Prevalence of non‐strabismic anomalies of binocular vision in Tamil Nadu: report 2 of BAND study

Neural consequences of symptomatic convergence insufficiency: A small sample study

INTRODUCTION

Convergence insufficiency (CI) is an oculomotor abnormality characterised by exophoria and inadequate convergence when focusing on nearby objects. CI has been shown to cause symptoms when reading. However, the downstream consequences on brain structure have yet to be investigated. Here, we investigated the neural consequences of symptomatic CI, focusing on the left arcuate fasciculus, a bundle of white matter fibres which supports reading ability and has been associated with reading deficits.

METHODS

We compared the arcuate fasciculus microstructure of participants with symptomatic CI versus normal binocular vision (NBV). Six CI participants and seven NBV controls were included in the analysis. All participants were scanned with 3 T magnetic resonance imaging (MRI), and anatomical and diffusion-weighted images were acquired. Diffusion-weighted images were processed with TRACULA to identify the arcuate fasciculus in each participant and compute volume and radial diffusivity (RD).

RESULTS

Compared with NBV controls, those with symptomatic CI had significantly smaller arcuate fasciculi bilaterally (left: t = -3.21, p = 0.008; right: t = -3.29, p = 0.007), and lower RD in the left (t = -2.66, p = 0.02), but not the right (t = -0.81, p = 0.44, false discovery rate (FDR)-corrected p > 0.05) arcuate fasciculus. Those with higher levels of reading symptoms had smaller arcuate fasciculi (r = -0.74, p = 0.004) with lower RD (r = -0.61, p = 0.03).

CONCLUSIONS

These findings suggest that symptomatic CI may lead to microstructural changes in the arcuate fasciculus. Since it is highly unlikely that abnormalities in the arcuate fasciculus are the cause of the neuromuscular deficits in the eyes, we argue that these changes may be a potential neuroplastic consequence of disruptions in sustained reading.

Pupillary dynamics and accommodative response in mild traumatic brain injury

PURPOSE

To measure the pupillary dynamics and accommodative response in individuals with mild traumatic brain injury (mTBI) as compared to age-matched controls.

MATERIALS AND METHODS

This prospective comparative study was carried out at the neuro-optometry clinic of a tertiary eye care hospital. Sixty-three subjects with a history of mTBI and ninety age-matched controls were enrolled in this study. Subjects in the age range of 18-35 years were included in the study. A comprehensive neuro-optometric assessment was performed followed by pupillary dynamics and accommodation response measurements using NeurOptics® pupillary light reflex™-3000 and Grand-Seiko WAM-5500 binocular accommodation auto ref/keratometer | shigiya machinery works LTD.

RESULTS

A statistically significant difference was noticed for constriction percentage (%): 32.73 ± 9.20 versus 39.93 ± 7.36 (P < 0.001), average constriction velocity (mm/s): 2.24 ± 0.85 versus 2.62 ± 0.68 (P = 0.002), maximum constriction velocity (mm/s): 3.82 ± 1.33 versus 4.42 ± 0.93 (P = 0.004) and T75 (recovery period to 75% of the baseline pupillary diameter in sec): 1.38 ± 0.36 versus 2.0 ± 0.82 (P < 0.001) in mTBI compared to age-matched controls. A statistically significant difference was noted for accommodative response (in D) as well as in the sample as compared to age-matched controls: -1.12 ± 0.64 versus - 1.39 ± 0.47 (P < 0.001).

CONCLUSION

Pupillary constriction velocities and accommodative response are significantly affected in mTBI. These findings have important clinical implications in being able to understand the visual symptoms following an mTBI.

Diagnostic Protocol for Accommodative and Vergence Anomalies - A Review

PURPOSE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Frequency of Non-strabismic Binocular Vision Anomalies among Optometrists in a Tertiary Eye Care Center in Southern India

Purpose

Lifestyle in the modern era has drastically changed across the globe, and the healthcare profession was no exception. The increased time spent in the virtual space for various purposes, including online classes and webinars, is hypothesized to increase the risk of vision-related disorders such as asthenopia, dry eyes, and visual fatigue. The purpose of this study was to evaluate fusional vergence and ocular accommodation among optometry professionals in a tertiary eye care center during the immediate post-coronavirus disease 2019 (post-COVID-19) lockdown period.

Methods

Optometrists posted in the general out-patient department, specialty clinics, and the ocular diagnostics department were included in the study. A total of 65 optometrists were included in the study. All optometrists underwent a comprehensive binocular vision assessment. Convergence Insufficiency Symptom Survey questionnaires were administered to all optometrists at the beginning of the assessment.

Results

Out of 65 optometrists, 48 (73.8%) were women. The mean (standard deviation) age of the participants was 24 (3) years. Eleven (16.9%) optometrists had normal binocular vision parameters, and the rest 54 (83.1%) had non-strabismic binocular vision anomalies. Reduced accommodative facility and convergence insufficiency were seen among 43 (66.2%) optometrists, whereas 30 (46.2%) had reduced accommodative facility alone. Twelve (18.5%) participants were symptomatic as per the convergence insufficiency symptom survey.

Conclusion

This study highlights the fact that a large proportion of optometrists have undetected non-strabismic binocular vision anomalies in a tertiary eye care center. It is important for eye care professionals to undergo regular binocular vision assessments in association with ophthalmic examinations and relevant management. This will ensure that these dysfunctions do not impede work productivity and overall quality of life.

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

Aim

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

Methods

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

Results

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

Conclusion

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

Impact of Covid-19 on Pediatric Ophthalmology Care: Lessons Learned

The COVID-19 pandemic came with many new challenges that forced personal and professional lifestyle modifications. Medical facilities were in scarcity against this new unknown enemy and were challenged with the overloaded patient flow, scarcity of healthcare staff, and evolving treatment modalities with a better understanding of the virus each day. Ophthalmology as a "branch of medicine" suffered challenges initially because of a lack of guidelines for patient management, close working distance during routine examinations, and halt of major surgeries, including cataracts. Pediatric ophthalmology had major implications, as reduced outpatient visits would mean deeper amblyopia, and changed lifestyles, including online classes and home refinement, predisposing children to myopia, digital eye strain, and worsening of strabismus. COVID-19 also unveiled underlying accommodation and convergence anomalies that predisposed pediatric and adolescent patients to an increased prevalence of headache and acute onset esotropia. Teleophthalmology and other innovative solutions, including the use of prism glasses, safe slit-lamp shields, alternative ways of school screening with the use of photoscreeners, performing retinoscopy only when needed, and using autorefractors were among the few guidelines or modifications adopted which helped in the efficient and safe management of pediatric patients. Many pediatric ophthalmologists also suffered in terms of financial constraints due to loss of salary or even closure of private practices. School screening and retinopathy of prematurity screening suffered a great setback and costed a lot of vision years, data of which remains under-reported. Important implications and learnings from the pandemic to mitigate future similar situations include using teleophthalmology and virtual platforms for the triage of patients, managing non-emergency conditions without physical consultations, and utilizing home-based vision assessment techniques customized for different age groups. Though this pandemic had a lot of negative implications, the innovations, modifications, and other important learnings helped pediatric ophthalmologists in navigating safely.

