Pilot Study of Normative Range of Field of Binocular Single Vision in Adults in Singapore
Tan Tock Seng Hospital
30 participants
Oct 15, 2025
OBSERVATIONAL
Conditions
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. 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.
Eligibility
Inclusion Criteria9
- 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
- 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
Exclusion Criteria22
- \- Communication barrier: Unable to understand verbal spoken instructions
- Medical history:
- Any facial trauma
- Any ocular trauma
- Any head trauma
- Any history of ocular disease
- 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
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Interventions
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
Locations(1)
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NCT07257341