Optometry and Vision Science

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This is the collection for the University of Waterloo's School of Optometry and Vision Science.

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Development of Form Visual Acuity in Infants Measured by Schematic Faces
(University of Waterloo, 2018-10-05) Alkanhal, Norah; Leat, Susan; Irving, Elizabeth
Purpose The purpose of this thesis was 1) to develop a test of visual acuity (VA) to measure recognition (form) acuity at a younger age than is currently clinically possible (3 years). Currently, it is only possible to measure resolution (grating) VA in this age group. 2) To validate infant’s recognition VA tests against gold standard ETDRS VA in adults. 3) To test the feasibility of using infant’s recognition VA tests to measure VA in infants 16 - 42 months of age in terms of the testability and ability to measure VA. Methods Preliminary study 1 – Development of Face targets: Adults participated and visual acuity for various versions of face targets were tested under blur in comparison to ETDRS or Tumbling E optotypes. The face targets were successively modified in six trials until the optimal agreement with ETDRS and Snellen Tumbling Es was obtained. Preliminary study 2 (Infants aged 3-15 months): In experiment 1, suprathreshold pairs of targets consisting of happy faces vs scrambled faces or happy faces vs dotted-target were presented either on preferential looking cards or on a computer screen with a non-contact gaze tracker. Percent accurate fixation towards the face compared to the non-face was observed by a naïve observer. In a second phase, habituation for the non-face stimuli were used in which the non-face target was presented twice before each face/non-face pair. Validation study (adults): A series of acuity cards with logarithmic progression in spacing and size (1.3 to -0.1 logMAR) designed for a 60 cm test distance was created. The Face Cards had a smiley face and a dotted target as optotypes. Patti Pics Cards used the house and the circle. Recognition VA was measured with Face Cards, Patti Pics Cards, and near ETDRS chart monocularly, in a counter-balanced order under 3 conditions of optical blur; +4.00D, +2.50D and no blur. Feasibility study (infants aged 16-42 months): Testability and form VA threshold were measured in infants on 2 visits using the Face Cards and Patti Pics Cards in a counter-balanced order. After initial training to point at the target stimulus (face or house), testability was measured using 30M target size with 3/4 correct responses as the criterion to be considered testable. If the infant was testable, two alternative forced choice VA measurement followed using a two down one up staircase procedure. For reference, testability for matching with the Patti Pics and VA with the Cardiff cards were measured. Results Preliminary study 1 – Development of Face targets: The modified border simple face was chosen as most suitable in terms of its apparent appeal as a face and similar results to ETDRS and tumbling Es. Preliminary study 2: Infants aged 3-15 months Eight infants took part in Phase 1 (median age 10.5 months, range 8.5 – 14 months). The percentage of correct looks with the eye tracker was not significantly different from 50% with either the cards or the eye tracker. Eleven infants participated in Phase 2 (median age 11.5 months, range 3.5 – 15 months). Percent correct looks was not significantly better with habituation. Validation study (adults): Twenty-two participants took part in this experiment, age range was 22 - 35 years, median age was 27 years. Repeated measure ANOVA showed a significant effect of VA method for all levels of blur (p<0.05). Post-hoc analysis showed that Patti Pics Cards gave significantly better VA than ETDRS and compared to Face Cards, but there was no significant difference between Face Cards and ETDRS. The same pattern of differences was found for all levels of blur. Feasibility study: (infants aged 16-42 months): Seventeen infants took part in this study, median age was 27 months. Testability of Face Cards was 70.5%, while the testability of the Patti Pics Cards and matching Patti Pics were both 64.7%. All participants aged ≥26 months could perform all three tests, including a VA result. Among infants in whom a measure of VA was obtained, a significant difference was found between Face Cards and Cardiff Cards (mean difference 0.35 logMAR, p=0.0007) and between Patti Pics Cards and Cardiff Cards (0.2 logMAR, p=0.049), while no significant difference was found between Face Cards and Patti Pics Cards (0.15 logMAR, p=0.15). Correlation between age and VA was; Face Cards r = 0.76 (p = 0.006), Patti Pics Cards r = 0.8 (p = 0.003), Cardiff Cards r = 0.72 (p = 0.001). Conclusion The preference for faces, even with habituation, was not sufficiently strong in babies aged 3 – 15 months to use for recognition visual acuity measurement. A pointing paradigm appears to have potential for children between 26 months and 3 years with either Face/non-face targets or Patti Pics symbols. However, in adults, Face Cards give VA more similar to ETDRS acuity than Patti Pics Cards and may provide a valuable alternative method for measuring recognition VA in young children. Recognition acuity increased with age over the infant range at a faster rate than resolution acuity.
