A virtual approach: Systematic review and meta-analysis of virtual reality-based therapies for convergence insufficiency

Convergence insufficiency (CI) is a common binocular vision disorder that significantly impacts visual comfort and quality of life. It has been hypothesized that CI therapy can also be provided effectively with Virtual reality (VR). Recently, a few studies were conducted on virtual reality-based CI therapy. However, to the best of the authors' knowledge, no systematic review and meta-analysis has been performed on the effectiveness of VR-based CI therapy. Therefore, this study aims to fill this critical gap and investigate the effectiveness of VR-based CI therapy. Consequently, it may be helpful to the clinicians, patients, and researchers to choose therapy, and develop future research studies. A systematic search was conducted on Google scholar, Scopus, PubMed and Science Direct until October 1, 2024. A total of 649 studies were screened, of which 3 studies were eligible to be included. We evaluated the quality and risk of bias for the included studies. Using the random-effects model, we found an overall mean difference of 3.38 (95% CI: 1.61, 5.16) before and after VR-based therapy. I² was 54.82% in our study, which indicates moderate heterogeneity. Then, we performed a Q test and found Q (df = 2) = 4.3593 and p-value = 0.1131, which indicates that albeit some heterogeneity observed in our analysis, it was not statistically significant. We also performed Leave-One-Out sensitivity analysis, which indicates that the overall findings of our analysis were relatively stable and not excessively dependent on any single selected study. No significant evidence of publication bias was found by using a funnel plot, Begg's test (Kendall's Tau = 1, p-value = 0.33), and Egger's test (intercept = 2.45, p-value = 0.40). Although we found VR based CI therapy has a positive effect, small sample size and variability in study methodologies make the current evidence insufficient to draw definitive conclusions regarding its effectiveness. Further studies are required to have more robust and reliable data.

Visual Quality Following Femtosecond Laser-Assisted In Situ Keratomileusis With Q-Value-Guided Optimized Monovision in Patients With Myopia and Presbyopia

PURPOSE

To evaluate the objective and subjective visual quality 3 months after femtosecond laser-assisted in situ keratomileusis (FS-LASIK) performed with Q-value-guided optimized monovision scheme (Custom-Q) for correction of myopia with or without astigmatism and compensate for age-related accommodation deficiency.

DESIGN

Prospective before-and-after study.

METHODS

Patients who had Custom-Q FS-LASIK for myopia with age-related accommodation deficiency were included in this prospective study. Distance, intermediate, and near visual acuities; refraction; Q value; corneal higher-order aberrations; accommodative and binocular function measurements; defocus curve; contrast sensitivity; and a subjective questionnaire assessing near visual ability and visual discomforts were evaluated before and after surgery.

RESULTS

Clinical data of 48 cases were analyzed. The mean age was 42.73 ± 2.67 years (range 40-50 years). At the 3-month follow-up, there were 100% (48/48), 92% (44/48), and 56% patients (27/48) who achieved a binocular uncorrected distance, intermediate, and near visual acuity not less than 20/20 separately. Defocus curves revealed better results postoperatively at -1.00 diopter (D) and -1.50 D. The Q value in the dominant eyes was more positive postoperatively (P < .001), and in the nondominant eyes, the Q value and corneal spherical aberration became more negative (P < .05). The accommodative amplitude and relative accommodation improved binocularly (P < .001). The questionnaire demonstrated high patient satisfaction with near vision, and patients' perceptions of visual discomforts had no significant difference compared with preoperative.

CONCLUSION

For myopic patients with age-related accommodation deficiency, the Custom-Q ablation could improve near vision without compromising distance vision. It also led to minimal changes in objective optical quality, coordination of accommodative and binocular functions, contrast sensitivity, and subjective visual discomfort perceptions.

The Prevalence of Accommodative and Binocular Dysfunctions in Children with Reading Difficulties

Uncorrected refractive error and unsatisfactory performance on several clinical accommodation and binocular vision tests are more common in children who struggle with reading. The aim of the current study is to explore the prevalence of accommodative and binocular dysfunctions in children with and without reading difficulties. Reading performance was assessed with the Acadience Reading (formerly DIBELS Next) test adjusted and validated for the Latvian language. Children with (N = 39) and without (N = 43) reading difficulties underwent thorough assessment of their subjective refraction, as well as binocular and accommodation functions. The results demonstrate no difference in the prevalence of complaints between children with and without reading difficulties (26% and 23%, respectively). However, children with reading difficulties more frequently present with significant uncorrected refractive errors and/or accommodative and binocular dysfunctions than children without reading difficulties (69% and 47%, respectively). According to the findings, even in cases where a child does not exhibit any ocular or visual complaints, a comprehensive visual function evaluation should be required for any child who struggles with reading.

Diagnostic Protocol for Accommodative and Vergence Anomalies - A Review

PURPOSE

To review the diagnostic protocols of non-strabismic binocular vision anomalies.

METHODS

We carried out a literature search on published articles of non-strabismic accommodative and vergence anomalies in different international optometry and ophthalmology journals found in the Pubmed, ResearchGate, Google Scholar, and MEDLINE databases.

RESULTS

The diagnostic criteria and normative data from the nine articles selected show discrepancies and variability in methodologies and techniques in the overall assessment of Non-Strabismic Binocular Vision Anomalies (NSBVA). Near point of convergence measurement is the most common assessment, whereas the vergence facility is the least commonly used assessment in terms of evaluating convergence insufficiency. Near point of convergence > 10 cm alone is the most sensitive sign to detect convergence insufficiency in a community set-up but high positive relative accommodation (>3.50D) is the most sensitive sign to diagnose accommodative excess. On the other hand, monocular accommodative facility < 7 CPM has the highest sensitivity to confirm the diagnosis of accommodative infacility. This review also indicates that the more clinical signs that are included in a set of diagnostic criteria, the lower the prevalence rate for that diagnosis.

CONCLUSIONS

There is no standardized and diagnostically validated protocol for the assessment of NSBVAs. Variable cutoff values obtained using different methods and the selection of diagnostic criteria by various researchers have led to discrepancies that highlight the need for diagnostic validity of available protocols (combination of tests) for each anomaly. Clinical signs such as positive relative accommodation (PRA) for accommodative excess, near point of convergence (NPC) for convergence insufficiency and monocular accommodative facility (MAF) for accommodative infacility were found to be useful diagnostic signs of these anomalies. Studies should be carried out for accommodative and vergence dysfunctions using proper designs and methods to validate diagnostic criteria for all age groups. Standardization of assessment protocol and cutoff criteria will also aid in calculating prevalence for non-strabismic binocular vision anomalies.

Levels of Awareness Regarding Pediatric Eye Diseases Among Saudi Parents From the Hail and Al-Qassim Regions, Saudi Arabia

BACKGROUND

The importance of children's eye health cannot be overstated as it has significant implications for personal life, education, career, health, financial status, and overall satisfaction. This study aims to assess the awareness of parents regarding pediatric eye diseases to identify potential gaps in knowledge. By understanding parental awareness, we can develop targeted educational initiatives to promote early detection, timely intervention, and overall improved eye health in children. This research seeks to contribute valuable insights for enhancing preventive measures and fostering healthier eyesight in younger generations.

METHODOLOGY

 A descriptive cross-sectional study was conducted in the Hail and Al-Qassim regions, of Saudi Arabia. Parents with children aged less than 15 years were included. Targeted parents were selected consecutively using an online questionnaire for data collection. Data included parents' data, children's eye diseases, and parents' knowledge, practice, and attitude toward pediatric eye diseases.  Results: A total of 618 eligible parents were included, 429 (69.4%) from Al-Qassim and 189 (30.6%) from Hail. Parents' ages ranged from 20 to 59 years with a mean age of 35.4 ± 11.5 years. A total of 510 (82.5%) respondents were females. A total of 442 (71.5%) of the study parents had poor knowledge about their pediatric eye problems, 154 (24.9%) had a good knowledge level, and only 22 (3.6%) had excellent knowledge. As for their practice, 458 (74.1%) of the parents arranged for their children to undergo an eye or visual test; 254 (55.5%) did so when the child was six to ten years of age.

