Orthoptic Findings and Asthenopia in a Population of Swedish Schoolchildren Aged 6 to 16 Years

Cross-Sectional Analyses of Factors Related to Digital Eye Strain Symptoms Among Children Using Online Learning Devices During the COVID-19 Pandemic in Thailand

Purpose

Globally, the COVID-19 pandemic has influenced academic studies. Since 2019, most schools in Thailand have implemented online learning. Thus, several students are experiencing eye problems, including stinging, blurred vision, and epiphora. This study investigated the prevalence, eye symptoms, and characteristics associated with digital eye strain (DES) in children using digital devices.

Patients and Methods

In this cross-sectional study, a self-administered electronic questionnaire via google forms was used to collect demographic data, digital device information, and DES characteristic information in children of age 8-18 years using online digital devices. The data collection was conducted between December 2021 and January 2022. Moreover, multivariable logistic regression analysis was performed to evaluate the potential characteristics associated with DES in children.

Results

From a total of 844 parents, 782 parents completed the questionnaire. The mean age of the children was 12.42 ± 2.82 years (8-18 years). During the pandemic, the most common duration of using digital devices was >8 hours (39.90%), compared to only 2-4 hours (36.70%) before. The prevalence of DES was 42.2% (330/782), divided into mild (29.8%), moderate (8.1%), and severe (4.3%) symptoms. The most common symptoms of DES included: a burning sensation in the eyes (55.24%), fear of worsening eyesight (53.07%), and excessive blinking of eyes (48.33%). The associated characteristics with DES were advanced age (OR=1.21, P<0.001), refractive error with (OR=2.04, P=0.004) and without (OR=6.11, P<0.001) correction, and unknown refractive error (OR=2.85, P<0.001).

Conclusion

The use of digital devices are inevitable; therefore, regulating the duration of study and entertainment using digital devices, especially in older ages, and correcting refractive error in children, is necessary to ameliorate DES.

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.

Contribution of Total Screen/Online-Course Time to Asthenopia in Children During COVID-19 Pandemic via Influencing Psychological Stress

Objectives: During the coronavirus disease 2019 (COVID-19) self-quarantine period, the transition to online-course has profoundly changed the learning modes of millions of school-aged children and put them at an increased risk of asthenopia. Therefore, we aimed to determine associations of the total screen/online-course time with asthenopia prevalence among that children during the COVID-19 pandemic, and whether the associations were mediated by psychological stress.

Methods: Asthenopia was defined according to a validated computer vision syndrome questionnaire (CVS-Q). We used CVS-Q to collect the frequency and intensity of 16 asthenopia-related eye symptoms of 25,781 children. Demographic features, eye care habits, visual disorders, lifestyle, psychological and environmental factors, were also collected.

Results: The overall asthenopia prevalence was 12.1%, varying from 5.4 to 18.2% across grade/gender-classified subgroups. A 100-h increment of total screen/online-course time were associated with an increased risk of asthenopia by 9% [odds ratio (OR) = 1.09] and 11% (OR = 1.11), respectively. Mediation analysis showed that the proportions of total effects mediated by psychological stress were 23.5 and 38.1%, respectively. Age, female gender, having myopia or astigmatism, bad habits when watching screens were also risk factors. Conversely, keeping 34–65 cm between eyes and screen, increased rest time between classes, and increased eye exercise were all associated with a decreased risk.

Conclusion: Our study indicated that the influence of long total screen or online-course time on psychological stress increases asthenopia risk. The findings of this study have provided a new avenue for intervening screen-related asthenopia in addition to incorporating a reasonable schedule of online courses into educational policy.

Impact of E-Schooling on Digital Eye Strain in Coronavirus Disease Era: A Survey of 654 Students

Purpose:

To assess digital eye strain (DES) among schoolchildren during lockdown.

