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This thesis discusses the research and development of a program to aid the aircraft designer with determining the pilot's visual acuity. The discussion involves the use of Object-Oriented programming, the use of a graphical user interface based upon the graphics standard PHIGS (Programmers Hierarchical interactive Graphics System) and the integration of this Pilot's View Module with an existing aircraft CAD (Computer Aided Design) program known as ACSYNT. The result is a program that lends itself to reuse and easy modification and is device independent. The main purpose of the pilot's view module is to provide total vision plots for the pilot in accordance with the military standards as stated in the document 850B. These standards include visibility design goals for several types of aircraft as well as methods for calculating and presenting the vision plots. The integration of the pilots view module with ACSYNT affords the designer the ability to examine the trade-offs associated with a particular cockpit design and the performance of that design within one CAD program. / Master of Science

The increased reliance on night operations by the military over the last few decades has led to the development of various night imaging devices. Night vision goggles (NVGs) are one device which have gained widespread use in nighttime helicopter operations. However, rotorcraft accident data have indicated an increased occurrence of "pilot error" type accidents when NVGs are in use. NVG related accidents often can be linked to extremely poor ambient lighting and contrast conditions during nighttime operations as well as the imaging limitations of the NVGs. Research has shown that NVGs reduce visual acuity and depth perception when compared to unaided daylight viewing conditions. In this study the effects of illumination and contrast on stereoscopic vision with and without AN/AVS-6 goggles were investigated. Stereoacuity was measured using a modified Howard-Dolman apparatus with four levels of illumination and three levels of contrast. Testing was performed with NVGs for nighttime illuminations and unaided for daytime levels of illumination. Image measurements were performed on the NVGs to determine the impact of illumination on resolution and signal-to-noise ratio. Stereoscopic vision with NVGs was found to be significantly worse than under daylight conditions. Low levels of contrast also were found to reduce stereoacuity significantly. It was found that the worst stereoacuity in this study occurred under half moon or higher illumination levels. This research revealed that further NVG development should focus on the limitations of the NVGs under high light levels, and special considerations should be made for using NVGs in low contrast, high luminance situations. / Master of Science

Yes / Purpose: To determine presenting visual acuity levels and explore the factors associated with failing vision screening in a multi-ethnic population of UK children aged 4–5 years. Methods: Visual acuity (VA) using the logMAR Crowded Test was measured in 16,541 children in a population-based vision screening programme. Referral for cycloplegic examination was based on national recommendations (>0.20logMAR in one or both eyes). Presenting visual impairment (PVI) was defined as VA >0.3logMAR in the better eye. Multivariable logistic regression was used to assess the association of ethnicity, maternal, and early-life factors with failing vision screening and PVI in participants of the Born in Bradford birth cohort. Results: In total, 2467/16,541 (15%) failed vision screening, 732 (4.4%) had PVI. Children of Pakistani (OR: 2.49; 95% CI: 1.74–3.60) and other ethnicities (OR: 2.00; 95% CI: 1.28–3.12) showed increased odds of PVI compared to white children. Children born to older mothers (OR: 1.63; 95% CI: 1.19–2.24) and of low birth weight (OR: 1.52; 95% CI: 1.00–2.34) also showed increased odds. Follow-up results were available for 1068 (43.3%) children, 993 (93%) were true positives; 932 (94%) of these had significant refractive error. Astigmatism (>1DC) (44%) was more common in children of Pakistani ethnicity and hypermetropia (>3.0DS) (27%) in white children (Fisher’s exact, p < 0.001). Conclusions: A high prevalence of PVI is reported. Failing vision screening and PVI were highly associated with ethnicity. The positive predictive value of the vision screening programme was good, with only 7% of children followed up confirmed as false positives. / National Institute for Health Research Post-Doctoral Fellowship Award (PDF-2013-06-050); The Born in Bradford study presents independent research commissioned by the National Institute for Health Research Collaboration for Applied Health Research and Care (NIHR CLAHRC) and the Programme Grants for Applied Research funding scheme (RP-PG-0407-10044).

