Normative values for clinical measures used to classify accommodative and vergence anomalies in a sample of high school children in South Africa

Comparing clinical measures of near point of convergence and accommodation from the lateral canthus and browline in a paediatric and adolescent population

PURPOSE

Clinicians measure the near point of convergence (NPC) and the amplitude of accommodation (AA) from the spectacle plane, the bridge of the nose or the lateral canthus when assessing visual function. These values are compared to standard clinical criteria to diagnose vergence and accommodation deficits, despite varying reference points. This prospective study explored measuring relative to the spectacle plane and from the lateral canthus for NPC and monocular AA, and the resulting clinical implications of diagnosing visual deficits.

METHODS

Participants were seen by a single clinician for an eye examination. NPC was measured from the forehead and the lateral canthus of the right eye. Monocular AA was measured from the brow and the lateral canthus. Differences between measurements were analysed using non-parametric statistical tests including Wilcoxon Signed Rank, as well as linear regression and a linear mixed effects model to adjust for inter-eye correlation and repeated measures. Chi-square tests were used to assess differences in rates of abnormal findings.

RESULTS

Data were collected from 70 participants (53% female, median age 13 [11-15] years). On average, measuring NPC from the lateral canthus yielded a value 1.8 cm higher than measuring from the forehead. Measuring AA from the lateral canthus resulted in an average difference of 1.5 cm compared to measuring from the brow. A total of 39% and 76% of subjects failed NPC compared to clinical norms when measured from the forehead or the lateral canthus, respectively, while 7% and 40% failed AA when measured from the brow or the lateral canthus, respectively.

CONCLUSION

With the variable anatomy of the eye, it is imperative to account for the measurement point when assessing visual function. Measuring from the lateral canthus greatly increased the failure rates for NPC and AA compared with measuring from the forehead and brow, respectively.

BCLA CLEAR Presbyopia: Epidemiology and impact

The global all-ages prevalence of epidemiologically-measured 'functional' presbyopia was estimated at 24.9% in 2015, affecting 1.8 billion people. This prevalence was projected to stabilise at 24.1% in 2030 due to increasing myopia, but to affect more people (2.1 billion) due to population dynamics. Factors affecting the prevalence of presbyopia include age, geographic location, urban versus rural location, sex, and, to a lesser extent, socioeconomic status, literacy and education, health literacy and inequality. Risk factors for early onset of presbyopia included environmental factors, nutrition, near demands, refractive error, accommodative dysfunction, medications, certain health conditions and sleep. Presbyopia was found to impact on quality-of-life, in particular quality of vision, labour force participation, work productivity and financial burden, mental health, social wellbeing and physical health. Current understanding makes it clear that presbyopia is a very common age-related condition that has significant impacts on both patient-reported outcome measures and economics. However, there are complexities in defining presbyopia for epidemiological and impact studies. Standardisation of definitions will assist future synthesis, pattern analysis and sense-making between studies.

Proposing the "Value- and Evidence-Based decision making and Practice" (VEDMAP) framework for Priority-Setting and knowledge translation in low and Middle-Income Countries: A novel framework for Decision-Making in Low-and middle income countries like Malawi

The existence and availability of evidence on its own does not guarantee that the evidence will be demanded and used by decision and policy makers. Decision and policy-makers, especially in low-income settings, often confront ethical dilemmas about determining the best available evidence and its utilization. This dilemma can be in the form of conflict of evidence, scientific and ethical equipoise and competing evidence or interests. Consequently, decisions are made based on convenience, personal preference, donor requirements, and political and social considerations which can result in wastage of resources and inefficiency. To mitigate these challenges, the use of "Value- and Evidence-Based Decision Making and Practice" (VEDMAP) framework is proposed. This framework was developed by Joseph Mfutso-Bengo in 2017 through a desk review. It was pretested through a scoping study under the Thanzi la Onse (TLO) Project which assessed the feasibility and acceptability of using the VEDMAP as a priority setting tool for Health Technology Assessment (HTA) in Malawi. The study used mixed methods whereby it conducted a desk review to map out and benchmark normative values of different countries in Africa and HTA; focus group discussion and key informant interviews to map out the actual (practised) values in Malawi. The results of this review confirmed that the use of VEDMAP framework was feasible and acceptable and can bring efficiency, traceability, transparency and integrity in decision- policy making process and implementation.

