Reliability of binocular vision measurements used in the classification of convergence insufficiency

Are Horizontal Fusional Vergences Comparable When Measured Using a Prism Bar and Synoptophore?

Aim

To determine whether horizontal fusional vergences are comparable when measured using a prism bar and synoptophore.

Methods

Thirty two participants (18-23 years) had their blur, break, and recovery points measured for convergence and divergence amplitudes using a prism bar (6 m) and synoptophore. All participants had VA of 0.1 LogMAR or better in either eye, were heterophoric or orthophoric and had binocular single vision. The prism bar target was a 0.2 LogMAR letter. The synoptophore target was the foveal 'rabbit' fusion slides. The prism bar was placed over the dominant eye and the testing speed was two seconds per two prism dioptres (Δ), increasing to five seconds per 5Δ when the increments began to increase in 5Δ. Synoptophore testing speed was two seconds per degree.

Results

The synoptophore measured significantly higher convergence break points than the prism bar (Z = 3.37, p = 0.001). No significant differences were found between both tests for divergence break points (Z = 0.99, p = 0.32). However, both tests displayed wide limits of agreement (LoA) when measuring convergence (-24Δ to + 49.59Δ) and divergence break points (-7.70Δ to + 10.19Δ). Differences when measuring convergence and divergence blur and recovery points were not statistically significant.

Conclusion

There was a statistically and clinically significant difference when measuring convergence break points using the prism bar and synoptophore but no significant difference when measuring divergence break points. However, both tests displayed wide LoA when measuring convergence and divergence break points, indicating they should not be used interchangeably in clinic to measure horizontal fusional vergences.

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.

Reliability and Agreement of an Integrated Platform for Intelligent Visual Function Measurement

INTRODUCTION

Phoropters are widely accepted for clinical use in refraction examination and visual function assessment. This study assessed the reliability of the new Inspection Platform of Visual Function (IPVF) in comparison with the conventional equipment phoropter (TOPCON VT-10) in visual function assessment.

METHODS

This prospective study enrolled 80 eyes of 80 healthy subjects. The horizontal phoria at distance and near (Phoria_D and Phoria_N, respectively) was measured with the von Graefe method, negative/positive relative accommodation (NRA/PRA) was measured with the positive/negative lens method, and accommodative amplitude (AMP) was measured with the minus lens method. Data of three consecutive measurements with each instrument were evaluated using the intraclass correlation coefficient (ICC) for repeatability, and the agreement of the two instruments was evaluated using a Bland-Altman plot.

RESULTS

The ICCs of the three consecutive measurements for phoria, NRA/PRA, and AMP using the IPVF instrument were high (0.87-0.96), indicating high repeatability. The ICCs of the three consecutive measurements using the phoropter were high (0.914-0.983) for phoria, NRA, and AMP, indicating high repeatability, while that of PRA was 0.732 (between 0.4 and 0.75), indicating acceptable repeatability. The 95% limits of agreement of phoria, NRA/PRA, and AMP were narrow, indicating good agreement between the two instruments.

CONCLUSION

The repeatability of both instruments was high, and the IPVF instrument was slightly better in terms of PRA repeatability than the phoropter. The agreement of phoria, NRA/PRA, and AMP measured by the new IPVF instrument and phoropter was also satisfactory.

Divergence excess and basic exotropia types of intermittent exotropia: a major review. Part 1: prevalence, classification, risk factors, natural history and clinical characteristics

INTRODUCTION

Intermittent exotropia (IXT) is a common form of strabismus. It is an outward deviation of one eye typically when viewing at distance. Symptoms include, but are not limited to double vision, eyes feeling tired, excessive blinking, and reduced quality of life. Its clinical characteristics are distinctive from other types of strabismus. This paper provides a comprehensive review of prevalence, classification, risk factors, natural history and clinical characteristics of the divergence excess and basic exotropia types of IXT.

METHODS

Search strategies involving combination of keywords including intermittent exotropia, exotropia, divergences excess, basic exotropia, prevalence, incidence, classification, terminology, risk factor, natural history, observation, angle of deviation, control, control score, symptom, quality of life, suppression, anomalous retinal correspondence, AC/A, accommodative convergence/accommodation, accommodative convergence, convergence, accommodation, vergence, incomitance and vertical were used in Medline. All English articles from 1900/01/01 to 2020/09/01 were reviewed. The reference list of the identified article was also checked for additional relevant article. Studies focused on animal model or strabismus associated with neurologic disorder or injury were excluded.

RESULTS

The estimated prevalence of IXT in children ranges from 0.1% to 3.7%. Hypoxia at birth and being female are potential risk factors of IXT. Using validated measures of control, multicenter prospective studies showed that the rate of conversion from IXT to constant exotropia is low. The angle of deviation is the most reported outcome measure in studies of IXT. It is often used to represent the severity of the condition and has been suggested as one of the four core outcomes for studies of the surgical management of IXT. Control of exodeviation is one of the four suggested core outcomes for study of surgery of IXT and is considered the main parameter of disease severity. Several validated tools for quality of life score are available to evaluate the subjective severity of IXT.

DISCUSSION

We reviewed the prevalence, classification, risk factors, natural history and clinical characteristics of the divergence excess and basic exotropia types of IXT. Further research into these areas, especially its clinical characteristics (e.g. suppression, dual retinal correspondence), will increase our understanding of this condition and potentially lead to better management of this common form of strabismus.

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.

The Function of the Proprioceptive, Vestibular and Visual Systems Following Fatigue in Individuals With and Without Chronic Ankle Instability

To maintain postural balance, the proprioceptive, vestibular, and visual systems continuously provide body position and movement data to the central nervous system. In this study, our main aim was to examine, for the first time, the influence of anaerobically or aerobically induced fatigue on these separate functions in persons with and without chronic ankle instability (CAI). We obtained assessments pre- and post-fatigue protocols from 60 physical education students (Mage = 24.3, SD = 3.4) Twenty-seven students had CAI, and 33 students did not have CAI). To measure proprioception, we used the AMEDA device; for vision, we used near point of convergence (NPC); and, for vestibular function, we used subjective visual vertical (SVV). We found a pre-post proprioception (AMEDA) effect in the aerobic group (p < .001), and a visual (NPC) effect in both anaerobic and aerobic participant groups (both p < .001). There were no visual system (NPC) fatigue effect differences among aerobic or anerobic participants who had or did not have CAI (p = .047); there was a significant aerobic fatigue effect on proprioception (AMEDA) (p = .010) that favored participants without CAI. There was a significant interaction effect between time of testing and CAI for visual (NPC) (p = .003) in the aerobic group only. In both the anaerobic and aerobic groups, post-fatigue vestibular function (AMEDA) was significantly lower for those with than those without CAI (anaerobic: p = .030; and aerobic: p =.016). Thus, post-fatigue, participants with CAI showed worse proprioceptive, visual, and vestibular function than those without CAI. Future investigators should further examine each movement sense system in individuals with CAI.

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.