CONCLUSION

 The current study showed poor awareness levels about pediatric eye diseases among parents, mainly regarding cataracts and glaucoma. On the other hand, parents demonstrated a high level of engagement in visually assessing their children. The primary hindrance to conducting assessments was the absence of symptoms and signs or active complaints, leading to a lack of proactive seeking of visual evaluations.

Accommodative Facility and Response Time before and after Computer Task of Varying Durations in Young Adults

Aim

To investigate the changes in near accommodative facility and response time in young adults following computer work of 30 minutes and 1 hour in duration.

Methods

A total of 50 young adults (37 females, 13 males) with mean age of 20.68 ± 1.33 years were included in this experimental study. Monocular near accommodative facility was measured using ±2.00 Dioptre Sphere (DS) flipper at 40 cm using the N6 (the smallest print size that can be read by an individual with normal visual acuity) target before and after two reading tasks. Both pre- and post-task measurements were video recorded using a smart phone and the number of cycles per minute, positive response time (time taken to stimulate accommodation), and negative response time (time taken to relax accommodation) were calculated from the video recording. Data were analysed using SPSS Version 22.0.

Results

Out of the 50 participants, 29 were emmetropes (Mean SER: 0.16 ± 0.29 D), and 21 were myopes (Mean SER: -1.89 ± 1.16 D). The mean pre-task accommodative facility was 6.79 ± 3.52 cycles per minute, and the post-task accommodative facility was 6.25 ± 3.65 cycles per minute (p = 0.10) for the 30-minutes task and 5.76 ± 3.89 cycles per minute (p = 0.01) for 1-hour task. The mean pre-task positive response time was 2.87 ± 1.55 seconds, and the post-task positive response times for 30 minutes and 1 hour were 2.86 ± 1.67 seconds (p = 0.88) and 2.98 ± 2.33 seconds (p = 0.42), respectively. The mean pre-task negative response time was 8.77 ± 8.83 seconds, and the post-task negative response times for 30 minutes and 1 hour task were 11.83 ± 14.28 seconds (p = 0.16) and 14.72 ± 17.32 seconds (p = 0.03), respectively.

Conclusion

Monocular near accommodative facility was significantly reduced, and negative response time was delayed following 1 hour of computer work.

Prevalence of vision conditions in children in a very remote Australian community

CLINICAL RELEVANCE

Understanding the prevalence of vision conditions in a population is critical for determining the most appropriate strategies for detecting and correcting eye conditions in a community. This is particularly important in very remote regions where access to vision testing services is limited.

BACKGROUND

Although recent studies have provided detailed analyses of the prevalence of vision conditions in Aboriginal and/or Torres Strait Islander children in urban and regional areas of Australia, there is a paucity of research examining vision conditions in children in remote regions. Importantly, a significant proportion of the population in remote and very remote regions identify as Aboriginal and/or Torres Strait Islander people.

METHODS

Comprehensive eye examinations were provided to 193 primary school children in a very remote Australian region. Ninety eight percent of children identified as Aboriginal and/or Torres Strait Islander. The eye examination included measures of visual acuity, cycloplegic autorefraction, binocular vision and accommodative function, ocular health and colour vision. Previous history of eye examinations and refractive correction were assessed through parental questionnaire.

RESULTS

Although the average unaided vision in the population was good (mean: 0.02 ± 0.13 logMAR) and the prevalence of reduced unaided visual acuity (>0.3 logMAR in either eye) was low (4%), vision conditions were detected in 32% of children. The most common conditions were clinically significant refractive errors (18% of children) and binocular vision or accommodative disorders (16%). Of the total population of children tested, 10% had previously had an eye examination, and 2% were reported to have previously been prescribed spectacles.

CONCLUSIONS

In this population of children in a very remote Australian region, up to 1 in 3 children had a vision condition, with many of these conditions being uncorrected and undetected. These findings highlight the important need for additional resources to be made available to very remote communities for the detection and correction of vision conditions in childhood.

Translation and validation of convergence insufficiency symptom survey to Italian: Psychometric results

PURPOSE

This study aimed to translate the Convergence Insufficiency Symptom Survey (CISS) into the Italian language and assess psychometric properties of the translated questionnaire (CISS_I).

METHODS

The CISS_I was arranged according to guidelines for a comprehensive multistep methodologic process for translating, adapting, and validating psychometric instruments in health care research. The CISS_I questionnaire was administered to 103 volunteers (21.8 ± 2.2 years), students in higher education, at two different times. A complete optometric evaluation was performed including subjective refraction, best corrected visual acuity, near point of convergence, prism fusional ranges to blur, diplopia and recovery, TNO stereo test and prism cover test for measurement of heterophoria.

RESULTS

The performance of the CISS_I in terms of validity showed some points of weakness. Sensitivity was 42%, specificity was 74%, positive predictive value was 27% and negative predictive value was 85%. The area under the ROC curve was 0.672. On the contrary, the results showed good internal consistency of the CISS_I (Cronbach's alpha - α=0.89) and good test-retest reliability (ICC = 0.92). Rasch analysis showed good model fit (all items, except one, with infit and outfit mean square between 0.7 and 1.3), good measurement precision (person separation = 2.66) and good targeting -0,81 logits but also some evidence of multidimensionality.

CONCLUSIONS

The CISS_I showed some point of weakness in terms of validity but also good psychometric properties and has been shown to be applicable to an Italian speaking population to quantify the visual discomfort associated with near vision in higher education students. The results show that high CISS_I score is not necessarily linked to convergence insufficiency, while low scores can exclude the presence of this anomaly. The CISS_I can help in interpreting and monitoring convergence insufficiency symptoms in already identified subjects, but it is not suitable for screening a general population of young adults.

Convergence insufficiency: Review of clinical diagnostic signs

Convergence insufficiency (CI) is a common binocular vision (BV) disorder characterized by difficulty in maintaining motor fusion at near, which affects approximately 7.5 percent of the population. Diagnostic criteria for the disorder are inconsistent, ranging from one to many clinical signs. Methodology for clinical tests is inconsistent in measurement technique, visual targets, required repetitions, and normative values. This manuscript demonstrates the inconsistencies amongst published studies, and highlights the importance of consistent clinical diagnostic signs, measurement techniques, visual targets, and cut-off criteria. For each clinical sign, the recommended methodology for the procedure is described. Several studies do not take age into account when diagnosing CI in their cohorts. As such, the review emphasizes changes in diagnostic signs with age. This manuscript highlights the need for consistent and clear procedures and diagnostic criteria amongst clinicians and provides the basis for future studies in terms of diagnostic testing required for CI of varying age groups.

Adverse Influences of Nonstrabismic Amblyopia on Quality of Life of Teenagers in China

The aim of this study was to explore the influences of nonstrabismic amblyopia on quality of life in adolescents. Health-related quality of life (HRQoL) scale, a multidimensional construct that indicates a fundamental health outcome, was used to measure physical and psychosocial functioning of the adolescents. Forty teenagers with nonstrabismic amblyopia and 40 control teenagers without nonstrabismic amblyopia were recruited between April 2019 and July 2021. The anthropometric measures, body image, physical activity outcome, and HRQoL scores including physical health, emotional functioning, social functioning, and school functioning were compared between the two groups. The results revealed that teenagers with nonstrabismic amblyopia had less weekly sedentary time (P < 0.001), weekly total steps (P < 0.001), and worse school functioning (P = 0.0211) than control teenagers. No significant difference was found in anthropometric measures and body image between the two groups (P > 0.05). This study implied the needs for teenagers with nonstrabismic amblyopia to enhance physical activities. Teachers and parents are encouraged to pay more attention to teenagers with nonstrabismic amblyopia to improve their school functioning.

Measures of accommodative function in secondary school year 9 and year 13: a 4-year longitudinal study

Purpose

To characterize accommodative function in secondary school children in year 9 and year 13 and assess the possible relationship between daily working conditions (number of near work hours and distances) and accommodation variables related to accommodative excess.

