The focus of this thesis is the improvement of acquisition and processing of Mueller matrix polarimetry using a confocal scanning laser ophthalmoscope (CSLO) and the application of Mueller matrix polarimetry to image the retina. Stepper motors were incorporated into a CSLO to semi-automate Mueller matrix polarimetry and were used in retinal image acquisition. Success rates of Fourier transform based edge detection filters, designed to improve the registration of retinal images, were compared. The acquired polarimetry images were used to reassess 2 image quality enhancement techniques, Mueller matrix reconstruction (MMR) and Stokes vector reconstruction (SVR), focusing on the role of auto-contrasting or normalization within the techniques and the degree to which auto-contrasting or normalization is responsible for image quality improvement of the resulting images. Mueller matrix polarimetry was also applied to find the retardance image of a malaria infected retinal blood vessel imaged in a confocal scanning laser microscope (CSLM) to visualize hemozoin within the vessel. Image quality enhancement techniques were also applied and image quality improvement was quantified for this blood vessel. The semi-automation of Mueller matrix polarimetry yielded a significant reduction in experimental acquisition time (80%) and a non-significant reduction in registration time (44%). A larger sample size would give higher power and this result might become significant. The reduction in registration time was most likely due to less movement of the eye, particularly in terms of decreased rotation seen between registered images. Fourier transform edge detection methods increased the success rate of registration from 73.9% to 92.3%. Assessment of the 2 MMR images (max entropy and max signal-to-noise ratio (SNR)) showed that comparison to the best CSLO images (not auto-contrasted) yielded significant average image quality improvements of 158% and 4% when quantified with entropy and SNR, respectively. When compared to best auto-contrasted CSLO images, significant image quality improvements were 11% and 5% for entropy and SNR, respectively. Images constructed from auto-contrasted input images were of significantly higher quality than images reconstructed from original images. Of the 2 other images assessed (modified degree of polarization (DOPM) and the first element of the Stokes vector (S0)), DOPM and S0 yielded significant average image quality improvements quantified by entropy except for the DOPM image of the RNFL. SNR was not improved significantly when either SVR image was compared to the best CSLO images. Compared to the best auto-contrasted CSLO images, neither DOPM nor S0 improved average image quality significantly. This result might change with a larger number of participants. When MMR were applied to images of malaria infected retinal slides, image quality was improved by 19.7% and 15.3% in terms of entropy and SNR, respectively, when compared to the best CSLO image. The DOPM image yielded image quality improvements of 8.6% and -24.3% and the S0 image gave improvements of 9.5% and 9.4% in entropy and SNR, respectively. Although percent increase in image quality was reduced when images were compared to initial auto-contrasted CSLO images, the final image quality was improved when auto-contrasting occurred prior to polarimetry calculations for max SNR and max entropy images. Quantitative values of retardance could not be found due to physical constraints in the CSLM that did not allow for characterization of its polarization properties and vibrational noise. Mueller matrix polarimetry used to find the retardance image of a malaria infected retina sample did yield visualization of hemozoin within the vessel but only qualitatively. In conclusion, improvements in the acquisition and registration of CSLO images were successful in leading to considerably shorter experimentation and processing times. In terms of polarimetric image quality improvement techniques, when compared to the best CSLO image. A large proportion of the improvement was in fact due to partially or completely stretching the pixel values across the dynamic range of the images within the algorithm of each technique. However, in general the image quality was still improved by the Mueller matrix reconstruction techniques using both entropy and SNR to generate the CSLO retinal images and the CSLM imaged malaria infected sample. In the malaria sample, retinal blood vessel visualization was also qualitatively improved. The images yielded from Mueller matrix polarimetry applied to a malaria infected retinal sample localized hemozoin within the blood vessel, but a quantitative image of the phase retardance could not be achieved.

