The Effects of Rotational Prisms on Badminton Players' Ocular Vergence Training and Enhancement of Shot Accuracy

NCT ID: NCT07105462

Last Updated: 2025-08-06

Basic Information

• Recruitment Status: COMPLETED
• Clinical Phase: NA
• Total Enrollment: 26 participants
• Study Classification: INTERVENTIONAL
• Study Start Date: 2025-03-24
• Study Completion Date: 2025-05-30

Brief Summary

This randomized controlled trial is designed to investigate whether a novel visual training system can improve eye coordination, reaction time, and hitting accuracy in competitive badminton players. The training utilizes a device called the Automatic Dual Rotational Risley Prisms (ADRRPs), which presents alternating base-in and base-out prism demands to stimulate vergence eye movements. This type of training aims to enhance the eyes' ability to converge and diverge quickly and accurately-a function that is important for visual clarity and motor performance during fast-paced sports.

A total of 26 collegiate badminton athletes aged 18 to 25 years will be recruited from two universities in Taiwan. Participants will be randomly assigned to one of two groups: a visual training group using the active ADRRPs system, and a control group using a sham version of the same device containing plano lenses (with no prism effect). Training will be delivered twice per week for four weeks, with each session lasting 15 minutes. During each session, participants will view a video while the device applies alternating prism stimulation based on each individual's pre-measured fusional vergence capacity.

Outcome measures will be assessed at baseline and after the four-week training period. These include vergence facility (cycles per minute), accommodative facility (flipper test), near point of convergence, and positive fusional vergence at near. Reaction time will be measured using a light-based agility task with BlazePod sensors, and hitting performance will be evaluated using a shuttlecock launcher that delivers randomized targets to various court zones.

All participants will be monitored for any adverse events, and any symptoms such as diplopia, dizziness, or discomfort will be documented. Data will be analyzed as described in the Statistical Analysis Plan.

Detailed Description

This randomized controlled trial explores the application of vergence eye movement training in enhancing visuomotor performance in competitive badminton athletes. The intervention utilizes a device known as the Automatic Dual Rotational Risley Prisms (ADRRPs), which delivers alternating base-out and base-in prism stimulation in an automated manner to engage binocular vergence mechanisms.

The study targets young adult badminton players with at least two years of consistent training. Participants are randomly allocated to either an experimental group, which receives active prism training using the ADRRPs, or a control group using an identical headset without prism rotation. Both groups undergo training sessions twice a week for four weeks, with each session lasting 15 minutes. Visual stimuli are standardized across groups and delivered at a fixed near working distance of 40 cm.

The prism rotation parameters are set to simulate dynamic vergence demands based on pre-measured individual capabilities. This approach aims to create a structured vergence load while minimizing visual discomfort. The control condition serves to control for placebo and attentional effects.

Outcome measures are selected to assess both oculomotor and performance domains. These include vergence facility, accommodative facility, near point of convergence, and positive fusional vergence-all measured using standardized optometric tools. Reaction time is assessed via a BlazePod light stimulus test, and hitting accuracy is evaluated through a shuttlecock launcher delivering randomized trajectories to simulate game-like performance.

The trial design incorporates single-blinding and concealed allocation procedures. Data analysis will follow a pre-specified statistical analysis plan, and participants will be closely monitored for any adverse symptoms during the course of the intervention. Ethics approval has been obtained from the relevant institutional review board.

Conditions

Eye Movements; Visual Perception; Psychomotor Performance; Sports

Study Design

• Allocation Method: RANDOMIZED
• Intervention Model: PARALLEL
• Primary Study Purpose: TREATMENT
• Blinding Strategy: SINGLE

Study Groups

Arm 1: Vergence Training with ADRRPs

Participants assigned to this arm will receive vergence training using Automatic Dual Rotational Risley Prisms (ADRRPs), a computerized visual device designed to induce alternating base-out and base-in prism stimulation. The prisms rotate automatically to simulate dynamic convergence and divergence demands, cycling between 0 to 30 prism diopters base-out over 5 seconds and 30 base-out to 10 base-in over 3 seconds. Each participant will undergo 8 training sessions over 4 weeks (twice weekly), with each session lasting 15 minutes. During training, participants view standardized video targets positioned at a 40 cm working distance while instructed to maintain clear and single binocular vision. The intervention aims to engage and strengthen vergence eye movements critical for visual performance in dynamic sports environments.

Group Type: EXPERIMENTAL

Arm 1 - Experimental Group Intervention Name: ADRRPs Vergence Training Intervention Description: Participants wore an Automatic Dual Rotational Risley Prism (ADRRPs) headset to perform vergence eye

Intervention Type: DEVICE

ADRRPs Vergence Training

Intervention Description:

Participants wore an ADRRPs headset that applied alternating base-in and base-out prism power to stimulate vergence eye movements. Prism levels were customized based on each participant's fusional vergence. Training was performed twice weekly for 15 minutes over four weeks while viewing a near video target.

