Short-Wavelength Light-Blocking Eyeglasses Attenuate Symptoms of Eye Fatigue

Abstract

Purpose:
The purpose of this study was to determine whether subjects who wear short wavelength-blocking eyeglasses during computer tasks exhibit less visual fatigue and report fewer symptoms of visual discomfort than subjects wearing eyeglasses with clear lenses.

Methods:
A total of 36 healthy subjects (20 male; 16 female) was randomized to wearing no-block, low-blocking, or high-blocking eyeglasses while performing a 2-hour computer task. A masked grader measured critical flicker fusion frequency (CFF) as a metric of eye fatigue and evaluated symptoms of eye strain with a 15-item questionnaire before and after computer use.

Results:
We found that the change in CFF after the computer task was significantly more positive (i.e., less eye fatigue) in the high-block versus the no-block (P = 0.027) and low-block (P = 0.008) groups. Moreover, random assignment to the high-block group but not to the low-block group predicted a more positive change in CFF (i.e., less eye fatigue) following the computer task (adjusted β = 2.310; P = 0.002). Additionally, subjects wearing high-blocking eyeglasses reported significantly less feeling pain around/inside the eye (P = 0.0063), less feeling that the eyes were heavy (P = 0.0189), and less feeling that the eyes were itchy (P = 0.0043) following the computer task, when compared to subjects not wearing high-blocking lenses.

Conclusions:
Our results support the hypothesis that short-wavelength light-blocking eyeglasses may reduce eye strain associated with computer use based on a physiologic correlate of eye fatigue and on subjects' reporting of symptoms typically associated with eye strain.

Full text

Clinical and Epidemiologic Research
Short-Wavelength Light-Blocking Eyeglasses Attenuate
Symptoms of Eye Fatigue
Jonathan B. Lin,
1,2
Blair W. Gerratt,
3
Carl J. Bassi,
3
and Rajendra S. Apte
1,4,5
1
Department of Ophthalmology & Visual Sciences, Washington University School of Medicine, St. Louis, Missouri, United States
2
Neuroscience Graduate Program, Division of Biology and Biomedical Sciences, Washington University School of Medicine, St.
Louis, Missouri, United States
3
College of Optometry, University of Missouri–St. Louis, St. Louis, Missouri, United States
4
Department of Developmental Biology, Washington University School of Medicine, St. Louis, Missouri, United States
5
Department of Medicine, Washington University School of Medicine, St. Louis, Missouri, United States
Correspondence: Rajendra S. Apte,
660 South Euclid Avenue, Box 8096,
St. Louis, MO 63110, USA;
apte@vision.wustl.edu.
Carl J. Bassi, College of Optometry,
University of Missouri–St. Louis, One
University Boulevard, St. Louis, MO
63121, USA;
bassi@umsl.edu.
Submitted: September 1, 2016
Accepted: December 5, 2016
Citation: Lin JB, Gerratt BW, Bassi CJ,
Apte RS. Short-wavelength light-
blocking eyeglasses attenuate symp-
toms of eye fatigue. Invest Ophthal-
mol Vis Sci. 2017;58:442–447. DOI:
10.1167/iovs.16-20663
PURPOSE.The purpose of this study was to determine whether subjects who wear short
wavelength–blocking eyeglasses during computer tasks exhibit less visual fatigue and report
fewer symptoms of visual discomfort than subjects wearing eyeglasses with clear lenses.
METHODS.A total of 36 healthy subjects (20 male; 16 female) was randomized to wearing no-
block, low-blocking, or high-blocking eyeglasses while performing a 2-hour computer task. A
masked grader measured critical flicker fusion frequency (CFF) as a metric of eye fatigue and
evaluated symptoms of eye strain with a 15-item questionnaire before and after computer use.
RESULTS.We found that the change in CFF after the computer task was significantly more
positive (i.e., less eye fatigue) in the high-block versus the no-block (P¼0.027) and low-block
(P¼0.008) groups. Moreover, random assignment to the high-block group but not to the
low-block group predicted a more positive change in CFF (i.e., less eye fatigue) following the
computer task (adjusted b¼2.310; P¼0.002). Additionally, subjects wearing high-blocking
eyeglasses reported significantly less feeling pain around/inside the eye (P¼0.0063), less
feeling that the eyes were heavy (P¼0.0189), and less feeling that the eyes were itchy (P¼
0.0043) following the computer task, when compared to subjects not wearing high-blocking
lenses.