Clinical features of Sudanese patients presenting with binocular vision anomalies: A hospital-based study

Binocular vision anomalies are major causes of asthenopia symptoms, particularly among the younger population. This study aimed to report the clinical characteristics of Sudanese patients with binocular disorders who attended the orthoptic clinic at Al-Neelain Eye Hospital. In this retrospective hospital-based study, we analyzed data from 304 patients with binocular vision anomalies who visited the orthoptic clinic between October 2020 and June 2021. We collected information on demographics, symptoms, and eye tests such as visual acuity (VA), refractive error (RE), angle of deviation, and the assessment of fusional vergence. Our findings indicated that exophoria was the most common binocular vision anomaly, affecting 79.8% of males and 71.6% of females (p=0.731). Children between 6 and 17 years old showed the highest prevalence of exophoria (75.9%) (p=0.0001). Among patients with exophoria, 100% reported itching associated with tearing during fixation, while 89.5% experienced difficulty in fixation. Refractive error varied by the type of binocular vision disorders (p=0.0001), with higher hyperopia observed in cases of unilateral esotropia and alternate esotropia (+3.571±1.238 D and +3.023±1.553 D, respectively). Positive fusional vergence (PFV) differed by types of binocular vision disorders (p=0.0001) with high PFV in esophoria (18.063±6.848∆) compared to low PFV in exophoria (12.80±5.313∆). The most common types of exophoria were convergence weakness exophoria (45.39%), followed by convergence insufficiency (20.39%). The study concluded that exophoria was the most common binocular vision anomaly among Sudanese patients, with convergence weakness and convergence insufficiency being the predominant anomalies. Headache was commonly prevalent among patients with binocular vision problems. Higher hyperopia was found in esodeviation, while low PFV was associated with exodeviation.

Convergence insufficiency symptom survey: A tool to evaluate convergence excess in young adults

PURPOSE

To determine the effectiveness of the Convergence Insufficiency Symptom Survey (CISS) in evaluating visual symptoms in young adults with convergence excess (CE).

METHODS

A cross-sectional study was performed based on a population of optometry students. Comprehensive binocular vision tests including cover test, near point of convergence, fusional vergence and accommodative amplitude, were performed. Participants were categorised into three groups: normal binocular vision (NBV), CE and CE + accommodative insufficiency (AI) (i.e., CE + AI). The CISS was administered to each participant. An analysis of variance with Bonferroni correction was performed to compare clinical measures among the three groups. A receiver-operating characteristic (ROC) curve was constructed to evaluate the ability of CISS to differentiate CE from the NBV population.

RESULTS

A total of 181 participants were enrolled, including 96 in the NBV group, 66 in the CE group and 19 in the CE + AI group. A significant difference in CISS score was detected between the three groups (p < 0.001). Post-hoc tests showed significantly higher CISS scores in the CE group (16.7 ± 10.8) and the CE + AI group (19.7 ± 10.9) compared with the NBV group (12.2 ± 7.8) (p = 0.01 and p = 0.005, respectively), with no difference between the CE and the CE + AI groups (p = 0.52). The ROC curve showed the CISS poorly (but significantly) differentiated CE from NBV (area under the curve = 0.62, p = 0.01). The optimal cutoff value for a CISS score to differentiate CE was 16, with sensitivity and specificity of 52% and 72%, respectively.

CONCLUSIONS

Young adults with CE had significantly higher CISS scores than those with NBV. Although using the CISS solely for diagnosing CE is not recommended, it can be used to provide a measure of symptoms in individuals identified as having CE based on clinical measurements.

Visual system and motor development in children: a systematic review

PURPOSE

The aim of this study was to review the available scientific literature on the possible relationship between the visual system and motor development in children.

METHODS

This study was performed according to the Preferred Reporting Items for Systematic Reviews (PRISMA) statement recommendations. The review protocol is available in PROSPERO (CRD42021245341). Four different databases, namely Scopus, PubMed, CINAHL and Web of Science, were assessed from April 2005 to February 2021. To determine the quality of the articles, we used the Critical Appraisal Skills Programme (CASP) Quality Appraisal Scale, and a protocol was followed to define the levels of evidence on the basis of the Centre for Evidence-Based Medicine Levels of Evidence. The search strategy included terms describing motor development in children and adolescents with visual disorders.

RESULTS

Among the identified studies, 23 were included in the study. All selected articles examined the relationship between the visual system and development in children. The quality of most of the studies was moderate-high, and they were between evidence levels 2 and 4.

CONCLUSIONS

Our systematic review revealed that all included studies established a relationship between the visual system and development in children. However, the methods for measuring the visual system and motor skills lacked uniformity.

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

PURPOSE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Accommodative and binocular vision dysfunctions in a Portuguese clinical population

BACKGROUND

Several studies have suggested that accommodative and non-strabismic binocular dysfunctions are commonly encountered in optometric practice. This study aims to verify whether these findings apply to a Portuguese clinical population.

METHODS

This study included consecutive nonpresbyopic subjects that came to two Portuguese optometric clinics over a period of six months. A complete visual exam was conducted and included the measurement of visual acuity (VA), refraction, near point of convergence (NPC), distance and near phoria, near and distance fusional vergences, amplitude of accommodation (AA), monocular accommodative facility (MAF), relative accommodation and lag of accommodation.

RESULTS

156 subjects with a mean age of 24.9 ± 5.3 years (from 18 to 35 years old) participated in the study. Of all subjects, 32 % presented binocular vision and/or accommodative disorders accompanied or not by refractive errors. Moreover, 21.1 % had accommodative disorders, and 10.9 % had a binocular vision dysfunction. Accommodative insufficiency (11.5 %) was the most prevalent disorder, followed by convergence insufficiency (7.1 %) and accommodative infacility (5. 8 %).

CONCLUSIONS

Clinicians should be aware that about one third of the optometric clinical population could have accommodative and/or non-strabismic binocular disorders. Accommodative insufficiency was the most prevalent dysfunction presented in the studied population, followed by accommodative infacility and convergence insufficiency.

Cataract surgery is not associated with post-operative binocular vision anomalies in age-related cataract patients

PURPOSE

To compare the binocular vision status of patients pre- and post-cataract surgery, and to investigate the risk factors for patients who develop binocular vision anomalies post-surgery.

METHODS

A prospective study of patients (≥50 years) who elected to undergo bilateral cataract surgery was implemented. A comprehensive binocular vision test battery including stereopsis, ocular alignment, fusional vergence, vergence facility, near point of convergence and the Convergence Insufficiency Symptom Survey (CISS) was administered before the first surgery and at the third visit after surgery on the second eye. A detailed diagnostic classification protocol was applied to identify the presence of binocular vision anomalies pre- and post-surgery.

RESULTS

Seventy-three participants were included at baseline, 24 (33%) of whom were diagnosed with non-strabismic binocular vision anomalies (NSBVA), mainly convergence insufficiency (18/73, 25%). Fifty-one participants completed the post-operative evaluation, 17 (33%) of whom had NSBVA pre-surgery and 13 (26%) post-surgery (p = 0.48). There were a number of conversions from NSBVA to normal binocular vision and vice versa. Logistic regression showed that the adjusted odds ratio of pre-existing NSBVA diagnosis for predicting the risk of post-operative NSBVA was 6.37 (p < 0.01). There were no significant changes in most binocular vision measures post-surgery, except for a significant improvement in the CISS score (p < 0.01, Cohen's d = 0.83).

CONCLUSIONS

Binocular vision anomalies, especially convergence insufficiency, are prevalent in the age-related cataract population. Cataract surgery does not appear to be a significant risk factor for the development of new binocular vision anomalies. A pre-existing binocular vision anomaly is the main risk factor for predicting a post-operative binocular vision anomaly in this population.