Methods

This was a prospective study. Participants were 43 subjects who were first examined in year 9 and then again when they were in year 13. The accommodation variables measured in each session were as follows: accommodation amplitude (AA), accommodative response (AR), monocular and binocular accommodation flexibility (MAF and BAF), negative relative accommodation (NRA), and positive relative accommodation (PRA). Other data recorded were the number of hours spent working at near vision tasks and the distances used for these tasks. Participants were classified as those with accommodation variables within the normal range (NA) and those with variables suggesting accommodative excess (AE).

Results

Several accommodative function variables were below normative values in both year 9 and year 13. The number of subjects classified as having AE went from 27.9% in year 9 to 58.1% in year 13 according to AR (p < 0.005) and from 23.3 to 46.5% according to MAF (p = 0.024). More near work was reported in year 13 (44.6 h/week) than year 9 (32.7 h/week) (p < 0.001). It emerged that subjects in year 13 spent more hours working at near if they had AE than if they were assigned to the NA group. No differences were detected in near work distances used by subjects in the NA and AE groups in both years.

Conclusions

In both school years, values outside the norm were detected in several accommodative function measures. Also, devoting more hours to near work was linked to a greater extent of accommodative excess. We would therefore recommend regular accommodative function assessment in secondary school children.

Comparison of Logarithmic Reading Charts for Visual Assessment in Normally Sighted Participants

SIGNIFICANCE

Logarithmic reading charts provide standardized measures of reading performance. Here we show that existing charts provide equivalent assessments of visual aspects of reading that are in good agreement with traditional measures of visual acuity and seem uninfluenced by cognitive (linguistic) factors.

PURPOSE

The aims of this study were to (1) determine the equivalence of logarithmic charts of sentence and word reading, (2) evaluate the relationship between reading chart performance and more traditional measures of visual assessment, and (3) establish the influence of linguistic factors on reading chart performance.

METHODS

In a sample of 82 normally sighted participants, we determined performance on the reading measures (e.g., reading acuity, reading speed, critical print size) of the following logarithmic charts of sentence and word reading: The Colenbrander English Continuous Text Near Vision Card, Radner Reading Chart, Minnesota Reading Acuity Chart, and Smith-Kettlewell Reading Chart. In doing so, we compared performance on reading measures between charts and with performance on more traditional measures of visual assessment (uncrowded and crowded letter acuity, stereoacuity, accommodation) and cognitive measures of word knowledge and ability (Wechsler Adult Intelligence Scale Vocabulary Subtest, National Adult Reading Test).

RESULTS

Factor analysis confirmed that performance on the reading measures (reading acuity, reading speed, critical print size) was equivalent across charts. Reading test performance was also related to more traditional measures of vision, the most consistent of which were significant associations between reading acuity and acuity for single-letter optotypes. There were no significant associations between reading chart performance and cognitive measures of word knowledge and ability.

CONCLUSIONS

The findings presented here suggest that logarithmic charts composed of sentences and words represent an alternative to traditional letter acuity testing. This is particularly the case for measures of reading acuity.

Vision screening as part of the school health policy in South Africa from the perspective of school health nurses

Background

Vision screenings of school-going children are essential in the early detection of visual anomalies common in different age categories, which may negatively affect their academic ability and social development. Hence, their inclusion in school health policies is imperative. The aim of this study was to assess the implementation of vision screening protocols in the current Integrated School Health Screening policy of South Africa from the perspective of school health personnel.

Aim

The study sought to explore the perceptions, experiences and attitudes of the school health nurses on vision screenings included as part of the school health screenings in Gauteng province (South Africa).

Setting

This study was located across three public healthcare facilities across Gauteng at primary healthcare levels.

Methods

Three teams of 13 school health personnel from three primary healthcare facilities in the district of Ekurhuleni were invited to participate in the study. Focus group interviews were conducted for generating information on collective opinions and the rationale behind their views.

Results

Results of the collected qualitative data revealed challenges related to training, vision screening tests, referral criteria and follow-ups or referral pathways. In addition, further challenges reported were related to communication, time, space and consent forms not signed by the parents.

Conclusion

Improved cohesion and communication between all role players will enable reasonable and professional provision of validated vision screening services that have the best chance of early detection of children with vision anomalies to negate possible adverse effects on their scholarly performance.

Relationship between decreased visual acuity and physical activity time in school age children

Objective

This study aimed to investigate the physical activity of children with decreased visual acuity, thereby providing basic data for developing strategies to enhance the physical activity of school-age children.

Methods

The participants were 1,194 children and 1,194 parents who participated in the 10th Korean Children Panel Survey. Logistic regression analysis was conducted to examine the status of the physical activity of children with decreased visual acuity according to the accessibility of community facilities.

Results

The mother perceived the accessibility of community facilities as low, children with decreased visual acuity reported 1.20 times shorter over-the-weekend leisure activity time compared with vision-typical children, and they spent 1.41 and 1.33 times shorter on caring for pets and religious activity, respectively.

Conclusions

To increase the physical activity of children with decreased visual acuity, family-oriented interventions should be provided. It is also important to establish a community environment with enhanced accessibility of community facilities by examining the level of accessibility perceived by parents.

Methodological variations in studies reporting normative data for binocular vision parameters: a scoping review protocol

OBJECTIVE

The objective of this scoping review is to map the methodological variations and population characteristics of the studies that report normative data for accommodation and vergence parameters.

INTRODUCTION

Accommodation and vergence are the two important parameters required for normal binocular vision. The presence of accommodation and vergence anomalies impairs the quality of life of an individual by interfering with their daily visual activities. Diagnosis of accommodative and vergence anomalies requires a series of test procedures. The test procedure or the tool used could influence the outcome measured. Different study designs and methods have been used to estimate the normative data; therefore, we aim to explore the variation in terms of population characteristics and methods used to measure accommodative and vergence parameters.

INCLUSION CRITERIA

This scoping review will include published literature that assesses normative function of various binocular vision parameters with a focus on mapping the methodological differences.

METHODOLOGY

JBI methodological framework for scoping reviews will be followed. The review will also be conducted in accordance with the Preferred Reporting Item for Systematic Review and Meta-analysis Extension for Scoping Reviews (PRISMA-ScR) checklist. Three-phase searches for identifying relevant articles will be conducted in the following electronic databases: PubMed, Scopus, CINAHL, Web of Science, African Journals Online, LILACS, China National Knowledge Infrastructure, and Google Scholar. The review undertakes two stages of screening: i) title/abstract screening and ii) full-text screening. The data will be extracted from the retrieved full text. The results will be tabulated and summarized descriptively.

Convergence Insufficiency in the Geriatric Population

SIGNIFICANCE

The present study is the first population-based study to examine the prevalence of convergence insufficiency and its associations specifically in the geriatric population. Knowledge of the population-based determination of prevalence of this disorder in the elderly is necessary to support proper clinical diagnosis and management.

PURPOSE

This study aimed to determine the prevalence of convergence insufficiency and its associated factors in a geriatric population.

METHODS

In this study, all residents older than 60 years in Tehran city were selected through random stratified cluster sampling. All participants underwent a complete ocular examination including the measurement of uncorrected and best-corrected visual acuity, objective and subjective refraction, binocular vision assessments including unilateral and alternating cover tests, measurement of the near point of convergence, the positive fusional vergence, and finally ocular health examination.

RESULTS

In this population-based sample of 1793 participants, the overall prevalences of two-sign and three-sign convergence insufficiency were 29.6% (95% confidence interval, 27.2 to 32.0%) and 21.5% (95% confidence interval, 19.5 to 23.6%), respectively. There were no statistically significant differences in the prevalence of both two-sign (P = .19) and three-sign (P = .41) convergence insufficiency between men and women. The highest and lowest prevalences of two-sign and three-sign convergence insufficiency were in the age groups 70 to 74 and 75 to 79 years, respectively. The prevalence showed no significant trend with age (P = .26 for two-sign convergence insufficiency, P = .33 for three-sign convergence insufficiency). In the multiple logistic regression model, none of the variables, including age, sex, and refractive errors, showed a significant relationship with convergence insufficiency (all, P > .05).

