Ongoing efforts to quantify changes in quality of life attributable to low vision rehabilitation have focused on the utility of a single test instrument to measure this multidimensional concept. It is hypothesized that quality of life is best assessed using multiple instruments to capture some of its component facets, including functional status and psychosocial impact. Low vision devices have a predictably spontaneous impact on functional vision status, but associated psychosocial impact occurs with different magnitudes and over more protracted time intervals. The National Eye Institute Visual Function Questionnaire (NEI VFQ-25) measures the functional status of individuals in key vision areas that are associated with quality of life. The Psychosocial Impact of Assistive Devices Scale (PIADS) is an instrument that measures the psychosocial impact of assistive device intervention in three quality of life domains: competence, adaptability, and self-esteem. 68 participants were obtained from an ongoing parent study. These participants were recruited through the Low Vision Clinic at the University of Waterloo. They had a primary diagnosis of age-related macular degeneration (ARMD) and were obtaining a CCTV system for the first time. Assessments from the parent study used in this thesis included follow-up from 2 weeks, 1 month, 3 months, and 6 months post-adoption of the CCTV. The two tests administered were to measure functional vision status (NEI VFQ-25) and perceived psychosocial impact (PIADS), according the framework outlined by the Consortium for Assistive Technology Outcomes Research (CATOR). Multivariate repeated-measures ANVOA results confirmed that CCTV systems have an immediate and robust effect on the daily visual functioning of their users, and that this effect is stable over long periods of device use. The psychosocial impact of CCTV device use peaks in the shorter term and then seems to wane in the longer term for reasons that are not yet understood. The NEI VFQ-25 and the PIADS appear to have differential sensitivity to important influences on low vision rehabilitation outcomes. This project has demonstrated the value of longitudinal outcomes research in low vision rehabilitation. After obtaining a CCTV, visual function status remains static while psychosocial impact is dynamic during 6-months of follow-up.

Although bevacizumab is one of the most commonly used treatments for DME and AMD, there are concerns regarding safety and effectiveness due to its off-label use. The study objectives were to determine if: 1) the risk of cardiovascular/ hemorrhagic events (safety) and visual impairment (effectiveness) differed by bevacizumab use (i.e., use vs. non-use and number of treatments) among DME and AMD patients; and 2) direct medical costs differed between DME and DME control patients. A retrospective cohort analysis was conducted with Texas Medicaid medical and prescription data (9/1/07-12/31/12) for patients: 18- 63 years, continuously enrolled 1-year pre- and post-index, and diagnosed with DME or AMD. The index date was the first date of diagnosis. The dependent variables were: 1) cardiovascular/hemorrhagic risk; 2) visual impairment; 3) direct medical costs. The independent variables were bevacizumab use and number of bevacizumab treatments. Covariates were disease state, Charlson Comorbidity Index (CCI) score, total medication use, number of laser treatments, and demographics. Propensity scoring technique was used to match: 1) bevacizumab users and non-users; and 2) DME and DME control cohorts. Descriptive analyses, logistic regression, Cox-regression, and generalized linear models were employed. A final cohort of 3,647 DME, 297 AMD, and 57,897 DME control patients were included. The majority (DME and AMD) was between 45-63 years of age (86.6%), Hispanic (54.0%), and female (65.1%). The mean total number of unique medications and mean CCI were 2.7 ± 3.4 and 6.0 ± 3.3, respectively. Total direct medical costs/person (Mean (±SD)) incurred by DME, DME control, and AMD subjects in the post-index period were $6,704(±9,338), $5,495(±10,153), and $4,935(±12,702), respectively. No differences in cardiovascular/ hemorrhagic risk were found between bevacizumab users and non-users. The claims data lacks the detail to determine the effectiveness of bevacizumab. DME control patients had lower overall direct medical costs than DME patients (p<0.0001). In conclusion, although bevacizumab is a less expensive off-label alternative of ranibizumab, the choice between bevacizumab and ranibizumab should be made through careful consideration. However, as the use of anti-VEGF agent increases, further research should be conducted to determine if any changes in cardiovascular adverse events occur. / text