CONCLUSIONS.Our results support the hypothesis that short-wavelength light-blocking
eyeglasses may reduce eye strain associated with computer use based on a physiologic
correlate of eye fatigue and on subjects’ reporting of symptoms typically associated with eye
strain.
Keywords: eye fatigue, eye strain, blue light, VDT, CVS
Blue light has the most energy of all light in the visible
electromagnetic spectrum. Although there is irradiance of
blue light from the sun at the Earth’s surface, our society’s
increasing use of technology has led to a significant increase in
daily exposure to this short-wavelength light. For example, the
majority of today’s computer screens and televisions use liquid
crystal displays (LCDs), which emit far more blue light than
cathode ray tube (CRT) displays. In addition, the now-popular
light-emitting diodes (LEDs) and fluorescent lights also emit
more short-wavelength light compared to their incandescent
predecessors. Of concern, past studies have reported that
short-wavelength light has a greater and often more hazardous
effect on human physiology compared to visible light of other
wavelengths.
1,2
Light toxicity to the retina is well established and occurs
when excess light exposure causes photochemical, photome-
chanical, and photothermal damage.
3
Some groups have
reported that short-wavelength light may be particularly
hazardous to the retina. For example, Kuse et al.
4
found that
visible light-induced damage in photoreceptor-derived cells is
wavelength-dependent: short-wavelength light in the blue
spectrum had a more severe toxic effect compared to either
white or green light. These findings are consistent with other
studies showing that retinal damage induced by LEDs in animal
models show similar wavelength dependence.
5
Other groups
have shown that this phototoxicity can be attenuated by
blocking blue light in cell models
6
and in animal models.
7
Although human exposure to short-wavelength light generally
is chronic and subthreshold rather than acute and suprathresh-
old, as is typical for most these animal models, these studies
implicate short-wavelength light as pathologic. Future studies
not only will explore the effects of chronic exposure to blue
light but also will identify the characteristics of blue light that
yield these toxic effects.
Some human studies have shown that chronic subthreshold
exposure to blue light may, indeed, have clinically relevant
consequences. For example, although short-wavelength light
also has been shown to be important for setting circadian
rhythms,
8
excessive exposure to blue light also has been
suggested to be a major cause of eye strain.
9
Consistently, Isono
et al.
10
reported that short wavelength-emitting devices
contribute to visual fatigue. In fact, prolonged use of short-
wavelength light-emitting devices can result in a constellation
of symptoms, which are now recognized as Visual Display
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Terminal (VDT) Syndrome and Computer Vision Syndrome
(CVS). Numerous groups have explored the possibility that
lenses that block short-wavelength light may reduce these
health hazards. Ayaki et al.
11
demonstrated that wearing short-
wavelength light-reducing eyeglasses when using electronic
devices at night improves sleep quality and increases overnight
melatonin secretion. Similarly, Ide et al.
12
found that wearing
short-wavelength light-blocking eyeglasses during intensive
computer tasks reduces eye fatigue and symptoms of eye
strain.
Nonetheless, no study to our knowledge has tested this
question rigorously in a North American population. In this
study, we performed a single-center, randomized study to
determine whether North American subjects who wear short-
wavelength light-blocking eyeglasses during a 2-hour computer
task exhibit less visual fatigue and report fewer symptoms of
visual discomfort than subjects wearing eyeglasses with clear
lenses.
MATERIALS AND METHODS
Subjects
We recruited 36 subjects at the College of Optometry at
University of Missouri–St. Louis. Demographic characteristics
are shown in Table 1. All participants gave written informed
consent. All procedures conformed to the Declaration of
Helsinki and were approved by the Institutional Review Board
of University of Missouri–Saint Louis. The inclusion criteria
included being a healthy (no known significant health
problems) volunteer, being male or female of any ethnic group
between 21 and 39 years of age, having uncorrected vision or
contact lens–corrected vision of 20/30 or better with both eyes
open, not having performed VDT work for at least 1 hour
before testing, and not having known visually significant
ophthalmic pathology, such as cataracts, macular degeneration,
glaucoma, eye surgeries, or injuries based on self-reported
history. Subjects were excluded if they were <21 or ‡40 years
of age; had uncorrected vision or contact lens–corrected vision
worse than 20/30 with both eyes open; self-reported a
concurrent eye injury or disease; had photosensitivity, which
would preclude them from comfortably performing 2 hours of
VDT work; had been diagnosed with epilepsy; or had
previously suffered a seizure. We confirmed that all subjects
had binocular visual acuity of 20/30 or better with a Snellen
chart.