Ischaemic cell death has been implicated in a number of retinal diseases, including glaucomatous neuropathy, proliferative diabetic retinopathy and a range of vascular diseases. The cascade of events leading to cell death involves both cellular metabolic changes and a functional component. However, it is yet unknown how long these changes persist, whether all cell classes are affected, and the characteristics of recovery. Moreover, there have been few studies correlating the neurochemical changes with the ensuing functional changes. The aim of this thesis was to track the metabolic and functional recovery of the ischaemic rat retina, given the premise that: (1) amino acid neurochemistry reflects metabolic integrity and cellular identity, and; (2) the permeation of a cation channel probe called agmatine reflects channel functionality. Quantitative pattern recognition analysis of overlapping amino acid and agmatine expression profiles were used to provide a statistically robust classification of cells according to metabolic and functional characteristics. This classification was spatially complete and with single cell resolution. Finally, the electroretinogram was used to also assess retinal function and corroborate the observed neurochemical changes. These measures were taken at intervals for up to two weeks of reperfusion. The results show that by 48 hours of reperfusion, amino acid metabolism had returned to near normal levels, although cell classes were missing, and there was persistant cation channel gating anomalies. Immunocytochemical labeling identified a preferential loss of cone bipolar cells, with all remaining rod bipolar cells showing increased cation channel gating. The electroretinogram and agmatine experiments showed that this dysfunction is likely due to abnormal glutamate release from pre-synaptic photoreceptors, detected by changes in post-synaptic agmatine permeation, and not due to the presence of anomalous metabotropic glutamate receptors. Cholinergic amacrine cells demonstrated persistant neurochemical labeling, but did not show cationic flux following stimulation by glutamate agonists. In conclusion, the retina shows remarkable recovery in the amino acid metabolism, although functional changes persist. Finally, structural integrity or immunocytochemical labeling does not necessarily imply that cells maintain functional receptors, or that neurotransmitter release is normal secondary to disease. / Whole document restricted, but available by request, use the feedback form to request access.

Ischaemic cell death has been implicated in a number of retinal diseases, including glaucomatous neuropathy, proliferative diabetic retinopathy and a range of vascular diseases. The cascade of events leading to cell death involves both cellular metabolic changes and a functional component. However, it is yet unknown how long these changes persist, whether all cell classes are affected, and the characteristics of recovery. Moreover, there have been few studies correlating the neurochemical changes with the ensuing functional changes. The aim of this thesis was to track the metabolic and functional recovery of the ischaemic rat retina, given the premise that: (1) amino acid neurochemistry reflects metabolic integrity and cellular identity, and; (2) the permeation of a cation channel probe called agmatine reflects channel functionality. Quantitative pattern recognition analysis of overlapping amino acid and agmatine expression profiles were used to provide a statistically robust classification of cells according to metabolic and functional characteristics. This classification was spatially complete and with single cell resolution. Finally, the electroretinogram was used to also assess retinal function and corroborate the observed neurochemical changes. These measures were taken at intervals for up to two weeks of reperfusion. The results show that by 48 hours of reperfusion, amino acid metabolism had returned to near normal levels, although cell classes were missing, and there was persistant cation channel gating anomalies. Immunocytochemical labeling identified a preferential loss of cone bipolar cells, with all remaining rod bipolar cells showing increased cation channel gating. The electroretinogram and agmatine experiments showed that this dysfunction is likely due to abnormal glutamate release from pre-synaptic photoreceptors, detected by changes in post-synaptic agmatine permeation, and not due to the presence of anomalous metabotropic glutamate receptors. Cholinergic amacrine cells demonstrated persistant neurochemical labeling, but did not show cationic flux following stimulation by glutamate agonists. In conclusion, the retina shows remarkable recovery in the amino acid metabolism, although functional changes persist. Finally, structural integrity or immunocytochemical labeling does not necessarily imply that cells maintain functional receptors, or that neurotransmitter release is normal secondary to disease. / Whole document restricted, but available by request, use the feedback form to request access.