Age-related macular degeneration (AMD) is the leading cause of blindness inAmerica. The fact that AMD wreaks most of the damage in the center of the retina raises the question of whether light, integrated over long periods, is more concentrated in the macula. A method, based on eye-tracking, was developed to measure the distribution of light in the retina under natural viewing conditions. The hypothesis was that integrated over time, retinal illumination peaked in the macula. Additionally a possible relationship between age and retinal illumination was investigated. The eye tracker superimposed the subject’s gaze position on a video recorded by a scene camera. Five informed subjects were employed in feasibility tests, and 58 naïve subjects participated in 5 phases. In phase 1 the subjects viewed a gray-scale image. In phase 2, they observed a sequence of photographic images. In phase 3 they viewed a video. In phase 4, they worked on a computer; in phase 5, the subjects walked around freely. The informed subjects were instructed to gaze at bright objects in the field of view and then at dark objects. Naïve subjects were allowed to gaze freely for all phases. Using the subject’s gaze coordinates, and the video provided by the scene camera, the cumulative light distribution on the retina was calculated for ~15° around the fovea. As expected for control subjects, cumulative retinal light distributions peaked and dipped in the fovea when they gazed at bright or dark objects respectively. The light distribution maps obtained from the naïve subjects presented a tendency to peak in the macula for phases 1, 2, and 3, a consistent tendency in phase 4 and a variable tendency in phase 5. The feasibility of using an eye-tracker system to measure the distribution of light in the retina was demonstrated, thus helping to understand the role played by light exposure in the etiology of AMD. Results showed that a tendency for light to peak in the macula is a characteristic of some individuals and of certain tasks. In these situations, risk of AMD could be increased. No significant difference was observed based on age.

No description available.

The purpose of this project is to find a mathematical model to describe the vision profile of patients after treatment for choroidal neovascularization. In this model the dependent variable is the level of vision which will be predicted by time after treatment and a number of other variables measured before treatment. A standard multiple regression analysis is used to find significant predictor variables, to investigate interactions and an appropriate transformation. To take the correlation of observations on the same patient into account a linear mixed effects model is fitted. Finally the usefulness of a nonlinear mixed effects model is investigated. / Thesis / Master of Science (MS)

Age-related macular degeneration (AMD) is one of the leading causes of blindness in adults over the age of 60. Currently, at least 11 million patients in the United States have some form of macular degeneration and this number is projected to grow as the population ages. The more severe form of the disease – neovascular (wet) AMD, is characterized by intraocular neovascularization, inflammation, and retinal damage; however, the disease progression can be deterred through intraocular injections of anti-angiogenic agents. The complications and burden that arise from repetitive injections as well as the difficulty posed by targeting the posterior segment of the eye make this an interesting territory for the development of novel drug delivery systems. New methods for drug delivery are being investigated exploring the use of nanoparticles and other polymeric materials. The goal of this project is to study the potential use of poly(lactide-co-glycolic acid)-polyethylene glycol (PLGA-PEG) nanoparticles in thermoreversible gels as localized sustained intraocular drug delivery. We prepared stable and reproducible corticosteroid-encapsulated nanoparticles in thermoreversible gels to inhibit vascular endothelial growth factor (VEGF) overexpression characteristic of neovascular AMD. We characterized the drug delivery system by obtaining size, shape, and drug encapsulation data. We also demonstrated that the polymer could be injected into the vitreous as a solution and transition to a gel phase based on the temperature difference between regular indoor environment and the vitreous body. The drug delivery system was tested on human retinal pigment epithelial cells (ARPE-19), for cytotoxicity, uptake and VEGF expression. We also examined the drug delivery system's ability to mitigate the disease progression in a mouse model of choroidal neovascularization (CNV). The effect on blood vessel area was shown and the changes in the mRNA expression of angiogenesis mediators were analyzed by real-time reverse transcription polymerase chain reaction (RT-PCR). These results indicate that the proposed drug delivery systems has the promise to be developed for retinal diseases, involving CNV, including neovascular AMD. Further studies are warranted in developing this promising intraocular drug delivery system for wet AMD and similar ophthalmic diseases. / Ph. D.

