Comparing paediatric optometric vision care in Canada over a 14-year period.

PURPOSE: In Canada, teaching in paediatric eye care has increased in the past decade both within the optometry curriculum and as continuing education to optometrists. Paediatric vision care guidelines have also been established by North American optometric associations. This study examined whether this exposure was associated with changes in paediatric eye care in Canada over a 14-year period. METHODS: Canadian optometrists were invited to participate in an anonymous 35-item survey in 2007 and 2021. The surveys sought to investigate optometrist's recommendations for first eye examinations, the number of paediatric patients seen in a typical week and preparedness to provide eye examinations to children. Response frequencies were determined for each survey item. RESULTS: Across Canada, 133/1000 (13.3%) and 261/~6419 (~4.1%) optometrists responded to the survey in 2007 and 2021, respectively. No significant difference was found in the number of years practicing, days per week in practice and total number of patients seen per week. The modal age optometrists recommended children be seen for their first eye examination changed from 3-4 years in 2007 (53%) to 6-12 months in 2021 (61%). In 2007, 87% of respondents provided eye examinations to children <2 years, increasing to 94% in 2021 (p = 0.02). Despite a reduction in the recommended age between the two survey years, the most frequent age children were seen for their first eye examination was 3-4 years (30% in both surveys) and the most common age seen in a typical week remained unchanged (4-6 years-56% 2007; 66% 2021). CONCLUSION: Although optometrists' willingness to provide paediatric eye care increased over the past 14 years, the number of children seen in a typical week did not change. Barriers to determine why more children are not being seen at an earlier age need to be investigated.

Trust and Access: Eye Information-seeking Practices and Preferences among Canadians.

SIGNIFICANCE: This study highlights the value that the public places on obtaining trusted and accessible health-related information and their preference for obtaining it from their health care practitioners. Previous research has not been specific to Canadians or vision. Findings can be used to increase eye health literacy and eye care utilization. PURPOSE: Canadians underuse eye care and underestimate the occurrence of asymptomatic eye disease. This study explored eye information-seeking practices and preferences among a group of Canadians. METHODS: Using snowball sampling, a 28-item online survey collected respondent perceptions about their eye and health information-seeking practices and preferences. Questions examined electronic device access, information source use, and demographics. Two open-ended questions examined information-seeking practices and preferences. Respondents were at least 18 years old and living in Canada. Individuals working in eye care were excluded. Response frequencies and z scores were computed. Written comments were assessed using content analysis. RESULTS: Respondents searched for less eye than health information ( z scores ≥ 2.25, P < .05). For eye and health information, primary care providers were the used and preferred source, and reliance on Internet searches was greater than desired. Trust and access drove information-seeking practices. Respondent comments suggested that a hierarchy of trust operates across My Health Team, My Network, and My External Sources, with a persistent threat posed by Discredited Sources. Access to information sources seemed mediated by enablers (Convenience and Accessible Features) and barriers (Unreachable Health Team and Absent Systems). Eye information was seen as more specialized and harder to find. There was a high regard for health care practitioners who provide their patients with curated trusted information. CONCLUSIONS: These Canadians value trusted and accessible health-related information. They prefer eye and health information from their health care practitioners and value when their health team provides online curated information, particularly regarding eyes.

Investigation of Camera-Free Eye-Tracking Glasses Compared to a Video-Based System.

