Binocular Visual FunctionNORVIBASNCT07257341
Pilot Study of Normative Range of Field of Binocular Single Vision in Adults in Singapore
An observational study of Binocular Visual Function, run by Tan Tock Seng Hospital at 1 site in Singapore.
Trial summary
The assessment and monitoring of the field of binocular single vision remains a crucial aspect of ophthalmological care, yet current clinical practice relies on normative standards established by Feibel \& Roper-Hall in 1974 that present significant limitations for contemporary application. Read more about this study
- Who is it for?
- Ages 21 to 59 yearsHealthy volunteers can take part
- Conditions the study is for
- Binocular Visual Function
- What is being tested?
- Field of Binocular Single Vision
- How many people
- 30 participants
- Where
- 1 siteSingapore
- Study dates
- 15 Oct 2025to 14 Oct 2026
- Phase
- Observational
- Are there results?
- Not yet: the study is under way
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 21 to 59 years
- All sexes
- Healthy volunteers accepted
- Adult
Study population: Healthy Individuals
Who may be able to join
- Age: 21 to 59 years old
- Gender: Males or females
- Ethnicity: Asian descent.
- Language comprehension: Able to understand verbal spoken instructions in:
- British/American English
- Mandarin Chinese
Show all 9Show fewer
- Bahasa Melayu
- Protocol compliance: Ability to comply with the study protocol, as determined by the investigator's judgment
- Consent capacity: Must be able to understand and provide informed consent, with signed informed consent form required before any study assessments
Who cannot join
- Communication barrier: Unable to understand verbal spoken instructions
- Medical history:
- Any facial trauma
- Any ocular trauma
- Any head trauma
- Any history of ocular disease
Show all 22Show fewer
- Any history of ocular surgery
- Systemic condition(s)
- Near visual acuity:
- o Right eye \& Left eye monocularly, binocularly unaided near vision: worse than N6 at 40cm from participant's nose
- Ocular alignment:
- o Prism cover test at near (30cm) of equal or greater than 10 prism diopters at these positions of gaze:
- Primary gaze
- Right gaze
- Left gaze
- Up gaze
- Down gaze
- Extraocular movement:
- o Extraocular movement of over-action or under-action of equal or greater than 0.5 in any of the nine cardinal positions of gaze
- Confrontational Visual field:
- o Abnormal monocular visual field on confrontational visual field test
- Hess chart test o Abnormal or asymmetry in pattern of extraocular muscle action in Hess chart test
Trial locations and contacts
1 site in 1 country. Contact the study team or a site near you to ask about taking part.
Singapore1 site, 1 recruiting
- Recruiting
Tan Tock Seng Hospital
Singapore, Singapore, 308433
Zheng Kuang Noel Soh, BSc, +65 6357 3693, zheng.kuang.soh@nhghealth.com.sg
Daniel Chin, MBBS
About this study
The assessment and monitoring of the field of binocular single vision remains a crucial aspect of ophthalmological care, yet current clinical practice relies on normative standards established by Feibel \& Roper-Hall in 1974 that present significant limitations for contemporary application. The original study, conducted with a demographically homogeneous Caucasian population in St Louis using only "several" normal individuals, raises concerns regarding its applicability to Asian populations, particularly in Singapore, where ethnic and genetic factors may influence ocular characteristics. The limited sample size significantly increases the likelihood of Type II errors, whilst the temporal gap of over five decades introduces additional concerns regarding population changes, environmental factors, and advances in measurement techniques that have not been incorporated into current normative data. Given these substantial limitations in demographic representation, statistical power, and temporal relevance, there exists a pressing need to establish population-specific normative data for the field of binocular single vision in Singapore's adult population, which would provide more clinically relevant reference values and potentially improve diagnostic accuracy for ocular conditions in the local context.
Read the detailed description
The assessment and monitoring of the field of binocular single vision is a crucial aspect of ophthalmological care, particularly in the management of oculoplastics and strabismus. Currently, clinicians worldwide, including those in Singapore, rely on the normal boundary of the field of binocular single vision established by Doctor Robert M. Feibel \& Gill Roper-Hall in 1974 as the gold-standard parameter for clinical assessment. However, this long-standing standard raises several significant concerns regarding its applicability to our current population.
