A Study of Full-Spectrum Screen Lighting for Reducing Screen-Related Eye Fatigue and Dry Eye

A Randomized Controlled Trial of the Effects of Full-Spectrum Screen Bar Lighting on Visual Fatigue and Dry Eye After a Standardized Screen Task

This study will evaluate whether full-spectrum screen bar lighting can reduce eye fatigue and dry eye symptoms after a standardized screen task. Prolonged screen use is common in daily work and study and may cause blurred vision, eye soreness, dryness, headache, and reduced attention. Light environment may be one way to improve visual comfort during screen use, but more controlled clinical evidence is needed.

In this randomized, parallel-group controlled study, 112 healthy adult participants will be assigned to either a full-spectrum screen bar lighting group or a brightness-matched control group without screen bar lighting. Participants in both groups will complete an approximately 2-hour standardized screen task in a controlled laboratory environment. The study will compare changes before and after the task in objective and subjective measures of visual fatigue and dry eye, including critical flicker fusion frequency, visual fatigue questionnaire scores, eye movement and blinking parameters, pupil parameters, tear film-related measurements, and dry eye symptom scores. Safety and discomfort during the study will also be recorded.

Study Overview

• Status: Not yet recruiting
• Conditions: Dry Eye; Computer Vision Syndrome; Visual Fatigue
• Intervention / Treatment: Device: Full-spectrum screen bar light; Other: Brightness-matched screen task without screen bar lighting

Detailed Description

Prolonged use of electronic screens is increasingly common in work, study, and daily life and may lead to visual fatigue and dry eye-related symptoms. These symptoms may include blurred vision, eye soreness, dryness, headache, and reduced attention. Although behavioral strategies such as taking breaks and adjusting viewing distance are commonly recommended, their effectiveness may be limited by individual adherence. Optimizing the lighting environment during screen use may provide a standardized and practical approach to improving visual comfort.

This is a single-center, randomized, parallel-group controlled study designed to evaluate the effects of full-spectrum screen bar lighting during a standardized screen task. Eligible healthy adult participants with regular daily screen exposure will be randomly assigned in a 1:1 ratio to either a full-spectrum screen bar lighting group or a brightness-matched control group without screen bar lighting. Both groups will complete the same approximately 2-hour standardized screen task in a controlled laboratory environment. The task may include computer-based text processing, screen reading, or viewing specified video materials, with the task content, duration, and completion requirements kept consistent between groups.

Assessments will be performed before and immediately after the standardized screen task. The study will evaluate changes in objective and subjective measures of visual fatigue, ocular behavioral parameters, and dry eye-related indicators. These include critical flicker fusion frequency, visual fatigue questionnaire scores, eye movement, blinking and pupil parameters, tear film-related measurements, conjunctival redness, and dry eye symptom scores. Safety will be assessed by recording any discomfort or adverse events, such as glare discomfort, eye dryness, tearing, conjunctival redness, headache, nausea, or dizziness.

This study is expected to provide clinical evidence on whether full-spectrum screen bar lighting can help reduce screen-related visual fatigue and dry eye symptoms, and may support the development of lighting strategies for visual health in daily screen-use environments.

• Study Type: Interventional
• Enrollment (Estimated): 112
• Phase: Not Applicable

Contacts and Locations

Study Locations

• China
  • Guangdong
    • Guangzhou, Guangdong, China, 510060
      • Zhongshan Ophthalmic Center

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult
• Accepts Healthy Volunteers: Yes

Description

Inclusion Criteria:

1. Age 18 to 35 years, male or female.
2. Average daily electronic screen exposure of at least 4 hours.
3. Near visual acuity at 40 cm of 0.5 or better, and able to complete the study 1. tasks and measurements stably.
4. Able and willing to provide written informed consent.

Exclusion Criteria:

1. Presence of ocular inflammation or ocular disease.
2. History of severe systemic disease, neurological disease, or psychiatric disorder.
3. Pregnancy or lactation.
4. Use of dry eye or visual fatigue treatments, or contact lens wear, within 1 month before the study.
5. History of ocular surgery within the past 6 months.
6. Daily use of lenses with blue-light blocking, photochromic, polarized, filtering, or similar optical functions.
7. Professional background in ophthalmology or optical products.
8. Intake of caffeine or other stimulants within 4 hours before the study.
9. Best-corrected visual acuity (BCVA) less than 0.8.
10. Anisometropia of 1.00 diopter or greater, or astigmatism of ±2.00 diopters or greater.
11. Intraocular pressure (IOP) less than 5 mmHg or greater than 21 mmHg.
12. Non-invasive tear breakup time (NIBUT) less than 5 seconds in either eye.
13. Ocular Surface Disease Index (OSDI) score of 33 or greater.

Study Plan

How is the study designed?