Methods:

An online questionnaire-based, cross-sectional study was conducted. A validated, self-administered, electronic questionnaire was circulated among students of 5–18 years of age. The duration of data collection was from May 18, 2020 to May 24, 2020. Rasch-based Computer-Vision Symptom Scale was deployed to measure the DES.

Results:

A total of 654 students (mean age: 12.02 ± 3.9 years) completed the survey. The average per day digital device exposure was 5.2 ± 2.2 h. A total of 507 (92.8%) children reported experiencing at least one asthenopic/dry eye symptom (AS/DS). The most prevalent symptoms were eye redness (69.1%) and heaviness of eyelids (79.7%). Significant positive correlation was reported between age and per day duration of digital device exposure (Pearson correlation 0.25; P < 0.001). Computer vision syndrome (CVS) score for spectacle users was significantly higher (P < 0.001). CVS score was found to correlate significantly with age and duration of digital device exposure (P < 0.001).

Conclusion:

Most of the students surveyed, experienced at least one symptom of DS or AS, indicating a need to educate them about the possible deleterious effects and help them adapt to the currently evolving education system.

Binocular vision disorders in a geriatric population

Clinical relevance: A population-based epidemiological survey is important to help establish the frequency of binocular vision disorders in a geriatric population. Such data will be useful to clinicians and help guide diagnostic testing for this age group.Background: To determine the prevalence of binocular vision disorders and their associations with age and sex in the geriatric population.Methods: This report is a part of the Tehran Geriatric Eye study (TGES); a population-based cross-sectional study conducted on residents over 60 years of age in Tehran, Iran, using random stratified cluster sampling. A total of 165 clusters were selected (proportionally to size) from 22 strata of Tehran city. All participants underwent a complete ocular examination including the measurement of visual acuity, refraction, unilateral and alternating cover tests, and the Worth 4-dot suppression test. Strabismus was defined as the presence of constant unilateral or alternating esotropia or exotropia at either near (40 cm) or far (6 m). Distance and near exophoria were defined as more than 3^Δ and 9^Δ of exophoria at 6 m and 40 cm, respectively. Distance and near esophoria were defined as more than 1^Δ and any amount of esophoria at 6 m and 40 cm, respectively.Results: Statistical analysis was performed on the data of 2,227 participants. The mean age of the participants was 66.6 ± 5.4 years and 59.4% were female. The prevalence of distance exophoria, esophoria, and hyperphoria was 8.9%, 0.34%, and 0.29%, respectively. The prevalence of near exophoria, esophoria, and hyperphoria was 32.4%, 0.61%, and 0.37%, respectively. The prevalence of distance exotropia and esotropia was 1.3% and 0.63%, respectively. The prevalence of near exotropia and esotropia was 4.6% and 0.59%, respectively.Conclusion: Non-strabismic binocular vision disorders were prevalent in an elderly population. Exo deviations were more prevalent than eso deviations.

Correlations between clinical measures and symptoms: Report 2: Accommodative and vergence measures with symptoms

AIM

The aim of this study was to explore associations among clinical measures of accommodation and vergences with symptoms, which could facilitate the validation of the Convergence Insufficiency Symptoms Survey to screen for deficient clinical measures.

METHODS

Using a multi-stage random cluster sampling, 1211 high school students (481 males and 730 females) between 13 and 18 years of age were selected and examined. Visual acuity, stereoacuity and suppression, refractive errors, near point of convergence, heterophoria and fusional vergences, as well as, amplitude of accommodation, accommodative response, facility and relative accommodation were evaluated. The validity of the Convergence Insufficiency Symptoms Survey to distinguish between children with and those without anomalies in the clinical measures were characterized using the Receiver Operation Curve, sensitivity and specificity of the tests.