The original study by Feibel \& Roper-Hall was conducted in St Louis, Missouri, United States of America, with participants who were likely of Caucasian descent. This demographic composition presents a potential limitation when applying these standards to Asian populations, particularly in Singapore, where ethnic and genetic factors may influence ocular characteristics. Furthermore, the study's methodology involved only "several" normal individuals, suggesting a sample size of more than two but fewer than ten participants. A sample size of this limited scope significantly increases the likelihood of Type II errors, potentially compromising the statistical power and reliability of the established normative values.
The temporal gap of over five decades since the original study adds another layer of concern. Population characteristics, environmental factors, and lifestyle patterns have undergone substantial changes during this period, potentially affecting ocular health parameters. Additionally, advances in measurement techniques and an understanding of ocular physiology suggest the need for updated normative data that reflect current population characteristics and incorporate modern assessment methodologies.
Given these limitations, there is a pressing need to establish population-specific normative data for the field of binocular single vision in Singapore's adult population. This would not only provide more relevant reference values for clinical assessment but also potentially improve the accuracy of diagnosis and monitoring of various ocular conditions in our local context.
- Conditions
- Binocular Visual Function
- Being tested
- Field of Binocular Single Vision
- Keywords
- Binocular field of vision
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Field of Binocular Single VisionDiagnostic test
The intervention involves a single field of binocular single vision assessment using the Takagi MT-325UD Projection Perimeter. Participants undergo binocular testing where they fixate and follow a single round light stimulus as it moves throughout the perimeter bowl. When participants perceive two distinct light stimuli (indicating loss of binocular single vision), they press a buzzer. The orthoptist records these responses and plots the boundaries on a standardised recording sheet to map the participant's field of binocular single vision.
This intervention addresses significant limitations of the current gold standard established by Feibel \& Roper-Hall (1974). The original study was conducted with "several" normal individuals (likely fewer than 10 participants) of Caucasian descent in St Louis, Missouri, creating potential issues with statistical power and population applicability. Our study uses a larger, more robust sample size of 32 participants specifically from Singapore's Asian
What is being measured
The primary outcome is the main question the study is designed to answer.
Field of Binocular Single Vision in Asian population
Establish comprehensive normative range of field of binocular single vision (BSV) specifically for healthy adults in Singapore's population aged 21-59, creating locally relevant reference standards that reflect ethnic, genetic, and contemporary population.
BSV is the ability to use both eyes simultaneously and coordinate the slightly different images from each eye into a single, unified, three-dimensional mental percept. The "field of binocular single vision" is the specific area within the overall visual field where this fusion and single vision can be maintained.
To measure the field of BSV using Goldmann perimetry, a moving light stimulus is presented while the patient uses both eyes. The test maps the area where the patient can maintain fusion (single vision). The boundary where fusion breaks (and diplopia starts) is plotted across different directions to define the BSV field.
Measured: up to 20 minutes during 1 study visit.
Secondary outcomes (1)
Comparison of current field of binocular single vision gold standard between Caucasian population vs Asian population
Conduct rigorous statistical comparison between newly established Singapore normative values and existing Feibel \& Roper-Hall (1974) standards to quantify differences and determine clinical significance.
Current benchmarks are based on a 1974 U.S. study by Feibel \& Roper-Hall that involved fewer than ten Caucasian subjects and no Asian representation. Consequently, clinicians may over- or under-diagnose ocular deviation and fusion deficits in Asian patients. The study validates a modern methodology using the Takagi MT-325UD Projection Perimeter to map BSV fields under standardized conditions.
Measured: Up to 20 minutes during 1 study visit.
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted2 Dec 2025
- Study start15 Oct 2025
- Primary completion30 Jun 2026 (estimated)
- Study completion14 Oct 2026 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Publications (2)Papers the sponsor has linked to this study.
- Other trials for Binocular Visual FunctionStudies of the same condition, open and under way.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Observational
- Observational model
- Cohort
- Time perspective
- Cross-sectional
- Enrolment
- 30 participants (estimated)
Sponsor and investigators
- Lead sponsor
- Tan Tock Seng Hospital
- Sponsor type
- University, hospital or other
- Responsible party
- Principal investigator, Daniel Chin Yuxiang, Tan Tock Seng Hospital
- Investigators
- Daniel Chin, MBBS, Principal investigator, Tan Tock Seng HospitalSebastian Yue, MSc, Study director, Tan Tock Seng Hospital
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07257341
- Sponsor's protocol ID
- 2025-1293
- Acronym
- NORVIBAS
- Status last verified
- Jan 2026
- First submitted
- 20 Nov 2025
- Last updated
- 9 Jan 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- No: Participant data cannot be shared due to local governing laws and institutional regulations.