Technological advances in eye-tracking have resulted in lightweight, portable solutions that are capable of capturing eye movements beyond laboratory settings. Eye-tracking devices have typically relied on heavier, video-based systems to detect pupil and corneal reflections. Advances in mobile eye-tracking technology could facilitate research and its application in ecological settings; more traditional laboratory research methods are able to be modified and transferred to real-world scenarios. One recent technology, the AdHawk MindLink, introduced a novel camera-free system embedded in typical eyeglass frames. This paper evaluates the AdHawk MindLink by comparing the eye-tracking recordings with a research "gold standard", the EyeLink II. By concurrently capturing data from both eyes, we compare the capability of each eye tracker to quantify metrics from fixation, saccade, and smooth pursuit tasks-typical elements in eye movement research-across a sample of 13 adults. The MindLink system was capable of capturing fixation stability within a radius of less than 0.5∘, estimating horizontal saccade amplitudes with an accuracy of 0.04∘± 2.3∘, vertical saccade amplitudes with an accuracy of 0.32∘± 2.3∘, and smooth pursuit speeds with an accuracy of 0.5 to 3∘s, depending on the pursuit speed. While the performance of the MindLink system in measuring fixation stability, saccade amplitude, and smooth pursuit eye movements were slightly inferior to the video-based system, MindLink provides sufficient gaze-tracking capabilities for dynamic settings and experiments.

Shape judgments in natural scenes: Convexity biases versus stereopsis.

Determining the relief of upcoming terrain is critical to locomotion over rough or uneven ground. Given the significant contribution of stereopsis to perceived surface shape, it should play a crucial role in determining the shape of ground surfaces. The aim of this series of experiments was to evaluate the relative contribution of monocular and binocular depth cues to judgments of ground relief. To accomplish this goal, we simulated a depth discrimination task using naturalistic imagery. Stimuli consisted of a stereoscopically rendered grassy terrain with a central mound or a dip with varying height. We measured thresholds for discrimination of the direction of the depth offset. To determine the relationship between relief discrimination and measures of stereopsis, we used two stereoacuity tasks performed under the same viewing conditions. To assess the impact of ambiguous two-dimensional shading cues on depth judgments in our terrain task, we manipulated the intensity of the shading (low and high). Our results show that observers reliably discriminated ground reliefs as small as 20 cm at a viewing distance of 9.1 m. As the shading was intensified, a large proportion of observers (30%) exhibited a strong convexity bias, even when stereopsis indicated a concave depression. This finding suggests that there are significant individual differences in the reliance on assumptions of surface curvature that must be considered in experimental conditions. In impoverished viewing environments with limiting depth cues, these convexity biases could persist in judgments of ground relief, especially when shading cues are highly salient.

Athletes Demonstrate Superior Dynamic Visual Acuity.

SIGNIFICANCE: Athletes exhibit better dynamic visual acuity (DVA) compared with nonathletes, whereas action video game players (VGPs) perform more similarly to controls despite having similar static visual acuity and refractive errors. The differences in DVA between groups were not related to differences in static visual acuity, refractive error, or smooth pursuit gain. PURPOSE: The purpose of the study was to examine whether athletes and VGPs have superior DVA than controls (nonathletes, nongamers). METHODS: Forty-six participants (15 athletes, 11 VGPs, 20 controls) aged 21.7 years (standard deviation, 2.8 years) were recruited. Participants were emmetropic with equivalent monocular and binocular static visual acuity between groups. Dynamic visual acuity was assessed using predictable (horizontal) and unpredictable (random) motion targets at velocities of 5, 10, 20, and 30°/s. Smooth pursuit eye movements were assessed using a horizontal motion step-ramp stimulus at the same speeds. This study was pre-registered with the Center for Open Science (https://osf.io/eu7qc). RESULTS: At 30°/s, there were significant main effects of group (F = 4.762, P = .01) and motion type (F = 9.538, P = .004). Tukey post hoc analysis for groups indicated that athletes performed better than did the control group (t = -2.919, P < .02). An omnibus (group × motion type × speed) repeated measures ANOVA showed a main effect of speed (F = 110.137, P < .001) and a speed × motion-type interaction (F = 27.825, P < .001). Dynamic visual acuity decreased as speed increased, and the slope of the change was greater for random than for horizontal motion. Smooth pursuit gains were not significantly different between groups (P > .05). CONCLUSIONS: Athletes have superior dynamic visual acuity performance compared with controls at 30°/s. This between-group difference cannot be fully explained by differences in smooth pursuit eye movements and therefore may reflect other differences between the groups.