RESULTS

The overall mean and standard deviation for symptoms score was 27.38 ± 11.04. Deficient accommodative measures revealed worse symptoms scores than did deficient vergence measures and children with deficient clinical measures had significantly higher mean symptoms scores. (p = 0.001) However, the correlations between defective clinical measures and symptoms were significant but relatively weak. The Receiver Operation Curve showed that the clinical measures with the highest sensitivities using the CISS (≥16) were: reduced amplitude of accommodation 0.63, 95% Confidence interval, 0.59-0.68%) accommodative facility 0.62 (95% Confidence interval, 0.58-0.67) and near point of convergence 0.60 (95% Confidence interval, 0.53-0.67).

CONCLUSION

Deficient clinical measures and symptoms of asthenopia are prevalent and correlated in the sample of school children studied. Overall, findings suggest that high school children with deficient clinical measures may be symptomatic when they perform intense near task compared to those without deficiencies. In addition, although validated for convergence insufficiency, the Convergence Insufficiency Symptoms Survey could barely distinguish between children with and without defective clinical measures. Findings highlight the need for and provide baseline data towards possible validation of a fast and reliable screening tool for vision anomalies. Further studies on similar populations are needed to confirm these findings and add to knowledge base.

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.

High Prevalence of Asthenopia among a Population of University Students

Purpose

To determine the prevalence of asthenopia and its associated factors in a sample of university students in Iran.

Methods

In this cross-sectional study, participants were selected using multistage cluster sampling. Presence of at least one of the 10 symptoms—foreign body sensation, diplopia, blurred vision, eye swelling, dry eye, eye pain, difficulty in sustaining visual operations, decreased visual acuity, tearing, and photophobia—was considered as asthenopia. Ocular examinations, including uncorrected/corrected visual acuity measurement, objective/subjective refraction, cover test, amplitude of accommodation (AA), and near point of convergence (NPC) were performed.

Results

Of the 1,462 students (mean age: 22.8 ± 3.1 years), 73% were women. The age- and gender-standardized prevalence was 70.9% (95% confidence interval [CI]: 68.3–73.5), 39.8% (95% CI: 36.4–43.1), and 19.7% (95% CI: 16.0–23.3) based on the presence of at least one, two, and three symptoms, respectively. The prevalence was significantly higher in females (P = 0.048), hyperopic students (P< 0.001), and astigmatic participants (P < 0.001). The mean AA and NPC were 9.7 ± 2.6 D and 10.2 ± 4.2 D (P = 0.008) and 7.0 ± 2.1 cm and 7.7 ± 3.9 cm (P< 0.001) in participants with and without asthenopia, respectively. Multiple regression model revealed age (28–29 years), astigmatism, and NPC as independent associated factors (odds ratios: 3.51, 1.61, and 0.91, respectively).

Conclusion

This study shows relatively high prevalence of asthenopia in university students. Demographic factors and visual system disorders are important risk factors and timely correction of conditions may lead to decreased asthenopia.

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.

Ametropia in children with headache

Objective

To measure the frequency of uncorrected ametropia in children with 2 to 8 weeks of persistent headache referred to ophthalmic outpatient department for evaluation.

Methods

This cross sectional study was conducted at CMH Gujranwala from March 2018 to November 2018.A total of 262 children, aged from 5 to 16 years, with 2 to 8 weeks history of persistent headache underwent detailed ophthalmic assessment for refractive errors, and other ophthalmic evaluation. Children with ametropia, confirmed with cycloplegic refraction and post-mydriatic testing were prescribed with glasses. Patients without any ophthalmic findings were referred back to pediatrics department for further evaluation.

Results

Mean age of study population was 8.97 ± 3.16 years. Mean duration of headache was 5.03 ± 1.81 weeks. Ametropia was found in 56 (21.4%) children, while 206 (78.6%) had no refractive error. Out of children with ametropia, 20 (35.7%) had myopia, 24 (42.8%) had astigmatism and 12 (21.5%) had hypermetropia. There was no difference in ametropic children and children without ametropia with respect to gender (p=0.73), age (p=0.54) and duration of headache (p=0.71).