CONCLUSIONS

The results of the present study showed a high prevalence of convergence insufficiency in the geriatric population. Clinicians should give special attention to this binocular vision disorder in this age group.

The Prevalence of Fusional Vergence Dysfunction in a Population in Iran

PURPOSE

To determine the prevalence of fusional vergence dysfunction (FVD) and its relationship with age, sex, and refractive errors in a population-based study.

METHODS

In this cross-sectional study, all residents of Mashhad, northeast of Iran, aged >1 year were subjected to random stratified cluster sampling. After selecting the participants, they all underwent complete optometric examinations including the measurement of visual acuity and refraction, assessment of binocular vision and accommodative status, and slit-lamp biomicroscopy.

RESULTS

Of 4453 invited individuals, 3132 participated in the study. After applying the exclusion criteria, statistical analysis was performed on the data of 1683 participants. The prevalence of FVD was 3.2% in all participants, 4.0% in men, and 2.9% in women (P = 0.234). The prevalence of FVD increased linearly with aging from 2.3% in the age group of 10-19 years to 5.4% in the age group of 40-49 years (P = 0.034). The prevalence of myopia, hyperopia, and emmetropia was 11.1%, 29.6%, and 59.3% in participants with FVD and 16.7%, 26.4%, and 57% in participants without FVD, respectively (P = 0.570). Multiple logistic regression analysis only showed a significant association between age and FVD (odds ratio =1.03 95% confidence interval: 1.02-1.05, P = 0.031).

CONCLUSION

The prevalence of FVD in this study was higher than most previous reports and increased significantly with aging. FVD had no significant association with sex and refractive errors.

High Rates of Uncorrected Vision Conditions among Schoolchildren in Rural Queensland, Australia

SIGNIFICANCE

This study is the first to report high rates of uncorrected vision conditions among Australian secondary schoolchildren living in a rural area and to comment on the rate of eye examinations undertaken on Australian Indigenous children. Uncorrected vision problems that continue throughout the school years have significant implications for children's quality of life and education.

PURPOSE

This study aimed to investigate the prevalence of uncorrected vision conditions among Australian schoolchildren.

METHODS

Participants included 280 students from rural primary and secondary schools (aged 4 to 18 years), of whom 40% identified as being of Aboriginal and/or Torres Strait Islander descent (Indigenous). All participants underwent an eye examination including measurements of monocular distance and near visual acuity, assessment of accommodative and vergence function, stereoacuity, color vision, and cycloplegic autorefraction. A parental questionnaire was used to determine whether the child had previously had his/her eyes examined.

RESULTS

The overall prevalence of uncorrected vision conditions in this population was 35%. The odds of previously having had an eye examination were 2.3× higher for non-Indigenous compared with Indigenous children despite both groups exhibiting high rates of uncorrected vision conditions (Indigenous, 31 [29%]; non-Indigenous, 66 [40%]; χ21 = 3.24, P = .07). Of the children who had significant refractive error (Indigenous, 23 [21%]; non-Indigenous, 49 [30%]; χ21 = 2.70, P = .10), 82% were uncorrected, and only 39% of Indigenous children and 54% of non-Indigenous children had previously had an eye examination.

CONCLUSIONS

These findings suggest that high rates of uncorrected vision conditions are present among Australian primary and secondary schoolchildren from a rural area and highlight that Indigenous children are much less likely to have had an eye examination. Understanding factors that affect the rate of eye examinations and compliance with spectacle correction must be addressed given the potential impact of these vision conditions.

Unexpectedly high prevalence of asthenopia in Australian school children identified by the CISS survey tool

Background

To date there have been few systematic attempts to establish the general prevalence of asthenopia in unselected populations of school-aged children. Thus, the aim of this study was to determine whether the incorporation of Borsting et al’s 2003 Revised Convergence-Insufficiency Symptom Survey (CISS) into a general school vision screening could aid in the identification of children with visual discomfort and indicate the need for further investigation.

Methods

Vision screening of an unselected middle school population investigated and analysed the incidence of self-reported nearwork-related visual discomfort via the CISS along with distance and near visual acuities plus non-cycloplegic autorefraction using a Shin-Nippon NVision-K 5001.

Results

Of the 384 unselected students approached in Grades 6–9, 353 participated (92.2%, mean 13.2 ± 1.4 years). The mean CISS score for the population without amblyopia and/or strabismus (96.0% of all students) was 16.8 ± 0.6, i.e., 45% of students in this cohort had CISS scores greater than one standard deviation above the mean found by Borsting et al. in 2003 during their validation study of the CISS on 9 to 18 year old children without binocular anomalies. Regression analyses indicated significantly higher (p < 0.001) mean CISS scores for the 3.2% who were hyperopes ≥ + 2.00D by non-cycloplegic autorefraction (27.7 ± 14.7) and for those who were amblyopic (24.3 ± 6.6) or strabismic (34.0 ± 9.8). The mean CISS score of 31.6 ± 9.0 for non-amblyopic/strabismic students having near vision poorer than 0.1 LogMAR was significantly higher (p < 0.001) than for those with good acuity.

Conclusion

The most important finding of this study was the high incidence of asthenopia in an unselected population and that refractive status per se was not a major contributor to CISS scores. The results highlight the usefulness of the CISS questionnaire for assessment of visual discomfort in school vision screenings and the need for future exploration of near binocular vision status as a potential driver of asthenopia in school students, especially given current trends for frequent daily use of computers and handheld devices and necessarily prolonged accommodative-convergence effort at near, both at school and at home.

The Influence of Binocular Vision Symptoms on Computerized Neurocognitive Testing of Adolescents With Concussion

Binocular vision disorders are commonly found postconcussion and associated with high symptom burden. We investigated the relationship between binocular vision symptoms and neurocognitive test performance. Thirty-four adolescents with concussion and 18 without concussion were assessed for cognitive performance using the CogState Brief Battery. Binocular vision disorders were determined using clinical examination and vision symptoms with the Convergence Insufficiency Symptoms Survey (CISS). A cutoff CISS score of 13 had high predictive accuracy for identifying individuals with a binocular vision disorder. CogState scores for processing speed and attention were significantly lower in the concussion group compared with the control group. Within the concussion group, scores for attention, learning, and working memory were significantly lower in those with vision symptoms. The presence of vision symptoms did not significantly affect CogState scores within the control group. The presence of vision symptoms in individuals with concussion is associated with significantly reduced scores on individual components of the CogState.

Visual Health and Academic Performance in School-Aged Children

BACKGROUND

Academic performance at different educational levels has become a very important subject of study in local, national and international institutions. A visual system working properly is critical to improving academic performance. It is important to check children's vision during the different stages of elementary school.

METHODS

A visual screening was carried out in elementary school children, aged between 6 and 12, across Spain. The screening included: the collection of demographic data, surveys of children and families about their vision habits and a basic optometric screening to detect visual problems.

RESULTS

Children with bad academic performance had worse visual health than those with good academic performance.

CONCLUSIONS

It would be highly recommendable to introduce policies that ensure the early detection of visual disorders in schools and primary care in order to improve the academic performance of elementary students.

Receipt of Corrective Lenses and Academic Performance of Low-Income Students

OBJECTIVE

Untreated vision problems are associated with poor school performance. Whether providing glasses alone improves performance, however, remains unknown. We sought to test whether receiving glasses was associated with improved school performance for low-income minority students in Los Angeles.

METHODS

From 2017 to 2018, we analyzed achievement marks in mathematics and language arts from 406 first to fifth grade students attending 24 public elementary schools who received glasses through a free school-based vision program between February and May 2014, and 23,393 of their nonparticipating same-school, same-grade peers. We calculated students' percentile rank during each grading period in 1 year before and 2 years since they received glasses. Multilevel linear regressions tested whether percentile rank differed from baseline at each subsequent grading period. Models accounted for clustering at the school level and controlled for gender, grade level, and baseline class rank. Interaction terms tested whether associations differed by gender and class rank.