Non-strabismic Binocular Vision Dysfunction among the Medical Students of a Teaching Hospital: A Descriptive Cross-sectional Study

Introduction

Non-strabismic binocular vision dysfunctions are visual disorders that affect the person's binocular vision and visual outcome while performing near tasks and are very common among medical students. This study aimed to find out the prevalence of non-strabismic binocular vision dysfunction among the medical students of a teaching hospital.

Methods

A descriptive cross-sectional study was conducted among medical students of a teaching hospital from 25 April 2022 to 25 May 2022. Ethical approval was obtained from the Institutional Review Committee of the same institute (Reference number: 139/17). A detailed ocular evaluation including history, visual acuity, refraction, and detailed orthoptic evaluation was done. Convenience sampling was done. Point estimate and 95% Confidence Interval were calculated.

Results

Out of 284 students, 79 (27.81%) (22.60-33.02, 95% Confidence Interval) had non-strabismic binocular vision dysfunctions. Convergence insufficiency was the commonest one seen in 38 (48.10%), followed by divergence excess seen in 8 (10.12%) and convergence excess seen in 8 (10.12%) students.

Conclusions

The prevalence of non-strabismic binocular vision dysfunction among medical students was lower than in other studies conducted in similar settings.

Keywords

binocular vision; convergence excess; convergence insufficiency; prevalence.

Preoperative binocular vision characteristics in the age-related cataract population

Background

This study is the first part of the “Binocular Vision Anomalies after Cataract Surgery” study that aimed to investigate the impact of cataract surgery on binocular vision status in adults with age-related cataract. This study aimed to investigate the preoperative binocular vision status of participants with age-related cataract.

Methods

Patients who elected to undergo bilateral cataract surgery (≥50 years of age) were recruited. Clinical measures of binocular vision including stereopsis, ocular alignment, fusional vergence, vergence facility, convergence amplitude and a symptom survey related to binocular vision anomalies were administered. A detailed classification protocol was established to identify the presence of binocular vision anomalies. The frequency of specific binocular vision anomalies and normative data of binocular vision measures were reported.

Results

A total of 73 subjects were evaluated. No strabismus was detected in the cohort. Non-strabismic binocular vision anomalies were detected in 24 subjects (32.9%), of whom 18 (24.7%) had convergence insufficiency, 3 (4.1%) had basic exophoria, 2 (2.7%) had convergence excess, and 1 (1.4%) had fusional vergence dysfunction. Decreased vergence facility and convergence amplitude were more common compared to the pre-presbyopes (P < 0.01).

Conclusion

Binocular vision problems, especially convergence insufficiency, are common in the adults with age-related cataract. The study results demonstrate that the lack of normative binocular vision data for the presbyopic population is a significant gap in the literature and suggest the need for a study of normative data for this population.

Trial registration

The study was registered at ClinicalTrials.gov (NCT03592615, USA).

Supplementary Information

The online version contains supplementary material available at 10.1186/s12886-022-02418-7.

Virtual reality-based vision therapy versus OBVAT in the treatment of convergence insufficiency, accommodative dysfunction: a pilot randomized controlled trial

Background

Virtual reality is being increasingly applied in vision therapy. However, the differences in effectiveness, optimal treatment cycle, and prognosis between virtual reality-based vision therapy and traditional therapies remain unknown. The purpose of this study was to compare the effectiveness of virtual reality-based vision therapy and office-based vergence/accommodative therapy in young adults with convergence insufficiency or accommodative dysfunction.

Methods

The patients were randomly assigned to either the virtual reality-based vision therapy group or the office-based vergence/accommodative therapy group. The vision therapy lasted 12 weeks (1 h/week) in both groups. Binocular visual functions (vergence and accommodation) were measured and a subjective questionnaire-based assessment was performed at baseline and after 6 and 12 weeks of therapy.

Results

In total, 33 patients with convergence insufficiency and 30 with accommodative dysfunction completed the study. After 12 weeks of treatment for convergence insufficiency, the Convergence Insufficiency Symptom Survey score (F_2,31 = 13.704, P < 0.001), near point of convergence (F_2,31 = 21.774, P < 0.001), positive fusional vergence (F_2,31 = 71.766, P < 0.001), and near horizontal phoria (F_2,31 = 16.482, P < 0.001) improved significantly in both groups. Moreover, the monocular accommodative amplitude (F_2,25 = 22.154, P < 0.001) and monocular accommodative facility (F_2,25 = 86.164, P < 0.001) improved significantly in both groups after 12 weeks of treatment. A statistically significant difference was observed in monocular accommodative facility (F_1,25 = 8.140, P = 0.009) between the two groups, but not in other vergence and accommodative functions (0.098 < P < 0.687).

Conclusion

Virtual reality-based vision therapy significantly improved binocular vision functions and symptoms in patients with convergence insufficiency and accommodative dysfunction, thereby suggesting its effectiveness as a new optional or additional treatment for young adults with these conditions.

Trial registration

This study was registered at the Chinese Clinical Trials Registry on 16/04/2019 (identifier: ChiCTR1900022556).

Supplementary Information

The online version contains supplementary material available at 10.1186/s12886-022-02393-z.

Binocular vision findings in normally-sighted school aged children who used digital devices

Purpose

To determine the binocular vision status in normally-sighted school aged children who used digital devices.

Methods

A cross-sectional study was conducted at B.P. Koirala Lions Center for Ophthalmic Studies, Kathmandu, Nepal for a duration of one year. One hundred and eighty school aged children (71 female and 109 male) aged 7 to 17 years were included in the study. All the children underwent detailed ophthalmic and binocular vision examinations. The duration of the use of digital devices by the children were asked to either the parents or guardians present at the time of the study. The study participants were divided into two groups: children who used digital devices for the last six months (users group) and those who hadn’t used digital devices for the last six months (non users group). The users group was again divided into two subgroups: children who used digital devices for less than 3 hours per day and a day per week (low digital device users subgroup) and children who used digital devices for more than 3 hours per day and all days in a week (high digital device users subgroup).

Results

Accommodative amplitudes, accommodative facility, and positive fusional vergence for both near and distance were significantly reduced in the high digital device users group than in the low digital device users subgroup (p <0.01). Stereo acuity, near point of convergence, and negative fusional vergences for both near and distance were not statistically significantly different between the two subgroups. Prevalence of accommodative and vergence anomalies (except convergence insufficiency) was more in the high digital device users subgroup than in the low digital device users subgroup (p<0.01).

Conclusions

Children who used digital devices for a significantly greater amount of time had significantly reduced amplitudes of accommodation, accommodative facility, and positive fusional vergence both at near and distance.

Agreement between three methods for measuring near point of convergence among patients with different refractive errors

PURPOSE:

To describe the agreement of three methods of Near Point of Convergence (NPC) measurement among patients with different refractive errors.

METHODS:

60 asymptomatic subjects, 18 – 25 yrs old, were included in 3 groups: emmetropes, myopes and hypermetropes. All subjects underwent NPC break point and recovery point measurement by Royal Air Force (RAF) rule, Pencil Rule (PR) and penlight with red green glasses (RG) using standard techniques. The values obtained were compared within each group by Friedman test. Bland Altman plots were constructed and Limits of Agreement calculated.

RESULTS:

Hypermetropes performed poorly in RG test with significantly receded break point and recovery point values (10.30 ± 1.45cm, 13.13± 1.20cm) compared to RAF test (7.18 ± 1.86 cm, 10.15 ± 2.11cm ) and PR test (7.78 ± 1.75 cm, 10.75 ± 1.44cm). The recovery point values of the emmetropes with RG test (10.15 ± 2.32cm) was significantly receded compared to PR (9.30 ± 1.72 cm) and RAF test (Emm: 9.08 ± 2.30cm). The myopes performed better with PR test with significantly better recovery point values with PR test (8.70 ± 1.97 cm) compared to RAF (9.68 ± 2.08) and RG (9.45 ± 1.73) tests. The limits of agreement were wide suggesting disagreement between the tests.

