Lactic Acid Bacteria for Reducing Blue Light-Induced Eye Fatigue

July 27, 2026 updated by: Synbio Tech Inc.

The Application of Lactic Acid Bacteria on Reducing Blue Light-Induced Eye Fatigue in Middle-Aged Adults

With the widespread use of digital devices and prolonged screen exposure, digital eye strain (DES), also known as computer vision syndrome, has become a global public health concern. Emerging evidence suggests that the gut-eye axis may play an important role in ocular health, as gut microbiota imbalance is associated with systemic inflammation and oxidative stress. Specific probiotics may help alleviate eye discomfort through modulation of immune responses and enhancement of antioxidant defense mechanisms. This randomized, double-blind, placebo-controlled study aims to evaluate the efficacy of supplementation with specific probiotics, Bifidobacterium longum BL531 and Lactobacillus reuteri LR1349, in improving digital eye strain symptoms in adults.

Study Overview

Status

Status

Indicates the current recruitment status or the expanded access status.
Not yet recruiting

Conditions

Conditions

The disease, disorder, syndrome, illness, or injury that is being studied. On ClinicalTrials.gov, conditions may also include other health-related issues, such as lifespan, quality of life, and health risks.

Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.

Study Type

Study Type

Describes the nature of a clinical study. Study types include interventional studies (also called clinical trials), observational studies (including patient registries), and expanded access.
Interventional

Enrollment (Estimated)

Enrollment

The number of participants in a clinical study. The "anticipated" enrollment is the target number of participants that the researchers need for the study.
150

Phase

Phase

The stage of a clinical trial studying a drug or biological product, based on definitions developed by the U.S. Food and Drug Administration (FDA). The phase is based on the study's objective, the number of participants, and other characteristics. There are five phases: Early Phase 1 (formerly listed as Phase 0), Phase 1, Phase 2, Phase 3, and Phase 4. Not Applicable is used to describe trials without FDA-defined phases, including trials of devices or behavioral interventions.
  • Not Applicable

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Contact

The name and contact information for the person who can answer enrollment questions for a clinical study. Each location where the study is being conducted may also have a specific contact, who may be better able to answer those questions.

Study Contact Backup

Study Locations

  • Taiwan
      • Taipei, Taiwan, 106
        • National Taiwan Normal University
        • Contact:

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Eligibility Criteria

The key requirements that people who want to participate in a clinical study must meet or the characteristics they must have. Eligibility criteria consist of both inclusion criteria (which are required for a person to participate in the study) and exclusion criteria (which prevent a person from participating). Types of eligibility criteria include whether a study accepts healthy volunteers, has age or age group requirements, or is limited by sex.

Ages Eligible for Study

  • Adult
  • Older Adult

Accepts Healthy Volunteers

Yes

Description

Inclusion Criteria:

  • Men and women aged 20-65 years
  • Daily digital screen use >6 hours for at least 1 year
  • Mild to severe digital eye strain (CVS-Q score ≥ 6)
  • Mild to moderate dry eye symptoms (OSDI ≥ 13)

Exclusion Criteria:

  • Amblyopia or strabismus
  • Severe eye diseases (e.g., glaucoma , cataract , retinal disorders, severe corneal disease)
  • Ocular surgery within the past 12 months
  • Chronic systemic diseases (e.g., uncontrolled diabetes, autoimmune disease, severe liver/kidney impairment, cancer)
  • Recent use (<1 months) of steroids, antibiotics, immunosuppressants, probiotics, prebiotics, or eye-health supplements
  • Pregnant or breastfeeding
  • Allergy to probiotics or study product ingredients
  • Eating disorders, psychiatric illness, or cognitive impairment affecting compliance
  • Any condition judged unsuitable by the investigator

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Prevention
  • Allocation: Randomized
  • Interventional Model: Parallel Assignment
  • Masking: Double