Ischaemic cell death has been implicated in a number of retinal diseases, including glaucomatous neuropathy, proliferative diabetic retinopathy and a range of vascular diseases. The cascade of events leading to cell death involves both cellular metabolic changes and a functional component. However, it is yet unknown how long these changes persist, whether all cell classes are affected, and the characteristics of recovery. Moreover, there have been few studies correlating the neurochemical changes with the ensuing functional changes. The aim of this thesis was to track the metabolic and functional recovery of the ischaemic rat retina, given the premise that: (1) amino acid neurochemistry reflects metabolic integrity and cellular identity, and; (2) the permeation of a cation channel probe called agmatine reflects channel functionality. Quantitative pattern recognition analysis of overlapping amino acid and agmatine expression profiles were used to provide a statistically robust classification of cells according to metabolic and functional characteristics. This classification was spatially complete and with single cell resolution. Finally, the electroretinogram was used to also assess retinal function and corroborate the observed neurochemical changes. These measures were taken at intervals for up to two weeks of reperfusion. The results show that by 48 hours of reperfusion, amino acid metabolism had returned to near normal levels, although cell classes were missing, and there was persistant cation channel gating anomalies. Immunocytochemical labeling identified a preferential loss of cone bipolar cells, with all remaining rod bipolar cells showing increased cation channel gating. The electroretinogram and agmatine experiments showed that this dysfunction is likely due to abnormal glutamate release from pre-synaptic photoreceptors, detected by changes in post-synaptic agmatine permeation, and not due to the presence of anomalous metabotropic glutamate receptors. Cholinergic amacrine cells demonstrated persistant neurochemical labeling, but did not show cationic flux following stimulation by glutamate agonists. In conclusion, the retina shows remarkable recovery in the amino acid metabolism, although functional changes persist. Finally, structural integrity or immunocytochemical labeling does not necessarily imply that cells maintain functional receptors, or that neurotransmitter release is normal secondary to disease. / Whole document restricted, but available by request, use the feedback form to request access.

Ischaemic cell death has been implicated in a number of retinal diseases, including glaucomatous neuropathy, proliferative diabetic retinopathy and a range of vascular diseases. The cascade of events leading to cell death involves both cellular metabolic changes and a functional component. However, it is yet unknown how long these changes persist, whether all cell classes are affected, and the characteristics of recovery. Moreover, there have been few studies correlating the neurochemical changes with the ensuing functional changes. The aim of this thesis was to track the metabolic and functional recovery of the ischaemic rat retina, given the premise that: (1) amino acid neurochemistry reflects metabolic integrity and cellular identity, and; (2) the permeation of a cation channel probe called agmatine reflects channel functionality. Quantitative pattern recognition analysis of overlapping amino acid and agmatine expression profiles were used to provide a statistically robust classification of cells according to metabolic and functional characteristics. This classification was spatially complete and with single cell resolution. Finally, the electroretinogram was used to also assess retinal function and corroborate the observed neurochemical changes. These measures were taken at intervals for up to two weeks of reperfusion. The results show that by 48 hours of reperfusion, amino acid metabolism had returned to near normal levels, although cell classes were missing, and there was persistant cation channel gating anomalies. Immunocytochemical labeling identified a preferential loss of cone bipolar cells, with all remaining rod bipolar cells showing increased cation channel gating. The electroretinogram and agmatine experiments showed that this dysfunction is likely due to abnormal glutamate release from pre-synaptic photoreceptors, detected by changes in post-synaptic agmatine permeation, and not due to the presence of anomalous metabotropic glutamate receptors. Cholinergic amacrine cells demonstrated persistant neurochemical labeling, but did not show cationic flux following stimulation by glutamate agonists. In conclusion, the retina shows remarkable recovery in the amino acid metabolism, although functional changes persist. Finally, structural integrity or immunocytochemical labeling does not necessarily imply that cells maintain functional receptors, or that neurotransmitter release is normal secondary to disease. / Whole document restricted, but available by request, use the feedback form to request access.

No description available.

<p>Older adults tend to show overall recognition deficits and qualitatively different patterns in the particular expressions that are most difficult to identify (Ruffman et al., 2008). In the current study, 23 younger (18-33 years old) and 23 older (60-80 years old) adults performed a 4AFC (angry, fearful, happy, sad) facial expression categorization task varying orientation (upright/inverted) and stimulus duration (100, 500, 1000 ms). For both groups, happiness was the easiest expression to identify and fear and sadness were the most difficult. Compared to younger adults, older adults were more affected by stimulus orientation, and generally benefit less from increased stimulus duration. For upright faces, there was no age difference in response accuracy but response latency was longer in older subjects. For inverted faces, older adults showed lower accuracy and longer latencies for expressions of anger, fear, and sadness. Recognition of inverted happy faces was spared in older adults for accuracy, but not response latency. These findings could not be explained by impaired detection sensitivity, as no systematic age differences were found for perceived intensity ratings. Finally, the expressions that were most to least difficult to identify was the same in each age group at both orientations. Overall, these results suggest that older individuals process expressive faces in a qualitatively similar way to their younger counterparts, but are less efficient at extracting the diagnostic information.</p> / Master of Science (MSc)