Yes / Purpose: To investigate how well visual field sensitivity predicts visual acuity at the same locations in macular disease, and to assess whether such predictions may be useful for selecting an optimum area for fixation training. Methods: Visual field sensitivity and acuity were measured at nine locations in the central 10° in 20 people with AMD and stable foveal fixation. A linear mixed model was constructed to predict acuity from sensitivity, taking into account within-subject effects and eccentricity. Cross validation was used to test the ability to predict acuity from sensitivity in a new patient. Simulations tested whether sensitivity can predict nonfoveal regions with greatest acuity in individual patients. Results: Visual field sensitivity (P < 0.0001), eccentricity (P = 0.007), and random effects of subject on eccentricity (P = 0.043) improved the model. For known subjects, 95% of acuity prediction errors (predicted − measured acuity) fell within −0.21 logMAR to +0.18 logMAR (median +0.00 logMAR). For unknown subjects, cross validation gave 95% of acuity prediction errors within −0.35 logMAR to +0.31 logMAR (median −0.01 logMAR). In simulations, the nonfoveal location with greatest predicted acuity had greatest “true” acuity on median 26% of occasions, and median difference in acuity between the location with greatest predicted acuity and the best possible location was +0.14 logMAR (range +0.04 to +0.17). Conclusions: The relationship between sensitivity and acuity in macular disease is not strongly predictive. The location with greatest sensitivity on microperimetry is unlikely to represent the location with the best visual acuity, even if eccentricity is taken into account. / College of Optometrists Postdoctoral Research Award (JD and ATA; London, UK) and National Institute for Health Research (NIHR) Postdoctoral Fellowship (ATA; London, UK). Presents independent research funded by the NIHR. / Research Development Fund Publication Prize Award winner, August 2018.

Yes / Large changes in spectacle prescription can increase falls risk in older people. We investigated the effect of induced astigmatism (a common cause of distorted or blurred vision in older people) on locomotor stepping patterns to determine whether the orientation of astigmatic changes could have differential effects on gait safety when negotiating steps and stairs. Methods 10 older adults (mean age 76.0±6.4 years) walked up to and stepped onto a raised block whilst wearing their spectacle prescription and when blurred with ±3.00D cylinders at axes 45°, 90°, 135° and 180°. Gait measurements included foot placement before the block, toe clearance over the block edge and foot placement on the block. Results Induced astigmatism with axes at 90°, providing magnification in the horizontal meridian only, caused no change in stepping pattern. Induced astigmatism with axes at 180° caused foot placement changes in the anterior or posterior direction according to whether magnification was positive or negative in the vertical meridian (block perceived higher or lower respectively). Induced astigmatism with axes oblique at 45° and 135° (causing the block to be perceived as a parallelogram sloping downwards either to the right or left) caused gait changes in the anterior and posterior, vertical and lateral directions. Changes in lateral foot placement appeared to be an attempt to maintain constant foot clearance levels over the block edge by stepping over the perceived ‘lower’ side of the ‘sloping’ block. Conclusions Astigmatic changes with oblique axes had the greatest effect on gait. Clinicians, including optometrists, physiotherapists, occupational therapists and nurses should counsel older patients about the effects of astigmatism on gait safety. Furthermore, partial prescribing of astigmatic corrections should be considered to reduce the risk of falling.