Efficacy of Vision Screenings in Waterloo Region
(University of Waterloo, 2025-01-22) McKinney, Marisa; Christian, Lisa; Irving, Elizabeth
Purpose: In 2018, the province of Ontario (Ontario) mandated a universal vision screening program for all senior kindergarten (SK) children (age 4-6 years). The purpose of the vision screening program is to detect children with risk factors for amblyopia, strabismus, and/or high refractive errors. The overarching aim of this thesis is to evaluate the effectiveness of Ontario’s universal vision screening program for SK children and how accurate the program is in identifying vision problems. These objectives are explored through two studies: parental adherence to vision screening recommendations survey, and investigation of the ability of Ontario’s vision screening program in identifying a SK child with a vision problem combined with determination of overall referral rates. Methods: All parents/guardians (parents) of SK students who participated in Ontario’s vision screening program in the Region of Waterloo (ROW) from October 2022 to December 2023 were invited to participate in the initial study to evaluate parental compliance to vision screening recommendations and barriers to seeking vision care. Following the first study, parents who reported taking their child to an optometrist following the vision screening were invited to participate in a follow-up study, evaluating the program sensitivity and specificity and overall screening accuracy. For the second study, the vision screening results were compared to the eye exam results, and all vision screening data (visual acuity, stereoacuity and autorefraction) for children who participated in the 2022-23 vision screening program were analyzed to determine the screening program’s overall referral rate and for all three screening tools. Results: 108 parents from 67 schools in the ROW responded to the survey to evaluate parental compliance in seeking vision services following the screening. The results of the survey found that over half (58/108, 54%) of the children screened were already under the care of an optometrist prior to the screening and less than half (48/108, 44%) of parents were prompted to obtain eye care, including 25% (27/108) who had already had a previous optometric examination. For the follow-up study that examined vision screening accuracy, 65 individuals participated. The vision screening program demonstrated a sensitivity of 0.935 and specificity of 0.406, producing a high rate of false positives (30%). Paired t-tests revealed significant differences in the accuracy of the vision screening tools compared with eye exam findings, particularly for refraction – sphere (OD: p = 0.005, OS: p < 0.001), cylinder (OD: p = < 0.001, OS: p < 0.001), and spherical equivalent (OD: p = 0.016, OS: p = 0.004). The retrospective review of the screening data included a total of 4837 vision screening results from 135 schools in ROW. The screening had an overall referral rate of 54% (2606/4837) and children were most commonly referred for autorefraction (43%; 2099) results followed by stereoacuity (31%; 1510). Conclusion: This analysis of Ontario's vision screening program for SK children in the ROW highlighted key findings. The program was effective at encouraging parents that received a refer to go to the optometrist (64%), though 31% of all parents misreported screening results, suggesting a need for clearer communication. The program showed high sensitivity (0.935) but low specificity (0.406), with a 54% referral rate and 30% false positives which may contribute to lack of public trust over time. Adjusting referral criteria based on evidence could reduce false positives.