RESULTS

Students increased 4.5 percentile points (P = .02) in language arts in the second year after receiving glasses. There was no change in math achievement overall; however, those with baseline performance in the bottom tercile had an immediate and sustained improvement of 10 to 24 percentile points from baseline (interaction term P < .001). Class rank for behavior marks decreased during the fourth grading period after receiving glasses but subsequently returned to baseline. There were no significant changes in work habits and no variation in results by gender.

CONCLUSIONS

Ensuring access to vision care may be a simple, scalable strategy to improve language arts performance for low-income minority children.

Vergence and Accommodative Dysfunctions in Emmetropic and Myopic Chinese Young Adults

Purpose

To investigate the association between refractive error and common binocular vision and accommodative dysfunctions in Chinese adults and to report the percentage of these disorders in this sample population.

Methods

This was a single-site, prospective cross-sectional clinic-based study. A total of 415 Chinese participants aged between 21 and 38 years were grouped into 4 refractive error groups (emmetropia, low, moderate, and high myopia) based on the spherical equivalent power of noncycloplegic refraction. Baseline testing including binocular vision and accommodative testing was performed on all eligible participants. A multiple-sign classification system was used to analyze these data for the diagnosis of common nonstrabismic binocular vision and accommodative dysfunctions. Associations between the diagnosis and refractive error groupings were examined by the chi-square test for the linear trend.

Results

Associations with refractive error groupings were found for convergence insufficiency (p=0.008, r = −0.13) and divergence insufficiency (p=0.008, r = 0.131). The 3 most common dysfunctions in this sample population were basic exophoria (10.8%), convergence insufficiency (9.6%), and divergence insufficiency (7.0%). Approximately 40% of the sample population demonstrated at least one type of binocular vision dysfunction.

Conclusion

Convergence insufficiency and divergence insufficiency were associated with refractive error groupings. Binocular vision dysfunction was a common finding in this sample population.

Accommodative insufficiency in a student population in Iran

PURPOSE

To determine the prevalence of accommodative insufficiency (AI) and its relation with age, gender, and refractive errors in a college-age student population in Iran.

METHODS

The present study was conducted cross-sectionally in 2017. All students had optometric tests including measurement of visual acuity, objective and subjective refraction, as well as binocular vision and accommodative examinations. Amplitude of accommodation was measured with the Donders' push-up method using the Royal Air Force (RAF) rule. Monocular accommodative facility was measured with ±2.00diopter flipper lenses. The accommodative response was tested using dynamic retinoscopy with the monocular estimation method (MEM).

RESULTS

The prevalence of AI in the studied population was 4.07% (95% CI: 2.61-5.52). The rate was 6.04% (95% CI: 3.58-8.50) in females and 2.01% (95% CI: 0.53-3.48) in males, and logistic regression showed a significantly higher odds of AI in females (OR=3.14, 95% CI: 1.33-7.45, p-value=0.009). The prevalence of AI was 2.59% (95% CI: 0.55-7.56) in the 18-19-year-old age group and 4.08% (95% CI: 0.09-8.07) in the 24-25-year-old group (p-value=0.848). The prevalence of AI among emmetropic, myopic, and hyperopic individuals was 3.74% (95% CI: 1.88-5.61), 4.44% (95% CI: 2.07-6.81), and 5.26% (95% CI: 4.79-16.32), respectively (p-value=0.869). In the multiple regression model, only gender showed significant relationship with AI (Odds ratio=3.14, 95% CI: 1.33-7.45; p-values=0.009).

CONCLUSION

The prevalence of AI in the present study is lower than the most prevalence rates reported in previous studies. In the present study, gender and AI showed a strong association, such that AI prevalence was significantly higher in females than males.

Sensitivity and specificity of school nurse screening for hypermetropia and convergence insufficiency exophoria in primary schoolchildren in Denmark

BACKGROUND

To determine the sensitivity and specificity of school nurse screening for hypermetropia and convergence insufficiency exophoria (CIE) in schoolchildren.

METHODS

Near point of convergence and distance visual acuity with +2.00D lenses were measured in 2097 children (6-15 years) during standard school nurse screening in the municipality of Randers, Denmark. One hundred and ninety-four children with positive screening results (near point of convergence >10 cm and/or distance visual acuity improved or maintained with +2.00D) and 182 controls with negative screening results received a full vision assessment, including cycloplegic refraction and orthoptic evaluation.

RESULTS

Sensitivity and specificity of screening was 0.75 and 0.69 for CIE and 0.59 and 0.87 for hypermetropia (≥+2.00), respectively. While precision of screening for CIE was significantly higher for symptomatic children aged 9-15 than for younger and asymptomatic children, precision of screening for hypermetropia was independent of age and presence of visually related symptoms.

CONCLUSION

While precision of screening for CIE and hypermetropia (>+2.00) was low, additional vision evaluation of children older than 9 years with asthenopic symptoms identified most children with CIE with a low absolute number of false positives.

Convergence insufficiency and accommodative insufficiency in children

PURPOSE

Convergence and accommodative insufficiency represent the main cause of complaints during close visual work and can reduce visual performance and comfort. Knowing their prevalence among schoolchildren is fundamental to define strategies for action. The purpose of this study was to estimate the frequency of these conditions in children in 5th and 6th school years in inland Portugal and to assess the impact that each visual condition has on their quality of life, based on the level of visual symptoms.

METHODS

a cross-sectional study was carried out with children enrolled in the 5th and 6th school years. 372 children (192 girls) were assessed, with average ages of 10.9 ± 0.9 years. Refractive error and binocular vision assessment, integrating accommodative parameters, were used to analyse the visual condition. Symptoms were quantified using the Portuguese version of the CISS (Convergence Insufficiency Symptom Survey).

RESULTS

The prevalence of definite Convergence Insufficiency (CI) in the children assessed was 2%. A prevalence of 6,8% could be considered if clinically significant CI (high suspect and definite categories) cases are accounted. In relation to Accommodative Insufficiency (AI), a frequency rate of 10% was recorded, with 3% of the evaluated children presenting AI and CI simultaneously. The symptoms score was higher in AI than in CI.

CONCLUSIONS

A frequency of approximately 10% was found for each one of the visual syndromes, and it was verified that visual discomfort is common among teenagers who carry these conditions. In cases of asthenopia, such as headaches and loss of concentration, associated with near vision activities, there is a requirement to evaluate the quality of binocular vision.

Induced vergence-accommodation conflict reduces cognitive performance in the Stroop test

Interaction mechanisms between cognition and binocular motor control in reading saccades remain unclear. In this study we examine objectively saccades and fixations parameters during the Stroop test, involving three different levels of cognitive demand (reading, color denomination and interference). In addition, we experimentally induce accommodation and vergence conflicts during the different tasks. Twenty-one visually normal subjects (age 20.9 ± 1.45) performed the Stroop test in three different randomized conditions: a control normal viewing condition, a 16Δ base-out prism condition, and a -2.50D spherical lenses condition. Prisms and spherical lenses induced Vergence-Accommodation conflict. Eye movements were recorded with the Eyeseecam video-oculography device. The results show (1) longer fixation duration in the interference task than in the denomination task, and shorter fixation duration in the reading task; (2) a higher interference effect in the conflict induced conditions compared to the control condition; (3) a lower tolerance to prism induced conflict, with a higher destabilization of the binocular motor control of saccades and fixations. This suggests an interplay between vergence accommodation conflict and cognitive load: tolerance to the conflict seems to be lower in the more cognitively demanding interference Stroop task. The results consolidate the link between cognition and high quality of single binocular vision.

