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Completed

NCT Number: NCT06745661

Impact of Red Light Therapy on Alleviating Visual Fatigue in Presbyopes

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.

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Key information

Conditions

Asthenopia Eye Diseases Presbyopia Refractive Errors Visual Fatigue

Age range

40 year and older

Sex eligibility

All sexes

Study type

Interventional

Phase

Not applicable

Primary location

The Hong Kong Polytchnic University

Hong Kong

Who can participate

Healthy volunteers accepted: No

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

  • 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.

Exclusion criteria

  • 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.

Treatment and study plan

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.

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.

Primary outcomes

  1. change in the asthenopia questionnaire scores

    Time frame: at 2 weeks and 1 month compared to baseline

    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)

Secondary outcomes

  1. Change in critical flicker fusion frequency (CFF)

    Time frame: at 2 weeks and 1 month compared to baseline

    •Change in CFF at 2 weeks and 1 month compared to baseline.

  2. Change in eye movement

    Time frame: at 2 weeks and 1 month compared to baseline

    •Change in eye movement at 2 weeks and 1 month compared to baseline.

  3. Change in pupil parameters

    Time frame: at 2 weeks and 1 month compared to baseline

    •Change in pupil parameters at 2 weeks and 1 month compared to baseline.

  4. Change in blink patterns

    Time frame: at 2 weeks and 1 month compared to baseline

    •Change in blink patterns at 2 weeks and 1 month compared to baseline.

  5. Change in accommodation function

    Time frame: at 2 weeks and 1 month compared to baseline

    •Change in accommodation function at 2 weeks and 1 month compared to baseline.

  6. Change in self-reported emotional states

    Time frame: at 2 weeks and 1 month compared to baseline

    Change in self-reported emotional states, assessed by the Positive and Negative Affect Schedule (PANAS-X) at 2 weeks and 1 month compared to baseline. The scores are divided into positive scores and negative scores. Items are rated for the past week on a 5-point scale. The Positive Affect subscale (items 1,3,5,9,10,12,14,16,17,19) and Negative Affect subscale (items 2,4,6,7,8,11,13,15,18,20) each total 10-50 points.

    Positive Affect Score: Higher scores indicate higher levels of positive affect. Negative Affect Score: Lower scores indicate lower levels of negative affect.

  7. Change in electroencephalogram (EEG)

    Time frame: at 2 weeks and 1 month compared to baseline

    •Change EEG at 2 weeks and 1 month compared to baseline.

  8. Change in cognitive questionnaire

    Time frame: at 2 weeks and 1 month compared to baseline

    •Change in cognitive questionnaire, measured by the Montreal Cognitive Assessment Scale (MoCA) at 2 weeks and 1 month compared to baseline. Total score 0-30; higher scores indicate better cognitive function.

  9. Change in near activity visual questionnaire

    Time frame: at 2 weeks and 1 month compared to baseline

    Change in near activity visual questionnaire (NAVQ) score at 2 weeks and 1 month compared to baseline. Scores are reported on the Rasch-transformed 0-100 scale, with higher scores indicating worse near-vision function (decreases = improvement).

Sponsors and collaborators

Lead sponsor

The Hong Kong Polytechnic University

Other

Registry information

Official study title

Investigating the Impact of RLRL on Alleviating Visual Fatigue in Presbyopic Population

Important dates

Study start
2025
Primary completion
2025
Study completion
2025
First posted
Dec 20, 2024
Registry last updated
Sep 24, 2025

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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