CONCLUSION:

The RG test yields more receded results in hypermetropes compared to the RAF and PR tests, and the PR test yields better results than the RAF test in myopes. Thus, the results obtained by these different methods show a lack of agreement. The variability is not uniform in patients with different refractive errors.

Association between post-concussion symptoms and oculomotor deficits among adolescents

PURPOSE

To examine the association between Post-Concussion Symptom Scale (PCSS) scores, Convergence Insufficiency Symptom Survey (CISS) scores, and oculomotor deficits post-concussion.

METHODS

Records of adolescent patients examined in a multidisciplinary concussion clinic between July 2014 and May 2019 were reviewed. PCSS and CISS scores, results of eye examination and oculomotor assessment, concussion history, and demographics were abstracted.

RESULTS

One hundred and forty patient records (median age, 15.3 years; 52 males, presented 109 days (median) from their most recent concussion) met inclusion criteria. Mean total scores on PCSS and CISS were 46.67 ± 25.89 and 27.13 ± 13.22, respectively, and were moderately correlated with each other (r = 0.53, p < .001). Oculomotor deficits were observed in 123 (88%) patients. Step-wise linear regression identified increased PCSS total score to be significantly associated with decreased amplitude of accommodation (p < .001). Increased CISS total score was significantly associated with receded near point of convergence, developmental eye movement test error scores, and cause of concussion.

CONCLUSION

High PCSS scores may indicate an accommodation deficit and thus prompt an oculomotor assessment in patients following a concussion. Using the CISS and a detailed oculomotor assessment may reveal underlying oculomotor deficits, which may benefit from treatment.

When virtual and real worlds coexist: Visualization and visual system affect spatial performance in augmented reality

New visualization approaches are being actively developed aiming to mitigate the effect of vergence-accommodation conflict in stereoscopic augmented reality; however, high interindividual variability in spatial performance makes it difficult to predict user gain. To address this issue, we investigated the effects of consistent and inconsistent binocular and focus cues on perceptual matching in the stereoscopic environment of augmented reality using a head-mounted display that was driven in multifocal and single focal plane modes. Participants matched the distance of a real object with images projected at three viewing distances, concordant with the display focal planes when driven in the multifocal mode. As a result, consistency of depth cues facilitated faster perceptual judgments on spatial relations. Moreover, the individuals with mild binocular and accommodative disorders benefited from the visualization of information on the focal planes corresponding to image planes more than individuals with normal vision, which was reflected in performance accuracy. Because symptoms and complaints may be absent when the functionality of the sensorimotor system is reduced, the results indicate the need for a detailed assessment of visual functions in research on spatial performance. This study highlights that the development of a visualization system that reduces visual stress and improves user performance should be a priority for the successful implementation of augmented reality displays.

Convergence Insufficiency Neuro-Mechanism Adult Population Study: Phoria Adaptation Results

Purpose

The purpose of this study was to compare changes in phoria adaptation between young adult binocularly normal controls (BNCs) and participants with symptomatic convergence insufficiency (CI), who were randomized to either office-based vergence accommodative therapy (OBVAT) or office-based placebo therapy (OBPT).

Methods

In the double-masked randomized clinical trial, 50 BNC and 50 CI participants were randomized to the following therapeutic interventions: OBVAT or OBPT with home reinforcement for 12 one-hour office sessions. A 6∆ base-out and 6∆ base-in phoria adaptation experiment at near (40 cm) was conducted using the flashed Maddox rod technique at baseline and at outcome. Measurements included the rate and the magnitude of phoria adaptation.

Results

At baseline, BNC and CI participants had significantly different rates and magnitudes of base-in and base-out phoria adaptation (P < 0.001). When comparing the outcome to baseline measurements, significant main effect differences in longitudinal measurements were observed for the magnitude and the rate of phoria adaptation for both base-out and base-in experiments (P < 0.05). For the magnitude and rate of phoria adaptation, post hoc analyses using paired t-tests revealed that the CI group administered the OBVAT intervention exhibited a significant increase in the magnitude and rate of phoria adaptation compared to baseline for both base-in and base-out phoria adaptation (P < 0.01) but not for those administered OBPT.

Conclusions

Phoria adaptation is significantly different at baseline between those with normal binocular vision and symptomatic CI participants. OBVAT significantly improves the rate and magnitude of both base-out and base-in phoria adaptation at near compared to OBPT. Results have clinical implications for new therapeutic interventions.

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.

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

OBJECTIVE

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

INTRODUCTION

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

INCLUSION CRITERIA

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

METHODOLOGY

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

Convergence Insufficiency in the Geriatric Population

SIGNIFICANCE

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

PURPOSE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Disparity vergence differences between typically occurring and concussion-related convergence insufficiency pediatric patients

This study sought to test the hypothesis that significant differences would be observed in clinical measures, symptoms, and objective assessments of vergence eye movements between children with typically developing convergence insufficiency (TYP-CI) and children with persistent post-concussion symptoms with convergence insufficiency (PPCS-CI). Data from age-matched binocularly normal controls (BNC) were used for comparison. Data from three groups of children 11 to 17 years of age are presented: BNC (N = 11), TYP-CI (N = 10), and PPCS-CI (N = 15). Clinical measures of vergence, accommodation, and symptom severity were collected. Symmetrical 4° disparity vergence eye movements were quantified with an eye tracker integrated into a head-mounted display (Oculus DK2). Peak velocity and final response amplitude of convergence and divergence eye movement responses were assessed. The mean near point of convergence (break) was more receded (worse), the amplitude of accommodation more deficient, and convergent and divergent peak velocities slower in the PPCS-CI group compared with the TYP-CI and BNC groups. These results suggest that PPCS-CI may be a different clinical entity than TYP-CI. Hence, more research is warranted to determine whether the therapeutic interventions that are effective for TYP-CI can also be used for PPCS-CI 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.

The Prevalence of Fusional Vergence Dysfunction in a Population in Iran

PURPOSE

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

METHODS

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

RESULTS

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

CONCLUSION

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

Underlying neurological mechanisms associated with symptomatic convergence insufficiency

Convergence insufficiency (CI) is the most common binocular vision problem, associated with blurred/double vision, headaches, and sore eyes that are exacerbated when doing prolonged near work, such as reading. The Convergence Insufficiency Neuro-mechanism Adult Population Study (NCT03593031) investigates the mechanistic neural differences between 50 binocularly normal controls (BNC) and 50 symptomatic CI participants by examining the fast and slow fusional disparity vergence systems. The fast fusional system is preprogrammed and is assessed with convergence peak velocity. The slow fusional system optimizes vergence effort and is assessed by measuring the phoria adaptation magnitude and rate. For the fast fusional system, significant differences are observed between the BNC and CI groups for convergence peak velocity, final position amplitude, and functional imaging activity within the secondary visual cortex, right cuneus, and oculomotor vermis. For the slow fusional system, the phoria adaptation magnitude and rate, and the medial cuneus functional activity, are significantly different between the groups. Significant correlations are observed between vergence peak velocity and right cuneus functional activity (p = 0.002) and the rate of phoria adaptation and medial cuneus functional activity (p = 0.02). These results map the brain-behavior of vergence. Future therapeutic interventions may consider implementing procedures that increase cuneus activity for this debilitating disorder.