Purpose: Contact lens (CL) materials, modalities of wear and replacement, and care systems have changed considerably since the early studies of CL compliance were first conducted. Silicone hydrogel (SiHy) and daily disposable (DD) lenses are now the most popular lenses worn worldwide and the care systems that are currently available for them have been designed to be straightforward to use. The purpose of this research was to investigate patient knowledge of and compliance with the use of these contemporary CLs and care products, to determine whether non-compliant CL wearers experience ocular complications relating to lens wear more frequently and are more likely to discontinue lens wear, and to try to determine the factors that may constrain or enable patients to follow recommendations for appropriate lens wear and care. Methods: There are many ways in which compliance can be assessed in health care. Several different methodologies were employed during this research: A questionnaire was administered to just over 100 current lens wearers to determine whether photographic aids would help them to recognize which products they were using. More than 500 contact lens (CL) wearers were recruited by their eye care practitioners (ECPs) and mailed a questionnaire designed to evaluate their compliance with contact lens wear and care and to determine whether they had experienced any contact lens related complications which may have occurred as a result of non-compliance. Close to 5000 Current and lapsed CL wearers in Canada were recruited using Facebook to take part in an on line survey investigating CL wearing experiences during 2008 – 2010 and to establish the percentage of participants who temporarily and permanently discontinued CL wear during the period surveyed, the reasons for discontinuation and whether compliance with lens wear and care may have played a role. ECPs and patients independently completed more than 2000 linked questionnaires evaluating their contact lens wear and care. In addition the frequency with which patients attended their ECP’s office for eye examinations was assessed to determine whether there was a relationship between this and their patients’ compliance. More than 800 daily disposable contact lens (DDCL) wearers in four countries completed an online questionnaire designed to investigate how frequently they reused their lenses, the reasons for reuse and how the lenses were stored between uses. Quantitative (online questionnaire) and qualitative (focus groups) research methods were used to explore in detail the lens wear and care habits of adapted contact lens wearers in an attempt to seek a better understanding of what enables and constrains patient compliance with appropriate lens wear and lens care. Results: The rates of non-compliance with the wear of contemporary CLs were found to be similar to those previously reported. Non-compliance with recommendations for CL replacement was shown to be associated with a higher rate of CL related problems. CL wearers continue to “drop-out” for reasons of discomfort and dryness with their lenses but the drop out rates were not found to be different between compliant and non-compliant CL wearers. Patients who were non-compliant with lens replacement were found to attend their ECP’s offices less frequently. Wearers of DDCLs were the most compliant with lens replacement; however, some did report reusing these lenses and sleeping overnight in them. Focus group participants were able to provide a greater insight into why non-compliant behaviour occurs in CL wearers with the most frequently occurring themes identified as the “consequences” that may occur if patients are non-compliant with one or more aspects of their contact lens wear and the importance of receiving “instructions” regarding the most appropriate way to wear and care for their lenses. Most of the themes that emerged from this qualitative research study were both constraints to, and enablers of, compliance. Conclusions: Compliance with contemporary CLs and care products remains poor. Non-compliant behaviour can result in serious complications and patients may not always be aware of this. Careful counseling and education on the risks associated with CL wear is required to provide patients with a better lens wearing experience and continued successful contact lens wear. ECPs and the contact lens industry can hopefully apply this greater understanding of why patients fail to wear and care for their lenses as they should and to help them develop strategies and tools to aid compliance and success in contact lens wear.