Sham Visual Training with Plano Lenses

Intervention Description:

Participants wore an identical ADRRPs headset fitted with plano lenses that produced no prism effect. The procedure and schedule matched the experimental group but provided no vergence stimulation, serving as a sham control.

Arm 2: Sham Training with Plano Lenses

Participants assigned to this arm will undergo sham vergence training using the same Automatic Dual Rotational Risley Prisms (ADRRPs) headset, but fitted with non-refractive plano lenses and with no prism rotation. The training schedule and environment are identical to the intervention arm: 8 sessions over 4 weeks (twice weekly), with each session lasting 15 minutes. Visual targets are presented at a 40 cm viewing distance using the same video stimuli. This sham training condition is designed to control for potential placebo effects and to isolate the specific influence of dynamic prism-induced vergence stimulation used in the experimental arm.

Group Type: SHAM_COMPARATOR

1. Experimental Group Intervention Name: ADRRPs-Based Vergence Training; 2. Control Group Intervention Name: Sham Training with Plano Lenses.

Intervention Type: DEVICE

ADRRPs-Based Vergence Training This intervention used the Automatic Dual Rotational Risley Prisms (ADRRPs) system to deliver alternating base-in and base-out prism stimulation for vergence training. Prism levels were customized based on each participant's fusional vergence. Training was conducted twice per week for four weeks, 15 minutes per session, while participants viewed a near video target. This protocol provides automated and symmetric vergence demand, distinguishing it from conventional near-point or static prism exercises.

Sham Training with Plano Lenses Participants used the same ADRRPs headset as the experimental group but with plano lenses that produced no prism effect. The training schedule and visual tasks matched the experimental condition, but no vergence stimulus was applied. This design enabled participant masking while providing no active optical stimulation, serving as a sham comparator distinct from both active training and no-treatment controls.

Interventions

Arm 1 - Experimental Group Intervention Name: ADRRPs Vergence Training Intervention Description: Participants wore an Automatic Dual Rotational Risley Prism (ADRRPs) headset to perform vergence eye

ADRRPs Vergence Training

Intervention Description:

Participants wore an ADRRPs headset that applied alternating base-in and base-out prism power to stimulate vergence eye movements. Prism levels were customized based on each participant's fusional vergence. Training was performed twice weekly for 15 minutes over four weeks while viewing a near video target.

Sham Visual Training with Plano Lenses

Intervention Description:

Participants wore an identical ADRRPs headset fitted with plano lenses that produced no prism effect. The procedure and schedule matched the experimental group but provided no vergence stimulation, serving as a sham control.

Intervention Type: DEVICE

1. Experimental Group Intervention Name: ADRRPs-Based Vergence Training; 2. Control Group Intervention Name: Sham Training with Plano Lenses.

ADRRPs-Based Vergence Training This intervention used the Automatic Dual Rotational Risley Prisms (ADRRPs) system to deliver alternating base-in and base-out prism stimulation for vergence training. Prism levels were customized based on each participant's fusional vergence. Training was conducted twice per week for four weeks, 15 minutes per session, while participants viewed a near video target. This protocol provides automated and symmetric vergence demand, distinguishing it from conventional near-point or static prism exercises.

Sham Training with Plano Lenses Participants used the same ADRRPs headset as the experimental group but with plano lenses that produced no prism effect. The training schedule and visual tasks matched the experimental condition, but no vergence stimulus was applied. This design enabled participant masking while providing no active optical stimulation, serving as a sham comparator distinct from both active training and no-treatment controls.

Intervention Type: DEVICE

Eligibility Criteria

Inclusion Criteria

• Aged between 18 and 30 years
• Minimum of 2 years of consistent badminton training
• Best-corrected visual acuity of 20/25 or better in both eyes (distance and near)
• No history of ocular pathology
• Willingness to comply with all study procedures and follow-up

Exclusion Criteria

• Presence of constant strabismus or binocular vision anomaly
• History of ocular trauma, strabismus surgery, or refractive surgery
• Neurological or systemic conditions affecting vision
• Ongoing medication that may influence ocular motor function

• Minimum Eligible Age: 18 Years
• Maximum Eligible Age: 25 Years
• Eligible Sex: ALL
• Accepts Healthy Volunteers: Yes

Sponsors

China Medical University Hospital

OTHER

Sponsor Role: lead

Responsible Party

Responsibility Role: SPONSOR

Principal Investigators

Hsuan-Yu Huang, Ph.D.

Role: STUDY_CHAIR

College of Health Sciences, Central Taiwan University of Science and Technology

Locations

Central Taiwan University of Science and Technology

Taichung, , Taiwan

Countries

Taiwan

Other Identifiers

CRREC-114-011

Identifier Type: -

Identifier Source: org_study_id