Ocular Perfusion Pressure in Spaceflight-Associated Neuro-Ocular Syndrome
(University of Waterloo, 2020-10-26) Mohiar, Yara; Irving, Elizabeth
Purpose: Spaceflight associated neuro-ocular syndrome (SANS) is considered by the National Aeronautics and Space Administration (NASA) as one of the most significant barriers to long term space exploration (Larkin, 2018). Its main features include posterior globe flattening, hyperopic shifts, choroidal and retinal folds, cotton wool spots, and optic disc edema (Lee, Mader, Gibson, Brunstetter, & Tarver, 2018). Currently, it is confined to males and its cause remains unknown (Mader et al., 2011). While there are terrestrial diseases with features similar to SANS, none of them completely match the syndrome. Understanding the mechanisms of these diseases as well as the relationship between IOP, eye size, gravity, ocular and systemic fluid dynamics, and ICP is vital to understand and develop ways to prevent, modulate, and treat SANS. A relatively new and unexplored possible contributor to SANS is ocular perfusion pressure (OPP). The purpose of this thesis is threefold: (1) To explore the effect of head-down tilt (HDT); a popular analog for spaceflight, on OPP, (2) to determine the effect of HDT on IOP, and (3) to determine the effect of sex on OPP and IOP. We hypothesize that OPP and IOP will vary in a statistically significant way with body position and sex. Methods: The right eye’s IOP was measured by Tonopen XL and mean arterial pressure (MAPheart) was measured continuously by the Finapres Nova System’s finger cuff which recalculated blood pressure at the brachial artery. To calculate MAPeye, MAPheart and the distance between the heart and eyes were obtained for 10 participants. Measurements were taken in 4 body positions: sitting, supine, 12° HDT and 30° HDT. Participants (19-41 years old) spent 5 minutes in the first two positions and approximately 25 minutes in the last two tilts. OPP was calculated for the various body positions. Additionally, available non-invasive ICP measures for 9 of the participants were examined in relation to OPP and IOP. Data were analyzed through a mixed ANOVA. Outcome variables were: OPP, IOP, MAPheart, MAPeye, ICP and translaminar pressure difference (TLPD) for the IOP/ICP mismatch. Results: Six men and four women completed the experiment. OPP & IOP were found to significantly increase with tilt angle (P< 0.001) statistically. OPP increased from 55.26 at baseline to 86.7 at 30° HDT while IOP increased from 14.1 to 22.2 at 30° HDT. We also found a statistically significant IOP/ICP mismatch (p= 0.013) between 12° HDT and 30° HDT as TLPD decreased by 10.24 at the last tilt. Within the power of our sample sex had no statistically significant effect on any variable (p> 0.05). Conclusions: Our findings show that OPP increases sufficient to compromise autoregulation do occur with change in body posture indicating a possible mechanism for the observed ocular changes that occur during spaceflight. In addition, it appears that an IOP/ICP mismatch may occur at high levels of tilt. However, as our findings are acute, further investigation is needed to determine long-term effects of HDT on OPP as well as the effects of lower body negative pressure (LBNP) devices and the minimum duration LBNP that would be required to protect the eyes.
