one day of incubation, both proteins could be located within all contact lens materials, except for lotrafilcon A and lotrafilcon B, which primarily allowed deposition on the lens surface. An increase in protein accumulation was found for most materials over the maximum investigated period of 14 days, using CLSM and radiolabel techniques. The efficiency of contact lens care regimens to remove lysozyme and albumin depended on the lens material, care regimen and protein type investigated. PMMA and silicone IOLs showed protein exclusively on the surface, while a hydrophilic acrylic IOL allowed penetration into the lens matrix over time. Despite the albumin penetration depth into hydrophilic acrylic, the highest albumin levels were determined for the silicone IOL. Conclusions: CLSM provides detailed information that can describe the protein distribution in transparent biomaterials, with scanning depths up to a few hundred microns. However, the CLSM data are primarily of qualitative value, which necessitates a quantitative technique (e.g. radiolabeling) to determine the total protein content.

The wettability of contact lenses has become an area of intense research, with the belief that the more "hydrophilic" or wettable the lens surface is, the more comfortable the lens may be, as the posterior surface of the eyelid will move more smoothly over it, hence increasing comfort. <br /><br /> There are many ways to assess the wettability of a given material, namely sessile drop,¹ captive bubble ² or Wilhelmy plate. ³ This thesis used the sessile drop method to determine the surface wettability of various hydrogel contact lens materials, by measuring the advancing contact angle made between the lens surface and a pre-determined volume of HPLC-grade water. This was followed by measuring the surface wettability following periods in which the lens materials were soaked in various contact lens care regimens. Further studies determined wettability of lens materials after various periods of in-eye wear and finally a study was undertaken to evaluate if a novel biological technique could be used to differentiate proteins that deposit on hydrogel lens materials that may affect wettability and cause discomfort. <br /><br /> A variety of hydrogel lenses, taken directly from their packaging and after soaking in various care regimens, were analyzed to determine their sessile drop advancing contact angles, in vitro. These studies indicated that poly-2-hydroxyethylmethacrylate (pHEMA)-based lenses are inherently more wettable than silicone-based lenses, unless they have a surface treatment that completely covers the hydrophobic siloxane groups. Additionally, certain combinations of lens materials and care regimens produce inherently more wettable surfaces when measured in vitro. <br /><br /> Suitable methods to assess contact lens wettability ex vivo, or after subjects had worn lenses for set periods of time, were developed. It was determined that using latex gloves to remove lenses had no impact upon the lens surface wettability and that rinsing of the lens surface after removal from the eye was required to determine the wettability of the underlying polymer. <br /><br /> The final wettability studies involved an analysis of various lens materials from clinical studies conducted within the Centre for Contact Lens Research (CCLR). These studies investigated differences in wettability between silicone hydrogel lenses manufactured from differing polymers and variations in ex vivo wettability of several combinations of lens materials and solutions, worn for varying periods of time. <br /><br /> A novel method to investigate proteins extracted from lenses using 2D-Difference in Gel Electrophoresis (DIGE) found that this technique could be used to analyze proteins extracted from contact lenses. The data obtained showed that there was no difference between a group of subjects who were symptomatic of lens-induced dryness or a control group, and that care solutions had a minimal influence on the pattern of deposition seen. <br /><br /> The overall conclusion of these studies is that hydrogel lens wettability is affected by the polymer composition and that care regimen components can modify the surface wettability.

Purpose: To locate protein sorption on the surface and inside the matrix of soft contact lens materials and intraocular lenses (IOL). Methods: The proteins albumin and lysozyme were investigated as they are highly abundant in blood serum and tears, respectively. Proteins were conjugated with organic fluorescent probes and using confocal laser scanning microscopy (CLSM) the sorption profile to contact lenses and IOL could be determined. Radiolabeled protein was used for quantification purposes. • Albumin sorption to etafilcon A and lotrafilcon B was determined (Chapter 3) • Different fluorescent probes were used for conjugation and the impact on albumin sorption behaviour was investigated (Chapter 4) • Lysozyme sorption to nine different pHEMA-based and silicone hydrogel contact lenses was determined using two fluorescent probes (Chapter 5) • The efficiency of protein removal from contact lenses using contact lens care regimens was investigated (Chapter 6) • Albumin sorption to IOL materials was quantified and imaged using a modified CLSM technique (Chapter 7) Results: Albumin and lysozyme sorption profiles differed between materials, and were influenced by the fluorescent probes used for conjugation. After one day of incubation, both proteins could be located within all contact lens materials, except for lotrafilcon A and lotrafilcon B, which primarily allowed deposition on the lens surface. An increase in protein accumulation was found for most materials over the maximum investigated period of 14 days, using CLSM and radiolabel techniques. The efficiency of contact lens care regimens to remove lysozyme and albumin depended on the lens material, care regimen and protein type investigated. PMMA and silicone IOLs showed protein exclusively on the surface, while a hydrophilic acrylic IOL allowed penetration into the lens matrix over time. Despite the albumin penetration depth into hydrophilic acrylic, the highest albumin levels were determined for the silicone IOL. Conclusions: CLSM provides detailed information that can describe the protein distribution in transparent biomaterials, with scanning depths up to a few hundred microns. However, the CLSM data are primarily of qualitative value, which necessitates a quantitative technique (e.g. radiolabeling) to determine the total protein content.

