Vergence disorders are common binocular vision conditions that can cause symptoms such as eyestrain, blurred vision, headaches, and difficulty maintaining clear vision during near tasks. These symptoms are particularly frequent in situations involving sustained near visual demand, such as prolonged use of digital devices, which is increasingly common in daily life.

Optometric vision therapy is considered the reference treatment for vergence disorders. However, not all individuals respond in the same way, and some continue to experience symptoms despite appropriate treatment. For this reason, adjunct therapeutic approaches are being explored to improve clinical outcomes.

The purpose of this study is to evaluate whether osteopathic manual therapy, when used as an adjunct to optometric vision therapy, provides additional benefits compared with vision therapy alone or vision therapy combined with a sham osteopathic intervention. This randomized, controlled, double-blind clinical trial will compare three parallel groups and will assess changes in vergence function, oculomotor performance measured by video-oculography, and symptom improvement related to vergence disorders.

Vergence disorders are binocular vision dysfunctions characterized by an impaired ability to coordinate eye movements during visual tasks, particularly at near distances. These disorders are associated with a range of symptoms, including visual discomfort, reduced visual efficiency, and decreased functional performance during sustained near-vision activities.

Optometric vision therapy is an evidence-based intervention aimed at improving vergence function and visual efficiency. Despite its effectiveness, clinical response varies among individuals, and a subset of participants may continue to experience persistent symptoms. This variability has prompted interest in adjunctive interventions that may influence neuromuscular, musculoskeletal, or functional components related to oculomotor control.

This study is designed as a randomized, controlled, double-blind clinical trial with three parallel arms. Participants diagnosed with vergence disorders will be randomly assigned to one of the following groups: (1) optometric vision therapy combined with osteopathic treatment, (2) optometric vision therapy combined with a sham osteopathic intervention, or (3) optometric vision therapy alone.

The primary objective of the study is to evaluate whether the addition of osteopathy to optometric vision therapy results in greater improvements in ocular mobility and efficiency, assessed using video-oculography systems (REMOBI and EyeSeeCam). Secondary objectives include the evaluation of symptom changes associated with vergence disorders using a validated questionnaire (CISS-V15), as well as the exploration of potential relationships between functional ocular impairment, identified somatic dysfunctions, and the anatomical distribution of reported symptoms.

Ocular motor performance will be objectively quantified through standardized vergence tasks recorded by video-oculography, including measures of reaction latency, amplitude variability, amplitude error, and neglect rate. Assessments will be conducted at baseline (pre-intervention), post-intervention (within two weeks after completion of the visual therapy program), and at follow-up time points of three and six months after the intervention.

The osteopathic intervention consists of a standardized manual treatment protocol targeting somatic dysfunctions potentially related to binocular vision and vergence function. The sham osteopathic intervention is designed to mimic the context, duration, and therapist-participant interaction of the active manual treatment without applying therapeutic osteopathic techniques, in order to preserve participant blinding.

The results of this study are expected to contribute to a better understanding of the potential role of osteopathy as an adjunctive intervention in the management of vergence disorders and to provide clinically relevant data on the relationship between somatic dysfunctions and functional visual alterations in individuals with high visual demand.

Inclusion Criteria:

• Adult workers (≥18 years) whose regular occupational duties involve screen-based work.
• Presence of symptoms consistent with binocular vision dysfunction, defined as a Convergence Insufficiency Symptom Survey (CISS-V15) score ≥21 at baseline screening.

Exclusion Criteria:

• Severe ocular disease or systemic conditions affecting vision (e.g., age-related macular degeneration, retinopathies, glaucoma, keratoconus).
• Neurological disorders affecting ocular motility or visual function (e.g., multiple sclerosis; cranial nerve III, IV, V, or VI palsy).
• Manifest ocular deviation not suitable for management with visual therapy.
• Inadequate refractive correction or prism requirement >10 prism diopters (>10Δ).
• Refractive surgery (LASIK/PRK), cataract surgery, or any ocular surgery likely to influence binocular vision within the past 6 months.
• Use of medications known to affect ocular motility or accommodative function.
• Cognitive impairment or neurological conditions interfering with adherence to therapy instructions.
• Suppression or severe amblyopia limiting response to visual therapy.
• Best-corrected visual acuity <0.5 decimal (equivalent to worse than 20/40) at distance or near.

Double-blind (Participants and Outcomes Assessors). The osteopathic treatment provider is not blinded due to the nature of the manual intervention. Participants are unaware of group allocation, and the sham intervention is designed to mimic the context, duration, and therapist-participant interaction of the active osteopathic treatment to maintain blinding.