A Comparative Study of Fusional Vergence According to Ocular Dominance in Healthy Subjects

NCT07697131 | Not Yet Recruiting

• 2 other identifiers: APHP2519872025-A02953-46
• Study Type: observational
• Target: 60
• Locations: 1 country
• Sites: 1

Brief Summary

In orthoptics, fusional vergence (FV) measurement is one of the key tests used to assess fusion ability. These amplitudes are generally reduced in individuals with convergence insufficiency. Fusional vergence are quantified by placing a prism bar randomly in front of one eye-first for distance vision and then for near vision. Rehabilitation exercises using the prism bar are also performed in the same manner. Depending on orthoptic practice, the prism bar is placed in front of the left eye or the right eye, in a dogmatic manner, or in front of the right eye, in a conventional manner, without any study providing any justification. However, some practitioners report interocular differences when measuring fusion amplitudes depending on which eye is prismed, while others do not. The hypothesis put forward is that, in individuals with an interocular difference in fusional vergence, ocular dominance (sensory and motor) could be the cause of this measurement discrepancy. The objective is therefore to compare the difference in fusional vergence depending on whether the dominant or non-dominant eye is tested, using a randomized order of eyes and tests. If this hypothesis is confirmed (greater fusional vergence when tested on the dominant eye), this would: (1) enhance our understanding of fusion mechanisms, (2) provide more targeted insights for the assessment, quantification, and rehabilitation of fusional vergence to improve the effectiveness of orthoptic intervention.

Conditions

No Eye Disorder

Keywords

Fusional vergence; Ocular dominance; Orthoptic practice

Outcome Measures

Primary Outcomes (3)

• Amplitude of fusional vergence

  Values of horizontal fusional vergence measured using a horizontal Berens prism bar in divergence and convergence, for distance and near vision, in the right eye and the left eye and reported in prism diopters.

  Day 0

• Laterality ocular dominance

  Assessment of ocular dominance for: * The dominant eye using the monocular blur test and the red-glass test * The leading eye using the Punctum Proximum of Convergence (PPC) test with the Mawas plate and bilateral prism test for oculomotor dominance * The preferred eye using the spontaneous ocular method * The target eye using the Hole-in-Card method: hole-in-card test All tests classify the ocular dominance into 3 categories : Left, Right, None.

  Day 0

• Lateralization quotient value (LQ)

  Determination of the lateralization quotient value by the mean of previous responses of the ocular dominance tests.

  Day 0

Secondary Outcomes (4)

• Assessment of the degree of agreement among the various tests for ocular dominance

  Day 0

• Agreeement between the bilateral prismatic test (new test for oculomotor dominance laterality determination and standard ocular dominance tests

  Day 0

• Assessment of the difference in fusional vergence measurements between the right and left eyes and the laterality quotient

  Day 0

• Correlation between inter-pupillary distance measurements and differences in fusion amplitude measurements between the right and left eyes

  Day 0

Study Arms (1)

Healthy individual

Individuals with no visual or oculomotor disorders.

Other: Fusional Vergence assessment; Other: Ocular dominance evaluation; Other: Complete Orthoptic

Interventions

Fusional Vergence assessment OTHER

Measurement of sensorimotor fusional vergence in the right and left eyes, in divergence and convergence, first for distance vision and then for near vision. A random draw will determine which eye is tested first for distance vision, followed by a second draw for near vision, in order to minimize training bias. Prior to this, a stereoscopic acuity test will be performed to confirm the presence of binocular vision.

Also known as: Measurements of sensorimotor fusion

Healthy individual

Ocular dominance evaluation OTHER

Assessment of ocular dominance for: * The dominant eye using the monocular blurriness test and the red-glass test * The leading eye using the Mawas plate Punctum Proximum convergence test and the bilateral prismatic test for oculomotor dominance * The preferred eye using the spontaneous ocular method * The target eye using the Hole-in-Card method: hole-in-card test

Also known as: Assessment of ocular dominance

Healthy individual

Complete Orthoptic OTHER

Conducting an orthoptic evaluation to verify that patients meet the study's inclusion criteria: * assessment of visual acuity and refraction * assessment of stereoscopic vision * cover-test to screen potential abnormal phorias * measurement of interpupillary distance

Also known as: Orthoptic evaluation

Healthy individual

Eligibility Criteria

• Age: 18 Years - 35 Years
• Sex: all
• Healthy Volunteers: Yes
• Age Groups: Adult (18-64)
• Sampling Method: Non-Probability Sample

Study Population

Any individual between the ages of 18 and 35, inclusive, with no organic ophthalmological disorders or oculomotor disorders.

