Effects of Blue-light Blocking Lens on Visual Functions
Conditions
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.
Interventions
DEVICEclear lens with regular coating
DEVICEregular coating lens with yellow tint
DEVICEclear lens with blue-light blocking coating
Sponsors
The Hong Kong Polytechnic University
Study design
Allocation
NON_RANDOMIZED
Intervention model
PARALLEL
Primary purpose
OTHER
Masking
SINGLE (Subject)
Eligibility
Sex/Gender
ALL
Age
18 Years to 55 Years
Healthy volunteers
Yes
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
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Contrast Sensitivity as Assessed by Mars Contrast Sensitivity Chart | 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. |
| Color Vision as Assessed by the Farnsworth Munsell 100 Hue Test | 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
| Measure | Time frame | Description |
|---|---|---|
| Self-assessment of Lens Performance Through Questionnaire | 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). |
Participant flow
Participants by arm
| Arm | Count |
|---|---|
| Young Adults adults without presbyopia who aged 18-35 years
Three spectacle lens designs: 1) clear lens with regular coating; 2) regular coating lens with yellow tint; 3) clear lens with blue-light blocking coating: 3 types of spectacle lenses were given to all participants: 1) clear lens with regular coating; 2) regular coating lens with yellow tint; 3) clear lens with blue-light blocking coating | 40 |
| Middle-aged Adults adults with presbyopia who aged over 40 years
Three spectacle lens designs: 1) clear lens with regular coating; 2) regular coating lens with yellow tint; 3) clear lens with blue-light blocking coating: 3 types of spectacle lenses were given to all participants: 1) clear lens with regular coating; 2) regular coating lens with yellow tint; 3) clear lens with blue-light blocking coating | 40 |
| Total | 80 |
Baseline characteristics
| Characteristic | Young Adults | Middle-aged Adults | Total |
|---|---|---|---|
| Age, Categorical <=18 years | 0 Participants | 0 Participants | 0 Participants |
| Age, Categorical >=65 years | 0 Participants | 0 Participants | 0 Participants |
| Age, Categorical Between 18 and 65 years | 40 Participants | 40 Participants | 80 Participants |
| Sex: Female, Male Female | 21 Participants | 29 Participants | 50 Participants |
| Sex: Female, Male Male | 19 Participants | 11 Participants | 30 Participants |
Adverse events
| Event type | EG000 affected / at risk | EG001 affected / at risk |
|---|---|---|
| deaths Total, all-cause mortality | — / — | — / — |
| other Total, other adverse events | 0 / 0 | 0 / 0 |
| serious Total, serious adverse events | 0 / 0 | 0 / 0 |
Outcome results
Primary
Color Vision as Assessed by the Farnsworth Munsell 100 Hue Test
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.
Time frame: Every 1-month interval from the date of randomization, up to 3 months
| Arm | Measure | Value (MEAN) | Dispersion |
|---|---|---|---|
| Young Adults: Clear Lens With Regular Coating | Color Vision as Assessed by the Farnsworth Munsell 100 Hue Test | 30.8 units on a scale | Standard Error 3.34 |
| Young Adults: Regular Coating Lens With Yellow Tint | Color Vision as Assessed by the Farnsworth Munsell 100 Hue Test | 33.3 units on a scale | Standard Error 3.36 |
| Young Adults: Clear Lens With Blue-light Blocking Coating | Color Vision as Assessed by the Farnsworth Munsell 100 Hue Test | 30.1 units on a scale | Standard Error 3 |
| Middle-aged Adults: Clear Lens With Regular Coating | Color Vision as Assessed by the Farnsworth Munsell 100 Hue Test | 49.1 units on a scale | Standard Error 5.49 |
| Middle-aged Adults: Regular Coating Lens With Yellow Tint | Color Vision as Assessed by the Farnsworth Munsell 100 Hue Test | 54.65 units on a scale | Standard Error 4.66 |
| Middle-aged Adults: Clear Lens With Blue-light Blocking Coatin | Color Vision as Assessed by the Farnsworth Munsell 100 Hue Test | 52.4 units on a scale | Standard Error 5.21 |
Primary
Contrast Sensitivity as Assessed by Mars Contrast Sensitivity Chart
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.