Frequency of oculomotor disorders in adolescents 11 to 17 years of age with concussion, 4 to 12 weeks post injury

The purpose of the study was to determine the frequency of vision diagnoses after concussion in adolescents and evaluate the sensitivity and specificity of physician-administered screening for detecting convergence and accommodative disorders post-concussion. We enrolled participants 11 to 17 years old, assessed 4 to 12 weeks following a diagnosed concussion. During the initial concussion examination, a sports medicine physician measured the near point of convergence (NPC), monocular accommodative amplitude (AA), and symptoms using the Convergence Insufficiency Symptom Survey (CISS). A comprehensive oculomotor evaluation was performed by an optometrist. One hundred and thirteen adolescents were enrolled, with a mean age of 15.2 years. Seventy-nine of the 113 (70%) participants had at least one oculomotor diagnosis after concussion, with the most common problems being vergence disorders (60%) and accommodative disorders (57%). The most common vergence disorder was convergence insufficiency (35%). Among accommodative disorders, the most common problem was accommodative insufficiency (35%). In all, 47% of the participants had more than one oculomotor diagnosis following concussion. The sensitivity of physician screening using measures of NPC, AA, and CISS for detecting convergence and accommodative insufficiency was 63%, 43%, 48%, respectively. The results of this study provide additional evidence that vision problems are common in adolescents with persistent concussion symptoms in the sub-acute phase 4 to 12 weeks post-concussion, and current physician screening methods using the NPC, AA, or the CISS underperform. Thus, it is prudent that adolescents with post-concussion symptoms lasting more than 4 weeks post injury receive a comprehensive oculomotor examination.

Effect of Vergence/Accommodative Therapy on Attention in Children with Convergence Insufficiency: A Randomized Clinical Trial

SIGNIFICANCE

The results of this study suggest that clinicians providing vergence/accommodative therapy for convergence insufficiency in children should not suggest that such treatment will lead to improvements in attention when compared with placebo treatment.

PURPOSE

This study aimed to compare the effects of 16 weeks of vergence/accommodative therapy and placebo therapy on changes in attention for children in the Convergence Insufficiency Treatment Trial-Attention and Reading Trial.

METHODS

Three hundred ten children 9 to 14 years old with convergence insufficiency were assigned to receive treatment with office-based vergence/accommodative therapy or placebo therapy. Attention tests were administered at baseline and after 16 weeks of treatment. The primary measure of attention was the Strengths and Weaknesses of Attention-Deficit/Hyperactivity Disorder Symptoms and Normal Behavior (SWAN) scale. Other measures included the Swanson, Nolan, and Pelham checklist; the Homework Problems Checklist; and the d2 Test of Attention. Within and between-group differences are reported using Cohen d effect sizes.

RESULTS

For the SWAN, there was no significant difference between the groups for the inattention scale parental report (d = 0.036; 95% confidence interval, -0.21 to 0.28) or for the hyperactivity impulsivity scale parental report (d = -0.003; 95% confidence interval, -0.24 to 0.24). Similar results were found for teacher reports and the secondary measures (d estimates from -0.97 to +0.10). There were, however, large within-group changes with d ≥ 1 in both treatment groups for the SWAN, the Homework Problems Checklist, and the d2 Test of Attention.

CONCLUSIONS

These results suggest that vergence/accommodative therapy is no better than placebo therapy in improving attention. Large improvements in inattention, completing homework, and selective and sustained attention were found in each group. However, these improvements cannot be attributed to improvements in vergence and accommodation and are likely due to nonspecific effects of an intensive therapy regimen.

Effect of corneal refractive surgery on accommodative and binocular dysfunctions among civilian pilots in Southwest China

Background

To analyze whether corneal refractive surgery (CRS) is associated with the distribution of different accommodative dysfunctions (ADs) and binocular dysfunctions (BDs) in civilian pilots. A further aim was to analyze the percentages and visual symptoms associated with ADs and/or BDs in this population.

Methods

One hundred and eight civilian pilots who underwent CRS from January 2001 to July 2012 (age: 30.33 ± 4.60 years) were enrolled, the mean preoperative SE was − 1.51 ± 1.15 D (range: − 1.00- − 5.00 D). Ninety-nine emmetropic civilian pilots (age: 29.64 ± 3.77 years) who were age- and sex-matched to the CRS group were also enrolled. Refractive status, accommodative and binocular tests of each subject were performed. Visually related symptoms were quantified using the 19-item College of Optometrists in Vision Development Quality of Life (COVD-QOL) questionnaire. The 19 items were summed to obtain visual symptom scores that might indicate visual dysfunctions. The chi-square test was used to analyze differences in percentages of ADs and/or BDs between the CRS and emmetropic groups. The Mann-Whitney U test was used to compare visual symptom scores between pilots with ADs and/or BDs and pilots with normal binocular vision.

Results

No significant difference was observed between the CRS and emmetropic groups in the overall prevalence of ADs and BDs (15.7% and 15.2% in the CRS and emmetropic groups, respectively; P = 0.185). ADs were present in 4.63% and 3.03% of the CRS and emmetropic group, respectively. BDs were observed in 11.1% and 12.1% of the CRS and emmetropic group, respectively, yielding no significant differences between the groups in the prevalence of ADs or BDs (AD: P = 0.094; BD: P = 0.105). Pilots with ADs and/or BDs had significantly more visual symptoms than pilots with normal binocular vision (p < 0.001).

Conclusions

CRS for civilian pilots with low-moderate myopia might not impact binocular functions. ADs and/or BDs commonly occur in both emmetropia pilots and pilots who undergo CRS, and pilots with ADs and/or BDs are associated with increased symptoms. This study confirms the importance of a full assessment of binocular visual functions in detecting and remedying these dysfunctions in this specific population.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12886-021-01855-0.

Comparison of home-based pencil push-up therapy and office-based orthoptic therapy in symptomatic patients of convergence insufficiency: a randomized controlled trial

PURPOSE

To assess and compare the effectiveness of home-based pencil push-up therapy (PPT) and office-based orthoptic therapy (OBOT) in patients with convergence insufficiency.

METHODS

In this randomized clinical trial, 176 symptomatic patients with convergence insufficiency, aged between 9 to 30 years, were randomly assigned to receive 6 weeks of home-based PPT (Group I) or OBOT (Group II) after determining refractive error, near point of convergence (NPC), convergence insufficiency symptom survey (CISS) score, near phoria and positive fusional vergences (PFV) at near. The participants of Group I underwent home-based PPT (pencil push-ups exercises15 minutes per day, daily for 6 weeks) and those of Group II OBOT (convergence fusional exercises on synoptophore for 20 min per day, 3 days a week, for 6 weeks) without home reinforcement. Patients were re-examined at 3 and 6 weeks after initiation of treatment. NPC and CISS score were the primary and secondary outcome measures, respectively. Statistical analysis was performed with the independent samples t-test, Friedman test and the analysis of variance (ANOVA). Statistical significance was indicated by p-value < 0.05.

RESULTS

Participants of both the groups had statistically significant improvement in NPC, CISS score, PFV and near phoria (p < 0.001), but there was no statistically significant difference between the two groups (p > 0.05). However, patients of Group II had significantly better PFV after final visit than those of Group I (p < 0.001).

CONCLUSION

Home-based PPT with good suppression control and with compliance ensured by log book entries, is a simple, cheap, less time consuming and comparably effective alternative to more expensive OBOT for patients suffering from CI. CTRI registration number: REF/2016/11/012,732, Date of registration 25/04/ 2016, Retrospectively Registered.

