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

NCT07105462 | Completed

• 1 other identifier: CRREC-114-011
• Study Type: interventional
• Target: 26
• Locations: 1 country
• Sites: 1

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.

Conditions

Eye Movements; Visual Perception; Psychomotor Performance; Sports

Outcome Measures

Primary Outcomes (1)

• Reaction Time Measured by BlazePod Test

  * Time in seconds required to complete 10 light-response trials using BlazePod; lower values indicate better performance. * Unit of Measure: seconds

  Baseline and Week 4 (post-intervention)

Secondary Outcomes (5)

• Vergence Facility in Cycles per Minute (cpm)

  Baseline and Week 4

• Accommodative Facility in Cycles per Minute (cpm)

  Baseline and Week 4

• Near Point of Convergence Distance

  Baseline and Week 4

• Positive Fusional Vergence Break and Recovery Points

  Baseline and Week 4

• Number of Successful Shuttlecock Hits

  Baseline and Week 4

Study Arms (2)

Arm 1: Vergence Training with ADRRPs

EXPERIMENTAL

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.

Device: 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

Arm 2: Sham Training with Plano Lenses

SHAM COMPARATOR

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.

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

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 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 1: Vergence Training with ADRRPs

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

Arm 2: Sham Training with Plano Lenses

Eligibility Criteria

• Age: 18 Years - 25 Years
• Sex: all
• Healthy Volunteers: Yes
• Age Groups: Adult (18-64)

You may qualify if:

• 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

You may not qualify if:

• 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

Sponsors & Collaborators

• China Medical University Hospital: lead

Study Sites (1)

Central Taiwan University of Science and Technology

Taichung, 402, Taiwan

Location

Study Officials

• Hsuan-Yu Huang, Ph.D.

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

  STUDY CHAIR

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: RANDOMIZED
• Masking: SINGLE
• Who Masked: PARTICIPANT
• Purpose: TREATMENT
• Intervention Model: PARALLEL
• Sponsor Type: OTHER
• Responsible Party: SPONSOR

Study Record Dates

• First Submitted: July 16, 2025
• First Posted: August 6, 2025
• Study Start: March 24, 2025
• Primary Completion: May 30, 2025
• Study Completion: May 30, 2025
• Last Updated: August 6, 2025

Record last verified: 2025-07

Locations

TW (1)