Creating consistency in the diagnosis of convergence insufficiency: screening methods

PURPOSE

To determine the sensitivity of various clinical tests in the diagnosis of convergence insufficiency.

METHODS

A total of 254 patients were recruited with complaints consistent with convergence problems but no prior history of strabismus surgery, eye exercises, prism use, recent concussion, or other ocular or neurological diseases. Each patient completed the convergence insufficiency symptom survey (CISS), and the following data were collected: ocular alignment at distance and near, convergence and divergence fusional amplitudes at distance and near, near-point of convergence (NPC) using an accommodative target and red lens, and assessment of quality of convergence movement (QoCM) and quality of fusional movements (QoFM). The sensitivity of each clinical test was calculated.

RESULTS

Measurement of NPC using red lens and subjective assessment of the QoCM and QoFM were the most sensitive diagnostic tools for near symptoms consistent with convergence insufficiency: 93.3%, 98.4%, and 94.5% respectively. CISS score, convergence fusional amplitude at near, and exophoria at near had lower sensitivities: 62.9%, 46.0%, and 72.0%, respectively. Although the majority of our patients had a heterophoria or heterotropia at distance (96.8%) and/or near (98.8%), most presented with only small phorias. Furthermore, of those who had a deviation at near, only 22% had the near exophoria exceeding the distance exophoria by 10Δ.

CONCLUSIONS

In our study cohort, NPC with red lens and subjective assessment of QoCM and QoFM proved to be the most sensitive screening tools for near symptoms consistent with convergence insufficiency.

Routine binocular examination of young Taiwanese adults as a predictor of visual behavior performance

BACKGROUND

Morgan and Scheiman's Optometric Extension Program (OEP) expected binocular vision findings have longstanding use in optometry. With technological advances, the demands and standards of binocular function have changed. This study aimed to investigate which binocular visual functions can effectively predict visual behavior performance.

METHODS

Participants aged 15-24 years were recruited from two colleges and two universities. After completing the CSMU-Visual Behavioral Performance questionnaire (CSMU-VBP, with four components: near work, visual perception, visual comfort, and whole-body balance), participants were divided into symptomatic and asymptomatic groups based on questionnaire findings (cutoff: < 12 vs. ≥ 12 symptoms). Then a 24-step binocular visual examination was undertaken. Data were analyzed with one-sample, Student's, and paired t-tests. Additionally, receiver operating characteristic analysis was used to determine the predictors of binocular visual function required for near work, visual perception, visual comfort, and body balance dimensions.

RESULTS

Among 308 participants, 43 (14%) and 265 (86%) were symptomatic and asymptomatic, respectively. Among the 46 participants with abnormal binocular vision, 36 (78%) reported that they had no obvious symptoms. The commonest dysfunctions were accommodative excess and convergence excess. Most of the binocular visual findings significantly diverged from traditional normal values: amplitude of accommodation, as well as base-in prism to break and recovery points at distance were higher than traditional normal values, whereas others were lower than traditional normal values. Total CSMU-VBP scores indicated that the asymptomatic and symptomatic groups had significant differences in DBO recovery (t = 2.334, p = 0.020) and BAF (t = 1.984, p = 0.048). Receiver operating characteristic curve analysis yielded the following binocular visual functional cutoff points: near work (DBO blur < 7, DBO recovery < 5.5), visual perception (MAF < 10.5, BAF < 10.25), visual comfort (DLP <  - 2.25, DBI break > 11.5, NBI blur > 15, NBI break > 17.5, NBI recovery > 13, NPC < 5.75), and body balance (NFD_H >  - 0.5, gradient AC/A [minus] > 2.25, NPC < 4.75).

CONCLUSIONS

The mean values of binocular visual function among young Taiwanese adults were statistically different from traditional normative values. Further research is required to confirm whether these findings reflect impaired binocular vision or stringent criteria. Assessments of binocular visual function, especially binocular accommodation sensitivity, are crucial in routine optometric examination.