The Optometric Management of Concussion
(University of Waterloo, 2022-01-31) Yeboah, Anne Marie; Dalton, Kristine; Irving, Elizabeth
Traumatic brain injury is a major public health problem that affects millions of people annually and hundreds of people experience brain injury daily. Many of these individuals develop visual symptoms. Optometrists play a prominent role in the management of patients with concussion-associated vision deficits and persistent concussion symptoms. At present, there is no accepted optometric standard of care for individuals with concussion. Patients receiving optometric concussion related care would benefit from a standardized evidence-based concussion management process. The purpose of this project was to determine the current assessment methods and prescribing practices of optometrists seeing individuals with persistent concussion-associated vision deficits in private practice and at a university academic optometry clinic. Study 1: A retrospective review examined the frequency of visual assessments and management strategies at an academic university optometry clinic. A total of 238 patient files were examined. Of the 238 patient files, 119 individuals had persistent concussion symptoms (concussed group) and 119 individuals did not have concussion (non-concussed cohort). The frequency of visual assessments (ocular structure and visual function) and management strategies were determined. A chi square test was used to compare the frequency of assessments and management strategies between cohorts. In the concussed group, an emphasis on visual function and management strategies, for example assessments of vergence, saccades, pursuits and stereopsis were observed in comparison to the reference group. In non-concussed individuals, ocular structure assessments (e.g., posterior segment, anterior segment and confrontation visual field) were more prevalent than in the concussed cohort. It is important to note that ocular structure assessments did not include assessments conducted by the referring optometrists. Diagnostic drugs, for example tropicamide and anesthetics, were used more commonly in the non-concussed group, while cycloplegia was more prevalent in the concussed group. Study 2: A 6-question online survey was distributed to optometric provincial and national regulators and associations in Canada. Questions pertaining to visual assessments, prescribed medications and supplements, advice about daily living activity, appointment duration and appointment follow-up were asked. Analysis consisted of binning and determining the frequency of responses. Of the 199 responses received, 142 were completed and analysis was only conducted from these responses. A total of 128 optometrists managed concussion and 13 optometrists did not. The top reasons for optometrists who did not manage concussion was referral and no training. Ocular structure assessments were more prevalent than visual function and management strategies of concussion. Optometrists most frequently recommended Omega 3 (54%) and oral supplements (38%). The majority of optometrist’s (64%) advice on daily living activity was to limit physical and cognitive activity, the second most common suggestion was to rest (12%). The majority of optometrists, 57%, employed 30 to 60-minute assessments and over one-fifth conducted follow-up appointments within 2-months. Conclusion: This project informs optometrists on the state of concussion management in Canadian private practice and at a university academic optometry clinic. Findings can be used to aid in the development of standardized strategies for the optometric management of concussion and related regulatory decisions. This can lead to reductions in persistent post-concussive symptoms, improved patient outcomes, and overall improved quality of life.
Optometry Outreach in Indigenous Communities in British Columbia, Saskatchewan, and Manitoba
(University of Waterloo, 2023-08-31) Warren, Adrianna; Woo, Stanley; Irving, Elizabeth
Introduction: Inuit, Métis, and First Nations, the three main Indigenous groups within Canada, face disproportionate barriers to access for primary eye and vision care. Optometrists visit rural and remote Indigenous communities to provide outreach care to areas without a local optometrist; however, the approach is fragmented and not well represented. The purpose of this project is to assess the current state of outreach optometry within Indigenous communities by surveying optometrists who provide outreach care. Methods: In collaboration with the provincial optometry regulatory bodies, eligible participants were identified as optometrists who travel outside of their primary clinics to provide care within non-urban Indigenous communities. A questionnaire was developed through iterative stakeholder review for phase I of the study. The online questionnaire captured the delivery of care across one year (2022). The process of planning logistics, distances travelled, patient care provided and associated expenses were queried. A Semi-structured interview guide was developed for phase II of the study. One-on-one interviews expanded on questionnaire themes, providing insight into individual experiences. Data was collated through descriptive statistics and thematic coding for case and cross-case analysis. Results: The overall response rate was 50% (18/36) for the questionnaire and 30.5% (11/36) for the interview. Total questionnaire responses represent 96 outreach visits, 312.5 optometry clinic days, and 8,386 patient encounters across 64 communities in the three provinces. Optometrists coordinate with health center employees and school contacts to plan outreach visits, travelling primarily north to some of the most remote areas within each province. Overall Euclidean distances between participants primary clinic locations and communities visited ranged from 65 to 1405 kilometers (kms) (median: 438 kms). Costs per clinic day were highly variable ($174.44 - $3,800, mean: $765 per clinic day). Challenges reported were related to logistics, economic burden, and organizational challenges. Complementary enablers were identified, and recommendations are provided. Conclusions: This study is the first to provide visibility to the current state of outreach optometry care to Indigenous communities in British Columbia, Saskatchewan, and Manitoba. The process of planning outreach visits was variable for individual optometrists and between provinces. High variability in reported costs associated with outreach visits requires additional investigation. Multi-stakeholder collaboration to support optometry outreach programming would encourage outreach participation and improve services towards reducing eye and vision health inequity experienced by non-urban Indigenous populations. Acknowledgements: Project supported by Anonymous Philanthropic Foundation, Canadian Institute for Health Research Canadian Graduate Scholarship, and Canadian Optometric Education Trust Fund. No conflicts to declare.