Publications
Feibel RM, Roper-Hall G. Evaluation of the field of binocular single vision in incomitant strabismus. Am J Ophthalmol. 1974 Nov;78(5):800-5. doi: 10.1016/0002-9394(74)90303-1. No abstract available.
PubMed 4425006Kakizaki H, Umezawa N, Takahashi Y, Selva D. Binocular single vision field. Ophthalmology. 2009 Feb;116(2):364. doi: 10.1016/j.ophtha.2008.08.046. No abstract available.
PubMed 19187829
Study at a glance
From the registry record, last updated by the sponsor on 9 Jan 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Pilot Study of Normative Range of Field of Binocular Single Vision in Adults in Singapore
- ClinicalTrials.gov ID
- NCT07257341
- Acronym / sponsor ID
- NORVIBAS / 2025-1293
- Conditions
- Binocular Visual Function
- Keywords
- Binocular field of vision
- Study type
- Observational
- Recruitment status
- Recruiting
- Enrolment
- 30 participants (estimated)
- Lead sponsor
- Tan Tock Seng HospitalUniversity, hospital or other
- Study start
- 15 Oct 2025 (actual)
- Primary completion
- 30 Jun 2026 (estimated)
- Study completion
- 14 Oct 2026 (estimated)
- First posted
- 2 Dec 2025 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
The assessment and monitoring of the field of binocular single vision remains a crucial aspect of ophthalmological care, yet current clinical practice relies on normative standards established by Feibel \& Roper-Hall in 1974 that present significant limitations for contemporary application. The original study, conducted with a demographically homogeneous Caucasian population in St Louis using only "several" normal individuals, raises concerns regarding its applicability to Asian populations, particularly in Singapore, where ethnic and genetic factors may influence ocular characteristics. The limited sample size significantly increases the likelihood of Type II errors, whilst the temporal gap of over five decades introduces additional concerns regarding population changes, environmental factors, and advances in measurement techniques that have not been incorporated into current normative data. Given these substantial limitations in demographic representation, statistical power, and temporal relevance, there exists a pressing need to establish population-specific normative data for the field of binocular single vision in Singapore's adult population, which would provide more clinically relevant reference values and potentially improve diagnostic accuracy for ocular conditions in the local context.
Detailed description
The assessment and monitoring of the field of binocular single vision is a crucial aspect of ophthalmological care, particularly in the management of oculoplastics and strabismus. Currently, clinicians worldwide, including those in Singapore, rely on the normal boundary of the field of binocular single vision established by Doctor Robert M. Feibel \& Gill Roper-Hall in 1974 as the gold-standard parameter for clinical assessment. However, this long-standing standard raises several significant concerns regarding its applicability to our current population.
The original study by Feibel \& Roper-Hall was conducted in St Louis, Missouri, United States of America, with participants who were likely of Caucasian descent. This demographic composition presents a potential limitation when applying these standards to Asian populations, particularly in Singapore, where ethnic and genetic factors may influence ocular characteristics. Furthermore, the study's methodology involved only "several" normal individuals, suggesting a sample size of more than two but fewer than ten participants. A sample size of this limited scope significantly increases the likelihood of Type II errors, potentially compromising the statistical power and reliability of the established normative values.
The temporal gap of over five decades since the original study adds another layer of concern. Population characteristics, environmental factors, and lifestyle patterns have undergone substantial changes during this period, potentially affecting ocular health parameters. Additionally, advances in measurement techniques and an understanding of ocular physiology suggest the need for updated normative data that reflect current population characteristics and incorporate modern assessment methodologies.
Given these limitations, there is a pressing need to establish population-specific normative data for the field of binocular single vision in Singapore's adult population. This would not only provide more relevant reference values for clinical assessment but also potentially improve the accuracy of diagnosis and monitoring of various ocular conditions in our local context.
Study design
- Observational model
- Cohort
- Time perspective
- Cross-sectional
Who may qualify
- Ages
- 21 to 59 years
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Adult
- Study population
- Healthy Individuals
Key inclusion criteria (9 listed)
- Age: 21 to 59 years old
- Gender: Males or females
- Ethnicity: Asian descent.