Contributions of Stereopsis and Aviation Experience to Simulated Rotary Wing Altitude Estimation.

OBJECTIVE: We examined the contribution of binocular vision and experience to performance on a simulated helicopter flight task. BACKGROUND: Although there is a long history of research on the role of binocular vision and stereopsis in aviation, there is no consensus on its operational relevance. This work addresses this using a naturalistic task in a virtual environment. METHOD: Four high-resolution stereoscopic terrain types were viewed monocularly and binocularly. In separate experiments, we evaluated performance of undergraduate students and military aircrew on a simulated low hover altitude judgment task. Observers were asked to judge the distance between a virtual helicopter skid and the ground plane. RESULTS: Our results show that for both groups, altitude judgments are more accurate in the binocular viewing condition than in the monocular condition. However, in the monocular condition, aircrew were more accurate than undergraduate observers in estimating height of the skid above the ground. CONCLUSION: At simulated altitudes of 5 ft (1.5 m) or less, binocular vision provides a significant advantage for estimation of the depth separation between the landing skid and the ground, regardless of relevant operational experience. However, when binocular cues are unavailable aircrew outperform undergraduate observers, a result that likely reflects the impact of training on the ability to interpret monocular depth cues.

Difference between vertical and horizontal saccades across the human lifespan.

The purpose of the study was to analyze vertical saccade parameters (latency, peak velocity, amplitude gain), and compare them to those of horizontal saccades in a cross-sectional study across the ages of the human lifespan. One hundred and thirty one participants (62 males) between the ages of 3 and 86 years made vertical prosaccades of 2-44° in response to a dot stimulus projected on a screen. A subset of participants also made horizontal prosaccades of 2-60° under the same conditions. The El-Mar (Downsview, Ontario, Canada) eye tracker was used to record binocular eye movements. Measures of saccadic latency, peak velocity and amplitude gain were calculated for each participant. Differences between saccade parameters for upward & downward saccades were calculated. Vertical saccade parameters were evaluated as a function of age and age related differences between vertical and horizontal saccade parameters were determined. There was no significant difference between upward and downward saccades and no effect of age for either latency or peak velocity. Downward saccades had significantly higher gains than upward saccades (p = 0.0001) and this difference increased significantly with age (p = 0.001). Vertical saccadic latency initially decreased from about 400 ms at 4 years of age, remained stable for a period of time and then increases again in later life. The lowest peak velocities were found in participants under 20 and over 70 years of age, while the highest peak velocities were seen in participants between 20 and 60 years of age. The majority of vertical saccades were hypometric. Saccadic amplitude gains varied depending on both the stimulus size (p = 0.0001) and age (p = 0.0001) of participants. Vertical saccades are most accurate for small amplitudes and for participants between 20 and 30 years of age. Vertical saccades had significantly longer latencies than horizontal saccades (p = 0.0001) but there was no significant effect of age. Vertical saccades had lower peak velocities than horizontal saccades in very young children but this difference decreased with age (p = 0.0015). Large vertical saccades were more hypometric than their horizontal counterparts across all ages. The observed differences in saccadic parameters could be related to the different areas in the brain used for saccadic generation, different periods and/or mechanisms of development and senescence within the visual system and brain and/or the effects of differential use.

"I can see fine": patient knowledge of eye care.