Feasibility of measuring fusional vergence amplitudes objectively

Two tests to measure fusional vergence amplitudes objectively were developed and validated against the two conventional clinical tests. Forty-nine adults participated in the study. Participants' negative (BI, base in) and positive (BO, base out) fusional vergence amplitudes at near were measured objectively in an haploscopic set-up by recording eye movements with an EyeLink 1000 Plus (SR Research). Stimulus disparity changed in steps or smoothly mimicking a prim bar and a Risley prism, respectively. Break and recovery points were determined offline using a custom Matlab algorithm for the analysis of eye movements. Fusional vergence amplitudes were also measured with two clinical tests using a Risley prism and a prism bar. A better agreement between tests was found for the measurement of BI than for BO fusional vergence amplitudes. The means ± SD of the differences between the BI break and recovery points measured with the two objective tests were -1.74 ± 3.35 PD and -1.97 ± 2.60 PD, respectively, which were comparable to those obtained for the subjective tests. For the BO break and recovery points, although the means of the differences between the two objective tests were small, high variability between subjects was found (0.31 ± 6.44 PD and -2.84 ± 7.01 PD, respectively). This study showed the feasibility to measure fusional vergence amplitudes objectively and overcome limitations of the conventional subjective tests. However, these tests cannot be used interchangeably due to their poor agreement.

Examination of Near Point of Convergence Scores in High-School Athletes: Implications for Identifying Binocular Vision Dysfunction After Concussion Injury

OBJECTIVE

To identify normative near point of convergence (NPC) data for healthy high-school-aged athletes (13-19 years old) and determine the percentage of individuals with NPC scores that fall outside the currently accepted clinical cutoff value of 5 cm. Another objective was to determine the relationship between sex, concussion history, and attention deficit disorder/attention deficit hyperactivity disorder (ADD/ADHD) with NPC scores, if any.

DESIGN

Case series.

SETTING

High-school sports medicine clinic.

PATIENTS OR PARTICIPANTS

Near point of convergence was assessed in 718 high-school student athletes (141 females and 577 males) with an average age of 15.96 ± 1.16 years.

INTERVENTIONS

None.

MAIN OUTCOME MEASURES

An accommodation convergence ruler was used to measure NPC. Near point of convergence scores were repeated a total of 3 times and the mean used for all statistical analyses.

RESULTS

The NPC scores for all participants averaged 3.58 cm, and the intraclass correlation coefficient for the 3 repeated measurements was 0.956. Approximately 20% of mean NPC scores were above the accepted upper limit of 5 cm. Although a statistically significant effect for sex was identified, the difference between them was considered clinically insignificant. No relationship between NPC and history of concussion or ADD/ADHD was identified.

CONCLUSIONS

Results indicate that in high-school-aged subjects, approximately 20% of individuals may have NPC values that fall outside the current critical cutoff value and may lead to incorrect diagnosis of ocular dysfunction. In addition, NPC does not seem to be affected by the history of concussion or a diagnosis of ADD/ADHD.

Characterizing Refractive Errors, Near Accommodative and Vergence Anomalies and Symptoms in an Optometry Clinic

Background:

Refractive, accommodative and vergence parameters and associated anomalies cause symptoms of asthenopia. Patients consult eye care practitioners mainly due to symptoms they experience. To enhance targeted treatments from various anomalies, it is relevant to study symptoms with associating anomalies.

Aim:

To determine the frequencies of refractive error, accommodative and vergence anomalies, and their associations with symptoms in sample of Black South Africans.

Method:

This prospective, cross-sectional study comprised consecutive participants aged 10–40 years who attended the author’s optometry practice in a Black population in South Africa. Visual acuity, refraction, accommodative and vergence tests were performed. Anomalies were classified as either single measure or syndromes based on the number of failed clinical signs.