Conclusion

A significant proportion of children with ametropia have initial symptoms of headache. Any child with un-explained headache must undergo ophthalmic evaluation to diagnose refractive error, if any.

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.

Prevalence of heterophoria and its association with near fusional vergence ranges and refractive errors

Background: Heterophoria is an error of binocular alignment that manifests only during monocular viewing or in conditions that disrupt binocular vision. Heterophoria is compensated for by fusional vergence through a mechanism that involves both sensory and motor fusion. The distribution of heterophoria has not been studied extensively in schoolchildren in South Africa and studies quantifying the magnitude of association between heterophoria and fusional vergences are scarce.Purpose: The aim of this study was to determine the prevalence of heterophoria and investigate its associations with fusional vergences and refractive errors.Methods: This was a cross-sectional study design and comprised data from 1056 high school students aged 13–18 years, who were randomly selected from 13 out of a sample frame of 60 high schools in uMhlathuze municipality in the province of KwaZulu-Natal, South Africa. The sample comprised 403 (38%) males and 653 (62%) females. The participants’ mean age was 15.89 ± 1.58 years. Visual acuity, refractive errors, heterophoria and fusional vergences were evaluated using conventional optometric techniques.Results: The overall prevalence of orthophoria at distance was 80.1% (95% confidence interval [CI]: 77.7% – 82.6%), that of exophoria was 13.9% (CI: 11.9% – 16.0%), while that of esophoria was 6.0% (CI: 4.5% – 7.4%). At near, the prevalence estimates were as follows: exophoria, 542 (51.3%, CI: 48.3% − 54.2%); orthophoria, 36.6% (CI: 33.9% − 39.5%); esophoria, 12.1% (CI: 10.2% − 14.0%). On the severities of near phoria, the frequencies were as follows: mild (1–7 prism dioptres [pd]), 41% (CI: 38.3% – 44.1%); moderate (8–13 pd), 9.7% (CI: 7.8% – 11.5%); and severe (> 13 pd), 1.1% (CI: 0.6% – 1.8%). For the severities of fusional vergences, the distributions were as follows: positive fusional vergences, mild (15–22 pd), 88.3% (CI: 86.4% – 90.4%); moderate (> 7 to < 15 pd), 10.1% (CI: 8.2% – 11.9%); and severe (≤ 7 pd), 1.6% (CI: 0.9% – 2.4%). For negative fusional vergences, the percentage of anomalous cases (≥ 22 pd) was 14.2% (CI: 12.3% – 16.3%), while that for normal (< 22) was 85.8% (CI: 83.7% – 87.7%). For vertical phoria, the prevalence was 2.7% and 3.6% at near. There was a weak but significant inverse correlation between near exophoria and positive fusional vergence break (r = −0.10, p = 0.01), whereas exophoria and negative fusional vergence break were positively correlated (r = 0.14, p = 0.01). Esophoria was inversely correlated with negative fusional vergence break values (r = 0.13, p= 0.01) and was positively correlated with positive fusional vergence break (r = 0.13, p = 0.03). Chi-square tests showed that exophoria was associated with astigmatism (p = 0.01), while esophoria was significantly associated with myopia (p = 0.01), astigmatism (p = 0.01) and anisometropia (p = 0.01).Conclusion: The data for far and near distance, horizontal and vertical heterophoria were not normally distributed. Orthophoria was most prevalent at far, exophoria at near and there was a significant association between phoria and fusional vergence. The significant associations between phoria and fusional vergence were at lower levels of fusional vergences.

Visual symptoms associated with refractive errors among Thangka artists of Kathmandu valley

BACKGROUND

Prolong near work, especially among people with uncorrected refractive error is considered a potential source of visual symptoms. The present study aims to determine the visual symptoms and the association of those with refractive errors among Thangka artists.