This research is about evaluating vision in the periphery. Peripheral vision is of fundamental importance in the performance of our everyday activities. The aim of this thesis is to develop methods suitable for the evaluation of peripheral vision and to assess how different visual functions vary across the visual field. The results have application both within the field of visual rehabilitation of people with central visual field loss (CFL)and as well as in myopia research. All methods for assessing peripheral vision were implemented with adaptive psychophysical algorithms based on Bayesian statistics. A routine for time-efficient evaluation of peripheral contrast sensitivity was implemented and verified for measurements out to 30° in the visual field. Peripheral vision was evaluated for different properties of the stimuli: sharpness, motion, orientation, and extent. Optical quality was controlled using adaptive optics and/or corrective spectacles specially adapted for the peripheral viewing angle. We found that many peripheral visual functions improved with optical correction, especially in people with CFL. We also found improvements in peripheral contrast sensitivity for low spatial frequencies when stimuli drifted at 5 to 10 Hz; this applies both for people with normal vision and those with CFL. In the periphery, it is easier to see lines that are oriented parallel with respect to the visual field meridian. We have shown that this directional bias is present for both resolution and detection tasks in the periphery, even when the asymmetric optical errors are minimized. For accurate evaluation of peripheral vision, we therefore recommend using gratings that are oriented oblique to the visual  field meridian. The directional bias may have implications in how peripheral image quality affects myopia progression. Another proof that peripheral vision can influence central visual function is the fact that, when the stimulus extent was increased beyond the fovea, the blur in the stimulus was less noticeable. / Denna forskning handlar om att utvärdera synen i periferin. Vår perifera syn är ovärderlig i det dagliga livet. Målsättningen med denna avhandling är dels att utveckla metoder speciellt lämpade för perifer synutvärdering och dels att mäta hur olika synfunktioner varierar över synfältet. Resultaten har tillämpning både inom synrehabilitering för personer med centraltsynfältsbortfall och inom närsynthetsforskning. Adaptiv psykofysisk metodologi baserad på Bayesiansk statistik användes vid all utvärdering av det perifera seendet. Vi implementerade en rutin för tidseffektiv mätning av perifer kontrastkänslighet och verifierade den ut till 30° i synfältet. Den perifera synen utvärderades för olika egenskaper hos objektet: skärpa, rörelse, riktning och utbredning. Skärpan kontrollerades med hjälp av adaptiv optik och/eller glasögonkorrektion speciellt anpassad för den perifera synvinkeln. Vi fann att många periferasynfunktioner förbättras av optisk korrektion, särskilt för personer med centralt synfältsbortfall. Vi hittade även förbättringar i periferkontrastkänslighet för låga ortsfrekvenser när objektet modulerades med hastigheter mellan 5 och 10 Hz, vilket gäller både normalseende och personer med centralt synfältsbortfall. I periferin är det lättare att se linjer som är orienterade parallellt med synfältsmeridianen. Vi har visat att denna riktningsbias gäller både för upplösning och detektion i periferin, även när de asymmetriska optiska felen minimeras. För bästa mätnoggrannhet rekommenderar vi därför att använda randmönster som ligger snett relativt synfältsmeridianen. Denna riktningsbias skulle även kunna påverka hur den perifera bildkvalitén inverkar på utvecklingen av närsynthet. Ytterligare ett bevis för att perifer syn kan påverka den centrala synfunktionen är att, när objektets utbredning ökades, uppfattade personen det som mindre suddigt. / <p>QC 20160826</p>

Os primeiros meses de vida são críticos para o desenvolvimento normal do sistema visual. Nesse período, os recém-nascidos desenvolvem habilidades visuais, algumas delas presentes ao nascimento, que serão refinadas durante a infância e utilizadas ao longo de toda a vida. A literatura mostra que em recém-nascidos as habilidades visuais, como fixação visual e acuidade visual, são desenvolvidas em períodos diferentes. Embora o desenvolvimento da acuidade visual seja semelhante entre recém-nascidos prematuros e termos quando se considera a idade corrigida para a prematuridade (IGc), ou seja, o tempo em semanas que o recém-nascido teria se nascesse com 40 semanas, não se sabe ao certo como se desenvolvem outras habilidades que dependem do sistema visual nesses recém-nascidos. O presente estudo, de caráter observacional, avaliou o desempenho visual através da medida do tempo de fixação visual para a face humana, baseado nos estímulos desenvolvidos por Fantz - face construída com padrões internos semelhantes à face humana (FC) e face desconstruída com padrões internos que não formavam face humana (FD), mas com contraste e luminância idênticos à face construída. Foram incluídos no estudo apenas os recém-nascidos com acuidade visual de resolução de grades, medida através dos cartões