Results:

Participants (n = 254) had mean age 22.6 ± 7.22 years. Ninety-four were male (37%) and 160 were female (63%). The frequencies of syndrome anomalies were accommodative insufficiency 17 [(6.6%) 95% CI 3.9–10.5%)], accommodative infacility 32 [(12.6%)] 8.7–17.3%] and convergence insufficiency 22 [(8.6%, 5.1–12.3%)]. Frequencies of coexisting anomalies were refractive error and accommodative 150 (60.0%), refractive error and vergence anomalies 136 (54.4%) and vergence and accommodative disorders 155 (62.0%). Most patients were symptomatic (70.9%). Headache was the most frequent symptom (41.1%).

Conclusion:

Accommodative anomalies were more frequent than refractive error and vergence anomalies. The high frequency of anomalies suggests a high uptake of optometric services for asthenopia. Accommodative anomalies were the most symptomatic. The study highlights the need for diagnosing visual symptoms and coexisting anomalies. Establishment of validated study protocols for all accommodative and vergence anomalies is recommended.

Quantitative Evaluation of the Association Between Fixation Stability and Phoria During Short-Term Binocular Viewing

Purpose

Fixation stability for binocular anomalies with a phoria cannot be detected by direct observations. This study aimed to quantitatively evaluate fixation stability using an eye tracker rather than direct directions in binocular vision with abnormal and normal phorias.

Methods

Thirty-five and 25 participants with abnormal and normal phoria, respectively, were included in the study. The horizontal and vertical gaze points and convergence were recorded for 10 s using a remote eye tracker while binocularly viewing a target on a display screen 550 mm away. Fixation stability was quantified using bivariate contour ellipse areas (BCEA).

Results

The fixation stability for all participants-based evaluations as a single cluster in the abnormal phoria group was lower than that in the normal phoria group (p = 0.005). There was no difference between the two groups in the evaluation based on the BCEA for each participant-based evaluation (p = 0.66). Fixation stability was also more related to convergence for the abnormal phoria group than for the normal phoria group (r = 0.769, p < 0.001; r = 0.417, p = 0.038, respectively).

Conclusion

As the first study to evaluate fixation stability using an eye-tracker to differentiate between abnormal and normal phoria for non-strabismus, these findings may provide evidence for improving the evaluation of binocular vision not detected with clinical diagnostic tests.

A longitudinal study of local stereoacuity and associated factors in schoolchildren: The Shahroud Schoolchildren Eye Cohort Study

CLINICAL RELEVANCE

Impaired stereoacuity is seen in some children without amblyopia, strabismus, and clinically significant refractive errors. Therefore, there are probably other factors affecting stereoacuity.

BACKGROUND

The aim of this work was to investigate the longitudinal changes of local stereoacuity and associated factors in schoolchildren.

METHODS

The present report is a part of the Shahroud Schoolchildren Eye Cohort Study. The target population was children aged 6 to 12 years in Shahroud, Iran. The second phase of the study was conducted in 2018 by re-inviting all participants in the first phase (2015). After an initial interview, study participants underwent optometric examination and ocular biometry. Stereoacuity was evaluated using Stereo Fly Test. Exclusion criteria were functional amblyopia, strabismus, significant refractive errors, probable ocular pathology/organic amblyopia in either of the two study phases, a history of intraocular surgery or ocular trauma, and incomplete data.

RESULTS

The data of 4666 children were analysed for this report, of which 53.7% were male. The mean age of the studied participants in the second phase was 12.37 ± 1.71 years. The mean stereoacuity was 42.31 (95% CI: 42.05 - 42.57) seconds of arc in the first phase, which reduced to 51.72 (95% CI: 50.79-52.65) seconds of arc in the second phase (P < 0.001). The prevalence of poor stereoacuity was 0.17% (95% CI: 0.06-0.29) in the first phase, which increased to 3.94% (95% CI: 3.34-4.54) in the second phase (P < 0.001). According to the multiple linear regression, older age in the first study phase (β = 0.011, P < 0.001), urban residence (β = -0.019, P = 0.006), increased spherical anisometropia (0.038, P = 0.013), and increased axial length (β = 0.062, P = 0.003) were significantly associated with reduction of stereoacuity (in log scale) after three years.

CONCLUSION

In addition to the known risk factors of amblyopia, strabismus, and significant refractive errors, other factors are also associated with stereoacuity changes in children.