Critical Flicker Fusion Frequency (CFF)
Measurements and Eye Strain Questionnaire
The primary outcome measure was the difference between the
pre- and posttask CFF, i.e., change in CFF after the task. A
reduction in CFF is associated with eye fatigue.
11,13,14
We
measured CFF before and after the task with the Handy Flicker
HF-II (Neitz Instrument, Tokyo, Japan), which emits a blinking
light whose frequency can be varied from 1 to 79 Hz. We
measured ascending and descending thresholds and averaged
these values to calculate the pre- and posttask CFF for each
subject. Study subjects did not wear the eyeglasses during CFF
measurements to ensure that the study personnel taking these
measurements were not biased by knowledge of group
assignment.
Additionally, we evaluated symptoms related to eye strain
with a 15-item questionnaire (Appendix A), adapted from a
previous study.
12
Subjects reported their responses on a Likert
scale (1, never; 2, rarely; 3, cannot say either way; 4, a little; 5,
very much) and were permitted to respond with noninteger
responses. We calculated the difference between the pre- and
posttask responses, such that a positive change in score
corresponds with an increase in eye strain, while a negative
change in score corresponds with a decrease in eye strain.
Although we also included two yes/no questions to assess eye
dryness (Question #6) and the sensation of a foreign body in
the eye (Question #7), we did not include these questionnaire
items in our analysis due to significant nonresponse by the
participants on these questions.
Computer Task
Subjects were assigned randomly based on a predetermined
schedule to one of the three lens groups: control lenses, low-
blocking lenses, and high-blocking lenses. Since the blocking
lenses can be identified potentially by their tint/color, the
manufacturer packaged the eyeglasses in opaque boxes that
TABLE 1. Demographic Information of Study Subjects
Demographic Variable No Block Low Block High Block PValue
Age, mean 6SD 23.25 60.75 24.58 61.38 25.00 62.73 0.012*
Sex, N
Male 9 5 6 0.232†
Female 3 7 6
Race/ethnicity, N
Caucasian 11 11 11 1.00‡
African-American 0 1 0
Asian 1 0 1
Contact lens use, N
Yes 6 5 8 0.458†
No 6 7 4
Sleep/night, mean 6SD 7.25 60.87 6.96 60.81 7.58 60.79 0.193§
Computer use/wk, mean 6SD 37.58 619.29 40.67 616.88 39.92 614.10 0.897§
N, number of subjects in each category.
* Significant by 1-way ANOVA with Welch correction; Games-Howell post hoc test revealed that the no-block group was significantly different
from the low-block group.
† Nonsignificant by the v
2
test.
‡ Nonsignificant by the Freeman-Halton extension of the Fisher exact test.
§ Nonsignificant by 1-way ANOVA.
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were marked with only a serial number to permit proper
randomization. We tested the lenses according to standard EN
ISO 12311:2013 and EN ISO 12312:2013: the transmission
spectra for each of the three lenses based on these testing
standards are shown in Figure 1, and the blue-range cuts are
shown in Table 2. Eyeglasses with these particular low- and
high-blocking lenses are available commercially from JINS CO.,
LTD as the JINS Screen Clear and JINS Screen Night models,
respectively. Because all study subjects had uncorrected or
contact lens-corrected vision of 20/30 or better, the eyeglasses
did not correct refractive error. Study subjects were blinded to
their group assignments until completion of all data collection.
For the computer task, subjects were instructed to place
the glasses over their eyes and to continuously use a laptop
computer VDT for 2 hours to view videos or to engage in
games. The examination room and testing conditions were
standardized for all subjects: the same laptops were used,
which all had the same 1366- 3768-pixel screen resolution
with a 60 Hz refresh rate; and the ambient room illumination
was set at 350 lux. Study personnel monitored subjects to
ensure compliance with the protocol and to time each session.