de Teller, dentro do esperado para a idade corrigida. Os participantes foram 50 recém-nascidos, 21 (idade média = 13,1 ± 7,1 semanas; peso ao nascimento = 3109 ± 468,9 g), nascidos a partir de 37 semanas de gestação (termo; idade média = 39,1 ± 1,2 semanas), e 29 (idade média = 11,1 ± 6,8 semanas; peso ao nascimento = 1544,3 ± 505,5g), nascidos antes de 37 semanas de gestação (prematuros; idade média = 31,7 ± 2,6 semanas). Os recém-nascidos foram avaliados no Setor de Neonatologia e Pediatria do Hospital Universitário da Universidade de São Paulo (HU-USP) e no Serviço de Neonatologia e Pediatria do Hospital das Clínicas de São Paulo (HCFMUSP). Durante a avaliação os recém-nascidos eram posicionados no bebê conforto, semi-elevados frente a um anteparo que impedia visualização do entorno para o teste de fixação das características faciais e no colo do responsável durante o teste de acuidade visual de Teller. O tempo médio de fixação à FC (termo = 56,9 ± 54,4 segundos; prematuros = 49,3 ± 42,8 segundos) e à FD (termo = 34,8 ± 41,5 segundos; prematuros = 44,1± 31,1 segundos) foi semelhante para recém-nascidos a termo e prematuros (FC: p = 0,723 e FD: p = 0,637). Entretanto, o tempo de fixação à FC foi estatisticamente superior (p = 0,014) ao tempo de fixação à FD para os recém-nascidos a termo, enquanto prematuros apresentaram tempos semelhantes (p = 0,75). A atenção às características faciais humanas possui papel fundamental no contexto diário dos recém-nascidos, pois influencia o desempenho de algumas habilidades que serão desenvolvidas posteriormente, como a comunicação e a interação visual, o reconhecimento de objetos, a resposta social e a orientação espacial. Os resultados do presente estudo mostram que contrariamente aos recém-nascidos a termo cuja preferência pela face humana construída é estatisticamente maior que pela face desconstruída, recém-nascidos prematuros não apresentam preferência pela face humana construída. Os achados indicam os efeitos da prematuridade na fixação à face humana e ressaltam a importância de se identificar alterações em habilidades que poderiam ser estimuladas precocemente / The first months of life are critical for the normal development of the visual system. In this period, newborns develop visual skills, some of which are present at birth, which will be refined during childhood and used throughout the life. The literature shows that in newborns some visual abilities, such as visual fixation and visual acuity, are developed in different periods. Although the development of visual acuity is similar between preterm newborns and terms when considering the corrected age for prematurity (the time in weeks that the newborn would have been born at 40 weeks), the development of other abilities that depend on the visual system in these preterm newborns is unknown. The present observational study evaluated visual performance by measuring the time of visual fixation to the human face, based on the Fantz real face with internal patterns similar to the human face and scrambled face with internal patterns that do not form a face, but with contrast and luminance identical to the real face. Only newborns with visual acuity as expected for the corrected age, as measured by Teller cards, were included in the study. Participants were 50 infants, 21 (mean age = 13.1 ± 7.1 weeks, birth weight = 3109 ± 468.9g) born after 37 weeks gestation (terms, mean age = 39.1 ± 1.2 weeks), and 29 (mean age = 11.1 ± 6.8 weeks, birth weight = 1544.3 ± 505.5g), born before 37 weeks gestation (preterms, mean age = 31, 7 ± 2.6 weeks). The newborns were evaluated in the Neonatology and Pediatrics Sector of the University Hospital (HU-USP) and in the Neonatology and Pediatrics Service of the Hospital das Clinicas de São Paulo (HCFMUSP) at the University of São Paulo. During the evaluation the newborns were placed in the comfort baby, semi-elevated against a bulkhead that prevented visualization of the surroundings to test the time of fixation for the facial characteristics and in the lap of his/her responsible during the visual acuity test. The mean fixation time to the real face (term = 56.9 ± 54.4 seconds, premature = 49.3 ± 42.8 seconds) and to the scrambled face (term = 34.8 ± 41.5 seconds, preterm = 44.1 ± 31.1 seconds) was similar for term and preterm newborns (p = 0.723 and FD: p = 0.637). However, the fixation time to the real face was statistically superior (p = 0.014) to the fixation time to the scrambled face for term newborns, whereas preterm infants presented similar times (p = 0.75). Fixation to human facial features plays a key role in the daily context of newborns, as it influences the performance of some skills that are in development, such as communication and visual interaction, object recognition, social response and spatial orientation. The results of the present study show that, contrary to the term newborns whose preference for the real human face is significantly higher than the scrambled face, preterm newborns have no preference for the real human face. The findings indicate the effects of prematurity on fixation to the human face and emphasize the importance of identifying changes in abilities that could be early stimulated