Accommodation Response Variations in University Students under High Demand for Near-Vision Activity

The objective of this study was to investigate accommodation changes and visual discomfort in a university student population after a period of high demand for near-vision activity. A total of 50 university students aged between 20 and 22 years were recruited. The tests performed involved positive relative accommodation (PRA), negative relative accommodation (NRA), accommodation amplitude (AA), and monocular and binocular accommodative facility (MAF and BAF). Visual discomfort was measured on a scale involving a visual discomfort questionnaire (VDQ). All accommodative variables underwent changes during the exam period; specifically, regarding NRA and PRA, 30.4% and 15.1% of the studied population, respectively, appeared to be below average. Moreover, 42.3% of the population exhibited values below average in the second measure of AA. On the other hand, a small percentage of the population was below average in MAF and BAF measurements: 3% in the monocular right eye test, 6% in the left eye test, and 9.1% in the binocular facility test. Finally, the VDQ score did not reveal a statistically significant difference between the two measurements. Prolonged near-distance work, such as a university exams period, changed all accommodation systems (amplitude of accommodation, relative accommodation, and accommodation facility). These changes influence an accommodation excess that results in blurred vision, headache, and problems with focusing.

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.

Reliability of step vergence method for assessing fusional vergence in intermittent exotropia

PURPOSE

To evaluate the reliability of the step vergence method in measuring fusional vergence in subjects with intermittent exotropia.

METHODS

Thirty-two Chinese participants aged 7-20 years with intermittent exotropia (excluding the convergence insufficiency type) were enrolled in this prospective study. At the eligibility screening, visual acuity, cover test and the Office Control Score were performed. For eligible participants at study visit 1, negative and positive fusional vergence at distance and near, eye dominance and the fusion maintenance test were performed. All eligible participants returned for study visit 2 on the same day (2-4 h later), and the testing was repeated. The primary outcome measures were the intra-class correlation coefficient, coefficient of repeatability and smallest detectable change in the break and recovery points of negative and positive fusional vergence between the two study visits.

RESULTS

The intra-class correlation coefficient for different vergence parameters ranged from 0.64 to 0.87. The coefficient of repeatability and the smallest detectable change for the distance positive fusional vergence break point were ±20.5 and 13.1 ∆, respectively. There was no significant difference in any vergence parameter between the first and second visits. The coefficient of repeatability and the smallest detectable change in all distance vergence parameters were high when compared to the mean value. The association between distance vergence parameters and the Office Control Score was significant only when including subjects who failed to fuse at the beginning of the test.

CONCLUSION

The data demonstrate that measurement of fusional vergence with a prism bar has low repeatability in subjects with intermittent exotropia. In these individuals, convergence ability at distance is compromised, whereas other vergence parameters are not adversely affected. While the step vergence method is a valuable test in daily practice, caution is warranted when using it in clinical research.

The repeatability and reproducibility of four techniques for measuring horizontal heterophoria: Implications for clinical practice

PURPOSE

Convergence insufficiency, the most common binocular vision anomaly, is characterised by a receded near point of convergence and an exophoria which is at least 4 prism dioptres (Δ) larger at near than at distance. However, the repeatability of standard heterophoria measures are poorly understood. This study assessed the ability of four common heterophoria tests to detect differences of 4Δ by evaluating the inter- and intra-examiner variability of the selected techniques.

METHODS

Distance and near horizontal heterophorias of 20 visually-normal adults were measured with the alternating prism cover test, von Graefe prism dissociation, Howell Card and Maddox Rod by two examiners at two separate visits using standardised instructions and techniques. We investigated inter- and intra-examiner variability using repeatability and reproducibility indices, as well as Bland-Altman analysis with acceptable limits of agreement defined as ±2Δ.

RESULTS

The Howell card test had the lowest intra-examiner variability at both distance and near, as well as the best 95% limits of agreement (±1.6Δ for distance and ±3.7Δ for near). Inter-examiner reproducibility results were similar, although at near the alternating prism cover test had better repeatability (1.1Δ, 95% confidence intervals -1.1Δ to 4.0Δ) than the Howell card (1.4Δ, 95% confidence intervals -1.9Δ to 5.9Δ).

CONCLUSION

The low repeatability of many standard clinical heterophoria tests limits the ability to reliably detect a 4Δ difference. The Howell Card provided the most repeatable and reproducible results indicating that this technique should be used to detect small changes in heterophoria magnitude and direction.

OculoMotor Assessment Tool Test Procedure and Normative Data

SIGNIFICANCE

This study establishes normative data and a testing procedure for the oculomotor assessment tool. The oculomotor assessment tool standardizes visual targets for the Vestibular/OculoMotor Screening assessment and provides additional metrics that may aid in the differentiation between those with normal and those with abnormal oculomotor function potentially caused by a concussion.

PURPOSE

This study aimed to assess the oculomotor endurance of healthy participants with no self-reported history of concussions using the oculomotor assessment tool.

METHODS

Healthy participants (n = 376, average age of 20.4 years, range of 11 to 34 years, with no self-reported history of concussions) were recruited to perform the following three tasks for 60 seconds each: (1) horizontal saccades, (2) vertical saccades, and (3) vergence jumps. The participants were instructed to alternate visual fixation between two targets for each of the tasks as fast as they could without overshooting or undershooting the visual target. The differences in the number of eye movements between the initial and latter 30 seconds of the 1-minute test were analyzed.

RESULTS

A statistical difference (P < .001) was observed in the number of eye movements for all three tasks (horizontal saccades [70 ± 15 for initial 30 seconds, 63 ± 13 for latter 30 seconds], vertical saccades [68 ± 14, 63 ± 13], and vergence jumps [43 ± 11, 39 ± 10]) between the initial and latter 30 seconds. No significant differences were identified in the number of eye movements or the change in eye movements between the initial and latter 30 seconds based on sex.

CONCLUSIONS

These results establish a normative database for various eye movements. These data could potentially be used to compare different patient populations who have binocular endurance dysfunctions potentially due to traumatic brain injury, such as patients with concussion(s).

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.

Treatment of Symptomatic Convergence Insufficiency in Children Enrolled in the Convergence Insufficiency Treatment Trial-Attention & Reading Trial: A Randomized Clinical Trial

SIGNIFICANCE

These data confirm the effectiveness of office-based vergence/accommodative therapy for improving convergence in children with symptomatic convergence insufficiency. They also highlight the importance of using a primary outcome measure that is as objective as possible rather than relying solely on self-reported symptoms for studies of binocular vision in children.

PURPOSE

The purpose of this study was to report changes in clinical signs and symptoms of convergence insufficiency (secondary outcome measures) from a multicenter clinical trial (Convergence Insufficiency Treatment Trial–Attention & Reading Trial [CITT-ART]) evaluating the effectiveness of vergence/accommodative therapy for improving reading and attention in children with symptomatic convergence insufficiency.

METHODS

Three hundred eleven children aged 9 to 14 years with symptomatic convergence insufficiency were randomly assigned to 16 weeks of office-based vergence/accommodative therapy or to placebo therapy. Improvements in (1) near point of convergence (NPC), (2) positive fusional vergence (PFV), and (3) self-reported symptoms (Convergence Insufficiency Symptom Survey [CISS] score) were compared after 16 weeks of treatment.

RESULTS

Mean NPC improved 10.4 cm in the vergence/accommodative and 6.2 cm in the placebo therapy group (mean difference of −4.2 cm [95% confidence interval {CI}, −5.2 to −3.2 cm; P < .001]); mean PFV increased 23.2 and 8.8Δ in the vergence/accommodative and placebo therapy groups, respectively (mean difference of 14.4Δ [95% CI, 12.1 to 16.8Δ; P < .001]). The mean CISS score improved 11.8 and 10.4 points in the vergence/accommodative and placebo therapy groups, respectively (mean difference of 1.5 points [95% CI, −3.8 to +0.8 points; P = .21]).