Effectiveness of vergence/accommodative therapy for accommodative dysfunction in children with convergence insufficiency

PURPOSE

To determine the effectiveness of office-based vergence/accommodative therapy for improving accommodative amplitude and accommodative facility in children with symptomatic convergence insufficiency and accommodative dysfunction.

METHODS

We report changes in accommodative function following therapy among participants in the Convergence Insufficiency Treatment Trial - Attention and Reading Trial with decreased accommodative amplitude (115 participants in vergence/accommodative therapy; 65 in placebo therapy) or decreased accommodative facility (71 participants in vergence/accommodative therapy; 37 in placebo therapy) at baseline. The primary analysis compared mean change in amplitude and facility between the vergence/accommodative and placebo therapy groups using analyses of variance models after 4, 8, 12 and 16 weeks of treatment. The proportions of participants with normal amplitude and facility at each time point were calculated. The average rate of change in amplitude and facility from baseline to week 4, and from weeks 4 to 16, were determined in the vergence/accommodative therapy group.

RESULTS

From baseline to 16 weeks, the mean improvement in amplitude was 8.6 dioptres (D) and 5.2 D in the vergence/accommodative and placebo therapy groups, respectively (mean difference = 3.5 D, 95% confidence interval (CI): 1.5 to 5.5 D; p = 0.01). The mean improvement in facility was 13.5 cycles per minute (cpm) and 7.6 cpm in the vergence/accommodative and placebo therapy groups, respectively (mean difference = 5.8 cpm, 95% CI: 3.8 to 7.9 cpm; p < 0.0001). Significantly greater proportions of participants treated with vergence/accommodative therapy achieved a normal amplitude (69% vs. 32%, difference = 37%, 95% CI: 22 to 51%; p < 0.0001) and facility (85% vs. 49%, difference = 36%, 95% CI: 18 to 55%; p < 0.0001) than those who received placebo therapy. In the vergence/accommodative therapy group, amplitude increased at an average rate of 1.5 D per week during the first 4 weeks (p < 0.0001), then slowed to 0.2 D per week (p = 0.002) from weeks 4 to 16. Similarly, facility increased at an average rate of 1.5 cpm per week during the first 4 weeks (p < 0.0001), then slowed to 0.6 cpm per week from weeks 4 to 16 (p < 0.0001).

CONCLUSION

Office-based vergence/accommodative therapy is effective for improving accommodative function in children with symptomatic convergence insufficiency and coexisting accommodative dysfunction.

Interventions for convergence insufficiency: a network meta-analysis

BACKGROUND

Convergence insufficiency is a common binocular vision disorder in which the eyes have a strong tendency to drift outward (exophoria) with difficulty turning the eyes inward when reading or doing close work.

OBJECTIVES

To assess the comparative effectiveness and relative ranking of non-surgical interventions for convergence insufficiency through a systematic review and network meta-analysis (NMA).

SEARCH METHODS

We searched CENTRAL, MEDLINE, Embase, PubMed and three trials registers up to 20 September 2019.

SELECTION CRITERIA

We included randomized controlled trials (RCTs) examining any form of non-surgical intervention versus placebo, no treatment, sham treatment, or other non-surgical interventions. Participants were children and adults with symptomatic convergence insufficiency.

DATA COLLECTION AND ANALYSIS

We followed standard Cochrane methodology. We performed NMAs separately for children and adults.

MAIN RESULTS

We included 12 trials (six in children and six in adults) with a total of 1289 participants. Trials evaluated seven interventions: 1) office-based vergence/accommodative therapy with home reinforcement; 2) home-based pencil/target push-ups; 3) home-based computer vergence/accommodative therapy; 4) office-based vergence/accommodative therapy alone; 5) placebo vergence/accommodative therapy or other placebo intervention; 6) prism reading glasses; and 7) placebo reading glasses. Six RCTs in the pediatric population randomized 968 participants. Of these, the Convergence Insufficiency Treatment Trial (CITT) Investigator Group completed four RCTs with 737 participants. All four CITT RCTs were rated at low risk of bias. Diagnostic criteria and outcome measures were identical or similar among these trials. The four CITT RCTs contributed data to the pediatric NMA, incorporating interventions 1, 2, 3 and 5. When treatment success was defined by a composite outcome requiring both clinical measures of convergence to be normal, and also show a pre-specified magnitude of improvement, we found high-certainty evidence that office-based vergence/accommodative therapy with home reinforcement increases the chance of a successful outcome, compared with home-based computer vergence/accommodative therapy (risk ratio (RR) 1.96, 95% confidence interval (CI) 1.32 to 2.94), home-based pencil/target push-ups (RR 2.86, 95% CI 1.82 to 4.35); and placebo (RR 3.04, 95% CI 2.32 to 3.98). However, there may be no evidence of any treatment difference between home-based computer vergence/accommodative therapy and home-based pencil/target push-ups (RR 1.44, 95% CI 0.93 to 2.24; low-certainty evidence), or between either of the two home-based therapies and placebo therapy, for the outcome of treatment success. When treatment success was defined as the composite convergence and symptom success outcome, we found moderate-certainty evidence that participants who received office-based vergence/accommodative therapy with home reinforcement were 5.12 (95% CI 2.01 to 13.07) times more likely to achieve treatment success than those who received placebo therapy. We found low-certainty evidence that participants who received office-based vergence/accommodative therapy with home reinforcement might be 4.41 (95% CI 1.26 to 15.38) times more likely to achieve treatment success than those who received home-based pencil push-ups, and 4.65 (95% CI 1.23 to 17.54) times more likely than those who received home-based computer vergence/accommodative therapy. There was no evidence of any treatment difference between home-based pencil push-ups and home-based computer vergence/accommodative therapy, or between either of the two home-based therapies and placebo therapy. One RCT evaluated the effectiveness of base-in prism reading glasses in children. When base-in prism reading glasses were compared with placebo reading glasses, investigators found no evidence of a difference in the three outcome measures of near point convergence (NPC), positive fusional vergence (PFV), or symptom scores measured by the Convergence Insufficiency Symptom Survey (CISS). Six RCTs in the adult population randomized 321 participants. We rated only one RCT at low risk of bias. Because not all studies of adults included composite success data, we could not conduct NMAs for treatment success. We thus were limited to comparing the mean difference (MD) between interventions for improving NPC, PFV, and CISS scores individually using data from three RCTs (107 participants; interventions 1, 2, 4 and 5). Compared with placebo treatment, office-based vergence accommodative therapy was relatively more effective in improving PFV (MD 16.73, 95% CI 6.96 to 26.60), but there was no evidence of a difference for NPC or the CISS score. There was no evidence of difference for any other comparisons for any outcomes. One trial evaluated base-in prism glasses prescribed for near-work activities and found that the prism glasses group had fewer symptoms compared with the placebo glasses group at three months (MD -8.9, 95% CI -11.6 to -6.3). The trial found no evidence of a difference with this intervention in NPC or PFV. No adverse effects related to study treatments were reported for any of the included studies. Excellent adherence was reported for office-based vergence/accommodative therapy (96.6% or higher) in two trials. Reported adherence with home-based therapy was less consistent, with one study reporting decreasing adherence over time (weeks 7 to 12) and lower completion rates with home-based pencil/target push-ups.

AUTHORS' CONCLUSIONS

Current research suggests that office-based vergence/accommodative therapy with home reinforcement is more effective than home-based pencil/target push-ups or home-based computer vergence/accommodative therapy for children. In adults, evidence of the effectiveness of various non-surgical interventions is less clear.