Time frame: Every 1-month interval from the date of randomization, up to 3 months
| Arm | Measure | Group | Value (MEAN) | Dispersion |
|---|---|---|---|---|
| Young Adults: Clear Lens With Regular Coating | Contrast Sensitivity as Assessed by Mars Contrast Sensitivity Chart | without glare | 1.866 log contrast sensitivity score | Standard Error 0.004 |
| Young Adults: Clear Lens With Regular Coating | Contrast Sensitivity as Assessed by Mars Contrast Sensitivity Chart | with glare | 1.817 log contrast sensitivity score | Standard Error 0.015 |
| Young Adults: Regular Coating Lens With Yellow Tint | Contrast Sensitivity as Assessed by Mars Contrast Sensitivity Chart | without glare | 1.861 log contrast sensitivity score | Standard Error 0.005 |
| Young Adults: Regular Coating Lens With Yellow Tint | Contrast Sensitivity as Assessed by Mars Contrast Sensitivity Chart | with glare | 1.802 log contrast sensitivity score | Standard Error 0.032 |
| Young Adults: Clear Lens With Blue-light Blocking Coating | Contrast Sensitivity as Assessed by Mars Contrast Sensitivity Chart | without glare | 1.856 log contrast sensitivity score | Standard Error 0.008 |
| Young Adults: Clear Lens With Blue-light Blocking Coating | Contrast Sensitivity as Assessed by Mars Contrast Sensitivity Chart | with glare | 1.777 log contrast sensitivity score | Standard Error 0.035 |
| Middle-aged Adults: Clear Lens With Regular Coating | Contrast Sensitivity as Assessed by Mars Contrast Sensitivity Chart | without glare | 1.818 log contrast sensitivity score | Standard Error 0.014 |
| Middle-aged Adults: Clear Lens With Regular Coating | Contrast Sensitivity as Assessed by Mars Contrast Sensitivity Chart | with glare | 1.759 log contrast sensitivity score | Standard Error 0.019 |
| Middle-aged Adults: Regular Coating Lens With Yellow Tint | Contrast Sensitivity as Assessed by Mars Contrast Sensitivity Chart | without glare | 1.799 log contrast sensitivity score | Standard Error 0.016 |
| Middle-aged Adults: Regular Coating Lens With Yellow Tint | Contrast Sensitivity as Assessed by Mars Contrast Sensitivity Chart | with glare | 1.768 log contrast sensitivity score | Standard Error 0.018 |
| Middle-aged Adults: Clear Lens With Blue-light Blocking Coatin | Contrast Sensitivity as Assessed by Mars Contrast Sensitivity Chart | without glare | 1.802 log contrast sensitivity score | Standard Error 0.013 |
| Middle-aged Adults: Clear Lens With Blue-light Blocking Coatin | Contrast Sensitivity as Assessed by Mars Contrast Sensitivity Chart | with glare | 1.785 log contrast sensitivity score | Standard Error 0.017 |
Secondary
Self-assessment of Lens Performance Through Questionnaire
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).
Time frame: Every 1-month interval from the date of randomization, up to 3 months
| Arm | Measure | Group | Value (COUNT_OF_PARTICIPANTS) |
|---|---|---|---|
| Young Adults: Clear Lens With Regular Coating | Self-assessment of Lens Performance Through Questionnaire | clear lens with regular coating | 20 Participants |
| Young Adults: Clear Lens With Regular Coating | Self-assessment of Lens Performance Through Questionnaire | regular coating lens with yellow tint | 1 Participants |
| Young Adults: Clear Lens With Regular Coating | Self-assessment of Lens Performance Through Questionnaire | clear lens with blue-light blocking coating | 19 Participants |
| Young Adults: Regular Coating Lens With Yellow Tint | Self-assessment of Lens Performance Through Questionnaire | clear lens with regular coating | 9 Participants |
| Young Adults: Regular Coating Lens With Yellow Tint | Self-assessment of Lens Performance Through Questionnaire | regular coating lens with yellow tint | 7 Participants |
| Young Adults: Regular Coating Lens With Yellow Tint | Self-assessment of Lens Performance Through Questionnaire | clear lens with blue-light blocking coating | 24 Participants |