CONCLUSIONS

Our results demonstrate that office-based vergence/accommodative therapy is effective for improving the NPC and PFV in children with symptomatic convergence insufficiency. However, given that both treatment groups had a similar reduction in self-reported symptoms, it may not be prudent to use the CISS alone as a measure of successful treatment.

The Convergence Insufficiency Neuro-mechanism in Adult Population Study (CINAPS) Randomized Clinical Trial: Design, Methods, and Clinical Data

Purpose: To describe the design and methodology of the Convergence Insufficiency Neuro-mechanism in Adult Population Study (CINAPS), the first randomized clinical trial (RCT) studying young adults with symptomatic convergence insufficiency (CI) using a combination of traditional clinical tests, objective eye movement recordings, and functional brain activities as outcome measures.Methods: In this double-masked RCT, binocularly normal controls (BNC) (N = 50) and CI patients (N = 50) are randomized into office-based vergence/accommodative therapy (OBVAT) or office-based placebo therapy (OBPT). Outcome measures included clinical signs and symptoms, phoria adaptation, forced fixation disparity curves, binocular rivalry, vergence and saccadic objective eye movements, and task-induced functional brain activities. This study is registered on ClinicalTrials.gov NCT03593031.Results: No significant baseline differences are observed between the BNC (p > .4) or CI (p > .3) participants assigned to OBVAT or OBPT for age, near point of convergence (NPC), positive fusional vergence (PFV), phoria at distance and near, amplitude of accommodation, or the Convergence Insufficiency Symptom Survey (CISS). Significant differences are observed between the CI and BNC cohorts at baseline measurements for NPC, PFV, difference in phoria from far to near, amplitude of accommodation, and CISS (p < .001). For the CI patients, 26% had a comorbidity of accommodation insufficiency, and 16% self-reported ADHD.Conclusion: Features of the study design include the following: standardized diagnostic and office-based therapeutic intervention, placebo treatment arm, masked clinical outcome examinations, objective eye movement recordings, functional imaging, phoria adaptation, fixation disparity curves and binocular rivalry measurements.

The Effect of Target Speed and Verbal Instruction on NPC Measures in a Young, Healthy, and Active Population

Purpose: Evaluate the effect of target speed and verbal instruction on near point of convergence (NPC) measurements in a young, healthy, and active population. Methods: NPC was measured in 20 individuals with three target speeds and two sets of verbal instruction. The target speeds used were 1 cm/s, 3 cm/s, 5 cm/s, and participant self-paced. The verbal instruction given was either to indicate when the target became “double” or “blurry”. Results: Paired-samples t-tests revealed significant differences between 5 cm/s (5.44 ± 2.01) and 1 cm/s (6.72 ± 2.39, p = .003), 3 cm/s (6.10 ± 2.36, p = .030) and self-paced (6.63 ± 2.26, p = .005). A significant difference (p < .001) was also found between the “double” (6.72 ± 2.39) and “blurry” (10.82 ± 3.08) conditions. Conclusion: For young, healthy and active individuals, target speed and verbal instruction matter when measuring NPC.

Postconcussion: Receded Near Point of Convergence is not Diagnostic of Convergence Insufficiency

PURPOSE

To determine the frequency of occurrence of receded near point of convergence (NPC) in patients with chronic concussion-related symptoms and in those with receded NPC to enumerate the frequency of convergence insufficiency and other oculomotor disorders.

DESIGN

Retrospective cross-sectional study.

METHODS

Clinic charts were retrospectively reviewed for the prior 3.5 years to identify all patients < 21 years old who were > 28 days postconcussion, had chronic concussion-related symptoms, had normal visual acuity, and had received a comprehensive sensorimotor examination. The frequency of receded NPC and oculomotor diagnoses were determined.

RESULTS

Of the 83 eligible patients, 74 (89%) had receded NPC. Of these, 70 (95%) had oculomotor disorders; 30 (41%) had disorders of accommodation only; 21 (28%) had convergence insufficiency and accommodation deficits; and 6 (8%) had convergence insufficiency only. Six (8%) had a convergence deficit other than convergence insufficiency (all with concurrent accommodative disorders); 4 (5%) had both a nonspecific vergence dysfunction and accommodation deficits; 2 (3%) had convergence excess only; and 1 (1%) had both convergence excess and accommodative deficits.

CONCLUSION

A receded NPC was present in the majority of young patients with chronic postconcussion symptoms. Associated with numerous underlying oculomotor dysfunctions, the clinical finding of a receded NPC is not synonymous with the diagnosis of convergence insufficiency. Because treatment options for the various oculomotor dysfunctions differ, it is prudent that these patients undergo a thorough examination of their vergence and accommodative systems so that an accurate diagnosis can be made and appropriate treatment prescribed.

One-year test-retest reliability of ten vision tests in Canadian athletes

Background: Vision tests are used in concussion management and baseline testing. Concussions, however, often occur months after baseline testing and reliability studies generally examine intervals limited to days or one week. Our objective was to determine the one-year test-retest reliability of these tests.

Methods: We assessed one-year test-retest reliability of ten vision tests in elite Canadian athletes followed by the Institut National du Sport du Quebec. We included athletes who completed two baseline (preseason) annual evaluations by one clinician within 365±30 days. We excluded athletes with any concussion or vision training in between the annual evaluations or presented with any factor that is believed to affect the tests (e.g. migraines). Data were collected from clinical charts. We evaluated test-retest reliability using Intraclass Correlation Coefficient (ICC) and 95% limits of agreement (LoA).

Results: We examined nine female and seven male athletes with a mean age of 22.7 (SD 4.5) years. Among the vision tests, we observed excellent test-retest reliability in Positive Fusional Vergence at 30cm (ICC=0.93) but this dropped to 0.53 when an outlier was excluded in a sensitivity analysis. There was good to moderate reliability in Negative Fusional Vergence at 30cm (ICC=0.78), Phoria at 30cm (ICC=0.68), Near Point of Convergence break (ICC=0.65) and Saccades (ICC=0.61). The ICC for Positive Fusional Vergence at 3m (ICC=0.56) also decreased to 0.45 after removing two outliers. We found poor reliability in Near Point of Convergence (ICC=0.47), Gross Stereoscopic Acuity (ICC=0.03) and Negative Fusional Vergence at 3m (ICC=0.0). ICC for Phoria at 3m was not appropriate because scores were identical in 14/16 athletes. 95% LoA of the majority of tests were ±40% to ±90%.

Conclusions: Five tests had good to moderate one-year test-retest reliability. The remaining tests had poor reliability. The tests would therefore be useful only if concussion has a moderate-large effect on scores.

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

AIM

To determine normative values for stereoacuity, accommodative and vergence measures for high school populations.

METHODS

Using a multi-stage random cluster sampling, 1211 children (481 males and 730 females) between 13 and 18 years of age, with a median age of 16 years, were selected. 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.