Integrating binocular vision assessment in refractive surgery work-up: Proposition and protocol

Refractive surgeries are one of most commonly performed surgeries for correcting visual impairment due to refractive errors. With the increase in demand for refractive surgeries, there is an enormous strain on the operating surgeon for delivering ideal outcomes i.e 20/20 visual acuity. Regression, under-correction and ectasia are the most dreaded complications post-refractive correction, for the surgeon as well as the patient. They have significant effects on the quantity of the vision and most importantly on the quality of life of the patient. With the advent of digital era and jobs requiring the eyes being glued to the screen for hours there has been a surge in the patients presenting with complaints of asthenopia, glare, halos, and difficulty in focusing; pointing towards diagnosis of non-strabismic binocular vision anomalies (NSBVA). NSBVA in a postrefractive surgery patient may masquerade as regression or under-correction. However, timely diagnosis of NSBVA in such patients would prevent the greater harm caused by wrongful re-correction. Home- and office-based vision therapy results in improvement in visual acuity in a large majority of these patients. This preferred practice pattern intends to guide the refractive surgeons to diagnose and treat the postrefractive surgery NSBVA following a case-based and algorithmic approach. It also emphasizes the inclusion of the binocular vision assessment as a part of the pre-operative workup for patients undergoing refractive procedures.

Accommodative Insufficiency: Prevalence, Impact and Treatment Options

PURPOSE

Accommodative insufficiency (AI), defined as the inability to stimulate accommodation in pre-presbyopic individuals, has gained much attention over recent years. Despite the enormity of the available information, there is a significant lack of clarity regarding the criteria for definition, methodology adopted for testing and diagnosis, and the varied prevalence across the globe. This review aims to gather evidence that is pertinent to the prevalence, impact and efficacy of available treatment options for AI.

METHODS

PubMed, Google Scholar and Cochrane Collaboration search engines were used with the keywords prevalence, accommodative insufficiency, symptoms, plus lens, vision therapy and treatment. Peer-reviewed articles published between 1992 and 2019 were included in the review. After reviewing the studies for study methodology and robustness, 83 articles were chosen for this literature review.

RESULTS

The prevalence of AI ranges between <1.00% and 61.6% across studies. The prevalence shows considerable variation across ethnicities and age groups. There is significant variation in the study methodology, diagnostic criteria and number of tests performed to arrive at the diagnosis. Not many studies have explored the prevalence beyond 20 years of age. The prevalence of AI is high among children with special needs. There is no high-quality evidence regarding the standard treatment protocol for AI. Both vision therapy and low plus lenses have shown efficacy in independent studies, and no studies have compared these two treatment options.

CONCLUSION

The understanding of AI prevalence is currently limited owing to the lack of a standard set of diagnostic criteria and wide variations in the study methodology. There is a lack of high-quality evidence suggesting the best possible treatment for AI. The current gaps in the literature have been identified and future scope for exploration is elucidated.

Evaluation of a Novel Quality of Life Scale for Schoolchildren with Nonstrabismic Binocular Vision Anomalies

BACKGROUND

The professional Quality of Life Scale (QLS) can provide a valuable reference for the diagnosis of visual function anomalies. In the present study, we aimed to design a novel QLS to specially quantify the life quality of schoolchildren with nonstrabismic binocular vision anomalies (NSBVAs) in China.

METHODS

The novel QLS, named QOL-CVF20, was established based on classical vision-related scales and the administration of the questionnaire to 116 schoolchildren with NSBVAs and 100 healthy schoolchildren in China. The diagnostic reference value between QOL-CVF20 and VF-14 was evaluated on the questionnaires to 240 schoolchildren with NSBVAs and 238 healthy schoolchildren.

RESULTS

All the subjects could complete the QOL-CVF20 questionnaires independently. QOL-CVF20 had good structural validity, content validity, and discriminant validity, when it was applied in Chinese schoolchildren. The average score of the NSBVA group was significantly lower than that of the control group (49.0 ± 6.9 vs. 69.7 ± 6.7, respectively; P < 0.01). Moreover, the average score of cured NSBVA schoolchildren after treatment (61.8 ± 22.6) was significantly improved (P < 0.01). Receiver operating characteristic curve analysis showed that QOL-CVF20 reflected strong separation between the NSBVA and healthy groups (AUC = 0.901). Meanwhile, QOL-CVF20 could detect individuals with NSBVAs with specificity of 0.847 and sensitivity of 0.846. The critical value of 58.50 in QOL-CVF20 could be effectively applied for quality of life assessment in schoolchildren with NSBVAs.

CONCLUSIONS

QOL-CVF20 could quantify the life quality of schoolchildren with NSBVAs and might be served as a valuable reference for early diagnosis and clinical evaluation of NSBVAs.

Vision Development Differences between Slow and Fast Motor Development in Typical Developing Toddlers: A Cross-Sectional Study

Many studies have established a relationship between visual function and motor development in toddlers. This is the first report to study two-year-olds via an assessment of their visual and motor skills. The purpose of this study is to describe the possible changes that can occur between visual and motor systems in typical developing toddlers. A total of 116 toddlers were included in this observational, descriptive, and cross-sectional study. Their mean age was 29.57 ± 3.45 months. Motor development variables studied were dominant hand/foot; stationary, locomotion, object manipulation, grasping, visual motor integration percentiles; gross motor, fine motor, and total motor percentiles; and gross motor, fine motor, and total motor quotients. Visual development variables were assessed including visual acuity, refractive error, ocular alignment, motor fusion and suppression, ocular motility, and stereopsis. Our findings demonstrated that typical developing toddlers with slow gross motor development had higher exophoria and further near point of convergence values compared to toddlers with fast gross motor development (p < 0.05). No statistically significant differences were found in visual acuity and stereopsis between slow and fast gross motor development toddlers.

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.

National consensus statement regarding pediatric eye examination, refraction, and amblyopia management

Childhood blindness causes significant social and economic burden. Even though pediatric eye care has gained priority under Vision 2020, it continues to come under the purview of tertiary care centers due to lack of knowhow and facilities at primary and secondary level. Currently, India does not have standard guidelines on pediatric eye examination, refraction, and amblyopia management and therefore these are being managed inadequately or inappropriately. In view of this, an expert group of pediatric ophthalmologists from across the country met under the aegis of All India Ophthalmological Society, and deliberated to reach a consensus on the correct method of pediatric eye examination, treating refractive error in children and managing amblyopia. The purpose of the consensus statement was to enable all ophthalmologists to have a broad set of guidelines, which can form the basic framework for managing common pediatric eye conditions, in most ophthalmic setups. The consensus statement is divided into three broad categories: Pediatric eye examination, pediatric refraction, and amblyopia management. The pediatric eye exam subsection discusses the recommended clinical history, which should be taken and the essential components of an ophthalmic examination including pediatric vision assessment. Additionally, it discusses the role of special tests and investigations such as imaging and electrophysiology. The section on pediatric refraction emphasizes the correct use of cycloplegia and prescribing glasses in the Indian context. The final section on amblyopia management presents the various options of treating amblyopia and provides standard guidelines for the use of occlusion therapy and its weaning over time.