The cornea is the anterior most surface of the eye and plays a critical role in vision. A thin fluid layer, the tear film, coats the outer surface of the cornea and serves to protect, nourish, and lubricate the cornea. At the same time, the tear film is responsible for creating a smooth continuous surface where the majority of refraction takes place in the eye. A significant component of vision quality is determined by the shape of the cornea and stability of the tear film. It is desirable to possess an instrument that can measure the corneal shape and tear film surface with the same accuracy and resolution that is currently performed on common optical elements. A dual interferometer system for measuring the dynamic corneal topography is designed, built, and verified. The completed system is validated by testing on human subjects. The system consists of two co-aligned polarization splitting Twyman-Green interferometers designed to measure phase instantaneously. The primary interferometer measures the surface of the tear film while the secondary interferometer simultaneously tracks the absolute position of the cornea. Eye motion, ocular variation, and a dynamic tear film surface will result in a non-null configuration of the surface with respect to the interferometer system. A non-null test results in significant interferometer induced errors that add to the measured phase. New algorithms are developed to recover the absolute surface topography of the tear film and corneal surface from the simultaneous interferometer measurements. The results are high-resolution and high-accuracy surface topography measurements of the in vivo cornea that are captured at standard camera frame rates. This dissertation will cover the development and construction of an interferometer system for measuring the dynamic corneal topography of the human eye. The discussion starts with the completion of an interferometer for measuring the tear film. The tear film interferometer is part of an ongoing research project that has spanned multiple dissertations. For this research, the instrument was tested on human subjects and resulted in refinements to the interferometer design. The final configuration of the tear film interferometer and results from human subjects testing are presented. Feedback from this instrument was used to support the development and construction of the interferometric corneal topographer system. A calibration is performed on the instrument, and then verified against simulated eye surfaces. Finally, the instrument is validated by testing on human subjects. The result is an interferometer system that can non-invasively measure the dynamic corneal topography with greater accuracy and resolution than existing technologies.

This project has provided a better understanding of the human conjunctiva, the glistening tissue covering the white of the eye, at the cellular level. The observations of this study may serve as a useful marker against which changes in conjunctival tissue due to disease, surgery, drug therapy or contact lens wear can be assessed. Laser scanning confocal microscopy was used to observe and measure characteristics the conjunctiva of healthy human volunteer subjects. It was concluded that this technique is a powerful tool for studying the human conjunctiva and assessing key aspects of the structure of this tissue. The effects of contact lens wear on the conjunctiva can be investigated effectively at a cellular level using this technology.

Contact lens production requires high accuracy and good surface integrity. Surface roughness is generally used to measure the index quality of a turning process. It has been an important response because it has direct influence toward the part performance and the production cost. Hence, choosing optimal cutting parameters will not only improve the quality measure but also the productivity. In this study, an ONSI-56 (Onsifocon A) contact lens buttons were used to investigate the triboelectric phenomena and the effects of turning parameters on surface finish of the lens materials. ONSI-56 specimens are machined by Precitech Nanoform Ultra-grind 250 precision machine and the roughness values of the diamond turned surfaces are measured by Taylor Hopson PGI Profilometer. Electrostatics values were measured using electrostatic voltmeter. An artificial neural network (ANN) and response surface (RS) model were developed to predict surface roughness and electrostatic discharge (ESD) on the turned ONSI-56. In the development of predictive models, turning parameters of cutting speed, feed rate and depth of cut were considered as model variables. The required data for predictive models were obtained by conducting a series of turning test and measuring the surface roughness and ESD data. Good agreement is observed between the predictive models results and the experimental measurements. The ANN and RSM models for ONSI-56 are compared with each other using mean absolute percentage error (MAPE) for accuracy and computational cost.

No description available.

Human tear film is an accessible biospecimen rich with useful biological information. As tear protein biomarkers for both ocular and systemic diseases have been identified in tears, efforts are being made to create point-of-care tests useful for clinical diagnoses. However, there are significant obstacles to tear diagnostics, including inadequate sampling methods and biomarkers with insufficient sensitivity and specificity. Furthermore, tear film diagnostics are particularly challenging for dry eye disease (DED) patients, where low tear volume makes sampling more difficult and the multifactorial nature of DED makes identifying the exact pathological subtype very complex. As soft contact lenses (SCLs) are designed for optimal ocular surface interaction and concentrate proteins on the eye regardless of tear volume, we hypothesized that we could improve tear sampling methods for research and diagnostic purposes. We further hypothesized that we could identify new and existing and DED biomarkers using SCL tear film sampling. To begin, we demonstrate SCL sampling in vitro and then compare SCLs to other current tear sampling methods in vivo. Objectively, we observe that SCLs do not show signs of ocular surface irritation, regardless of previous SCL use. We also see that SCLs sample similar types and amounts of proteins relative to other methods. Subjective assessments of tear sampling methods are also made by subjects. Our results indicate that training and experience in tear sampling are key components which may significantly impact subject experience as well as the tear type collected. Next, we optimized our tear sampling method by comparing different SCLs materials in search of an ideal lens. Our data show that certain combinations of SCL materials and mass spectrometry (MS) sample preparation methods can lead to significant polymer contamination in MS. Furthermore, we observe individual protein binding specificity based on SCL chemistry. Our experiments reveal etafilcon A and verofilcon A lenses as the optimal SCL materials for tear film sampling. Finally, a pilot study in DED candidates using SCL sampling confirms the presence of previously reported biomarkers in DED subjects as well as identifies new biomarkers for future validation studies. We also correlate clinical metrics to biochemical findings and identify correlations between tear film homeostasis and pathologic phenotypes. Ultimately, these studies demonstrate SCL sampling is an advantageous alternative to current tear film sampling methods, useful for biomarker discovery, and potentially, clinical diagnostics.

No description available.

No description available.