Normative Data for Parameters of Accommodation in African Schoolchildren

SIGNIFICANCE

The reported interracial differences in normative data for parameters of accommodation call for investigating population-specific normative values. The study investigated and presents expected data for accommodative parameters among Ghanaian children.

PURPOSE

This study aimed to determine expected values for parameters of accommodation among schoolchildren in the Central Region of Ghana.

METHODS

This prospective cross-sectional study used a multistage cluster sampling approach. Normal participants were asymptomatic (Convergence Insufficiency Symptom Survey score ˂16), with unaided visual acuity or best-corrected visual acuity of 0.0 or better logMAR for each eye and having no ocular disease or no manifest strabismus. Normal participants underwent push-up and minus-lens-to-blur amplitude of accommodation tests, accuracy of accommodative response (using the monocular estimation method), and monocular and binocular accommodative facility testing.

RESULTS

A total of 1261 normal participants within ages 11 to 17 years (mean, 14.75 ± 1.53 years) met the inclusion criteria. The mean normative data for the population include push-up amplitude of accommodation (14.04 ± 2.95 D), minus-lens-to-blur amplitude of accommodation (12.33 ± 2.55 D), and accuracy of accommodative response using the monocular estimation method (0.62 ± 0.22 D), monocular accommodative facility (9.80 ± 3.20 cycles per minute), and binocular accommodative facility (9.40 ± 3.30 cycles per minute). Age-predicted linear regression equations for the amplitude of accommodation are push-up amplitude of accommodation (16.74 - 0.18 × age in years) and minus-lens-to-blur amplitude of accommodation (15.7 - 0.23 × age in years).

CONCLUSIONS

The study provides normative data for accommodative parameters that clinicians may use with Ghanaian populations of similar ages.

Is reading rate in digital eyestrain influenced by binocular and accommodative anomalies?

INTRODUCTION

Symptoms experienced when using digital devices are known as digital eyestrain (DES) or computer vision syndrome. They can be categorised as either external (associated with dry eye) or internal (related to refractive, accommodative or binocular vision anomalies). In a large cohort of adults with DES, we investigate the prevalence of binocular and accommodative anomalies, contrasting different diagnostic approaches, to evaluate potential mechanisms for the benefit from +0.75D addition lens that has been previously reported.

METHODS

Participants (20-40y) were selected using the Computer Vision Syndrome Questionnaire (CVS-Q) tool as suffering with DES. A comprehensive eye examination was given to each participant, and this paper concentrates on "internal factors", detected with a refraction and comprehensive testing of binocular and accommodative functions. The effects of low-powered addition lenses (+0.50D, +0.75D, +1.25D; and plano controls) were assessed by double-masked testing with the Wilkins Rate of Reading Test (WRRT) and by subjective preference.

RESULTS

As previously reported, most participants showed a subjective preference for one of the three convex lenses we used, with +0.75D chosen most frequently. Performance at the WRRT was significantly improved with +0.50D and +0.75D, but not +1.25D. Using a variety of diagnostic criteria, there were no strong associations between WRRT results or CVS-Q scores and any binocular or accommodation functions. The one finding of significance is that a disproportionate number of participants who benefited from adds had an eso-fixation disparity on the near Mallett unit, although this only affected 5% of the population.

CONCLUSIONS

DES is a collection of diverse symptoms that have a multifactorial aetiology. In the sample described here, binocular and accommodative anomalies do not seem to be a major cause of DES. Nevertheless, in view of the multifactorial aetiology it is recommended that patients with the symptoms of DES are assessed with a comprehensive eye examination. Patients with an esophoric fixation disparity on the near Mallett unit are particularly likely to benefit from near additions.

Comparison, within-session repeatability and normative data of three phoria tests

PURPOSE

Phoria measurements form a routine part of the examination of binocular vision. Various studies have compared different methods of phoria measurement and their repeatability between sessions. However, no studies have accounted for within-session repeatability, and few norms have been available to date. Our aims were to assess the short-term within-session repeatability, the agreement and the comparisons between three phoria tests and the delineation of normative data.

