Changes in Tear Lipid Layer Thickness After Short Exposure to Light Emitting Diode Displays
Condition: Lipid Tear Deficiency (Disorder); Dry Eye Disease
MeSH terms: Dry Eye Syndromes; Keratoconjunctivitis Sicca; Eye Diseases
Study type: Interventional

Summary: 
      Video display terminals (VDTs) are ubiquitous, and engagement in digital screens has grown
      substantially across all age groups worldwide. Prolonged exposure to VDTs is associated with
      the development of various health problems. By now, it is unclear whether transient exposure
      to VDTs leads to ocular surface changes, especially regarding lipid layer thickness (LLT).
      This study aim to determine if short-term exposure to light-emitting diodes (LEDs) leads to
      ocular parameter changes.

      This is a prospective, cross-sectional study. Patients were recruited at the National
      Cheng-Kung University Hospital, a tertiary referral center in southern Taiwan, for
      examination, including best-corrected visual acuity (BCVA), intraocular pressure (IOP), lipid
      layer thickness (LLT), and blink rates and patterns before and after watching an LED display
      for 15 minutes. The estimated result is that the LLT and blink rates will decrease after VDT
      watching.
    

Detailed description: 
      Video display terminals (VDTs) are ubiquitous, and engagement in digital screens has grown
      substantially across all age groups worldwide. During the coronavirus disease 2019 (COVID-19)
      pandemic, lockdowns and increasing demand for digital learning and working have led to more
      frequent and sustained VDT use. Prolonged exposure to VDTs is associated with the development
      of various health problems, including psychosocial issues, venous thromboembolism, fatigue,
      and visual complaints.

      Computer vision syndrome (CVS) is one of the most frequently encountered problems among VDT
      users. CVS comprises several visual and musculoskeletal symptoms resulting from VDT use, such
      as eye strain, dryness and burning sensation of the eye, blurred vision, and neck and
      shoulder pain. A major alteration is the development of dry eye disease (DED), occurring in
      60 % of those with CVS. Dry eye symptoms, corneal erosions, short tear-film breakup time
      (BUT), low tear meniscus height, and meibomian gland dysfunction (MGD) are all DED
      presentations encountered by VDT users. The continuous use of VDTs is an established risk
      factor for CVS and DED. However, it is unclear whether transient exposure to VDTs leads to
      ocular surface changes, especially regarding lipid layer thickness (LLT).

      This study investigated if the short-term use of light-emitting diode (LED) displays (one
      type of VDT) changed the ocular parameters, including best-corrected visual acuity (BCVA),
      intraocular ocular pressure (IOP), the CVS-Questionnaire (CVS-Q) score, the blink rate, the
      partial blink ratio, and LLT. To our knowledge, this is the first study to focus on the
      immediate effects of LEDs on the eye.

      This prospective clinical study was conducted in the Ophthalmology Department of the National
      Cheng Kung University Hospital (NCKUH), Tainan, Taiwan. The study was approved by the
      Institutional Review Board of NCKUH and followed the tenets of the Declaration of Helsinki.
      Written informed consent was obtained from all the participants.

      The inclusion criteria were generally healthy individuals aged between 20 and 65 years who
      were willing to participate in the study. The exclusion criteria were ages below 20 or over
      65 years, a BCVA score of <0.1 on the Landolt C chart in either eye, a BCVA difference of
      >0.2 between the eyes, and a history of ocular diseases or previous ocular surgery.

      Participants were instructed to fill out a basic information form, including their name, sex,
      age, and contact information. They were also informed to avoid wearing contact lenses for two
      days before the test. The experiment was conducted on August 22, 2020. For the baseline test,
      the participants were asked to complete the CVS-Q to assess their CVS. Next was a series of
      ocular examinations, including BCVA, IOP, LLT, an optical coherence tomography (OCT) scan of
      the macula, and fundus autofluorescence (FAF) imaging. The LLT and blink rates were measured
      using the LipiView II Ocular Surface Interferometer following the standard protocol
      (TearScience, Morrisville, NC, USA). After the examination, the participants watched a short
      movie on an LED screen (InnoLux, Taiwan) for 15 minutes in a bright room. The viewing
      distance was approximately 1.5 meters. After the movie ended, the participants were
      instructed to complete the CVS-Q and undergo the BCVA, IOP, and LLT tests again. The baseline
      BCVA, IOP, OCT, and FAF images of each participant were reviewed by three NCKUH
      ophthalmologists to screen for clinically significant ocular pathology.

      Statistical analyses were performed using R software version 4.1.0 (R Core Team, Vienna,
      Austria) and SAS Enterprise Guide (version 9.4; SAS Institute Inc., Cary, NC, USA). Paired
      t-tests were used to compare the BCVA, IOP, CVS-Q score, LLT, blink rate, and the partial
      blink ratio before and after watching the LED display. Statistical significance was set at P
      <0.05.
    

Intervention name(s): LED screen (InnoLux, Taiwan)
Intervention type(s): Device
Intervention description(s): Participants watch a short movie on an LED screen (InnoLux, Taiwan) for 15 minutes in a bright room. The viewing distance was approximately 1.5 meters.
Intervention model: Single Group Assignment
Masking: None (Open Label)
Primary purpose: Other
Keywords: Computer vision syndrome; Dry eye disease; Light emitting diode; Lipid layer thickness; Video display terminals