RESULTS

Most data did not have a normal distribution. The range of normality for the vergence measures were: near point of convergence break, 5-10cm, recovery, 6-13cm, near lateral phoria, 2.5-6 prism dioptre (pd) (nasal), near vertical, orthophoria to 0.50pd, negative fusional vergence break, 12-23pd, recovery, 8-17pd, positive fusional vergence break, 16-35 and recovery 11-24pd. For accommodative measures, the range of normality for accommodative measures was: amplitude of accommodation, 12-18pd, accommodative response, plano to +0.75D, binocular accommodative facility, 5-12 cycles per minute (cpm), negative relative accommodation, 1.75-2.50DS, positive relative accommodation, -2.0 to -3.0DS and 17-69s arc for stereoacuity.

CONCLUSION

This study provides norms for clinical measures which could be used to classify accommodative and vergence parameters for children aged 13-18 years in this population or beyond. Findings should be applied in the context of the measurement techniques and the associated limitations outlined in this report.

The distribution of near point of convergence in an Iranian rural population: A population-based cross-sectional study

OBJECTIVE

To determine the distribution of near point of convergence (NPC) according to age, sex, and refractive error in a rural population above 1 year of age in 2015.

METHODS

In this population-based cross-sectional study, multistage cluster sampling was applied to randomly select two underserved areas from the north and southwest of Iran and all individuals above 1 year living in these areas were invited to participate in the study. All participants underwent ocular examinations including visual acuity measurement, refraction, binocular vision testing including cover test and measurement of NPC, and slit lamp biomicroscopy.

RESULTS

Of 3851 who were invited, 3314 participated in the study (response rate: 86.5%). The NPC was 8.42 ± 2.94 cm in the whole population, 8.59 ± 3.07 cm in men, and 8.30 ± 2.84 cm in women. Subjects above 70 years of age had the most remote NPC (mean: 10.44 ± 3.07 cm). The mean NPC was 7.79 ± 2.93, 8.83 ± 2.72, and 9.63 ± 2.70 cm in emmetropic, myopic, and hyperopic participants, respectively. According to the results of a multiple linear regression model, NPC had a positive correlation with age (b: 0.058, p < 0.001), male sex (b: 0.336, p: 0.005), and hyperopia (b: 0.044, p: 0.011). Among the evaluated variables, age had the greatest effect on NPC (Standardized coefficient: 0.402).

CONCLUSION

The distribution of NPC in the Iranian population is different from other populations. Since NPC is influenced by age more than any other variable and presented normal values according to age in this study, the results can be used to interpret clinical measurements for diagnosis and treatment purposes.

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.

2017 Glenn A. Fry Award Lecture: Establishing an Evidence-based Literature for Vision Therapy - A 25-year Journey

In this article, I summarize the 2017 Glenn A. Fry Award Lecture and my journey from student, to clinician, to optometric educator, and finally researcher/vision scientist. Although content for many years of teaching and practicing vision therapy, the era of evidence-based health care created a level of discomfort, as it became evident that my area of interest, vision therapy, had minimal quality evidence to support its use. Joining forces with a group of exceptional colleagues, we established the Convergence Insufficiency Treatment Trial Investigator group, and we were able to achieve funding from the National Eye Institute for multiple randomized clinical trials. The results of our studies demonstrate that vision therapy is an effective treatment option for convergence insufficiency in children, and office-based therapy is more effective than home-based therapy. These studies also demonstrated that home-based pencil push-ups commonly used by both optometrists and ophthalmologists are no more effective than placebo therapy. More recently, working in a new arena of objective recording of vergence, accommodative, and versional eye movements, my research has demonstrated that objective outcome measures of vergence are feasible for future randomized clinical trials. In pilot studies with both naturally occurring convergence insufficiency and concussion-related convergence insufficiency, statistically significant and clinically meaningful changes have been found in both disparity vergence peak velocity and response amplitude after office-based vision therapy. With new evidence about the high prevalence of concussion-related convergence insufficiency, there is much work to be accomplished to study the effectiveness of vision therapy for convergence insufficiency as well as the underlying mechanisms for how and why vision therapy is effective.

Measuring the heterophoria: Agreement between two methods in non-presbyopic and presbyopic patients

PURPOSE

To establish whether the cover test and von Graefe methods are interchangeable in a non-presbyopic and presbyopic population.

METHODS

We performed a prospective study on a sample of 127 non-presbyopic subjects between 20 and 45 years old and 56 presbyopic between 40 and 78 years old. Distance and near vision phoria were measured using the von Graefe method (VG) and cover test (CT). We analyzed the significant differences between methods, their correlation and the agreement between them using the Bland and Altman method.

RESULTS

For distance vision, heterophoria values for non-presbyopic subjects were -0.61±1.86Δ with CT and -0.88±2.37Δ with VG, and for presbyopic subjects were -0.56±1.64Δ with CT and -0.85±1.94Δ with VG. For near vision, CT yielded -3.02±3.97Δ, while VG achieved -3.49±4.70Δ in non-presbyopic subjects. For presbyopic subjects these values were -6.05±4.38Δ with CT and -6.29±4.19Δ with VG, respectively. Statistically significant differences between the two methods were observed for all groups analyzed (p<0.05), except for near vision in presbyopic subjects (p>0.05). Coefficient of agreement for non-presbyopic was ±2.97Δ for distance vision and ±6.74Δ at near. For presbyopic patients, this coefficient was ±1.59Δ for distance and ±1.86Δ for near vision.

CONCLUSION

Cover test and von Graefe methods have a high level of agreement for both distance and near vision when considering presbyopic subjects. For non-presbyopic patients, the level of agreement is very low. Both methods for measuring heterophoria can only be considered interchangeable for presbyopic patients. For clinical purposes, this implies that any method can be used for measuring heterophoria in presbyopic patients.

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.

Comparison of three monocular methods for measuring accommodative stimulus-response curves

PURPOSE

The aim was to evaluate the repeatability of dynamic measurement of the accommodative stimulus-response curve (ASRC) at three different dioptric speeds using a modified instrument and its agreement with two other methods.

METHODS

Twenty-nine adults (23.5 ± 2.0 years) were enrolled in the study. ASRC was measured monocularly using three methods: dynamic and static measurement using a motorised Badal system mounted on an open-field auto-refractor (WAM-5500, Grand Seiko Co., Ltd, Japan) and the minus lens technique. Dynamic measurements were conducted at three dioptric stimulus speeds to simulate continuous stimuli for ASRC (0.25, 0.40 and 0.55 D/s), with three repetitions for each speed. All three types of ASRCs were fitted with third-degree polynomial equations. The slope and objective accommodative amplitude of the ASRC were analysed.

RESULTS

The repeatability of objective accommodative amplitude worsened as the speed of the stimuli increased. The repeatability of the slope was best at a speed of 0.40 D/s and worst at 0.55 D/s. The measurement method significantly influenced the objective accommodative amplitude values and slope (both, p < 0.001). The minus lens technique yielded the highest amplitude of accommodation (6.21 ± 0.84 D) and steepest slope (1.11 ± 0.14), followed by the static Badal method (5.60 ± 0.83 D and 0.89 ± 0.09 D). The objective accommodative amplitude decreased with increasing speed during dynamic measurements. There was no difference between the slopes at 0.25 D and 0.40 D/s (p > 0.05) and the slope was lowest at 0.55 D/s.