Understanding concussion in para athletes with vision impairment
(University of Waterloo, 2023-02-15) Teodoro, Juliette; Dalton, Kristine; Irving, Elizabeth
Sports-related concussions occur in para sport as they do in able-bodied sport. There is evidence to suggest athletes with vision impairment (VI) may be more likely to sustain concussion injuries compared to athletes with other impairment types. However, there is limited understanding of best practices in concussion assessment and management for athletes with VI. Symptoms intrinsic to pre-existing conditions in para athletes are also commonly seen in athletes suffering from a concussion, which makes the assessment and management of concussion more challenging in the para athlete population. Perspectives and experiences of VI para sport athletes and coaches with concussion are also poorly understood. The purpose of this project was to understand how concussions are currently assessed and managed in elite para athletes with vision impairment, to move toward establishing clinical practice guidelines and critical research priorities in concussion management for elite athletes with VI. The secondary objective of this thesis was to understand the perspectives, experiences, and knowledge of elite athletes with VI and coaches concerning concussion in VI para sport. A two-round Delphi study was conducted to solicit the opinions of healthcare professionals, researchers, and administrators in VI para sport concerning concussion assessment and management practices. Eight out of the nine interested participants completed the first-round survey; seven of those completed the second-round survey. Five out of eight participants were sports medicine physicians, and the remaining three participants had a background in physical therapy. Experts identified that VI athletes may exhibit different observable signs of concussion (e.g., lack of blank look, balance issues at baseline, etc.) compared to able-bodied athletes. Experts unanimously agreed that pre-season baseline testing is necessary for para athletes with VI. While most experts (86%) agreed the SCAT5 currently represents the most effective assessment tool available for the evaluation of suspected concussion, one expert disagreed and explained that the SCAT5 is too complex for regular sideline use. Some experts suggested prescribing a longer period of initial rest or doubling the time between return-to-sport steps for athletes with VI. Experts came to a unanimous consensus that there is a lack of after-care in VI para sport in addition to the lack of on-site specially trained medical support. Elite para athletes with VI and coaches were invited to participate in a single-round survey study. The survey questions covered the following topics: Demographics; Concussion incidence, recognition, response, assessment, and management; Return-to-sport; and Education. Analysis consisted of categorizing written responses and analyzing response frequencies. A total of 8 participants (athletes (n = 4); coaches (n = 4)) from elite VI para sport took part. Athletes were found to have less awareness of medics at sidelines, assessment tools, how decisions are made to investigate for concussion, and the need for concussion assessments than coaches. Athletes were also more likely to not report incidents with reasons for not reporting including “don’t think it’s serious”, “time and money”, and “misdiagnosis because of underlying conditions”. Coaches are not considering athlete involvement in return-to-play decisions. Athletes and coaches agreed that it is important for medical professionals to have concussion education but differ on the need for education of athletes and guides. Athletes reported having little and poor quality concussion education. Future investment in the provision of specially trained on-site medical support is needed to ensure the safety and well-being of VI para athletes. Education strategies should prioritize informing para athletes of the potential long-term consequences of concussion, so they understand the significance of failing to report concussion symptoms and of neglecting concussion injury protocol.

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