We tested all subjects in late morning through early afternoon
to minimize confounding effects of the time of day.
Statistics
We use d G * P o wer 3.1
15
to perform an a priori power
calculation to determine the appropriate sample size. To
detect a significant difference between the groups at the two-
sided a¼0.05 level with an estimated effect size f of 0.8 based
on a previous study
12
and 95% power, we calculated that we
needed to recruit 30 subjects. To account for up to 20% drop
out, we recruited 36 subjects in total; that is,12 per group. We
performed statistics with GraphPad Prism 5.0 (La Jolla, CA,
USA) and IBM SPSS Version 18.0 (Armonk, NY, USA). To
compare categorical variables, we used the v
2
test of
Independence. For race/ethnicity, we used the Freeman-Halton
extension of the Fisher exact test to account for sparse
expected cell values. To compare three means, we used the 1-
way ANOVA with Tukey HSD post hoc test. To compare the
changes in the scores after the task on the questionnaire items,
we used the Mann-Whitney Utest. As needed, we assessed the
normality of the data graphically and with the Kolmogorov-
Smirnov test. To determine whether variables significantly
differed from 0, we used the 1-sample t-test or the 1-sample
Wilcoxon signed-rank test. To determine whether wearing low-
blocking or high-blocking eyeglasses during the computer task
attenuated eye fatigue as measured by the change in CFF after
computer use after adjusting for possible confounding
variables, we generated a multivariable linear regression
model. Our model included forced entry of the following
predictor variables: age, sex, contact lens use (dichotomized as
yes or no), and lens group assignment (dummy-coded as two
dichotomous variables to indicate assignment to one of three
groups). We considered P<0.05 to be statistically significant.
RESULTS
There were no differences among the three groups based on
sex or race/ethnicity (Table 1). Although subjects were
randomized to each lens group, post hoc testing revealed that
there was a statistically significant difference between the ages
of the subjects randomly assigned to the no-block and low-
block groups (P¼0.024), but no statistically significant
differences in age (P>0.05) between any other pairs of
groups (Table 1). Furthermore, there were no differences
between the groups with regard to their average number of
hours of sleep per night, their average weekly computer use,
or whether they wore contact lenses (Table 1).
We calculated the change in CFF after the computer task for
each subject by subtracting the pretask CFF from the posttask
CFF such that a negative change in CFF corresponds with an
increase in eye fatigue. There was a significant difference in the
change in CFF after the computer task among the three lens
groups (F
2,33
¼6.035, P¼0.006). Although there was no
difference in the change in CFF between the no- and low-block
groups (P¼0.869), the change in CFF in the high-block group
was significantly less negative than in the no- and low-block
groups (P¼0.027 and 0.008, respectively; Fig. 2), indicating
that the high-blocking eyeglasses indeed attenuated eye fatigue
associated with computer use. In fact, our secondary analysis
revealed the change in CFF after the computer task was
significantly greater than 0 in the high-block group (t
11
¼2.976,
P¼0.013), suggesting that subjects wearing high-blocking
eyeglasses had even less fatigue after compared to before the
task. These findings supported our hypothesis that blue-
blocking eyeglasses reduced eye fatigue associated with
excessive blue light exposure.
Although we randomly assigned subjects to each of the
three lens groups, we observed a statistically significant
TABLE 2. Blue-Range Cut (%) of Lenses Used in This Study as Measured
According to the EN ISO 12311:2013 and EN ISO 12312:2013 Testing
Standards
Level of Blue Block Blue-Range Cut (%)
No block 3.2
Low block 24.2
High block 60.0
FIGURE 2. Subjects wearing high-blocking eyeglasses had a significant-
ly less negative change in CFF (negative change ¼more eye fatigue)
after the computer task compared to subjects wearing either the no-
blocking or low-blocking eyeglasses. Horizontal tick marks denote
individual data points; vertical lines depict group means 6SEM.
FIGURE 1. Transmission spectra of the no-blocking, low-blocking, and
high-blocking lenses as measured according to the EN ISO 12311:2013
and EN ISO 12312:2013 testing standards.