PURPOSE: To learn more about the perceptions and attitudes toward eye care of members of the public - in particular, their knowledge of the purpose, components and providers of eye examinations, their ability to self-monitor ocular status and their awareness of major sight threatening eye conditions. METHODS: This study used the qualitative research strategy, grounded theory. Participants were recruited via poster and social media. Two researchers, one with optometric knowledge and one without, moderated seven 60- to 90-min, semi-structured focus group discussions, which were audiotaped and transcribed. Participants also completed a short demographic questionnaire. Three researchers employed constant comparative coding strategies to identify common themes within the focus group transcripts. The number of participants represented by identified themes were tracked and themes were listed in order of decreasing frequency. RESULTS: Focus groups included 25 participants (nine male, 16 female), ranging in age from 18 to 71 years (mean: 41.7). Five themes related to eye care awareness were identified: eye examination purpose, test procedure identification, eye care professional roles, asymptomatic eye disease awareness, and significant eye disease awareness. Perceived eye examination purposes were vision/prescription priority with some eye health knowledge, comprehensive evaluation of visual system, and vision/prescription only. Most participants who responded could correctly identify the use of an eye chart and a phoroptor; fewer were able to do the same for a direct ophthalmoscope and slit lamp biomicroscope. Less than a quarter of participants could accurately identify the roles of all three major eye care providers. Trauma was the most commonly mentioned risk for vision loss, followed by diabetes and infection. Participants' knowledge appeared most often to have been obtained from personal experience rather than as the result of any systematic educational initiative. CONCLUSIONS: This study found notable gaps in knowledge of eye care and sight risks. If these gaps result in fewer eye examinations, they potentially contribute to increased risk of vision loss due to later stage detection. The results provide motivation for further study and development of effective public health education strategies.

Prevalence of Convergence Insufficiency-Type Symptomatology in Parkinson's Disease.

BACKGROUND: Individuals with Parkinson's disease (PD) often present with visual symptoms (e.g., difficulty in reading, double vision) that can also be found in convergence insufficiency (CI). Our objective was to estimate the prevalence of CI-type visual symptomatology in individuals with PD, in comparison with controls. METHODS: Participants ≥50 years with (n=300) and without (n=300) PD were recruited. They were administered the Convergence Insufficiency Symptom Survey (CISS-15) over the phone. A score of ≥21 on the CISS-15, considered positive for CI-type symptomatology, served as the cutoff. Data from individuals (n=87 with, n=94 without PD) who were approached but who reported having a known oculovisual condition were analysed separately. Student's t test and chi-square at the 0.05 level were employed for statistical significance. RESULTS: A total of 29.3% of participants with versus 7.3% without PD presented with a score of ≥21 on the CISS-15 (p=0.001). Of the participants having a known oculovisual condition, 39.1% with versus 19.1% without PD presented with a score of ≥21 on the CISS-15 (p=0.01). CONCLUSIONS: The prevalence of CI-type visual symptoms is higher in individuals with versus without PD whether or not they have a coexisting oculovisual condition. These results suggest that PD per se places individuals with the disease at greater risk of visual symptomatology. These results further underline the importance of providing regular eye exams for individuals with PD.

Visual Acuity and Contrast Sensitivity Development in Children: Sweep Visually Evoked Potential and Psychophysics.

PURPOSE: The purpose of this study was to investigate the development of visual acuity (VA) and contrast sensitivity in children as measured with objective (sweep visually evoked potential) and subjective, psychophysical techniques, including signal detection theory (SDT), which attempts to control for differences in criterion or behavior between adults and children. Furthermore, this study examines the possibility of applying SDT methods with children. METHODS: Visual acuity and contrast thresholds were measured in 12 children 6 to 7 years old, 10 children 8 to 9 years old, 10 children 10 to 12 years old, and 16 adults. For sweep visually evoked potential measurements, spatial frequency was swept from 1 to 40 cpd to measure VA, and contrast of sine-wave gratings (1 or 8 cpd) was swept from 0.33 to 30% to measure contrast thresholds. For psychophysical measurements, VA and contrast thresholds (1 or 8 cpd) were measured using a temporal two-alternative forced-choice staircase procedure and also with a yes-no SDT procedure. Optotype (logMAR [log of the minimum angle of resolution]) VA was also measured. RESULTS: The results of the various procedures were in agreement showing that there are age-related changes in threshold values and logMAR VA after the age of 6 years and that these visual functions do not become adult-like until the age of 8 to 9 years at the earliest. It was also found that children can participate in SDT procedures and do show differences in criterion compared with adults in psychophysical testing. CONCLUSIONS: These findings confirm a slightly later development of VA and contrast sensitivity (8 years or older) and indicate the importance of using SDT or forced-choice procedures in any developmental study to attempt to overcome the effect of criterion in children.