METHOD

The participants comprised 315 refractive corrected participants with a normal binocular vision, with ages between 20 and 80 years. Phoria was measured using three methods: von Graefe (VG), modified Thorington (MT) and Thorighton (TH) procedures. Each measurement was taken 3 consecutive times at far and near.

RESULTS

The repeatability between measurements was high (0.87 to 0.96), but the relationship between tests was medium (0.407 to 0.682). About the mean bias, VG show more exo values (0.02 to 0.14 at far and 0.07 to 0.14 at near) and MT and TH similar values (-0.04 to 0.08 at far and -0.1 to 0.03 at near). The best agreement between tests was for TH and MT (LoA = 2.33 at far and LoA = 4.44 at near). Normative data for non-presbyopic were provided.

CONCLUSION

Overall, there is a high agreement between MT and TH. Conversely, VG shows more exo values at near and shows large limits of agreement. We recommend that subjective measurements of phoria can best be quantified once using the MT or TH techniques in free space and the values compared with updated norms.

Normative Data for Nonstrabismic Binocular Vision Parameters in African Schoolchildren

SIGNIFICANCE

With reported population differences in parameters of nonstrabismic binocular vision, the present study investigated and reports normative data among a sample of African children.

PURPOSE

This study aimed to determine expected binocular visual function data among schoolchildren in the Central Region of Ghana.

METHODS

The study used a prospective cross-sectional design and used a multistage cluster sampling approach. Eligible normal participants selected through the administration of Convergence Insufficiency Symptom Survey questionnaire (score <16) and preliminary vision screening underwent comprehensive binocular vision testing. Only data for participants who expressed no difficulty with the specific procedures were analyzed.

RESULTS

A total of 1261 normal participants (11 to 17 years [mean, 14.75 ± 1.530 years]) were selected for comprehensive binocular vision testing in the normative data study. The means with ±1 standard deviation for normative data for the nonstrabismic binocular vision parameters include the following: accommodative target near point of convergence (NPC) break (6.10 ± 1.67 cm), NPC recovery (8.17 ± 1.67 cm), fixation light with red-green anaglyph (RG NPC) break (8.51 ± 2.43 cm), RG NPC recovery (10.95 ± 2.60 cm), cover test distance phoria (0.12 ± 0.79 exophoria), cover test near phoria (2.1 ± 2.3 exophoria), modified Thorington test near phoria (1.9 ± 2.5 exophoria), negative relative accommodation (+2.54 ± 0.75 D), positive relative accommodation (-2.58 ± 0.81 D), and the accommodative convergence over accommodation ratio (2.80 ± 1.07:1). Age (in years)-predicted normal linear regression equations for NPC break (5.13 + 0.07 × age), RG NPC break (10.00 - 0.10 × age), RG NPC recovery (12.83 - 0.13 × age), positive relative accommodation (2.05 + 0.04 × age), and the gradient accommodative convergence over accommodation ratio (3.97 - 0.08 × age) serve as a guide.

CONCLUSIONS

The study provides expected data that optometrists may use with similar aged Black African populations.

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.

Distribution of Visual and Oculomotor Alterations in a Clinical Population of Children with and without Neurodevelopmental Disorders

A prospective, non-randomized comparative study was conducted to compare the distribution of oculomotor and visual alterations in children with neurodevelopmental disorders and healthy children without such disorders. Sixty-nine children (aged 6-13 years) were enrolled and divided into three groups: a control group (CG) of 23 healthy children; a group of 18 healthy children with oculomotor abnormalities (OAG); and a group of 28 children with a neurodevelopmental disorder (NDDG), with 15 cases of dyslexia, 7 cases of developmental coordination disorder (DCD) and 6 cases of attention deficit/hyperactivity disorder (ADHD). Significantly worse near stereopsis was found in NDDG compared with CG (p < 0.001) and OAG (p = 0.001). Likewise, a significantly lower amplitude of accommodation was found in NDDG compared with CG in both the right (p = 0.001) and left eyes (p < 0.001). No statistically significant differences between groups were found in the measurement of near and distance phoria (p ≥ 0.557), near point of convergence (p = 0.700) and fusional vergences (p ≥ 0.059). Significantly impaired oculomotor test scores were found in NDDG compared with CG (p < 0.001), with no significant differences between OAG and NDDG (p ≥ 0.063). The comparison between the three types of neurodevelopmental disorders included revealed the presence of a significantly lower amplitude of accommodation in children with DCD compared with dyslexics. Furthermore, less exophoria at near was present in children with dyslexia compared with children with ADHD (p = 0.018) and DCD (p = 0.054). In conclusion, children with dyslexia, ADHD and DCD show an altered oculomotor pattern and a more reduced amplitude of accommodation, not always compatible with the diagnostic criteria of an accommodative insufficiency. Accommodative and binocular vision problems are not always present in these children and cannot be considered an etiologic factor.