Review of school vision screening guidelines

Background: Vision screenings are important in identifying visual anomalies likely to disrupt the physical, intellectual, social and emotional development of children. School health services globally include vision screenings, complementing a variety of associated screening services.Aim: This review article provides evidence for content, provision and efficacy of the vision screening services for children of school-going age and reports on the current practice of children’s vision screenings worldwide including in South Africa.Methods: Studies were identified from PubMed, Ebscohost and Science Direct with the search terms utilised during the selection of electronic articles and journals for the review. The target population includes children of school-going age from 6 to 19 years without previously known conditions associated with visual anomalies and learning-related problems. The quality of vision screening programmes and policies for the school-going age children in different countries were evaluated using Wilson and Jungner criteria.1Results: Vision screening programmes worldwide appear to support comprehensive vision screening methods among pre-schoolers (from birth to ≤ 6 years vs. children of school-going age). The development of vision screening procedures in some countries in the United States of America (USA) was found to be grounded on epidemiologic findings and principles. These may have contributed towards the formulation of national vision screening guidelines for pre-schoolers that supported the detection of amblyopia and its associated conditions such as strabismus, anisometropia and myopia. School-going children’s vision screenings are not supported worldwide as research has shown that there is lack of benefits for detecting other visual anomalies such as vergence and accommodative dysfunctions. This is despite evidence provided by the literature reviewed that an association exists between prevalent accommodation and vergence dysfunctions including poor ocular motilities and poor near-vision, among children of school-going age with poor academic performance.Conclusion: The guidelines worldwide support school vision screenings, especially for the pre-schoolers by the school health nurses, with other programs having considered the teachers, optometrists or orthoptists as the appropriate personnel to conduct the school vision screenings. There is still a need for the effectiveness of the school vision-screening programmes to be investigated related to the importance of detecting convergence and accommodative dysfunctions for the school going age children.

[Development and Effects of Social Learning Theory Based Eye-Health Program for Preschoolers]

PURPOSE

The purpose of this study was to develop an eye-health program based on social learning theory (EPST) of preschoolers and evaluate its effectiveness.

METHODS

A nonequivalent control group pre-post test design was utilized and 141 six-year-old preschoolers and their parents participated (experimental group=69, control group=72) in the study. The EPST in this study included eye-health education and eye exercises. Attention, memory, replay, motivation, reinforcement, and self-efficacy were used as interventional strategies. To examine the effectiveness of EPST, proficiency in eye-health activities, refractive power, and visual acuity were measured before and after the intervention. Data were analyzed with SPSS WIN 21.0 using the Shapiro-Wilk test, χ²-test, Mann-Whitney U test and Wilcoxon signed rank test.

RESULTS

Following the intervention, eye-health activities, refractive power, and visual acuity significantly improved in the experimental group compared to the control group.

CONCLUSION

The results of this study suggest that EPST is effective in improving eye-health activities, refractive power, and visual acuity in preschoolers, and its wider implementation in educational institutions will promise improved eye-health among preschoolers.

Visual Aspects of Reading Performance in Myalgic Encephalomyelitis (ME)

People with Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS) report vision-related reading difficulty, although this has not been demonstrated objectively. Accordingly, we assessed reading speed and acuity, including crowded acuity and acuity for isolated words using standardized tests of reading and vision, in 27 ME/CFS patients and matched controls. We found that the ME/CFS group exhibited slower maximum reading speed, and had poorer crowded acuity than controls. Moreover, crowded acuity was significantly associated with maximum reading speed, indicating that patients who were more susceptible to visual crowding read more slowly. These findings suggest vision-related reading difficulty belongs to a class of measureable symptoms for ME/CFS patients.

Near Point of Convergence in Iranian Schoolchildren: Normative Values and Associated Factors

PURPOSE

To determine the distribution of near point of convergence (NPC) and its related factors in 6 to 12-year-old children.

METHODS

In a cross-sectional study in 2015, the urban and rural children of Shahroud, north of Iran, were sampled. All rural schoolchildren were invited to the study, and in the urban area, we conducted random cluster sampling. Examinations included measurement of uncorrected and corrected visual acuity, manifest, subjective, and cycloplegic refraction. NPC and near point of accommodation (NPA) were measured with the best optical correction.

RESULTS

Of the 6624 sampled schoolchildren, 5620 participated in the study, and after applying the exclusion criteria, the final analysis was conducted on data from 5444 students; their mean age was 9.24 ± 1.71 years (6-12 years) and 53.6% (n = 2918) of them were male. Mean NPC was 8.08 cm [95% confidence interval (CI): 7.96-8.19]; 8.07 cm (95% CI: 7.92-8.22) in males and 8.08 cm (95% CI: 7.91-8.25) in females (p = 0.954). NPC significantly recessed with age (p < 0.001). Mean NPC in emmetropic, myopic, and hyperopic children were 8.13, 7.04, and 8.23 cm, respectively (p < 0.001). The multiple linear regression model revealed significant associations for NPC with age (coefficient = 0.10, 0.95% CI: 0.05-0.15, p < 0.001), spherical equivalent refraction (coefficient = 0.17, 95% CI: 0.10-0.24, p < 0.001), and NPA (coefficient = 0.83, 0.95% CI: 0.76-0.90, p < 0.001).

CONCLUSION

Mean NPC in 6-12-year-old Iranian children was 8.08 cm, which is worse than values reported in previous studies. Mean NPC showed a slight recession with age. Myopic schoolchildren had the least remote and hyperopes had the most remote NPC values. More remote values of NPA were associated with receded NPC.

Stereoacuity and refractive, accommodative and vergence anomalies of South African school children, aged 13–18 years

Aim: The aim of this study was to explore possible associations between stereoacuity and refractive, accommodative and vergence anomalies.Methods: The study design was cross-sectional and comprised data from 1056 high school children aged between 13 and 18 years; mean age and standard deviation were 15.89 ± 1.58 years. Using a multi-stage random cluster sampling, participants were selected from 13 high schools out of a sample frame of 60 schools in the municipality concerned. In the final sample, 403 (38%) were males and 653 (62%) females. Refractive errors, heterophoria, near point of convergence, fusional vergences and accommodative functions (amplitude, facility, response and relative) were evaluated. Stereoacuity was evaluated using the Randot stereotest and recorded in seconds of arc where reduced stereoacuity was defined as worse than 40 s arc.Results: Overall, the mean stereoacuities (in seconds of arc) of the children with anomalies were the following: those with refractive errors (52.6 ± 36.9), with accommodative anomalies (53.1 ± 34.1) and with vergence anomalies (48.29 ± 31.1). The mean stereoacuity of those with vergence anomalies was significantly better than that of those with either refractive errors or accommodative anomalies (p = 0.02). In the refractive error category, only anisometropia had significantly reduced mean stereoacuity compared to emmetropia (Mann–Whitney U: p = 0.01). The mean stereoacuity of cases of accommodative anomalies was significantly reduced compared to those without such anomalies (Mann–Whitney U: p = 0.01). Similarly, the mean stereoacuity of cases with vergence anomalies was significantly reduced compared to those without vergence anomalies (p = 0.02).Conclusion: Refractive errors, accommodative or vergence anomalies are more likely to have reduced mean stereoacuity than cases without such anomalies. Refractive errors or accommodative anomalies had significantly more reduced stereoacuity than vergence anomalies. These findings suggest that the Randot stereotest could be used to identify those with such anomalies, and this study extends knowledge regarding the possible use of stereoacuity as a useful tool to screen for binocular anomalies.

Combined Office-based Vergence Therapy and Home Therapy System for Convergence Insufficiency in Egyptian Children

Background:

Convergence Insufficiency (CI) is a common binocular vision disorder characterized by exophoria more at near than at far, a receded Near Point of Convergence (NPC), and decreased Positive Fusional Vergence (PFV) at near. This disorder is often associated with several symptoms that may disturb the person’s quality of life. Therefore, diagnosis and treatment of CI is a vital issue.

Objectives:

To compare therapeutic yield of Office Based Vision Therapy (OBVT) and combined OBVT with Home Therapy System (HTS) in patients with CI.

Methods:

The study included 102 patients with age range of 7-13 years. All patients underwent Convergence Insufficiency Symptom Survey (CISS) scoring, estimation of Near Point of Convergence (NPC) and determination of Positive Fusional Vergence at near (PFV) using Sheard’s criterion. Patients were randomly allocated in two groups: Group I: received Office-based Vision Therapy (OBVT) and Group II: received OBVT with home reinforcement using the Home Therapy System (HTS). At the end of 12^th week of therapy; outcome was determined as Successful (all the following: CISS score of <16, NPC <6 cm and PFV >15Δ), Improved (CISS score of <16 or a 10 points-decrease and one of the following: NPC <6cm or improved by >4 cm, PFV >15Δ or increased by > 10Δ), Insufficient response (NPC <6cm or improved by >4 cm, PFV >15Δ or increased by > 10Δ) and non-responders.