Clinical and Functional Imaging Changes Induced from Vision Therapy in Patients with Convergence Insufficiency

Office-Based Vergence/Accommodative Therapy (OBVAT) is an effective treatment for convergence insufficiency (CI) and remediates symptoms in about 75% of patients. Hence, the study of CI patients can serve as a systems-level model to understand the neural mechanisms evoked from rehabilitation. Symptomatic young adult CI patients (N=25) participated in 12 hours of OBVAT and were compared to 25 binocularly normal controls (BNC) using unpaired t-tests. CI patients have significantly lower near point of convergence and positive fusional vergence and were more symptomatic compared to BNC (p<; 0.0001). Using paired t-tests, significant differences (p<; 0.0001) were observed between CI patients' baseline and post-OBVAT measurements where the near point of convergence decreased, positive fusional vergence increased, and the results from the Convergence Insufficiency Symptom Survey (CISS) decreased. Using paired t-tests, the mean beta weights of the functional activity significantly increased for the frontal eye fields (p<; 0.01) and the oculomotor vermis (p<; 0.05) for CI patients post-OBVAT compared to baseline measurements. These data demonstrate that OBVAT increases functional activity within the brain and improves clinical function and visual symptoms in CI patients.

Test-Retest Reliability of Functional Magnetic Resonance Imaging Activation for a Vergence Eye Movement Task

Vergence eye movements are the inward and outward rotation of the eyes responsible for binocular coordination. While studies have mapped and investigated the neural substrates of vergence, it is not well understood whether vergence eye movements evoke the blood oxygen level-dependent signal reliably in separate experimental visits. The test-retest reliability of stimulus-induced vergence eye movement tasks during a functional magnetic resonance imaging (fMRI) experiment is important for future randomized clinical trials (RCTs). In this study, we established region of interest (ROI) masks for the vergence neural circuit. Twenty-seven binocularly normal young adults participated in two functional imaging sessions measured on different days on the same 3T Siemens scanner. The fMRI experiments used a block design of sustained visual fixation and rest blocks interleaved between task blocks that stimulated eight or four vergence eye movements. The test-retest reliability of task-activation was assessed using the intraclass correlation coefficient (ICC), and that of spatial extent was assessed using the Dice coefficient. Functional activation during the vergence eye movement task of eight movements compared to rest was repeatable within the primary visual cortex (ICC = 0.8), parietal eye fields (ICC = 0.6), supplementary eye field (ICC = 0.5), frontal eye fields (ICC = 0.5), and oculomotor vermis (ICC = 0.6). The results demonstrate significant test-retest reliability in the ROIs of the vergence neural substrates for functional activation magnitude and spatial extent using the stimulus protocol of a task block stimulating eight vergence eye movements compared to sustained fixation. These ROIs can be used in future longitudinal RCTs to study patient populations with vergence dysfunctions.

Quality of Life in Children With Sturge-Weber Syndrome

AIM

We assessed the utilization of the National Institutes of Health Quality of Life in Neurological Disorders (Neuro-QoL) in pediatric patients with Sturge-Weber syndrome, a rare neurovascular disorder which frequently results in seizures, brain atrophy, calcification, and a range of neurological impairments.

METHODS

Subjects were seen clinically and consented for research. All 22 patients filled out the Pediatric Neuro-QoL. The Neuro-QoL subscores were converted to T-scores to compare with the referenced control population. Twenty-one participants also filled out the Brain Vascular Malformation Consortium Database Questionnaire containing data pertaining to Sturge-Weber syndrome-related medical history, medications, comorbidities, and family history. All data were analyzed with a significance threshold of P < 0.05.

RESULTS

Cognitive function quality of life was significantly lower (P < 0.001) in pediatric patients with Sturge-Weber syndrome compared with referenced control subjects. Male gender (P = 0.02) was associated with lower cognitive function Neuro-QoL. The extent of skin (R = -0.46, P = 0.04), total eyelid port-wine birthmark (R = -0.56, P = 0.007), eye (R = -0.58, P = 0.005), and total Sturge-Weber syndrome involvement (R = -0.63, P = 0.002) were negatively correlated with cognitive function Neuro-QoL. A younger age at seizure onset was associated with lower cognitive function Neuro-QoL (hazard ratio = 0.90, P = 0.004) even after controlling for extent of brain, skin, or eye involvement. Antidepressant use was associated with lower cognitive function Neuro-QoL (P = 0.005), and cognitive function Neuro-QoL was negatively correlated with depression Neuro-QoL; however, after adjusting for depression this relationship was no longer significant.

CONCLUSIONS

The results suggest targeting cognitive function Neuro-QoL in treatment trials and reiterate the prognostic value of early seizure onset. In addition, sex-related differences were noted, which should be further studied.

Effect of Vergence/Accommodative Therapy on Reading in Children with Convergence Insufficiency: A Randomized Clinical Trial

SIGNIFICANCE

The results of this study suggest that clinicians providing vergence/accommodative therapy for the treatment of childhood convergence insufficiency should not suggest that such treatment, on average, will lead to improvements on standardized assessments of reading performance after 16 weeks of treatment.

PURPOSE

The purpose of this study was to determine the effect of office-based vergence/accommodative therapy on reading performance in 9- to 14-year-old children with symptomatic convergence insufficiency.

METHODS

In a multicenter clinical trial, 310 children 9 to 14 years old with symptomatic convergence insufficiency were randomized in a 2:1 ratio to 16 weeks of office-based vergence/accommodative therapy or office-based placebo therapy, respectively. The primary outcome was change in reading comprehension as measured by the reading comprehension subtest of the Wechsler Individual Achievement Test, Third Edition (WIAT-III) at the 16-week outcome. Secondary reading outcomes of word identification, reading fluency, listening comprehension, comprehension of extended text, and reading comprehension were also evaluated.

RESULTS

The adjusted mean improvement in WIAT-III reading comprehension was 3.7 (95% confidence interval [CI], 2.6 to 4.7) standard score points in the vergence/accommodative therapy group and 3.8 (95% CI, 2.4 to 5.2) points in the placebo therapy group, with an adjusted mean group difference of -0.12 (95% CI, -1.89 to 1.66) points that was not statistically significant. No statistically significant treatment group differences were found for any of the secondary reading outcome measures.

CONCLUSIONS

For children aged 9 to 14 years with symptomatic convergence insufficiency, office-based vergence/accommodative therapy was no more effective than office-based placebo therapy for improving reading performance on standardized reading tests after 16 weeks of treatment.

Vergence and Accommodative Dysfunctions in Emmetropic and Myopic Chinese Young Adults

Purpose

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

Methods

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

Results

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

Conclusion

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

Near Points of Convergence and Accommodation in a Population of University Students in Iran

PURPOSE

To determine the distribution of the near point of convergence (NPC) and near point of accommodation (NPA) in a young student population in Iran.

METHODS

The subjects were selected using a cluster sampling method. All students underwent optometry tests, including visual acuity measurement, refraction, and cover test, as well as ophthalmic examinations. The NPC and NPA were measured using an accommodative target (near Snellen chart).

RESULTS

Of 1,595 students, the data of 1,357 were analyzed. The mean NPC and NPA in the total sample were 7.25 cm (95% confidence interval [CI], 7.02 to 7.48) and 9.99 cm (95% CI, 9.69 to 10.29), respectively. Older age was associated with an increase in the NPC, which increased from 6.98 cm in 18-20 years olds to 9.51 cm in those over 30 years. The NPA was significantly associated with age and refractive errors in the multiple linear regression model, increasing from 9.92 cm in 18-20 years olds to 11.44 cm in those over 30 years ( P = 0.003). Hyperopic eyes had lower NPA than myopic and emmetropic eyes ( P = 0.001). In younger age groups, the mean accommodation amplitude was lower than the mean Hofstetter value. Moreover, with age, especially after 30 years, the mean values surpassed those determined using the Hofstetter formula.

CONCLUSION

The NPC values in this study were lower than those previously reported for identical age groups. The Hofstetter formula is not always an accurate predictor of the accommodation amplitude in the Iranian adult population.