METHODS

In a descriptive cross-sectional study, 242 (46.1%) participants of 525 thangka artists examined, with age ranged between 16 years to 39 years which comprised of 112 participants with significant refractive errors and 130 absolutely emmetropic participants, were enrolled from six Thangka painting schools. The visual symptoms were assessed using a structured questionnaire consisting of nine items and scoring from 0 to 6 consecutive scales. The eye examination included detailed anterior and posterior segment examination, objective and subjective refraction, and assessment of heterophoria, vergence and accommodation. Symptoms were presented in percentage and median. Variation in distribution of participants and symptoms was analysed using the Kruskal Wallis test for mean, and the correlation with the Pearson correlation coefficient. A significance level of 0.05 was applied for 95% confidence interval. The majority of participants (65.1%) among refractive error group (REG) were above the age of 30 years, with a male predominance (61.6%), compared to the participants in the normal cohort group (NCG), where majority of them (72.3%) were below 30 years of age (72.3%) and female (51.5%).

RESULT

Overall, the visual symptoms are high among Thangka artists. However, blurred vision (p = 0.003) and dry eye (p = 0.004) are higher among the REG than the NCG. Females have slightly higher symptoms than males. Most of the symptoms, such as sore/aching eye (p = 0.003), feeling dry (p = 0.005) and blurred vision (p = 0.02) are significantly associated with astigmatism.

CONCLUSION

Thangka artists present with significant proportion of refractive error and visual symptoms, especially among females. The most commonly reported symptoms are blurred vision, dry eye and watering of the eye. The visual symptoms are more correlated with astigmatism.

Refractive Error in a Sample of Black High School Children in South Africa

SIGNIFICANCE

This study focused on a cohort that has not been studied and who currently have limited access to eye care services. The findings, while improving the understanding of the distribution of refractive errors, also enabled identification of children requiring intervention and provided a guide for future resource allocation.

PURPOSE

The aim of conducting the study was to determine the prevalence and distribution of refractive error and its association with gender, age, and school grade level.

METHODS

Using a multistage random cluster sampling, 1586 children, 632 males (40%) and 954 females (60%), were selected. Their ages ranged between 13 and 18 years with a mean of 15.81 ± 1.56 years. The visual functions evaluated included visual acuity using the logarithm of minimum angle of resolution chart and refractive error measured using the autorefractor and then refined subjectively. Axis astigmatism was presented in the vector method where positive values of J0 indicated with-the-rule astigmatism, negative values indicated against-the-rule astigmatism, whereas J45 represented oblique astigmatism.

RESULTS

Overall, patients were myopic with a mean spherical power for right eye of -0.02 ± 0.47; mean astigmatic cylinder power was -0.09 ± 0.27 with mainly with-the-rule astigmatism (J0 = 0.01 ± 0.11). The prevalence estimates were as follows: myopia (at least -0.50) 7% (95% confidence interval [CI], 6 to 9%), hyperopia (at least 0.5) 5% (95% CI, 4 to 6%), astigmatism (at least -0.75 cylinder) 3% (95% CI, 2 to 4%), and anisometropia 3% (95% CI, 2 to 4%). There was no significant association between refractive error and any of the categories (gender, age, and grade levels).

CONCLUSIONS

The prevalence of refractive error in the sample of high school children was relatively low. Myopia was the most prevalent, and findings on its association with age suggest that the prevalence of myopia may be stabilizing at late teenage years.

Characteristics of astigmatism in Black South African high school children

Background

Astigmatism impairs vision at various distances and causes symptoms of asthenopia which negatively impacts reading efficiency.

Objective

The aim of conducting this study was to determine the prevalence and distribution of astigmatism and its relationship to gender, age, school grade levels and spherical ametropia.

Methods

Using a multi-stage random cluster sampling, 1589 children who included 635 (40%), males, and 954 (60%), females were selected from 13 out of a sample frame of 60 schools. Their ages ranged between 13 and 18 years with a mean of 15.81±1.56 years. The parameters evaluated included visual acuity using the LogMAR chart and refractive errors measured using an autorefractor and then refined subjectively. Axis of astigmatism was presented in the vector method where positive values of J0 indicated with-the-rule, negative values described against-the-rule and J45 represented oblique astigmatism.