Correlations between clinical measures and symptoms: Report 1: Stereoacuity with accommodative, vergence measures, and symptoms

AIM

The aim of this study was to explore associations between reduced stereoacuity and clinical measures of accommodation, vergences, and symptoms which could facilitate the development of quick and reliable screening tools.

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. Correlations among variables and the validity of Randot stereoacuity to distinguish between children with and without defective clinical measures as well as symptomatic versus asymptomatic children were characterized by the sensitivity and specificity of the tests.

RESULTS

The overall mean stereoacuity was 43.9 ± 25.23 s arc, and 18.9% [95% Confidence Interval, 16.6-21.4%)] of the participants had reduced stereoacuity (defined as ≥60). Stereoacuity values and symptoms scores were worse in children with defective clinical measures. The Receiver Operation Curve showed that maximum sensitivity and specificity was obtained with near point of convergence break (≥10 cm) of (0.70 95% confidence interval: 0.63-0.77) with Randot stereoacuity test (defined as ≥60 s arc). The correlations between reduced stereoacuity and symptoms scores was moderately strong and statistically significant (Pearson's, r = 0.507, p = 0.01). The Receiver Operation Curve showed that maximum sensitivity and specificity obtained with the Convergence Insufficiency Symptoms Survey was 0.57 (95% Confidence interval = 0.53-0.62, p = 0.001), sensitivity of 90.26%, and specificity 15.26% with the Randot stereoacuity test.

CONCLUSION

Reduced stereoacuity, defective clinical measures and symptoms of asthenopia were prevalent among sample of school children studied. Randot stereoacuity test could fairly distinguish between defective and normal clinical measures; though the accuracy to differentiate between symptomatic and asymptomatic school children is poor. These findings highlight the need for validation of a simple and fast screening tool in school settings. Further studies to confirm above findings will be needed.

A review of normative data for parameters of functional non-strabismic binocular vision

Background: There was a need to document population-expected normative data for parameters of non-strabismic binocular vision (NSBV) as the analysis and diagnosis of binocular vision disorders required comparison of patient’s clinical signs with expected data in their specific population.Aim: This article sought to review and map population-expected continental normative data for visual function parameters for evaluating the functional non-strabismic accommodative and vergence system, as these systems are very relevant to evaluate the comfort of visual system.Method: Search engines – namely, Google Scholar, Microsoft Academic, Web of Science database and Ovid MEDLINE database – were used to search studies published in English across different continents using keywords such as ‘normative or expected data’ and ‘specific NSBV parameter’. Results were summarised in tables for easy comparison; data were presented based on the geographical location, year of publication, demographics of the population studied and the techniques used for measuring the parameters. A summary of observed challenges with reviewed works and recommendations for the future studies are indicated. The article is delimited to studies published between 1910 and September 2019 only.Results: Most of the studies investigated specific parameters of either accommodation only or vergence only; few recent studies have comprehensively investigated both parameters. Most studies were conducted in North America followed by Asia and Europe, with a few in Africa. No studies were found with Oceania populations. There were discrepancies and differences in methodologies and techniques used by the studies reviewed and normative data varied among different continents and different populations within each continent.Conclusion: As the observed differences in reviewed studies could be attributed to differences in test techniques, the future studies should consider using identical, reliable, repeatable, objective and subjective techniques with good methodological designs to clarify these results. More studies should be conducted in African and Oceania populations.