Myopia progression control lens reverses induced myopia in chicks.

PURPOSE: To determine whether lens induced myopia in chicks can be reversed or reduced by wearing myopia progression control lenses of the same nominal (central) power but different peripheral designs. METHODS: Newly hatched chicks wore -10D Conventional lenses unilaterally for 7 days. The myopic chicks were then randomly divided into three groups: one fitted with Type 1 myopia progression control lenses, the second with Type 2 myopia progression control lenses and the third continued to wear Conventional lenses for seven more days. All lenses had -10D central power, but Type 1 and Type 2 lenses had differing peripheral designs; +2.75D and +1.32D power rise at pupil edge, respectively. Axial length and refractive error were measured on Days 0, 7 and 14. Analyses were performed on the mean differences between treated and untreated eyes. RESULTS: Refractive error and axial length differences between treated and untreated eyes were insignificant on Day 0. On Day 7 treated eyes were longer (T1; 0.44 ± 0.07 mm, T2; 0.27 ± 0.06 mm, C; 0.40 ± 0.06 mm) and more myopic (T1; -9.61 ± 0.52D, T2; -9.57 ± 0.61D, C; -9.50 ± 0.58D) than untreated eyes with no significant differences between treatment groups. On Day 14 myopia was reversed (+2.91 ± 1.08D), reduced (-3.83 ± 0.94D) or insignificantly increased (-11.89 ± 0.79D) in treated eyes of Type 1, Type 2 and Conventional treated chicks respectively. Relative changes in axial lengths (T1; -0.13 ± 0.09 mm, T2; 0.36 ± 0.09 mm, C; 0.56 ± 0.05 mm) were consistent with changes in refraction. Refractive error differences were significant for all group comparisons (p < 0.001). Type 1 length differences were significantly different from Conventional and Type 2 groups (p < 0.001). CONCLUSIONS: Myopia progression control lens designs can reverse lens-induced myopia in chicks. The effect is primarily due to axial length changes. Different lens designs produce different effects indicating that lens design is important in modifying refractive error.

Value of Routine Eye Examinations in Asymptomatic Patients.

PURPOSE: To determine if routine eye examinations in asymptomatic patients result in spectacle prescription change, new critical diagnosis, or new management of existing conditions. We also investigate whether age and time between assessments (assessment interval) impact detection rates. METHODS: The Waterloo Eye Study (WatES) database was created from a retrospective file review of 6397 patients seen at the University of Waterloo Optometry Clinic. Significant changes since the previous assessment (significant change) were defined as a change in spectacle prescription, presence of a new critical diagnosis, or a new management. Significant change, assessment interval, and age were extracted from the database for all asymptomatic patients presenting for a routine eye examination. The frequency of patients with significant change and the median assessment interval were determined for different age groups. RESULTS: Of 2656 asymptomatic patients, 1078 (41%) patients had spectacle prescription changes, 434 (16%) patients had new critical diagnoses, 809 (31%) patients had new managements, and 1535 (58%) patients had at least one of these (significant change). Median assessment intervals were 2.9 and 2.8 years for age groups 40 to <65 years and 20 to <40 years, respectively, approximately 1.5 years for patients 7 to <20, and between 1 and 1.5 years for patients <7 or >64. Controlling for assessment interval and sex, increasing age was associated with having a significant change (OR = 1.03, 95% CI 1.029-1.037). Similarly, controlling for age and sex, increased assessment interval was associated with having a significant change (OR = 1.06, 95% CI 1.02-1.11). CONCLUSIONS: In asymptomatic patients, comprehensive routine optometric eye examinations detect a significant number of new eye conditions and/or result in management changes. The number detected increases with age and assessment interval.