Arms and Interventions

Participant Group / Arm

Participant Group / Arm

A group or subgroup of participants in a clinical trial that receives a specific intervention/treatment, or no intervention, according to the trial's protocol.
Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.
Placebo Comparator: Placebo
Subjects assigned to the placebo group will take one placebo capsule daily within 30 minutes before breakfast throughout the 12-week intervention period.
Dietary supplement: Placebo
Maltodextrin
Experimental: BL531_low dose
Subjects assigned to each intervention group will take one capsule daily within 30 minutes before breakfast throughout the 12-week intervention period.
Dietary supplement: BL531_low dose
1×10^10 cfu/day
Experimental: BL531_high dose
Subjects assigned to each intervention group will take one capsule daily within 30 minutes before breakfast throughout the 12-week intervention period.
Dietary supplement: BL531_high dose
2.5×10^10 cfu/day
Experimental: LR1349_low dose
Subjects assigned to each intervention group will take one capsule daily within 30 minutes before breakfast throughout the 12-week intervention period.
Dietary supplement: LR1349_low dose
1×10^10 cfu/day
Experimental: LR1349_high dose
Subjects assigned to each intervention group will take one capsule daily within 30 minutes before breakfast throughout the 12-week intervention period.
Dietary supplement: LR1349_high dose
2.5×10^10 cfu/day

What is the study measuring?

Primary Outcome Measures

Primary Outcome Measures

In a clinical study's protocol, the planned outcome measure that is the most important for evaluating the effect of an intervention/treatment. Most clinical studies have one primary outcome measure, but some have more than one.
Outcome Measure
Measure Description
Time Frame
Computer Vision Syndrome Questionnaire (CVS-Q)
Time Frame: Baseline, Week 6, Week 12
The CVS-Q is a questionnaire used to assess digital eye strain associated with prolonged digital screen use. It includes 16 symptoms related to screen exposure. Total scores are classified as 0-5 (none/minimal), 6-12 (mild), 13-18 (moderate), and ≥19 (severe), with scores ≥6 indicating clinically significant digital eye strain.
Baseline, Week 6, Week 12

Secondary Outcome Measures

Secondary Outcome Measures

In a clinical study's protocol, a planned outcome measure that is not as important as the primary outcome measure for evaluating the effect of an intervention but is still of interest. Most clinical studies have more than one secondary outcome measure.
Outcome Measure
Measure Description
Time Frame
Ocular Surface Disease Index (OSDI)
Time Frame: Baseline, Week 6, Week 12
The Ocular Surface Disease Index (OSDI) is a 12-item questionnaire used to assess the severity of dry eye symptoms and their impact on vision-related function and daily activities. Total scores range from 0 to 100, with higher scores indicating greater symptom severity.
Baseline, Week 6, Week 12
Basic vision examination
Time Frame: Baseline and Week 12
A comprehensive ophthalmic examination will be performed, including uncorrected distance and near visual acuity, automated refraction, presbyopia assessment, distance and near vision correction, intraocular pressure measurement, and external eye photography for conjunctival hyperemia assessment.
Baseline and Week 12
Pupillary Response Test
Time Frame: Baseline and Week 12
Pupillary response testing will be performed using the Oculus Pentacam HR or an equivalent device to evaluate pupil size and response time under light and dark conditions. This assessment provides information on the visual system's adaptation to changes in illumination.
Baseline and Week 12
Tear Secretion Assessment
Time Frame: Baseline and Week 12
Tear meniscus height will be measured using the OS1000 Corneal Topographer (SBM sistemi, Italy) or an equivalent device as an indicator of tear secretion.
Baseline and Week 12
Non-Invasive Tear Break-Up Time (NIBUT)
Time Frame: Baseline and Week 12
Non-invasive tear break-up time (NIBUT) will be measured using the OS1000 Corneal Topographer (SBM sistemi, Italy) or an equivalent device to evaluate tear film stability. A shorter NIBUT is commonly associated with dry eye symptoms and digital eye strain.
Baseline and Week 12
Corneal Tomography and Topography Analysis
Time Frame: Baseline and Week 12
Corneal tomography and topography analysis will be performed using the Oculus Pentacam HR or an equivalent device to evaluate corneal morphology, curvature, thickness, and regularity.
Baseline and Week 12
Accommodative Function Assessment
Time Frame: Baseline and Week 12
Accommodative function will be assessed using the ARK-1s Auto Ref-Keratometer (NIDEK, Japan) or an equivalent device to evaluate the eye's focusing ability and quantify accommodative responses associated with ciliary muscle contraction and relaxation.
Baseline and Week 12
Worth Four Dot Test
Time Frame: Baseline and Week 12
The Worth Four Dot Test will be used to assess binocular vision and fusion ability by evaluating responses to red and green visual targets, including the presence of suppression or diplopia.
Baseline and Week 12