Results:

At the end of the 12^th week of therapy, the applied therapeutic polices were successful in 48 patients (47.1%), the symptoms were improved in 30 patients (29.4%), improvement was insufficient in 13 patients (12.7%) and 11 patients (10.8%) were considered as non-responders. There was significantly higher frequency of patients with improved outcome in group II (86%) compared to group I (69.2%).

Conclusion:

OBVT with home supplement using HTS provided a high success rate, and it seems to be superior to OBVT alone in treatment of children with convergence insufficiency after 12-week course of therapy.

Does Hofstetter's equation predict the real amplitude of accommodation in children?

PURPOSE

The aim was to determine the distribution and associated factors of accommodative amplitude (AA) in six- to 12-year-old children and compare the results with those calculated using Hofstetter's formula.

METHODS

In a cross-sectional study in 2015, random sampling was done from urban and rural populations of Shahroud, northern Iran. Participating schoolchildren were examined for manifest, cycloplegic and subjective refraction, as well as uncorrected vision and visual acuity. The AA was measured with Donders' push-up method using a ruler. The near point of convergence (NPC) was also measured.

RESULTS

Of the 6,624 selected children, 5,620 participated in the study and after applying the exclusion criteria, the final analyses were done on data from 5,444 schoolchildren. The mean age of the final sample was 9.24 ± 1.71 years (from six to 12 years) and 53.6 per cent (n = 2,919) were boys. Mean measured AA was 14.44 D (95 per cent confidence interval [CI]: 14.33-14.55). In all age groups, the mean measured AA was less than the predicted mean value calculated with the Hofstetter's equation. Mean measured AA was 14.44 D (95 per cent CI: 14.28-14.59) and 14.45 D (95 per cent CI: 14.29-14.6) in boys and girls, respectively (p = 0.926). AA significantly declined with age (coefficient: -0.18, 95 per cent CI: -0.23 to -0.12, p < 0.001). Mean AA in emmetropic, myopic and hyperopic children was 14.31 D, 17.30 D and 14.87 D, respectively. Older age (coefficient = -0.18), living in rural areas (coefficient = -0.48) and NPC (coefficient = 0.47) inversely related with AA and higher AA was associated with a shift of the spherical equivalent refraction toward myopia (coefficient = -0.41).

CONCLUSION

The differences among groups with different types of refractive error and high AA in children with myopia are important findings of this study. The results of the present study suggest that Hofstetter's formula provides inaccurate AA estimates in children and thus, the interpretation of this index requires further population-based studies in different racial and ethnic groups.

Is there an association between convergence insufficiency and refractive errors?

Background: Refractive errors and convergence insufficiency play major roles in reading efficiency. Uncorrected refractive errors are a primary cause of binocular anomalies, including convergence insufficiency. Symptoms of asthenopia in both refractive and binocular vision anomalies are similar. Despite the relationships that exist between them, the extent of association between refractive errors and convergence insufficiency has not been studied extensively.Aim: The aim of this study was to determine the prevalence of convergence insufficiency and refractive errors and investigate their associations with gender and age in a sample of high school children.Methods: The study design was cross-sectional and comprised data from 1056 African high school students aged 13–18 years, who were randomly selected from 13 high schools in uMhlathuze municipality in the province of KwaZulu-Natal, South Africa. In the final sample, 403 (38%) were males and 653 (62%) were females. The participants’ mean age and standard deviation were 15.89 ± 1.58 years and median age was 16 years. Refractive errors, heterophoria, near point of convergence, fusional vergences and accommodative functions were evaluated.Results: Prevalences for convergence insufficiency were as follows: low suspect 12.4% (confidence interval, [CI] 10.2–14.4), high suspect 6.3% (CI, 5.0–7.9), definite 4.6% (CI, 3.4–5.9), and pseudo-convergence insufficiency 2.1% (CI, 1.2–3.0). Refractive errors were: hyperopia 6.8% (CI, 5.3–8.4), myopia 6.0% (CI, 4.6–7.5), astigmatism 2.3% (CI, 1.8–3.2), anisometropia 1.3% (CI, 0.7–2.0) and emmetropia 86.2% (CI, 85.1–89.1). There were no significant associations between convergence insufficiency and gender (p = 0.32), age (p = 0.38), grade levels (p = 0.99) or refractive errors (p = 0.08).Conclusion: The prevalence of clinically significant convergence insufficiency and refractive errors was low in this sample of black high school students in South Africa, and there was no significant correlation between them.

Parent, Teacher, and Student Perspectives on How Corrective Lenses Improve Child Wellbeing and School Function

OBJECTIVES

Up to 20 % of school-age children have a vision problem identifiable by screening, over 80 % of which can be corrected with glasses. While vision problems are associated with poor school performance, few studies describe whether and how corrective lenses affect academic achievement and health. Further, there are virtually no studies exploring how children with correctable visual deficits, their parents, and teachers perceive the connection between vision care and school function.

METHODS

We conducted a qualitative evaluation of Vision to Learn (VTL), a school-based program providing free corrective lenses to low-income students in Los Angeles. Nine focus groups with students, parents, and teachers from three schools served by VTL explored the relationships between poor vision, receipt of corrective lenses, and school performance and health.

RESULTS

Twenty parents, 25 teachers, and 21 students from three elementary schools participated. Participants described how uncorrected visual deficits reduced students' focus, perseverance, and class participation, affecting academic functioning and psychosocial stress; how receiving corrective lenses improved classroom attention, task persistence, and willingness to practice academic skills; and how serving students in school rather than in clinics increased both access to and use of corrective lenses.

CONCLUSIONS

for Practice Corrective lenses may positively impact families, teachers, and students coping with visual deficits by improving school function and psychosocial wellbeing. Practices that increase ownership and use of glasses, such as serving students in school, may significantly improve both child health and academic performance.

The heterophoria of 3-5 year old children as a function of viewing distance and target type

PURPOSE

Heterophoria is the misalignment of the eyes in monocular viewing and represents the accuracy of vergence driven by all classical cues except disparity. It is challenging to assess restless children using clinical cover tests, and phoria in early childhood is poorly understood. Here we used eye tracking to assess phoria as a function of viewing distance and target in adults and young children, with comparison to clinical cover tests.

METHODS

Purkinje image tracking (MCS PowerRefractor) was used to record eye alignment in adults (19-28 years, N = 24) and typically developing children (3-5 years, N = 24). Objective unilateral and alternating cover tests were performed using an infrared filter while participants viewed a pseudo-randomised sequence of Lea symbols (0.18 logMAR; Snellen: 20/30 or 6/9) and animated cartoon movies at distances of 40 cm, 1 m, and 6 m. For the unilateral cover test, a 10 s binocular period preceded and followed 30 s of occlusion of the right eye. For the alternating cover test, a 10 s binocular period preceded and followed alternate covering of right and left eyes for 3-s each. Phoria was derived from the difference in weighted average binocular and monocular alignment. A masked prism-neutralised clinical cover test was performed for each of the conditions for comparison.

RESULTS

Closer viewing distance resulted in greater exophoria for both children and adults (p < 0.001). Phorias were similar for adults and children for each viewing distance and target, with mean differences of less than 2 prism dioptres (pd). Overall, the average PowerRefractor phorias (pooled across protocols) for adults were 1.3, 2.3 and 3.8 pd exophoria and for children were 0.1 pd esophoria, 0.94 and 3.8 pd exophoria for the 6 m, 1 m and 40 cm distances respectively. The corresponding clinical cover test values were 0.7, 1.9, and 4.1 pd exophoria for adults and 0, 1.5 and 3.3 pd exophoria for the children. Refractive states were also similar (≤0.5 D difference) for viewing the Lea symbols or movie for any protocol tested.

CONCLUSIONS

Phoria estimation can be challenging for a pre-school child. These data suggest that by 3-5 years of age objective eye-tracking measures in a typically developing group are adult-like at the range of distances tested, and that use of an animated movie produces similar average results to a small optotype (0.18 logMAR; Snellen 20/30 or 6/9).

