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

Обзор

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.

Подробное описание

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.

The study consists of one-hour eye examinations of healthy individuals with no visual or oculomotor disorders.

Вмешательства

• Другое Fusional Vergence assessment
  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.
• Другое Ocular dominance evaluation
  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
• Другое Complete Orthoptic
  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

Первичные конечные точки

• Amplitude of fusional vergence [Срок оценки: Day 0]
• Laterality ocular dominance [Срок оценки: Day 0]
• Lateralization quotient value (LQ) [Срок оценки: Day 0]

Вторичные конечные точки (4)

• Assessment of the degree of agreement among the various tests for ocular dominance [Срок оценки: Day 0]
• Agreeement between the bilateral prismatic test (new test for oculomotor dominance laterality determination and standard ocular dominance tests [Срок оценки: Day 0]
• Assessment of the difference in fusional vergence measurements between the right and left eyes and the laterality quotient [Срок оценки: Day 0]
• Correlation between inter-pupillary distance measurements and differences in fusion amplitude measurements between the right and left eyes [Срок оценки: Day 0]

Критерии участия

Критерии включения

• 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

Критерии исключения

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

Критерии приведены из реестра в оригинале (на английском). Окончательную оценку соответствия проводит исследовательский центр.

Здоровые добровольцы: Да

Дизайн исследования

Модель наблюдения

Другое

Центры проведения

Франция · 1 центр

• Hôpital Necker-Enfants Malades — Paris

Публикации

• 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
• Rowe FJ. Fusional vergence measures and their significance in clinical assessment. Strabismus. 2010 Jun;18(2):48-57. doi: 10.3109/09273971003758412. PMID 20521879
• 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
• 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
• Fray KJ. Fusional amplitudes: exploring where fusion falters. Am Orthopt J. 2013;63:41-54. doi: 10.3368/aoj.63.1.41. PMID 24141750
• 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
• 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
• 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

Идентификаторы

NCT: NCT07697131 · APHP251987 · 2025-A02953-46

Первоисточники (государственные реестры)

• ClinicalTrials.gov (NIH, США)

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