Impact of Red Light Therapy on Alleviating Visual Fatigue in Presbyopes

NCT06745661 | Completed DMC

• 1 other identifier: HSEARS20240916007
• Study Type: interventional
• Target: 66
• Locations: 1 country
• Sites: 1

Brief Summary

Visual fatigue, or asthenopia, occurs when visual demands exceed the capacity of the visual system, leading to various ocular discomfort and systemic symptoms. This condition can negatively affect personal activities, quality of life, and work productivity. Given the high prevalence of asthenopia in presbyopic population, finding effective methods to alleviate these symptoms is crucial. This study aims to evaluate the effects of repeated low-level red-light (RLRL) therapy on alleviating visual fatigue in individuals with presbyopia over a one-month period. Additionally, we will assess the potential benefits on accommodation function, cognition, and emotional effects of RLRL in this population. Interested individuals will be invited to the PolyU Optometry Clinic to undergo an eligibility examination. An estimated sample size of 66 participants will be recruited. The inclusion criteria specify individuals aged 40 years or older who self-report visual fatigue symptoms and require near correction in daily life. Exclusion criteria include those with ocular disease, systemic diseases, illiteracy, or an afterimage duration longer than 6 minutes. Eligible participants will be randomly assigned in a 1:1 ratio to either the intervention group or the control group. Each participant in the intervention group will be provided an RLRL therapy device, which they are required to use twice daily for 3 minutes per session, with a minimum interval of 4 hours between sessions, 7 days a week for one month. Participants in the control group will receive a sham device, following the same usage schedule. The study will evaluate changes in asthenopia questionnaire scores, CFF scores, other objective asthenopia indicators (i.e., eye movement, pupil parameters, and blink patterns), accommodation function, cognitive function, and emotional states at 2 weeks and 1 month compared to baseline. Statistical analysis will be conducted to explore evaluate within-subject changes over time and between-group differences in visual fatigue metrics, accommodation metrics, cognitive metrics, and emotional metrics. The findings will contribute to evaluating the effectiveness of RLRL therapy in reducing asthenopia and presbyopia symptoms, as well as its impact on cognitive function and emotional well-being.

Conditions

Asthenopia; Visual Fatigue; Presbyopia

Keywords

asthenopia; visual fatigue; presbyopia; red light therapy

Outcome Measures

Primary Outcomes (1)

• change in the asthenopia questionnaire scores

  The primary outcome is the change in the asthenopia questionnaire scores at 2 weeks and 1 month compared to baseline. These scores will be derived from the Computer Vision Syndrome Questionnaire (CVS-Q), a widely recognized tool for assessing subjective symptoms of asthenopia. The CVS-Q ranges from 0 (no symptoms) to 32 (most severe), with higher scores indicating worse symptoms (negative change = improvement)

  at 2 weeks and 1 month compared to baseline

Secondary Outcomes (9)

• Change in critical flicker fusion frequency (CFF)

  at 2 weeks and 1 month compared to baseline

• Change in eye movement

  at 2 weeks and 1 month compared to baseline

• Change in pupil parameters

  at 2 weeks and 1 month compared to baseline

• Change in blink patterns

  at 2 weeks and 1 month compared to baseline

• Change in accommodation function

  at 2 weeks and 1 month compared to baseline

Study Arms (2)

RLRL therapy group

EXPERIMENTAL

The experimental group will undergo repeated low-level red-light therapy (RLRL). The light power through a 4-mm pupil is 0.29 mW for the RLRL device.

Device: RLRL device

Sham therapy group

SHAM COMPARATOR

The sham group will use a sham device, which operates at only 10% of the active RLRL device's power. The light power through a 4-mm pupil is 0.03 mW for the sham device.

Device: sham device

Interventions

RLRL device DEVICE

Each participant in the intervention group will be provided a repeated low-level red-light therapy (RLRL) device, which they are required to use twice daily for 3 minutes per session, with a minimum interval of 4 hours between sessions, 7 days a week for one month.

RLRL therapy group

sham device DEVICE

Each participant in the sham group will be provided a sham therapy device, which they are required to use twice daily for 3 minutes per session, with a minimum interval of 4 hours between sessions, 7 days a week for one month.

Sham therapy group

Eligibility Criteria

• Age: 40 Years+
• Sex: all
• Healthy Volunteers: No
• Age Groups: Adult (18-64), Older Adult (65+)

You may qualify if:

• Individuals aged over 40 years old.
• Self-reported visual fatigue symptoms.
• Distance best-corrected visual acuity (BCVA) of 0.5 LogMAR or better, and near visual acuity worse than N8 (20/50) at 40 cm with the subject's habitual distance correction.
• Require near correction in daily life.
• No light therapy received in the past six months.
• Giving informed written consent.

You may not qualify if:

• Presence of diseases that can cause eye pain or headaches, such as strabismus, glaucoma, ocular trauma, conjunctivitis, migraines, keratitis, iridocyclitis, or other self-reported diseases.
• Systemic diseases (e.g., epilepsy, photosensitivity, seizure) or illiteracy.
• Afterimage time longer than 6 minutes.

Sponsors & Collaborators

• The Hong Kong Polytechnic University: lead

Study Sites (1)

The Hong Kong Polytchnic University

Hong Kong, Hong Kong

Location

MeSH Terms

Conditions

Asthenopia; Presbyopia

Condition Hierarchy (Ancestors)

Eye Diseases; Refractive Errors

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: RANDOMIZED
• Masking: QUADRUPLE
• Who Masked: PARTICIPANT, CARE PROVIDER, INVESTIGATOR, OUTCOMES ASSESSOR
• Purpose: TREATMENT
• Intervention Model: PARALLEL
• Sponsor Type: OTHER
• Responsible Party: SPONSOR

Study Record Dates

• First Submitted: December 8, 2024
• First Posted: December 20, 2024
• Study Start: February 10, 2025
• Primary Completion: May 23, 2025
• Study Completion: May 23, 2025
• Last Updated: September 24, 2025

Record last verified: 2024-12

Data Sharing

• IPD Sharing: Will not share

Locations

HK (1)