Vergence anomalies in a sample of high school students in South Africa

AIM

To study the prevalence of nearpoint vergence anomalies (convergence insufficiency, convergence excess and fusional vergence dysfunction) and association with gender, age groups, grade level and study site (suburban and rural).

METHODS

The study design was cross sectional and data was analyzed for 1201 high school students aged 13-19 years who were randomly selected from 13 high schools in uMhlathuze municipality. Of the total sample, 476 (39.5%) were males and 725 (60.5%) were females. The visual functions evaluated included refractive errors, heterophoria, near point of convergence, accommodative functions and fusional vergences. Possible associations between vergence anomalies and demographic variables (gender, age groups, school grade levels and study site) were explored.

RESULTS

Prevalence estimates were 11.8%, 6% and 4.3% for low suspect, high suspect and definite convergence insufficiency, and 1.9% for the pseudo convergence insufficiency. Convergence excess prevalence was 5.6%, and fusional vergence dysfunction was 3.3%. The prevalence of low suspect CI was significantly higher in suburban than in rural participants (p=0.01), the reverse was the case for pseudoconvergence insufficiency while the prevalence of convergence excess was significantly higher in the younger than in the older age group (p=0.02). No other category showed any statistically significant associations with vergence anomalies.

CONCLUSION

The prevalence estimates for vergence anomalies in a sample of black high school students in South Africa were relatively low. Only study location and age influenced some vergence anomalies. Identification and referrals are important steps toward diagnosis and treatment for vergence anomalies. Further studies to compare vergence anomalies in various racial populations will be relevant.

Accommodative and binocular dysfunctions: prevalence in a randomised sample of university students

BACKGROUND

The aim was to analyse the prevalence of symptomatic accommodative and non-strabismic binocular dysfunctions in a randomised population of university subjects.

METHODS

A cross-sectional study was conducted with a randomised sample of 175 university students aged between 18 and 35 years. All subjects were given a visual examination in which their symptoms were recorded, as well as performing objective and subjective refractive examinations and accommodative and binocular tests. Each subject was tested for the presence of uncorrected refractive error. Accommodative dysfunctions (AD) and binocular dysfunctions (BD) were diagnosed according to the number of clinical signs associated with each disorder, considering the signs that could be associated with each dysfunction as fundamental or complementary. An accommodative or binocular dysfunction was diagnosed when the subjects met two conditions: presenting with any kind of visual symptom in their clinical history and presenting the fundamental sign associated with each dysfunction as well as two or more complementary signs. Those subjects who presented with only an uncorrected refractive error were considered within the group called refractive dysfunction (RD).

RESULTS

The overall prevalence of accommodative and/or binocular dysfunctions was 13.15 per cent and for refractive dysfunction it was 45.14 per cent. Accommodative dysfunctions were present in 2.29 per cent of the population, binocular dysfunctions were observed in eight per cent and accommodative dysfunctions together were found in 2.86 per cent of the university students. Within the accommodative and binocular disorders, the most prevalent dysfunctions were convergence insufficiency, with a prevalence of 3.43 per cent and convergence excess and accommodation excess, both with a prevalence of 2.29 per cent.

CONCLUSION

Binocular dysfunctions were more prevalent than accommodative dysfunctions or accommodative and binocular dysfunctions together in a randomised population of university students.

The prevalence of poor ocular motilities in a mainstream school compared to two learning-disabled schools in Johannesburg

Background: Ocular motilities play a major role when reading for the continuous acquisition and updating of visually presented information. Accurate oculomotor control is required to be able to learn how to read and to efficiently read to learn. This process requires accurate decoding accomplished by precise oculomotor control.Aim: A comparison of the prevalence of poor ocular motilities between mainstream and learning-disabled schools were explored from three different schools; one mainstream and two disabled schools. One hundred and ninety-two children, age range 8–13 years (mean = 10.30, s.d.: ± 0.999) in grades 3 and 4, with 112 children from the two learning-disabled schools and 80 children from the mainstream school participated in the study.Method: The standardised direct observation test, using the Northeastern State University College of Optometry scoring criteria, was used to evaluate saccadic and pursuit eye movements. Fixation maintenance was evaluated using the Southern California College of Optometry scoring criteria. The Gulden fixation stick with a 6/24 letter E was used as a fixation target.Results: The results showed that children from the learning-disabled schools appeared to have a higher incidence of poor saccadic accuracy compared with children from the mainstream school. No significant associations in both the mainstream and the learning-disabled children were found for head movements, pursuits and fixation ability. However, the results suggest a statistically significant association between poor saccadic accuracy and children from the learning-disabled schools. Conclusion: This study provides further evidence for a link between poor saccadic accuracy and children from the school of the learning disabled. Keywords: Ocular motor dysfunction, saccadics, pursuits, learning disability, schools, fixation ability, visual attention

A Visual Profile of Queensland Indigenous Children

PURPOSE

Little is known about the prevalence of refractive error, binocular vision, and other visual conditions in Australian Indigenous children. This is important given the association of these visual conditions with reduced reading performance in the wider population, which may also contribute to the suboptimal reading performance reported in this population. The aim of this study was to develop a visual profile of Queensland Indigenous children.

METHODS

Vision testing was performed on 595 primary schoolchildren in Queensland, Australia. Vision parameters measured included visual acuity, refractive error, color vision, nearpoint of convergence, horizontal heterophoria, fusional vergence range, accommodative facility, AC/A ratio, visual motor integration, and rapid automatized naming. Near heterophoria, nearpoint of convergence, and near fusional vergence range were used to classify convergence insufficiency (CI).

RESULTS

Although refractive error (Indigenous, 10%; non-Indigenous, 16%; p = 0.04) and strabismus (Indigenous, 0%; non-Indigenous, 3%; p = 0.03) were significantly less common in Indigenous children, CI was twice as prevalent (Indigenous, 10%; non-Indigenous, 5%; p = 0.04). Reduced visual information processing skills were more common in Indigenous children (reduced visual motor integration [Indigenous, 28%; non-Indigenous, 16%; p < 0.01] and slower rapid automatized naming [Indigenous, 67%; non-Indigenous, 59%; p = 0.04]). The prevalence of visual impairment (reduced visual acuity) and color vision deficiency was similar between groups.

CONCLUSIONS

Indigenous children have less refractive error and strabismus than their non-Indigenous peers. However, CI and reduced visual information processing skills were more common in this group. Given that vision screenings primarily target visual acuity assessment and strabismus detection, this is an important finding as many Indigenous children with CI and reduced visual information processing may be missed. Emphasis should be placed on identifying children with CI and reduced visual information processing given the potential effect of these conditions on school performance.

Binocular Vision and the Stroop Test

PURPOSE

Recent studies report a link between optometric results, learning disabilities, and problems in reading. This study examines the correlations between optometric tests of binocular vision, namely, of vergence and accommodation, reading speed, and cognitive executive functions as measured by the Stroop test.

METHODS

Fifty-one students (mean age, 20.43 ± 1.25 years) were given a complete eye examination. They then performed the reading test L'Alouette and the Stroop interference test at their usual reading distance. Criteria for selection were the absence of significant refractive uncorrected error, strabismus, amblyopia, color vision defects, and other neurologic findings.

RESULTS

The results show a correlation between positive fusional vergences (PFVs) at near distance and the interference effect (IE) in the Stroop test: the higher the PFV value is, the less the IE. Furthermore, the subgroup of 11 students presenting convergence insufficiency, according to Scheiman and Wick criteria (2002), showed a significantly higher IE during the Stroop test than the other students (N = 18) who had normal binocular vision without symptoms at near. Importantly, there is no correlation between reading speed and PFV either for the entire sample or for the subgroups.

CONCLUSIONS

These results suggest for the first time a link between convergence capacity and the interference score in the Stroop test. Such a link is attributable to the fact that vergence control and cognitive functions mobilize the same cortical areas, for example, parietofrontal areas. The results are in favor of our hypothesis that vergence is a vector of attentional and cognitive functions.