- Language comprehension: Able to understand verbal spoken instructions in:
- Protocol compliance: Ability to comply with the study protocol, as determined by the investigator's judgment
Key exclusion criteria (22 listed)
- Communication barrier: Unable to understand verbal spoken instructions
- Medical history:
- Near visual acuity:
- o Right eye \& Left eye monocularly, binocularly unaided near vision: worse than N6 at 40cm from participant's nose
- Ocular alignment:
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| Field of Binocular Single VisionThe intervention involves a single field of binocular single vision assessment using the Takagi MT-325UD Projection Perimeter. Participants undergo binocular testing where they fixate and follow a single round light stimulus as it moves throughout the perimeter bowl. When participants perceive two distinct light stimuli (indicating loss of binocular single vision), they press a buzzer. The orthoptist records these responses and plots the boundaries on a standardised recording sheet to map the participant's field of binocular single vision. This intervention addresses significant limitations of the current gold standard established by Feibel \& Roper-Hall (1974). The original study was conducted with "several" normal individuals (likely fewer than 10 participants) of Caucasian descent in St Louis, Missouri, creating potential issues with statistical power and population applicability. Our study uses a larger, more robust sample size of 32 participants specifically from Singapore's Asian | Diagnostic test | – |
Primary outcome
Field of Binocular Single Vision in Asian population
Time frame: up to 20 minutes during 1 study visit.
Establish comprehensive normative range of field of binocular single vision (BSV) specifically for healthy adults in Singapore's population aged 21-59, creating locally relevant reference standards that reflect ethnic, genetic, and contemporary population. BSV is the ability to use both eyes simultaneously and coordinate the slightly different images from each eye into a single, unified, three-dimensional mental percept. The "field of binocular single vision" is the specific area within the overall visual field where this fusion and single vision can be maintained. To measure the field of BSV using Goldmann perimetry, a moving light stimulus is presented while the patient uses both eyes. The test maps the area where the patient can maintain fusion (single vision). The boundary where fusion breaks (and diplopia starts) is plotted across different directions to define the BSV field.
1 secondary outcome
Comparison of current field of binocular single vision gold standard between Caucasian population vs Asian population
Time frame: Up to 20 minutes during 1 study visit.
Results and safety
This study is still under way. Results are not available in the source record yet.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 9 Jan 2026.
- Results publication: PubMed 4425006Feibel RM, Roper-Hall G. Evaluation of the field of binocular single vision in incomitant strabismus. Am J Ophthalmol. 1974 Nov;78(5):800-5. doi: 10.1016/0002-9394(74)90303-1. No abstract available.
- Results publication: PubMed 19187829Kakizaki H, Umezawa N, Takahashi Y, Selva D. Binocular single vision field. Ophthalmology. 2009 Feb;116(2):364. doi: 10.1016/j.ophtha.2008.08.046. No abstract available.
- Individual participant dataSharing planned: No. Participant data cannot be shared due to local governing laws and institutional regulations.
Related trials for Binocular Visual Function
Not yet recruiting
Assessment of Binocular Vision Function With Neos™ (ROCKET)
Binocular Vision Dysfunction
Recruiting
Effectiveness of Osteopathy as an Adjunct to Optometric Vision Therapy in Vergence Disorders
Vergence Disorders, Binocular Vision Dysfunction
Not yet recruiting
Study in Young Adults to Understand How Glasses With a Small Reading Addition Affect Focusing and Eye Coordination During Vision Tasks
Healthy Young Adults, Accommodation Disorder
Recruiting
Combining Noninvasive Brain Stimulation and Augmented Reality-based Dichoptic Therapy for Treating Amblyopic Adults
Amblyopia, Anisometropic Amblyopia
Recruiting
Augmented Reality-Based Binocular Therapy for Visual Rehabilitation in Adults With Amblyopia
Amblyopia, Anisometropic Amblyopia
Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part.
Daniel Chin, MBBS principal investigator
Tan Tock Seng Hospital
Sebastian Yue, MSc study director
Tan Tock Seng Hospital
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
An observational study of Binocular Visual Function, run by Tan Tock Seng Hospital at 1 site in Singapore.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 9 inclusion and 22 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: looking for participants now, as of the sponsor's last update on 9 Jan 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in Singapore. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
This study is still under way. Results are not available in the source record yet.
How can a doctor refer a patient or contact the research team?
Contact Zheng Kuang Noel Soh, BSc (+65 6357 3693, zheng.kuang.soh@nhghealth.com.sg), or a site near the patient. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Field of Binocular Single Vision in Asian population (time frame: up to 20 minutes during 1 study visit.). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
On the ClinicalTrials.gov record for NCT07257341, which also lists 2 linked publications.
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 9 Jan 2026.