CONCLUSION

The accommodative stimulus-response curve values are method-dependent and the significant differences between three methods used to determine the ASRC based on slope and accommodative amplitude indicate that these methods are non-interchangeable. Using dynamic measurements, accommodative behaviour varies with the speed of dioptric-change of the stimulus. A speed of 0.40 D/s appears to be the best compromise in terms of time, results and repeatability for dynamic ASRC measurement.

Binocular vision anomalies and normative data (BAND) in Tamil Nadu: report 1

BACKGROUND

This population-based, cross-sectional study was designed to determine normative data for binocular vision and accommodative testing in rural and urban populations of Tamil Nadu.

METHODS

A sample of 936 was determined, based on a previous pilot study. The epidemiological field work included a comprehensive eye examination and a binocular vision and accommodative assessment carried out in a total of four public schools, two each in the rural and urban arms of Chennai. An overall sample of 3,024 children between seven and 17 years of age was screened in the four schools and 920 children were included in the study.

RESULTS

We found significant differences in expected values from the current clinical criteria for near point of convergence (NPC) with penlight, distance and near horizontal phorias, vergence facility, accommodation convergence/accommodation (AC/A) ratio, accommodative amplitudes, monocular and binocular accommodative facility (t-test: p < 0.001). The mean and standard deviation break/recovery values for NPC (in centimetres) with an accommodative target and penlight with red filter was 3 ± 3/4 ± 4 and 7 ± 5/10 ± 7, respectively. The mean accommodative amplitudes for the population could be estimated from the linear regression equation 16 - 0.3 × (age). The vergence facility was 12 ± 4 cycles/minute and 14 ± 4 cycles/minute in the seven to 10 and 11 to 17 age groups, respectively. Monocular accommodative facility was 11 ± 4 cycles/minute and 14 ± 5 cycles/minute and binocular accommodative facility was 10 ± 4 cycles/minute and 14 ± 5 cycles/minute in the seven to 12 and 13 to 17 age groups, respectively. The mean calculated AC/A ratio was 5.4 ± 0.6/1.

CONCLUSION

The normative data for vergence and accommodative parameters for the Indian children between seven and 17 years of age are reported. The developmental trend of accommodation and vergence differences and significant differences in cut-off between the current data and available literature are reported. These differences have clinical implications for the interpretation, diagnosis and management of anomalies of binocular vision.

Autorefraction, Retinoscopy, Javal's Rule, and Grosvenor's Modified Javal's Rule: The Best Predictor of Refractive Astigmatism

The aim of the study was to determine the level of agreement between Javal's rule, autorefraction, retinoscopy, and refractive astigmatism and to determine which technique is the most suitable substitute when subjective refraction is not applicable using a clinical sample. A total of 36 subjects, 14 males and 22 females, were involved in this study. The intraclass correlation coefficients between subjective refraction, autorefraction, and retinoscopy were 0.895 and 0.989, respectively, for the spherical equivalent. The Bland-Altman 95% limits of agreement between subjective refraction and autorefraction; subjective refraction and retinoscopy; and autorefraction and retinoscopy were −2.84 to 3.58, −0.88 to 1.12, and −3.01 to 3.53, respectively, for the spherical equivalent. The intraclass correlation coefficients between spectacle total astigmatism and the following techniques were as follows: retinoscopy (0.85); autorefraction (0.92); Javal's rule (0.82); and Grosvenor et al. version (0.85). The Bland-Altman 95% limits of agreement between subjective refraction and autorefraction; subjective refraction and retinoscopy; subjective refraction and Javal's rule; and subjective refraction and Grosvenor et al. version were −0.87 to 1.25, −1.49 to 1.99, −0.73 to 1.93, and −0.89 to 1.7, respectively, for the total astigmatism. The study showed that autorefraction and Javal's rule may provide a starting point for subjective refraction cylinder power determination but only retinoscopy may satisfactorily replace subjective refraction total astigmatism when subjective refraction is not applicable.

The distribution of near point of convergence, near horizontal heterophoria, and near vergence among myopic children in South Korea

Background/Purpose:

To assess the distribution of near point of convergence (NPC), near heterophoria, and near vergence among myopic school children in South Korea.

Methods:

One hundred and thirty-six elementary school children, aged 8–13 years, were each given a thorough eye examination including binocular vision testing, NPC using standard push-up technique, horizontal heterophoria measurement by Von Graefe, distance, and near negative and positive vergence with a phoropter and phoropter replacement card.

Results:

NPC break and recovery points were highest in the age 9 years group, but the mean values of NPC were within the normal range. Of 136 individuals, 52 presented with esophoria, 53 presented with 0 –6-Δ exophoria, and 31 presented with ≥7-Δ exophoria. In the younger age groups (8 years and 10 years) 0–6-Δ exophoria was prevalent, whereas in the older age groups (11 years, 12 years, and 13 years) esophoria was prevalent. Near positive fusional vergence (break and recovery point) presented with statistically significant correlations with the participants’ ages. Esophoria showed higher correlations with high myopia (8.00 ± 0.000) rather than with low myopia (3.36 ± 2.499) or medium myopia (3.42 ± 2.149). The mean value of 0–6Δ exophoria was highest in medium myopia (4.04 ± 1.517), and of ≥7-Δ exophoria was the highest in high myopia (12.66 ± 1.154).

Conclusion:

There were no statistically significant correlations between the school childrens’ ages and NPC, near horizontal heterophoria, and near fusional vergence, except near positive fusional vergence. Also, unlike many studies, myopic magnitude did not present a significant correlation with near phoria and fusional vergence.

The distribution of near point of convergence and its association with age, gender and refractive error: a population-based study

PURPOSE

The aim was to determine the distribution of the near point of convergence (NPC) and its association with age, gender and refractive errors through a population-based study.

METHODS

In this cross-sectional study, samples were randomly selected from the population of Mashhad city in the northeast of Iran through stratified cluster sampling. In each of the 120 randomly selected clusters, 10 households were systematically chosen. Examinations included visual acuity testing, refractive and binocular vision examination. NPC was measured using a 6/12 single target on a Gulden fixation stick. Positive and negative fusional vergences were measured by the step method at far and near fixation distances.

RESULTS

Of the 4,453 invitees, 3,132 people participated (response rate of 70.4 per cent) and after applying the exclusion criteria, analysis was conducted on data from 2,433 individuals whose mean age was 31.2 ± 15.1 years (range: 10 to 86 years). Mean NPC was 8.59 ± 4.82 cm (range: 2 to 40 cm) in the total sample, 6.95 ± 3.87 cm in the 10-19 years age group and 13.06 ± 5.2 cm in those over 70 years. The relationships of NPC with the variables ages, gender and refractive errors (spherical equivalent) was assessed in a multiple linear regression model. Based on this model, older age (p < 0.001, coefficient = 0.106), male gender (p = 0.002, coefficient = 0.608) maintained a significant correlation with NPC, while the association with refractive error was no longer significant (p = 0.109, coefficient = 0.128) after adjusting for age and gender.

CONCLUSION

This is the first population-based study to examine the normal ranges of NPC and also the first to describe normal values in a presbyopic population. The results of this study indicate an age-related change in NPC. These changes should be noted in the interpretation of tests for the diagnosis and treatment of problems with binocular vision.

