Comparison of a structured vision-therapy program versus usual care on visual performance, fear of falling, and quality of life in individuals with idiopathic Parkinson’s disease: a randomized clinical trial

The aim of this study is to design and conduct a clinical trial to evaluate the effects of vision therapy interventions on visual function, fear of falling, and quality of life in patients with idiopathic Parkinson’s disease.

Randomized controlled trial (RCT) with parallel groups and single-blind design. Participants are allocated to groups using 1:1 block randomization with sealed opaque envelopes. Outcome assessments are conducted by independent blinded assessors.

The study is conducted in healthcare and rehabilitation centers for Parkinson’s patients. Participants provide informed consent, are assessed, and receive either vision therapy (intervention) or general health information (control). All procedures are supervised with blinding and randomization.

Inclusion criteria (short): Idiopathic Parkinson’s patients aged 30–75, disease stage 1–3 (Hoehn & Yahr), adequate cognition (MoCA > 24, PD-CRS > 82), corrected visual acuity ≥ 20/40, binocular vision problems (CISS > 21, NPC > 8 cm), able to read and write in Persian. Exclusion criteria (short): Severe ocular or neurological diseases, history of brain surgery (except DBS), strabismus or amblyopia, medication changes or disease stage change, drugs affecting binocular vision (except Parkinson’s), incapacitating comorbidities.

Control group: Receives general health information. Intervention group: Receives vision therapy progressing from simple to complex exercises, monitored with checklists, administered during the ON medication phase.

The main outcome variables include: Visual function (visual acuity, stereopsis, contrast sensitivity, near point of convergence, reading speed, fusional vergence reserves, heterophoria, and vergence facility and saccade and pursuit) Fear of falling Vision-related quality of life

After screening and confirming eligibility, participants will be assigned to either the intervention or control group using 1:1 block randomization. Sealed, opaque envelopes will be used to ensure allocation concealment for both participants and researchers. Block sizes and sequences will be generated by a randomization software. Optometrists assigned to the intervention and control groups will be different and trained by the research team to ensure standardized administration and minimize bias. To ensure reliability of assessments, the agreement between these evaluators will be tested in a pilot study of ten participants.

This study is a participant-blinded randomized controlled trial. Due to the use of a placebo vision-therapy protocol in the control group, participants will remain blinded to their group allocation. The placebo exercises will be designed to mimic the structure, duration, and therapist–participant interaction of the active vision-therapy sessions, ensuring that participants cannot distinguish between the intervention and control conditions. Outcome assessors will not be blinded to group allocation due to the nature of the visual, functional, and mobility assessments, which require detailed clinical judgment and cannot feasibly be conducted under blinded conditions. Randomization will be performed using a block randomization method with allocation concealment ensured through sequentially numbered, opaque, sealed envelopes (SNOSE). The data analyst will remain blinded to the group assignments, and all datasets will be coded prior to statistical analysis. Accordingly, participants will be blinded to their assigned group, while outcome assessors will not be blinded. The trial will therefore operate as a participant-blinded randomized controlled study.

Title: Data and documents from the clinical trial on vision therapy in patients with idiopathic Parkinson’s disease Details: The dataset includes de-identified participant data, baseline and outcome measures, and study-related documents such as protocol, informed consent forms, and statistical analysis plan. Data may be shared for scientific research purposes upon reasonable request and approval by the ethics committee.

The data and study-related documents will become available after publication of the primary results and will remain accessible for up to 5 years.

Data and study-related documents will be available to researchers who submit a reasonable request for scientific purposes and receive approval from the principal investigator and the ethics committee.

Data and study-related documents may be used only for scientific research purposes, with appropriate ethical approval, and in accordance with the conditions set by the principal investigator and the ethics committee.

Data and study-related documents can be obtained by contacting the principal investigator of the study. Contact details will be provided in the study registry.

Researchers must submit a reasonable request specifying the purpose of data use. The request will be reviewed and approved by the principal investigator and the ethics committee. Upon approval, the requested de-identified data and documents will be shared under the agreed conditions.