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Sponsor

The organization or person who initiates the study and who has authority and control over the study.
Synbio Tech Inc.

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Estimated)

Study Start

The actual date on which the first participant was enrolled in a clinical study. The "anticipated" study start date is the date that the researchers think will be the study start date.
September 1, 2026

Primary Completion (Estimated)

Primary Completion

The date on which the last participant in a clinical study was examined or received an intervention to collect final data for the primary outcome measure. Whether the clinical study ended according to the protocol or was terminated does not affect this date. For clinical studies with more than one primary outcome measure with different completion dates, this term refers to the date on which data collection is completed for all the primary outcome measures. The "anticipated" primary completion date is the date that the researchers think will be the primary completion date for the study.
August 31, 2027

Study Completion (Estimated)

Study Completion

The date on which the last participant in a clinical study was examined or received an intervention/treatment to collect final data for the primary outcome measures, secondary outcome measures, and adverse events (that is, the last participant's last visit). The "anticipated" study completion date is the date that the researchers think will be the study completion date.
December 31, 2027

Study Registration Dates

First Submitted

First Submitted

The date on which the study sponsor or investigator first submitted a study record to ClinicalTrials.gov. There is typically a delay of a few days between the first submitted date and the record's availability on ClinicalTrials.gov (the first posted date).
July 27, 2026

First Submitted That Met QC Criteria

First Submitted That Met QC Criteria

The date on which the study sponsor or investigator first submits a study record that is consistent with National Library of Medicine (NLM) quality control (QC) review criteria. The sponsor or investigator may need to revise and submit a study record one or more times before NLM's QC review criteria are met. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
July 27, 2026

First Posted (Actual)

First Posted

The date on which the study record was first available on ClinicalTrials.gov after National Library of Medicine (NLM) quality control (QC) review has concluded. There is typically a delay of a few days between the date the study sponsor or investigator submitted the study record and the first posted date.
July 30, 2026

Study Record Updates

Last Update Posted (Actual)

Last Update Posted

The most recent date on which changes to a study record were made available on ClinicalTrials.gov. There may be a delay between when the changes were submitted to ClinicalTrials.gov by the study's sponsor or investigator (the last update submitted date) and the last update posted date.
July 30, 2026

Last Update Submitted That Met QC Criteria

Last Update Submitted That Met QC Criteria

The most recent date on which the study sponsor or investigator submitted changes to a study record that are consistent with National Library of Medicine (NLM) quality control (QC) review criteria. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
July 27, 2026

Last Verified

Last Verified

The most recent date on which the study sponsor or investigator confirmed the information about a clinical study on ClinicalTrials.gov as accurate and current. If a study with a recruitment status of recruiting; not yet recruiting; or active, not recruiting has not been confirmed within the past 2 years, the study's recruitment status is shown as unknown.
July 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

Other Study ID Numbers

Identifiers or ID numbers other than the NCT number that are assigned to a clinical study by the study's sponsor, funders, or others. These numbers may include unique identifiers from other trial registries and National Institutes of Health grant numbers.
  • C202605115

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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