Yes / PURPOSE. To compare microperimetric sensitivity around the monocular preferred retinal locus (mPRL) in age-related macular degeneration (AMD) to normative data, and to describe the characteristics of visual field defects around the mPRL in AMD. METHODS. Participants with AMD (total n ¼ 185) were either prospectively recruited (n ¼ 135) or retrospectively reviewed from an existing database (n ¼ 50). Participants underwent microperimetry using a test pattern (37 point, 58 radius) centered on their mPRL. Sensitivities were compared to normative data by spatial interpolation, and conventional perimetric indices were calculated. The location of the mPRL relative to the fovea and to visual field defects was also investigated. RESULTS. Location of mPRL varied approximately 158 horizontally and vertically. Visual field loss within 58 of the mPRL was considerable in the majority of participants (median mean deviation 14.7 dB, interquartile range [IQR] 19.6 to 9.6 dB, median pattern standard deviation 7.1 dB [IQR 4.8–9.0 dB]). Over 95% of participants had mean total deviation worse than 2 dB across all tested locations and similarly within 18 of their mPRL. A common pattern of placing the mPRL just foveal to a region of normal pattern deviation was found in 78% of participants. Total deviation was outside normal limits in this region in 68%. CONCLUSIONS. Despite altering fixation to improve vision, people with AMD exhibit considerable visual field loss at and around their mPRL. The location of the mPRL was typically just foveal to, but not within, a region of relatively normal sensitivity for the individual, suggesting that a combination of factors drives mPRL selection. / This report presents independent research funded by the NIHR

Yes / Purpose: Frequency-of-seeing (FoS) curves (psychometric functions) for perimetric stimuli have been widely used in computer simulations of new visual field test procedures. FoS curves for age-related macular degeneration (AMD) are not available in the literature and are needed for the development of improved microperimetry test procedures, which are of particular interest for use as clinical trial endpoints. Methods: Data were refitted from a previous study to generate FoS curves for 20 participants with AMD, each tested at nine locations within the central 10°. Stimulus parameters, background luminance and dB scale were matched to the MAIA-2 microperimeter, and stimuli were presented in a method of constant stimuli to build up FoS curves over multiple runs. FoS curves were fitted with a modified cumulative Gaussian function. The relationship between sensitivity and slope of fitted FoS curves was modelled by robust linear regression, producing models both with and without an eccentricity parameter. Results: FoS curves were satisfactorily fitted to data from 174 visual field locations in 20 participants (age 65–83 years, 11 female). Each curve was made up of a median of 243 (range 177–297) stimulus presentations over a median of 12 (range 9–32) levels. Median sensitivity was 25.5dB (range 3.8–31.4dB). The median slope (SD of fitted function) was 1.6dB (range 0.5–8.5dB). As in previous studies of other conditions, the slope of fitted FoS curves increased as sensitivity decreased (p<0.001). Conclusions: FoS are provided for participants with AMD, as well as models of the relationship between sensitivity and slope. These fitted models and data may be useful for computer simulation studies of microperimetry procedures. Full details of the fitted curves are provided as supporting information.

Yes / We investigated whether perceptual learning could be used to improve peripheral word identification speed. The relationship between the magnitude of learning and age was established in normal participants to determine whether perceptual learning effects are age invariant. We then investigated whether training could lead to improvements in patients with age-related macular degeneration (AMD). Twenty-eight participants with normal vision and five participants with AMD trained on a word identification task. They were required to identify three-letter words, presented 10° from fixation. To standardize crowding across each of the letters that made up the word, words were flanked laterally by randomly chosen letters. Word identification performance was measured psychophysically using a staircase procedure. Significant improvements in peripheral word identification speed were demonstrated following training (71% ± 18%). Initial task performance was correlated with age, with older participants having poorer performance. However, older adults learned more rapidly such that, following training, they reached the same level of performance as their younger counterparts. As a function of number of trials completed, patients with AMD learned at an equivalent rate as age-matched participants with normal vision. Improvements in word identification speed were maintained at least 6 months after training. We have demonstrated that temporal aspects of word recognition can be improved in peripheral vision with training across a range of ages and these learned improvements are relatively enduring. However, training targeted at other bottlenecks to peripheral reading ability, such as visual crowding, may need to be incorporated to optimize this approach. / This work was supported by a National Institute of Health Research (NIHR) Post Doctoral Fellowship awarded to ATA, an Age UK Studentship awarded to AJB, and a Wellcome Trust Career Development Fellowship awarded to BSW. This article presents independent research funded by the NIHR.

Yes / Microperimetry, also referred to as fundus perimetry or fundus-driven perimetry, enables simultaneous acquisition of visual sensitivity and eye movement data. We present sensitivity data collected from 60 participants with normal vision using gaze-contingent perimetry. A custom designed spatially dense test grid was used to collect data across the visual field within 13° of fixation. These data are supplemental to a study in which we demonstrated a spatial interpolation method that facilitates comparison of acquired data from any set of spatial locations to normative data and thus screening of individuals with both normal and non-foveal fixation (Denniss and Astle, 2016)[1].