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Effects of Blue-light Blocking Lens on Visual Functions

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ClinicalTrials.gov Identifier: NCT02821403
Recruitment Status : Completed
First Posted : July 1, 2016
Results First Posted : April 7, 2017
Last Update Posted : April 7, 2017
Sponsor:
Information provided by (Responsible Party):
The Hong Kong Polytechnic University

Brief Summary:

Working Hypothesis: The blue-light blocking lens has no effect on the contrast sensitivity, accommodative response, color vision, and subjective grading of the quality of life and vision.

Purpose: To determine and compare the visual performances after wearing the blue-light blocking lenses in participants with and without presbyopia.

Methods: One hundred and sixty computer users (computer usage >2 hours/day) with (n=120, aged >40years) and without presbyopia (n=40, aged 18-35 years) will be recruited. Three pairs of ophthalmic lenses will be prescribed for the participants, in which one pair of them will be the blue-light blocking lenses (StressFree, Swisscoat, HK). The lenses will be used for intermediate vision (i.e., computer usage) in presbyopic group, and for distant vision in non-presbyopic group. The adaptation period for each pair of lenses will be 1 month. The pre- and post-treatment contrast sensitivity, accommodative response and color vision will be measured. The participants will also be asked to complete questionnaires about their quality of life and vision, and the performances of these ophthalmic lenses.

Significance: The blue-light blocking lens reflects the short-wavelength lights and protects the retina from "blue-light hazards"; however, blue lights are essential for various visual function and circadian rhythms. This study will evaluate the impact of the blue-light blocking lenses on visual function and quality of life, and determine whether the blue-light blocking lenses are good choices for extra ocular protection.


Condition or disease Intervention/treatment Phase
Effects of Blue-light Blocking Lens on Visual Functions Device: clear lens with regular coating Device: regular coating lens with yellow tint Device: clear lens with blue-light blocking coating Not Applicable

Study Type : Interventional  (Clinical Trial)
Actual Enrollment : 80 participants
Allocation: Non-Randomized
Intervention Model: Parallel Assignment
Masking: Single (Participant)
Primary Purpose: Other
Study Start Date : July 2014
Actual Primary Completion Date : May 2015
Actual Study Completion Date : May 2015

Arm Intervention/treatment
Experimental: Young adults
adults without presbyopia who aged 18-35 years
Device: clear lens with regular coating
Device: regular coating lens with yellow tint
Device: clear lens with blue-light blocking coating
Experimental: Middle-aged adults
adults with presbyopia who aged over 40 years
Device: clear lens with regular coating
Device: regular coating lens with yellow tint
Device: clear lens with blue-light blocking coating



Primary Outcome Measures :
  1. Contrast Sensitivity as Assessed by Mars Contrast Sensitivity Chart [ Time Frame: Every 1-month interval from the date of randomization, up to 3 months ]

    Contrast sensitivity was measured using the Mars contrast sensitivity letter chart (Mars Perceptrix, Chappaqua, NY). One out of three charts differing in the letter combinations was selected randomly in order to avoid memorization of the charts. The chart was placed at 50 cm with each letter subtended 2° visual angle. We followed the recording procedures as specified by the manufacturer: participants were instructed to read the letters from high to low contrasts and the test ended when two consecutive errors were made. The contrast sensitivity was scored as the log contrast sensitivity of the last correct letter minus 0.04 log unit for every prior error. The test was administered under normal (room illumination, 400 lux) and glare conditions. A brightness acuity tester set at its medium light intensity level (100 foot lamberts) simulated the glaring condition.

    A higher mean indicates improved contrast sensitivity.


  2. Color Vision as Assessed by the Farnsworth Munsell 100 Hue Test [ Time Frame: Every 1-month interval from the date of randomization, up to 3 months ]

    The Farnsworth Munsell 100 hue test (X-Rite, USA) was used to evaluate colour vision. Each of the four trays consisted of 21 movable caps. Participants were asked to sort the randomly arranged caps following the hue order from the first to the last fixed caps. The total error score was calculated, as documented in the instruction manual, to quantify the accuracy of color discrimination.

    There are no defined endpoints to the "total error score" range.

    A lower score indicates improved color discrimination ability.



Secondary Outcome Measures :
  1. Self-assessment of Lens Performance Through Questionnaire [ Time Frame: Every 1-month interval from the date of randomization, up to 3 months ]

    After each monthly wearing period (visits 3-5), the participants' lens performance, night vision quality and sleep quality (total 13 questions) were assessed subjectively using a questionnaire (scoring from 1 [very unsatisfactory] to 5 [very satisfactory]).

    At the end of the study, the participants were asked to choose their preferred lens type among the three pairs of lenses based on their subjective feeling of the "best lens type" (i.e., either clear lens, yellow tinted lens or blue-filtering coated lens).

    To make it clear and simple, here we only present the data on the participants choice of their preferred lens type (i.e., simply choosing the "best lens" among clear lens, yellow tinted lens or blue-filtering coated lens).




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Ages Eligible for Study:   18 Years to 55 Years   (Adult)
Sexes Eligible for Study:   All
Accepts Healthy Volunteers:   Yes
Criteria

Inclusion Criteria:

  • age: 18 to 35 years OR 40 to 55 years
  • daily computer usage over over 2 hours per day

Exclusion Criteria:

  • visual acuity worst than 0 logMAR
  • abnormal binocular and color vision
  • previous history of ocular surgeries

Study Data/Documents: Study Protocol  This link exits the ClinicalTrials.gov site

Publications:
Publications automatically indexed to this study by ClinicalTrials.gov Identifier (NCT Number):
Responsible Party: The Hong Kong Polytechnic University
ClinicalTrials.gov Identifier: NCT02821403     History of Changes
Other Study ID Numbers: HSEARS20140512001-03
First Posted: July 1, 2016    Key Record Dates
Results First Posted: April 7, 2017
Last Update Posted: April 7, 2017
Last Verified: June 2016
Individual Participant Data (IPD) Sharing Statement:
Plan to Share IPD: Undecided