You may qualify if:

• Adults between the ages of 18 and 35 with no known eye conditions, with or without ametropia. If ametropia is present: it must be corrected
• Subjects with no history of eye surgery, including refractive surgery
• Subjects who have been informed about the study and have freely and knowingly consented to participate in the study and to the collection of data

You may not qualify if:

• Subjects with strabismus
• Subjects with visual acuity of less than 20/20; or anisometropia

Sponsors & Collaborators

• Assistance Publique - Hôpitaux de Paris: lead
• URC-CIC Paris Descartes Necker Cochin: collaborator

Study Sites (1)

Hôpital Necker-Enfants Malades

Paris, 75015, France

Location

Related Publications (10)

• Rovira-Gay C, Mestre C, Argiles M, Vinuela-Navarro V, Pujol J. Feasibility of measuring fusional vergence amplitudes objectively. PLoS One. 2023 May 4;18(5):e0284552. doi: 10.1371/journal.pone.0284552. eCollection 2023.

  PMID: 37141181 BACKGROUND

• Rowe FJ. Fusional vergence measures and their significance in clinical assessment. Strabismus. 2010 Jun;18(2):48-57. doi: 10.3109/09273971003758412.

  PMID: 20521879 BACKGROUND

• Bossi M, Hamm LM, Dahlmann-Noor A, Dakin SC. A comparison of tests for quantifying sensory eye dominance. Vision Res. 2018 Dec;153:60-69. doi: 10.1016/j.visres.2018.09.006. Epub 2018 Oct 22.

  PMID: 30292725 BACKGROUND

• Lanca CC, Rowe FJ. Measurement of fusional vergence: a systematic review. Strabismus. 2019 Jun;27(2):88-113. doi: 10.1080/09273972.2019.1583675. Epub 2019 Mar 1.

  PMID: 30821611 BACKGROUND

• Fray KJ. Fusional amplitudes: exploring where fusion falters. Am Orthopt J. 2013;63:41-54. doi: 10.3368/aoj.63.1.41.

  PMID: 24141750 BACKGROUND

• Fray KJ. Fusional Amplitudes: Developing Testing Standards. Strabismus. 2017 Sep;25(3):145-155. doi: 10.1080/09273972.2017.1349814. Epub 2017 Jul 31.

  PMID: 28759298 BACKGROUND

• Lopes-Ferreira D, Neves H, Queiros A, Faria-Ribeiro M, Peixoto-de-Matos SC, Gonzalez-Meijome JM. Ocular dominance and visual function testing. Biomed Res Int. 2013;2013:238943. doi: 10.1155/2013/238943. Epub 2013 Nov 11.

  PMID: 24319677 BACKGROUND

• Ho R, Thompson B, Babu RJ, Dalton K. Sighting ocular dominance magnitude varies with test distance. Clin Exp Optom. 2018 Mar;101(2):276-280. doi: 10.1111/cxo.12627. Epub 2017 Oct 31.

  PMID: 29090482 BACKGROUND

• Kommerell G, Schmitt C, Kromeier M, Bach M. Ocular prevalence versus ocular dominance. Vision Res. 2003 Jun;43(12):1397-403. doi: 10.1016/s0042-6989(03)00121-4.

  PMID: 12742109 BACKGROUND

• Garcia-Perez MA, Peli E. Psychophysical Tests Do Not Identify Ocular Dominance Consistently. Iperception. 2019 Apr 29;10(2):2041669519841397. doi: 10.1177/2041669519841397. eCollection 2019 Mar-Apr.

  PMID: 31069044 BACKGROUND

Study Officials

• Maxence Rateaux, PhD

  Assistance Publique - Hôpitaux de Paris

  PRINCIPAL INVESTIGATOR

• Dominique MD, PhD BREMOND-GIGNAC

  Assistance Publique - Hôpitaux de Paris

  STUDY DIRECTOR

Central Study Contacts

Maxence Rateaux, PhD

CONTACT

01 44 49 53 62; maxence.rateaux@aphp.fr

Hélène Morel

CONTACT

01 44 38 16 53; helene.morel@aphp.fr

Study Design

• Study Type: observational
• Observational Model: OTHER
• Time Perspective: PROSPECTIVE
• Sponsor Type: OTHER
• Responsible Party: SPONSOR

Study Record Dates

• First Submitted: June 22, 2026
• First Posted: July 13, 2026
• Study Start (Estimated): September 1, 2026
• Primary Completion (Estimated): July 1, 2027
• Study Completion (Estimated): July 1, 2027
• Last Updated: July 13, 2026

Record last verified: 2026-06

Data Sharing

• IPD Sharing: Will not share

Locations

FR (1)