Near Point of Convergence After a Sport-Related Concussion: Measurement Reliability and Relationship to Neurocognitive Impairment and Symptoms

BACKGROUND

Convergence insufficiency (CI) is a common binocular vision deficit after a sport-related concussion (SRC). CI may result in visual discomfort and vision-mediated functional difficulties such as slowed reading and compromised attention, leading to impaired academic, work, and sport performance.

PURPOSE

To test the reliability of repeated near point of convergence (NPC) measurements in a sample of athletes after an SRC; compare the symptoms and cognitive impairment of athletes with normal NPC to those with CI after an SRC; and explore the relationship among age, sex, learning disability, migraine history, and CI.

STUDY DESIGN

Cross-sectional study; Level of evidence, 3.

METHODS

A total of 78 athletes (mean age, 14.31 ± 2.77 years) who were seen a mean 5.79 ± 5.63 days after an SRC were administered 3 trials of an NPC assessment, along with neurocognitive (Immediate Post-Concussion Assessment and Cognitive Testing [ImPACT]) and symptom assessments. Patients were divided into normal NPC (NPC ≤ 5 cm; n = 45) and CI (NPC >5 cm; n = 33) groups. Intraclass correlation coefficients (ICCs) and repeated-measures analyses of variance (ANOVAs) assessed the consistency of NPC across the 3 trials. The ANOVAs were employed to examine differences on neurocognitive composites and symptoms between the normal NPC and CI groups. Stepwise regressions (controlling for age and symptom scores on the Post-Concussion Symptom Scale [PCSS]) were conducted to evaluate the predictive utility of the NPC distance for neurocognitive impairment.

RESULTS

Groups did not differ on demographic or injury characteristics. NPC differed between trial 1 and trials 2 (P = .02) and 3 (P = .01) for the CI group but not the normal NPC group. Internal consistency was high across NPC measurements (ICC range, 0.95-0.98). Patients with CI performed worse on verbal memory (P = .02), visual motor speed (P = .02), and reaction time (P = .001, η(2) = .13) and had greater total symptom scores (P = .02) after the injury. Results of hierarchical regression revealed that the NPC distance contributed significantly to the model for reaction time (P < .001).

CONCLUSION

CI was common (~42%) in athletes evaluated within 1 month after an SRC. Athletes with CI had worse neurocognitive impairment and higher symptom scores than did those with normal NPC. Clinicians should consider routinely screening for NPC as part of a comprehensive concussion evaluation to help inform treatment recommendations, academic accommodations, and referrals for vision therapy.

Diagnostic validity of clinical signs associated with a large exophoria at near

Purpose. To analyze the diagnostic validity of accommodative and binocular tests in a sample of patients with a large near exophoria with moderate to severe symptoms. Methods. Two groups of patients between 19 and 35 years were recruited from a university clinic: 33 subjects with large exophoria at near vision and moderate or high visual discomfort and 33 patients with normal heterophoria and low visual discomfort. Visual discomfort was defined using the Conlon survey. A refractive exam and an exhaustive evaluation of accommodation and vergence were assessed. Diagnostic validity by means of receiver operator characteristic (ROC) curves, sensitivity (S), specificity (Sp), and positive and negative likelihood ratios (LR+, LR-) were assessed. This analysis was also carried out considering multiple tests as serial testing strategy. Results. ROC analysis showed the best diagnostic accuracy for receded near point of convergence (NPC) recovery (area = 0.929) and binocular accommodative facility (BAF) (area = 0.886). Using the cut-offs obtained with ROC analysis, the best diagnostic validity was obtained for the combination of NPC recovery and BAF (S  =  0.77, Sp = 1, LR+ = value tending to infinity, LR- = 0.23) and the combination of NPC break and recovery with BAF (S  =  0.73, Sp = 1, LR+ = tending to infinity, LR- = 0.27). Conclusions. NPC and BAF tests were the tests with the best diagnostic accuracy for subjects with large near exophoria and moderate to severe symptoms.

The relationship between binocular vision symptoms and near point of convergence

AIM AND BACKGROUND

Due to the relatively high prevalence of binocular vision anomalies, a regular examination including tests for assessment and determination of these anomalies is necessary. The aim of this study was to assess the relationship between near point of convergence (NPC) and near binocular vision symptoms and finding of an NPC cutoff point for symptoms in university students.

MATERIALS AND METHODS

In this cross-sectional study, 124 students of different majors of Zahedan University of Medical Sciences were randomly selected. If they met the inclusion criteria, they were divided into two groups (symptomatic and asymptomatic) according to the convergence insufficiency symptom survey questionnaire. For NPC measurement, a small isolated letter "E" of approximately 20/30 size on a metal rod was used. After data collection, data were analyzed in SPSS.17 software (SPSS for Windows, SPSS Inc., Chicago, IL) using descriptive and analytical statistics, including Mann-Whitney U test and receiver operating characteristic (ROC) curve.

RESULTS

The mean NPC findings in the symptomatic and asymptomatic groups were 11.7 ± 5.0 and 8.4 ± 3.4 cm, respectively, with a significant difference between the two groups (P < 0.001). The ROC curve suggests an NPC cutoff point of 9.5 cm for the presence of symptoms with the testing procedures used in this study. Conclusion : The determination of NPC is helpful in the differentiation of symptomatic from asymptomatic subjects.

A review of convergence insufficiency: what are we really accomplishing with exercises?

INTRODUCTION

Orthoptic exercises have been the primary treatment for convergence insufficiency since this condition's first description in 1855. It is presumed that exercises work by improving fusional convergence. In recent years, research from eye movement laboratories has challenged our theories on the nature and dynamics of convergence, the effect of convergence exercises, and the etiology of primary convergence insufficiency.

METHODS

A review of the ophthalmological, optometric, and basic science literature was done to retrieve the most recent research on vergence eye movements and convergence insufficiency.

RESULTS

Convergence appears to be a bi-phasic response to a change in stimulus position in depth. The first phase, which may represent the contribution of proximal convergence, is not under visual feedback, is fast with a short latency, and is triggered by stimuli moving rapidly in depth or by large, sudden changes in fixation. This phase is followed by a slow vergence movement with a slightly longer latency, triggered by small disparity vergence errors. The second phase is under the control of visual feedback, and represents the contributions of fusional and accommodative convergence. Eye movement recordings indicate that the velocity and amplitude of the first phase of convergence are temporarily adaptable with exercises. The second phase does not appear to be amenable to training. Tonic convergence is also trainable.

CONCLUSION

Convergence exercises are effective in temporarily improving the dynamics of proximal and tonic convergence, but have little effect on fusional or accommodative convergence.

The changes in phoria and convergence to divergence peak velocity ratio are correlated

PURPOSE

Phoria is used in the diagnosis of binocular dysfunctions, such as convergence insufficiency. A common treatment for convergence insufficiency is vision therapy, yet it is controversial whether the phoria changes as a result of rehabilitation. Phoria can vary due to the duration and/or the type of prior visual tasks. The variability potentially observed within phoria measurements leads to difficulties in confidently assessing changes within longitudinal studies. Hence, we propose to measure phoria and vergence peak velocities on separate days to evaluate whether a more robust measurement can be attained.

METHODS

Eleven subjects with normal binocular vision participated in two identical experimental sessions. Four-degree convergence and divergence steps stimulated from targets at far, middle, and near initial vergence positions were recorded using a limbus tracking system. Near dissociated phoria was measured after a set of step stimuli. The vergence ratio was defined as the convergence peak velocity divided by the divergence peak velocity. Linear regression analyses calculated the correlation between the phoria and the vergence ratio, and the difference between phoria measurements and vergence ratio measurements, recorded on different days.