Purpose: Contact lens (CL) materials, modalities of wear and replacement, and care systems have changed considerably since the early studies of CL compliance were first conducted. Silicone hydrogel (SiHy) and daily disposable (DD) lenses are now the most popular lenses worn worldwide and the care systems that are currently available for them have been designed to be straightforward to use. The purpose of this research was to investigate patient knowledge of and compliance with the use of these contemporary CLs and care products, to determine whether non-compliant CL wearers experience ocular complications relating to lens wear more frequently and are more likely to discontinue lens wear, and to try to determine the factors that may constrain or enable patients to follow recommendations for appropriate lens wear and care. Methods: There are many ways in which compliance can be assessed in health care. Several different methodologies were employed during this research: A questionnaire was administered to just over 100 current lens wearers to determine whether photographic aids would help them to recognize which products they were using. More than 500 contact lens (CL) wearers were recruited by their eye care practitioners (ECPs) and mailed a questionnaire designed to evaluate their compliance with contact lens wear and care and to determine whether they had experienced any contact lens related complications which may have occurred as a result of non-compliance. Close to 5000 Current and lapsed CL wearers in Canada were recruited using Facebook to take part in an on line survey investigating CL wearing experiences during 2008 – 2010 and to establish the percentage of participants who temporarily and permanently discontinued CL wear during the period surveyed, the reasons for discontinuation and whether compliance with lens wear and care may have played a role. ECPs and patients independently completed more than 2000 linked questionnaires evaluating their contact lens wear and care. In addition the frequency with which patients attended their ECP’s office for eye examinations was assessed to determine whether there was a relationship between this and their patients’ compliance. More than 800 daily disposable contact lens (DDCL) wearers in four countries completed an online questionnaire designed to investigate how frequently they reused their lenses, the reasons for reuse and how the lenses were stored between uses. Quantitative (online questionnaire) and qualitative (focus groups) research methods were used to explore in detail the lens wear and care habits of adapted contact lens wearers in an attempt to seek a better understanding of what enables and constrains patient compliance with appropriate lens wear and lens care. Results: The rates of non-compliance with the wear of contemporary CLs were found to be similar to those previously reported. Non-compliance with recommendations for CL replacement was shown to be associated with a higher rate of CL related problems. CL wearers continue to “drop-out” for reasons of discomfort and dryness with their lenses but the drop out rates were not found to be different between compliant and non-compliant CL wearers. Patients who were non-compliant with lens replacement were found to attend their ECP’s offices less frequently. Wearers of DDCLs were the most compliant with lens replacement; however, some did report reusing these lenses and sleeping overnight in them. Focus group participants were able to provide a greater insight into why non-compliant behaviour occurs in CL wearers with the most frequently occurring themes identified as the “consequences” that may occur if patients are non-compliant with one or more aspects of their contact lens wear and the importance of receiving “instructions” regarding the most appropriate way to wear and care for their lenses. Most of the themes that emerged from this qualitative research study were both constraints to, and enablers of, compliance. Conclusions: Compliance with contemporary CLs and care products remains poor. Non-compliant behaviour can result in serious complications and patients may not always be aware of this. Careful counseling and education on the risks associated with CL wear is required to provide patients with a better lens wearing experience and continued successful contact lens wear. ECPs and the contact lens industry can hopefully apply this greater understanding of why patients fail to wear and care for their lenses as they should and to help them develop strategies and tools to aid compliance and success in contact lens wear.

Athletic potential is one of the most complex human traits. An elite athlete is produced from a complex interaction of an innumerable number of traits exhibited by the athlete. However, it’s not clear whether these traits are innate, allowing the athlete to excel, or, alternatively, are a consequence of practice. To be successful, athletes rely heavily on sensory information from the visual and vestibular systems. This study investigated the relationship eye movement control has with innate athleticism by comparing the saccadic and Vestibulo-Ocular Reflex (VOR) responses of former, no longer practicing, elite athletes against their age and gender matched counterparts who were non-elite or non-athletes. Results showed subjects who participated in athletic activities longer (regardless of type or level achieved), showed both significantly better VOR suppression capabilities, as well as higher head velocities while suppressing their VOR. Although, these results are correlative in nature, they do not support the potential that VOR suppression is a learned trait of athletes. A longitudinal study would be required to assess this relationship fully.