Measuring Infant Visual Acuity with Gaze Tracker Monitored Visual Fixation.

PURPOSE: To validate a method of measuring grating acuity with remote gaze tracking (GT) against a current clinical test of visual acuity (VA), the Teller Acuity Cards (TACs), as part of the development of an automated VA test for infants. METHODS: Visual acuity for computer-generated horizontal square-wave gratings was determined from relative fixation time on a grating area compared with the background. In experiment 1, binocular VA was based on eye movements with a GT in 15 uncorrected myopic adults and compared with VA measured with subjective responses with the same stimuli and with the TACs. In experiment 2, binocular VA was determined in 19 typically developing infants aged 3 to 11 months on two visits with both the GT and TACs. RESULTS: In adults, the mean difference between VA measured by the GT and TACs was 0.01 log cycles per degree (cpd) and the 95% limits of agreement were 0.11. One hundred percent of GT VA results were within 0.5 octave of the TACs' VAs. The mean difference between the GT and TACs for infants was 0.17 log cpd on both the first and second visit (95% limits of agreement, 0.42 and 0.47, respectively). The mean difference between test and retest for infant GT VA was 0.06 log cpd, and limits of agreement for repeatability were 0.48 log cpd. In infants, both the TACs and the GT had a reliability of 89% within less than or equal to 1 octave between visits. Gaze tracking VA improved with age and is in agreement with published norms. CONCLUSIONS: The agreement between the TACs and GT in adults and infants validates the method of measuring grating acuity with the remote GT. These results demonstrate its potential for an automated test of infant VA.

Refractive plasticity of the developing chick eye: a summary and update.

PURPOSE: To summarize the OPO 1992 Classic Paper: Refractive plasticity of the developing chick eye (12: 448-452) and discuss recent findings in refractive development. SUMMARY AND RECENT FINDINGS: The classic paper shows that when lightweight plastic goggles with rigid contact lens inserts are applied to the eyes of newly hatched chicks, the eye responds accurately to defocus between -10 and +20 D, although hyperopia develops more rapidly. While the changes largely are due to change in axial length, high levels of hyperopia are associated with corneal flattening. Also, newly hatched chicks are better able to compensate for the induced defocus than chicks that are 9 days old. In addition, astigmatism of 2-6 D can be produced by applying 9 D toric inducing lenses on the day of hatching, and the most myopic meridian coincides with the power meridian of the inducing lens. This astigmatism appears to be primarily due to corneal toricity. Furthermore, the greatest magnitude was produced when the plano meridian of the inducing lens was placed 45° from the line of the palpebral fissure. Since our publication in 1992, it has been shown that similar results can be produced in a variety of species, including; tree shrews, marmosets, monkeys and fish. Considerable effort has been spent in trying to determine what the eye uses, if not the brain, as the signal to the sign of the defocus. Accommodation, chromatic aberration, diurnal variation, astigmatism and higher order monochromatic aberrations have all been considered. Choroidal thinning and thickening play a role in myopia and hyperopia development, respectively, in chicks. High light levels (15,000 lux) increase the rate at which chicks compensate for positive lenses and decrease the compensation rate for negative lenses. However these light levels do not prevent the eye from fully compensating for either type of lens. It has also been shown that brief periods of normal vision prevent the development of form deprivation myopia. Finally, the importance of the peripheral retina in refractive development has been explored and lenses designed to reduce relative peripheral hyperopia have resulted in variable effects as far as myopia control is concerned. CONCLUSIONS: A growing body of evidence, from both animal models and human clinical trials indicates that the development of myopia is related both to genetics and environment / lifestyle. Nevertheless, we are far from understanding how this interaction takes place.