RESULTS

Near dissociated phoria measurements and vergence ratios were highly correlated for all three initial vergence positions (r > 0.85, p < 0.005). The change in phoria was significantly correlated to the change in vergence ratio (r > 0.94, p = 0.0001). The slope of the linear regression analysis between the phoria and the vergence ratio using individual subject data was repeatable between the sessions (r = 0.99, p < 0.00001) despite large changes in phoria observed in a few individuals.

CONCLUSIONS

The change in phoria is significantly correlated to the change in vergence ratio. For longitudinal studies including the efficacy of vision therapies for patients with binocular dysfunctions, we suggest assessing both phoria and vergence velocities to reduce the variability potentially observed from different days.

Reliability of acuities determined with the sweep visual evoked potential (sVEP)

sVEPs are generally used to rapidly obtain visual acuity. Several studies have determined the reliability of acuity measurements with psychophysical techniques. The aim of this study was to determine the intersession and intrasession variabilities of sVEP measurements. Twenty-four normal, adult subjects took part in this project. Stimulus production and data analyses were done using an Enfant 4010. Standard VEP recording techniques were employed. Data were collected on two separate days (at least 1 week apart). At each visit, two complete sets of sVEP data were collected and averaged. A logMAR acuity chart was also used to determine the acuity at each visit. Paired t tests, 95% confidence intervals, intraclass correlation coefficients, and coefficients of repeatability were used to determine whether there was a difference in the intrasession and intersession acuities. The mean acuity difference and coefficient of repeatability were +0.01 and 0.191 for visit 1 and -0.019 and 0.186 for visit 2, respectively. The mean acuity difference and coefficient of repeatability across visits were +0.008 and 0.176 for the first acuity and-0.02 and 0.170 for the second acuity, respectively. Paired t tests did not find a significant difference between any set of data or the average for visits one and two (all P values > 0.05). The intraclass correlation coefficients comparing the average sVEP data and the logMAR data for visits 1 and 2 were 0.71 and 0.88, respectively. The coefficients of repeatability for the averaged sVEP acuity and the logMAR acuity for the two visits were 0.11 and 0.07, respectively. The repeatability of the sVEP acuity estimate in a large population of adults is similar to that of previous published reports on infants and is nearly as high as that of logMAR acuity chart data. The repeatability is the same for single best estimates of acuity and averaged estimates of acuity across visits.

Ten-year changes in fusional vergence, phoria, and nearpoint of convergence in myopic children

PURPOSE

To identify longitudinal changes in fusional vergence ranges and their relationship to other clinical measures in young myopic subjects.

METHODS

Measurements were collected annually for 10 years on 114 subjects from the University of Houston Correction of Myopia Evaluation Trial cohort. Subject age was 7 to 13 years at year 1 of follow-up. Measurements included refractive error, distance and near phoria, interpupillary distance (IPD), prism bar fusional vergence ranges, and nearpoint of convergence (NPC). Multilevel modeling was used to determine baseline and rate of change for fusional vergence ranges and the impact of phoria, IPD, and NPC on these measures.

RESULTS

Year 1 mean distance base-out (BO) break was 20 prism diopters (pd) and decreased 5.6 pd over 10 years (p < 0.001). Mean near BO break was 30 pd at year 1 and decreased 9.4 pd over 10 years (p < 0.001). Greater esophoria was significantly related to greater BO break (p < 0.02) and receded NPC was significantly related to lower magnitude BO break at near (p < 0.001). Distance IPD increased 3 mm over 10 years (p < 0.001) but was unrelated to the magnitude of the BO ranges (p > 0.2). Mean distance base-in (BI) break was 7 pd at year 1 and increased 0.5 pd in 10 years (p = 0.04). Mean near BI break was 13 pd at year 1 and did not significantly change. Mean distance phoria was 0.1 pd exophoria at year 1 and did not change, whereas near phoria was 2.4 pd esophoria at year 1 and became more exophoric (4 pd in 10 years, p < 0.001).

CONCLUSIONS

These results suggest that for myopic children convergence ranges decrease for both distance and near viewing during the school years as near phoria becomes more exophoric. These findings could have clinical implications given that compensating convergence ranges decrease as near phoria becomes more divergent.

Effect of vergence adaptation and positive fusional vergence training on oculomotor parameters

PURPOSE

Clinical studies have shown that positive fusional vergence (PFV) can be trained through a program of orthoptic exercises. Models of accommodation and vergence predict that training PFV would require a reduction in the convergence accommodation (CA) cross-link. Recent investigations have found that the CA/C ratio is not changed in a clinical population after orthoptics. We hypothesized that such orthoptic programs may instead act to reduce CA through changes in the relationship between fast and slow vergence components. METHODS.: Eleven visually normal subjects were tested. Phoria adaptation to a 12-Delta base-out (BO) wedge prism and the resulting CA responses were monitored every 3 min for 15 min to a DoG target at 0.4 m. These measures were repeated after 2 weeks of orthoptics. Phorias, stimulus accommodative convergence (AC)/A and CA/C ratios, and PFV amplitudes at near were also determined. Before the orthoptics program, these measures were repeated under "adapted" conditions.

RESULTS

Phoria adaptation following prolonged viewing through the 12-Delta BO wedge prism was associated with a concomitant reduction in the CA. These changes were asymptotic over time with 95% of the change occurring within the first 3 to 6 min. After 2 week of orthoptics, the rates and magnitudes of both phoria adaptation and CA reduction increased significantly (p < 0.01). PFV at 40-cm limits showed increases with orthoptics and under vergence adaptation. CA/C and AC/A ratios were unchanged after orthoptics, but the former was reduced, and the latter increased under the vergence adapted condition.

CONCLUSIONS

Orthoptics acts to change the time constant and magnitude of vergence adaptation to BO prisms, which leads to a concomitant reduction of CA over a similar time course. This process appears to underlie the increase in positive fusion limits. Although reductions in CA/C ratio occur under the vergence adapted state, this ratio is not directly changed with orthoptics.

Randomized clinical trial of treatments for symptomatic convergence insufficiency in children

OBJECTIVE

To compare home-based pencil push-ups (HBPP), home-based computer vergence/accommodative therapy and pencil push-ups (HBCVAT+), office-based vergence/accommodative therapy with home reinforcement (OBVAT), and office-based placebo therapy with home reinforcement (OBPT) as treatments for symptomatic convergence insufficiency.

METHODS

In a randomized clinical trial, 221 children aged 9 to 17 years with symptomatic convergence insufficiency were assigned to 1 of 4 treatments.

MAIN OUTCOME MEASURES

Convergence Insufficiency Symptom Survey score after 12 weeks of treatment. Secondary outcomes were near point of convergence and positive fusional vergence at near.

