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NCT Number: NCT07737938

Lactic Acid Bacteria for Reducing Blue Light-Induced Eye Fatigue

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.

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Key information

Age range

20 year–65 year

Sex eligibility

All sexes

Study type

Interventional

Phase

Not applicable

Primary location

Who can participate

Healthy volunteers accepted: Yes

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

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

Treatment and study plan

Placebo

Dietary Supplement

Maltodextrin

BL531_low dose

Dietary Supplement

1×10^10 cfu/day

BL531_high dose

Dietary Supplement

2.5×10^10 cfu/day

LR1349_low dose

Dietary Supplement

1×10^10 cfu/day

LR1349_high dose

Dietary Supplement

2.5×10^10 cfu/day

Primary outcomes

  1. 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.

Secondary outcomes

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

Study contacts

Contact information is provided by the study sponsor or research team.

Chia-Chia Lee

CONTACT

[email protected]

+886-07-6955680 Ext. 2921

Han-Yin Hsu

CONTACT

[email protected]

+886-07-6955680 Ext. 2923

Sponsors and collaborators

Lead sponsor

Synbio Tech Inc.

Industry

Registry information

Official study title

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

Important dates

Study start
2026
Primary completion
2027
Study completion
2027
First posted
Jul 30, 2026
Registry last updated
Jul 30, 2026

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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