Results

The mean cylinder power was −0.09 ± 0.27 and mainly with-the-rule, J0 = 0.01 ± 0.11. The overall prevalence of clinically significant astigmatism (≤ − 0.75 cylinder) in the sample was 3.1% [(95% Confidence interval = 2.1–4.1%)]. Cylinder of at least − 0.25 power was considered to classify astigmatism types. Thus, the estimated distributions of types of astigmatism were: axis- 11.5%, sphero-astigmatism 10.1% and magnitude-astigmatism 11.2% while 67.2% had no cylinder of any magnitude.

Conclusion

The prevalence of astigmatism is relatively low in this population studied. Older children and those in high school grade levels were more likely to have with-the-rule or against-the-rule astigmatism. The prevalence of astigmatism were comparable within but not across regions.

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.

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.

A review of non-strabismic accommodative-vergence anomalies in school-age children. Part 1: Vergence anomalies

Comfortable reading and the performance of near point activities involve efficient accommodative and vergence systems. However, accommodative and vergence anomalies are associated with various symptoms that impair efficient near point tasks. Although several studies investigated accommodative-vergence anomalies in school-age populations, their findings were diverse owing to differences in diagnostic techniques and the criteria used to define the variables. The aim of this paper is to derive prevalence and distribution estimates of vergence anomalies in school-age children and address variations in the study methods and findings. Despite variations in the study methods and findings, accommodativevergence anomalies were common in school-age populations. Variations and limitations of previous studies are discussed and recommendations for improving future studies are suggested.

Frequency of asthenopia and its association with refractive errors

Background: Asthenopia is a common complaint amongst patients who attend eye care settings. Owing to associated discomfort or distress, asthenopia affects efficient reading and performance of near tasks.Purpose: To study the prevalence of asthenopia and any association with refractive errors in a clinical setting.Methods: In this cross-sectional practice-based study, the clinic records of 1109 school-aged children (mean age and standard deviation 14.39 ± 3.39 years) were analysed. The sample comprised 427 (38.5%) male and 682 (61.5%) female patients between the ages of 6 and 19 years. Refractive errors were classified into various types, and the association between these refractive types and symptoms in asthenopia were explored.Results: The most common symptom of asthenopia was headaches (40.8%), of which temporal headaches were the most frequent type (15.7%). Various symptoms were significantly associated with mainly astigmatism.Conclusion: Headaches were the most frequent complaint amongst patients who attended the author’s optometric practice. Astigmatism was the most frequent cause of asthenopia. Female patients were more likely than male patients to complain of asthenopia, whilst high school students were more likely than primary school children to complain of asthenopia. Further studies to relate asthenopia to binocular anomalies will be relevant in enhancing our understanding of the relationship between asthenopia and vision anomalies.

A review of non-strabismic accommodative and vergence anomalies in school-age children. Part 2: Accommodative anomalies

Comfortable reading and the performance of related near point activities involve efficient accommodative and vergence systems. However, accommodative and convergence anomalies are associated with various symptoms of asthenopia that impair efficient near point tasks. In Part 1 of this two-part article, studies on vergence anomalies were reviewed. In the current paper (Part 2), anomalies of accommodation are reviewed. The aims of the latter paper were to derive the prevalence and distribution estimates of anomalies of accommodation in school-age children and address variations in the study methods and findings. Despite variations in the study methods and findings, anomalies of accommodation are prevalent among school-age populations. Variations and limitations of previous studies are discussed and recommendations for improving future studies are suggested.

Myopia and international educational performance

PURPOSE

To analyse the relationship between myopia, educational performance and engagement in after-school tutorial classes.