Investigating the role of flight phase and task difficulty on low-time pilot performance, gaze dynamics and subjective situation awareness during simulated flight.

Gaze behaviour has been used as a proxy for information processing capabilities that underlie complex skill performance in real-world domains such as aviation. These processes are highly influenced by task requirements, expertise and can provide insight into situation awareness (SA). Little research has been done to examine the extent to which gaze behaviour, task performance and SA are impacted by various task manipulations within the confines of early-stage skill development. Accordingly, the current study aimed to understand the impact of task difficulty on landing performance, gaze behaviour and SA across different phases of flight. Twenty-four low-time (<300 hours) pilots completed simulated landing scenarios under visual flight rules conditions. Traditional gaze metrics, entropybased metrics, and blink rate provided meaningful insight about the extent to which information processing is modulated by flight phase and task difficulty. The results also suggested that gaze behavior changes compensated for increased task demands and minimized the impact on task performance. Dynamic gaze analyses were shown to be a robust measure of task difficulty and pilot flight hours. Recommendations for the effective implementation of gaze behaviour metrics and their utility in examining information processing changes are discussed.

An Urgent Call for Concussion Incidence Measures in Para Sport for Athletes with Vision Impairment: A Narrative Review.

Concussion in para athletes with vision impairment (VI) is poorly understood. Recently published studies have suggested that athletes with VI may be more likely to sustain sport-related concussions compared to non-disabled athletes and athletes with other impairment types. There is a critical need for objective concussion incidence measures to determine concussion injury rates and risks more accurately. The aim of this review was to examine the limited available evidence of concussion incidence rates across six different para sports for athletes with VI and encourage the future collection of concussion incidence data and the adoption of injury prevention strategies in VI para sport. A literature search was conducted using four unique databases, which formed the basis of this narrative review. Injury prevention strategies such as modifying sport rules, introducing protective equipment, and incorporating additional safety measures into the field of play have been introduced sporadically, but the effectiveness of most strategies remains unknown. More prospective, sport-specific research examining mechanisms of injury and risk factors for concussion injuries in athletes with VI in both training and competition is needed. This research will help inform the development of targeted injury prevention strategies to reduce the likelihood of concussion for athletes with VI.

Increase in myopia prevalence in clinic-based populations across a century.

PURPOSE: The study's aim was to report prevalence estimates and age-related trends in refractive error in a clinic-based series and compare them to results from studies of a similar nature conducted since 1892. METHODS: Refractive error, patient age, and sex were collected from the files of all patients seen at the University of Waterloo School of Optometry and Vision Science clinic between January 2007 and January 2008. Patients were categorized as having myopia (<-0.5D mean ocular refraction [MOR]), hyperopia (>0.5D MOR), emmetropia, astigmatism (<-0.5D), and/or anisometropia (>1.0D difference between eyes). The prevalence of all refractive components was determined overall and in 1- and 5-year age groups, and then compared to data from older clinic-based studies. Refractive trends over time were noted. The prevalence of myopia and hyperopia were compared to older studies. RESULTS: The lowest prevalence of myopia was 5% at 0 to 5 years of age, after which it increased to 72% at 20 to 30 years of age and then decreased to 22% in patients older than 70 years. A myopic peak occurred at 24 years of age. The prevalence of hyperopia followed opposite trends with a minimum prevalence of 6% at 25 to 30 years of age. Peaks in emmetropia prevalence were 55% at 5 to 10 years of age and 37% at 45 to 50 years of age. The prevalence of astigmatism and anisometropia increased with age. The Waterloo Eye Study showed a higher prevalence of myopia across all ages compared to the older studies with a peak prevalence of 72% compared to 21% in the oldest (Herrnheiser) study from 1892. CONCLUSIONS: In the last 100 years, there appears to have been a myopic shift in clinic-based populations and myopia prevalence appears to follow a predictable pattern with age.