RESULTS

After 12 weeks of treatment, the OBVAT group's mean Convergence Insufficiency Symptom Survey score (15.1) was statistically significantly lower than those of 21.3, 24.7, and 21.9 in the HBCVAT+, HBPP, and OBPT groups, respectively (P < .001). The OBVAT group also demonstrated a significantly improved near point of convergence and positive fusional vergence at near compared with the other groups (P

CONCLUSIONS

Twelve weeks of OBVAT results in a significantly greater improvement in symptoms and clinical measures of near point of convergence and positive fusional vergence and a greater percentage of patients reaching the predetermined criteria of success compared with HBPP, HBCVAT+, and OBPT. Application to Clinical Practice Office-based vergence accommodative therapy is an effective treatment for children with symptomatic convergence insufficiency.

TRIAL REGISTRATION

clinicaltrials.gov Identifier: NCT00338611.

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Key Words

• convergence insufficiency
• asthenopia
• vision therapy
• orthoptics
• vergence/accommodative therapy
• pencil push-ups
• computer vergence/accommodative therapy
• placebo therapy
• exophoria
• eyestrain
• symptom survey

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MESH Headings

• Adolescent
• Child
• Confidence Intervals
• Convergence, Ocular
• Female
• Home Nursing
• Humans
• Male
• Multivariate Analysis
• Ocular Motility Disorders/diagnosis
• Ocular Motility Disorders/therapy
• Office Visits
• Ophthalmology/methods
• Orthoptics/methods
• Patient Compliance
• Probability
• Recovery of Function
• Reference Values
• Sensitivity and Specificity
• Severity of Illness Index
• Strabismus/diagnosis
• Strabismus/therapy
• Treatment Outcome
• Vision, Binocular
• Visual Acuity

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Grants

• U10 EY014712 NEI NIH HHS
• U10 EY014676-02 NEI NIH HHS
• U10 EY014712-04 NEI NIH HHS
• U10 EY014659-03 NEI NIH HHS
• U10 EY014676-01A1 NEI NIH HHS
• U10 EY014713-01A2 NEI NIH HHS
• U10 EY014713-02 NEI NIH HHS
• U10 EY014715-01A1S1 NEI NIH HHS
• U10 EY014716-04 NEI NIH HHS
• U10 EY014710-04 NEI NIH HHS
• U10 EY014676 NEI NIH HHS
• U10 EY014706-01A1S1 NEI NIH HHS
• U10 EY014713 NEI NIH HHS
• U10 EY014709 NEI NIH HHS
• U10 EY014659-01A2 NEI NIH HHS
• U10 EY014715-04 NEI NIH HHS
• U10 EY014712-01A1 NEI NIH HHS
• U10 EY014713-03 NEI NIH HHS
• U10 EY014706-01A1 NEI NIH HHS
• U10 EY014715-02 NEI NIH HHS
• U10 EY014709-03 NEI NIH HHS
• U10 EY014715-03 NEI NIH HHS
• U10 EY014676-04 NEI NIH HHS
• U10 EY014715 NEI NIH HHS
• U10 EY014716-03 NEI NIH HHS
• U10 EY014710-02 NEI NIH HHS
• U10 EY014709-04 NEI NIH HHS
• U10 EY014716-02 NEI NIH HHS
• U10 EY014716-02S1 NEI NIH HHS
• U10 EY014706-02 NEI NIH HHS
• U10 EY014713-04 NEI NIH HHS
• U10 EY014709-02 NEI NIH HHS
• U10 EY014712-03 NEI NIH HHS
• U10 EY014706-04 NEI NIH HHS
• U10 EY014710-01A1S1 NEI NIH HHS
• U10 EY014710-01A1 NEI NIH HHS
• U10 EY014659-04 NEI NIH HHS
• U10 EY014676-03 NEI NIH HHS
• U10 EY014712-01A1S1 NEI NIH HHS
• U10 EY014659-02 NEI NIH HHS
• U10 EY014676-01A1S1 NEI NIH HHS
• U10 EY014716-01A1 NEI NIH HHS
• U10 EY014709-01A1 NEI NIH HHS
• U10 EY014706-03 NEI NIH HHS
• U10 EY014716-01A1S1 NEI NIH HHS
• U10 EY014716 NEI NIH HHS
• U10 EY014715-01A1 NEI NIH HHS
• U10 EY014709-01A1S1 NEI NIH HHS
• U10 EY014712-02 NEI NIH HHS
• U10 EY014710-03 NEI NIH HHS
• U10 EY014659 NEI NIH HHS

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Affiliation(s) Collapse

Binocular vision changes in university students: a 3-year longitudinal study

PURPOSE

The aim of this study was to investigate the changes in accommodation and binocular vision parameters during a period of 3 years and to evaluate their potential influence on the refractive changes observed over the same period of time in a population of university students in Portugal.

METHODS

A 3-year longitudinal study was conducted comprising 118 young adults (34 males and 84 females; mean age: 20.6 +/- 2.3 years). Examinations consisted of subjective refraction, dissociated phoria and vergences at distance and near vision, accommodative convergence/accommodative ratio, lag of accommodation, and the negative and positive relative accommodation.

RESULTS

There were statistically significant differences between the first (2002) and the second examination (2005) relative to distance and near phoria, and break and recovery points for the base-in and base-out at distance vision. Statistically significant differences were also obtained for the blur and break points for the base-out, and for break and recovery points for the base-in at near vision. As regards accommodation parameters, we verified a statistically significant difference for all parameters measured. Comparing the baseline values of patients who suffered a myopic shift > or =0.50 D with those from patients who did not experience such a shift, we observed a statistically significant difference for the break value of the base-in at distance vision (equal to 12.2 +/- 3.6 for the group without refractive error alteration and 15.8 +/- 6.8 for the other group) and for the break value of the base-in at near vision (equal to 22.4 +/- 5.2 and 24.8 +/- 5.5 for the group without refractive error alteration and for the other group, respectively).

CONCLUSIONS

We observed significant changes in near heterophoria, fusional vergences, and positive relative accommodation. The break values of the base-in fusional vergence account as significant predictors of myopic shift in young adults.

Repeatability intraexaminer and agreement in amplitude of accommodation measurements

BACKGROUND

Clinical measurement of the amplitude of accommodation (AA) provides an indication of maximum accommodative ability. To determine whether there has been a significant change in the AA, it is important to have a good idea of the repeatability of the measurement method used. The aim of the present study was to compare AA measurements made using three different subjective clinical methods: the push-up, push-down, and minus lens techniques. These methods differ in terms of the apparent size of the target, the end point used, or the components of the accommodation response stimulated. Our working hypothesis was that these methods are likely to show different degrees of repeatability such that they should not be used interchangeably.

METHODS

The AA of the right eye was measured on two separate occasions in 61 visually normal subjects of mean age 19.7 years (range 18 to 32). The repeatability of the tests and agreement between them was estimated by the Bland and Altman method. We determined the mean difference (MD) and the 95% limits of agreement for the repeatability study (COR) and for the agreement study (COA).

RESULTS

The COR for the push-up, push-down, and minus lens techniques were +/-4.76, +/-4.00, and +/-2.52D, respectively. Higher values of AA were obtained using the push-up procedure compared to the push-down and minus lens methods. The push-down method also yielded a larger mean AA than the negative-lens method. MD between the three methods were high in clinical terms, always over 1.75D, and the COA differed substantially by at least +/-4.50D. The highest agreement interval was observed when we compared AA measurements made using minus lenses and the push-up method (+/-5.65D).

CONCLUSIONS

The minus lens method exhibited the best repeatability, least MD (-0.08D) and the smallest COR. Agreement between the three techniques was poor.