METHODS

Educational performance data and data on engagement in after-school tutorial classes were taken from the results of the Organisation for Economic Cooperation and Development (OECD) Program in Secondary Assessment (PISA) reports for 2009, which tested educational outcomes in representative samples of 15 year-old school children from 65 jurisdictions. High prevalence of myopia (>70%) and low prevalence of myopia (<40%) locations were identified by systematic literature search.

RESULTS

Six locations with a high prevalence of myopia were identified from among the participants in PISA 2009 - Shanghai-China, Hong Kong-China, Taiwan, Singapore, Japan and South Korea. All were ranked in the top quartile on educational performance. Other participants in the top educational performance quartile were identified as locations with a low prevalence of myopia, including Australia and Finland. The locations with a high prevalence of myopia combined high educational performance and high engagement in after-school tutorials, whereas the locations with a low prevalence of myopia combined high educational performance with little engagement in tutorials.

DISCUSSION

These results show that it is possible to achieve high educational outcomes without extensive engagement in after-school tutorials, and that the combination of high educational outcomes with extensive use of tutorials is associated with high prevalence rates of myopia. We suggest that extensive use of after-school tutorials may be a marker of educational environments which impose high educational loads. Further quantification of educational loads to include after- school educational activities, such as homework, tutorials and other after-school classes, as well as formal school classes, is desirable. Policy initiatives to decrease these loads may contribute to the prevention of myopia, perhaps, at least in part, by enabling children to spend more time outdoors.

Discrepancies between parental reports and clinical diagnoses of strabismus in Korean children

PURPOSE

To compare the accuracy of parental observation of strabismus with clinical evaluation in Korean children.

METHODS

The medical records of 228 children <15 years of age who visited the pediatric strabismus clinic from 2002 to 2007 and whose parents reported a horizontal deviation were retrospectively reviewed. We compared subjective parent-reported direction of ocular deviation with the objective results after clinical evaluation.

RESULTS

The mean age of the 228 children was 3.9 ± 3.0 years. Of these, 178 children (78%) were diagnosed with strabismus; 50 (22%), with orthotropia. The overall concordance rate was 67% (152/228). The concordance rate was lower for parents reporting inward deviation of the eye (P < 0.001), younger age group at presentation (P = 0.004), experienced onset of ocular deviation at younger age group (P = 0.001), and had fewer diopters of deviation (P < 0.001). Patient sex, family history of strabismus, observed frequency of deviation, and laterality of deviated eye did not show statistical differences in concordance rates (all P values >0.05).

CONCLUSIONS

Parental observation correlated with clinical assessment two-thirds of the time. Exotropia was more reliably detected by the parents than esotropia.

Relief of asthenopic symptoms with orthoptic exercises in convergence insufficiency is achieved in both adults and children

Background

Asthenopic symptoms associated with convergence insufficiency (CI) may compromise a person's ability to work or study. We investigated the effectiveness of orthoptic exercises in relieving symptoms related to CI and long-time results in adults and children.

Methods

The data were retrospectively gathered from the patient clinical files. A total of 135 patients met the inclusion criteria of suffering asthenopic symptoms and CI but had not received prior strabismus surgery or orthoptic exercises.

Results

The mean age was 26 ± 17 years, 74% of them were female. The patients (N = 135) suffered from CI and had at least one of the following symptoms: eyestrain, blurring of vision, problems in reading and while doing work-up at close distance or headache. In the two-year follow-up time, 4% of the patients needed to be retreated and 3% of the patients required strabismus surgery. There were no significant differences between adults and children in near point of convergence (NPC), number of visits needed or fusional vergence at the end of treatment nor did the outcome depend on the number of visits. 59.5% of children vs. 51.9% of adults were free of symptoms when completing the exercises.

Conclusions

In conclusion orthoptic exercises are effective in relieving asthenopic symptoms in adults and children. The effects of orthoptic exercises on NPC and fusional vergence were equal in adults and in children and not dependent on the number of visits needed for successful outcome. With orthoptic exercises it is possible to achieve longstanding relief on the symptoms of CI.