An interventional study of RLRL device and sham device in Asthenopia, Visual Fatigue and Presbyopia, sponsored by The Hong Kong Polytechnic University. Completed at 1 site in Hong Kong. Open to participants aged 40 Years and older. Per ClinicalTrials.gov, last updated 2025-09-24.
Sponsored by The Hong Kong Polytechnic University · Not applicable, Interventional, and Treatment
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.
67 studies on the registry are indexed under Asthenopia; 10 are open to participants now.
This study's enrollment of 66 is above the median of 56 across 56 interventional studies indexed under Asthenopia.
Browse Asthenopia studies →The Hong Kong Polytechnic University is the lead sponsor of 679 studies on the registry; 257 are open to participants now.
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Exclusion Criteria:
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
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
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.
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.
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)
Time frame: at 2 weeks and 1 month compared to baseline
Change in critical flicker fusion frequency (CFF)
•Change in CFF at 2 weeks and 1 month compared to baseline.
Time frame: at 2 weeks and 1 month compared to baseline
Change in eye movement
•Change in eye movement at 2 weeks and 1 month compared to baseline.
Time frame: at 2 weeks and 1 month compared to baseline
Change in pupil parameters
•Change in pupil parameters at 2 weeks and 1 month compared to baseline.
Time frame: at 2 weeks and 1 month compared to baseline
Change in blink patterns
•Change in blink patterns at 2 weeks and 1 month compared to baseline.
Time frame: at 2 weeks and 1 month compared to baseline
Change in accommodation function
•Change in accommodation function at 2 weeks and 1 month compared to baseline.
Time frame: at 2 weeks and 1 month compared to baseline
Change in self-reported emotional states
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.
Time frame: at 2 weeks and 1 month compared to baseline
Change in electroencephalogram (EEG)
•Change EEG at 2 weeks and 1 month compared to baseline.
Time frame: at 2 weeks and 1 month compared to baseline
Change in cognitive questionnaire
•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.
Time frame: at 2 weeks and 1 month compared to baseline
Change in near activity visual questionnaire
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).
Time frame: at 2 weeks and 1 month compared to baseline
Plan to share: No — According to the relevant agreement, all parties involved must keep study data confidential throughout the study process.
This study is completed, as verified in Dec 2024. You cannot join it, but the record below documents what was studied.
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