Design Details

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

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Full-Spectrum Screen Bar Lighting; Participants assigned to this arm will complete an approximately 2-hour standardized screen task in a controlled laboratory environment using a full-spectrum screen bar light (MB23001032H-1B) as task lighting. The screen task may include computer-based text processing, screen reading, or viewing specified video materials. Task content, duration, and completion requirements will be kept consistent with the control arm.	Device: Full-spectrum screen bar light; The full-spectrum screen bar light will be used as task lighting during an approximately 2-hour standardized screen task in a controlled laboratory environment. Participants will complete computer-based text processing, screen reading, or viewing of specified video materials to simulate prolonged near-screen use.
Placebo Comparator: Brightness-Matched Control; Participants assigned to this arm will complete the same approximately 2-hour standardized screen task in the same controlled laboratory environment without using a full-spectrum screen bar light or any additional screen bar lighting. Screen brightness will be adjusted to match the brightness condition of the full-spectrum screen bar lighting arm. Task content, duration, and completion requirements will be kept consistent with the experimental arm.	Other: Brightness-matched screen task without screen bar lighting; Participants will complete the standardized screen task without using a screen bar light. Screen brightness will be adjusted to match the brightness condition of the full-spectrum screen bar lighting arm. The task type, content, duration, and completion requirements will be the same as those in the experimental arm.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change in Critical Flicker Fusion Frequency	Critical flicker fusion frequency (CFF) will be measured in Hz using the Handy Flicker HF-III device. The outcome will be calculated as the post-task CFF value minus the baseline CFF value. This measure will be used as an objective indicator of visual fatigue after the standardized screen task.	Baseline and immediately after completion of the approximately 2-hour standardized screen task

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change in Computer Vision Syndrome Questionnaire Score	The Computer Vision Syndrome Questionnaire (CVS-Q) will be used to assess subjective visual fatigue symptoms. The outcome will be calculated as the post-task total score minus the baseline total score.	Baseline and immediately after completion of the approximately 2-hour standardized screen task
Change in EyeFatigue Tracker Ocular Behavioral Parameters	Ocular behavioral parameters will be recorded using the EyeFatigue Tracker system during a standardized 1-minute reading task. The assessment will include eye movement, blink, and pupil-related parameters. Change values will be calculated as post-task values minus baseline values.	Baseline and immediately after completion of the approximately 2-hour standardized screen task
Change in Keratograph 5M Ocular Surface Assessment	Objective ocular surface and dry eye-related parameters will be measured using the Keratograph 5M system. The assessment will include non-invasive tear breakup time, tear meniscus height, and conjunctival redness. Change values will be calculated as post-task values minus baseline values.	Baseline and immediately after completion of the approximately 2-hour standardized screen task
Change in Eye Dryness Score on the 0-100 Visual Analog Scale	Eye dryness will be assessed using the Eye Dryness Score on a 0-100 visual analog scale. Participants will indicate the severity of eye dryness by placing a mark on a 100-mm horizontal line, where 0 represents no eye dryness and 100 represents the most severe eye dryness. Higher scores indicate worse symptoms. The change score will be calculated as the score immediately after the standardized screen task minus the baseline score. A positive change indicates worsening of eye dryness, whereas a negative change indicates improvement.	Baseline and immediately after completion of the approximately 2-hour standardized screen task

Collaborators and Investigators

• Sponsor: Zhongshan Ophthalmic Center, Sun Yat-sen University

Publications and helpful links

General Publications

• Chen H, Ratanapakorn T, Sukonpatip M, Asawaphureekorn S, Thinkhamrop W, Wang X, Eungpinichpong W. Effects of yoga facial massage on computer vision syndrome and ocular motor function: A randomised controlled trial. Complement Ther Med. 2025 Dec;95:103270. doi: 10.1016/j.ctim.2025.103270. Epub 2025 Oct 22.
• Ide T, Toda I, Miki E, Tsubota K. Effect of Blue Light-Reducing Eye Glasses on Critical Flicker Frequency. Asia Pac J Ophthalmol (Phila). 2015 Mar-Apr;4(2):80-5. doi: 10.1097/APO.0000000000000069.
• Singh S, Downie LE, Anderson AJ. Do Blue-blocking Lenses Reduce Eye Strain From Extended Screen Time? A Double-Masked Randomized Controlled Trial. Am J Ophthalmol. 2021 Jun;226:243-251. doi: 10.1016/j.ajo.2021.02.010. Epub 2021 Feb 12.
• Lin JB, Gerratt BW, Bassi CJ, Apte RS. Short-Wavelength Light-Blocking Eyeglasses Attenuate Symptoms of Eye Fatigue. Invest Ophthalmol Vis Sci. 2017 Jan 1;58(1):442-447. doi: 10.1167/iovs.16-20663.

Study record dates

Study Major Dates

• Study Start (Estimated): July 20, 2026
• Primary Completion (Estimated): December 31, 2026
• Study Completion (Estimated): December 31, 2026

Study Registration Dates

• First Submitted: July 9, 2026
• First Submitted That Met QC Criteria: July 9, 2026
• First Posted (Actual): July 15, 2026

Study Record Updates

• Last Update Posted (Actual): July 22, 2026
• Last Update Submitted That Met QC Criteria: July 20, 2026
• Last Verified: July 1, 2026

More Information

Terms related to this study

• Keywords: Dry Eye; Computer vision syndrome; Visual fatigue; Critical flicker fusion frequency; Full-spectrum
• Additional Relevant MeSH Terms: Eye Diseases; Lacrimal Apparatus Diseases; Dry Eye Syndromes; Asthenopia
• Other Study ID Numbers: SIT2026005

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No