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difference in baseline CFF when comparing subjects assigned
to each of the lens groups (F
2,33
¼6.827, P¼0.003): subjects in
the high-block group had lower baseline CFF compared to
subjects in the low-block group (P¼0.002). These findings
suggested that confounding variables may affect our results. To
adjust our results for potential confounding variables, we
generated a multivariable linear regression model to determine
whether assignment to the low-block or high-block lens groups
was associated with more positive changes in CFF after
adjusting for age, sex, and contact lens use. After controlling
for these covariates, assignment to the high-block group was
still a significant predictor of a more positive change in CFF
(adjusted b¼2.310; 95% confidence interval [CI]: 0.959 –
3.661; P¼0.002; Table 3). In contrast, assignment to the low-
block group was not a significant predictor of the change in
CFF (adjusted b¼0.145; 95% CI: 1.193 – 1.484; P¼0.826;
Table 3). Our final model had an R
2
of 0.457, indicating good
explanatory power. Overall, these findings supported our
assertion that high-blocking glasses do, indeed, appear to
attenuate eye fatigue associated with computer use, even after
controlling for confounding variables, such as age, sex, and
contact lens use.
Additionally, we collected pre- and posttask information on
symptoms of eye strain (Appendix A). Since there was no
statistically significant difference between the no- and low-
block groups based on CFF changes, we pooled these subjects
for further analysis to determine whether the significant
change in CFF scores in the high-block group corresponded
with improvement of symptoms of eye strain. For each subject,
we calculated a change in symptom score by subtracting the
pretask symptom score from the posttask symptom score such
that a less positive change in symptom score would indicate a
reduction of eye strain associated with computer use. Of
interest, the high-block group exhibited a significantly more
negative change in symptom score on three of the question-
naire items related to pain around or inside the eyes (U¼
70.50, P¼0.0063; Question #11; Fig. 3A), the eyes feeling
heavy (U¼79.50, P¼0.0189; Question #14; Fig. 3B), and the
eyes feeling itchy (U¼66.00, P¼0.0043; Question #15; Fig.
3C). In fact, secondary analysis revealed that the change in
score for two of these questionnaire items (Questions #11 and
#15) was significantly less than 0 in the high-block group (P¼
0.034 and 0.006, respectively), suggesting that subjects
wearing high-blocking eyeglasses reported less pain around
or inside the eye and less feelings of itchy eyes after the task
compared to their baseline.
Moreover, although not statistically significant, there were
clear trends (0.05 <P<0.10) for three other questionnaire
items with the high-block group being associated with a less
positive change in score, indicating ‘‘less’’ eye strain, including
those related to the eyes feeling tired (U¼91.50, P¼0.0669;
Question #1; Fig. 4A), finding it hard to focus eyesight when
doing work at the desk or at the computer (U¼99.00, P¼
0.0862; Question #2; Fig. 4B), and feeling tired when doing
work at a desk or at a computer (U¼97.50, P¼0.0656;
Question #5; Fig. 4C). There were no statistically significant
differences or trends for the other questionnaire items (Figs.
4D–J). Cumulatively, these findings supported our hypothesis
that short wavelength–blocking eyeglasses may reduce specific
symptoms of eye strain associated with computer use.
DISCUSSION
The results from our randomized study suggested that high-
blocking eyeglasses reduce eye fatigue associated with
computer use as measured quantitatively by the change in
CFF after the 2-hour computer task. Moreover, subjects
wearing high-blocking eyeglasses also reported fewer symp-
toms associated with eye strain after computer use compared
to subjects not wearing the high-blocking eyeglasses. These
findings not only validated past studies that have reported that
short-wavelength light-blocking eyewear may attenuate eye
strain,
11,12
but also extended these findings to a North
American population. In addition, although a formal double-
blind study design is impossible given the nature of the
experiment, our rigorous study design, including careful
control of experimental conditions (e.g., monitoring subjects
for the duration of the task, standardizing testing room
conditions, testing subjects at roughly the same time of day),
minimized the risks of potential confounding factors.
We did not find a statistically significant improvement in eye
fatigue when comparing the eyeglasses with low-blocking
lenses to those with the control lens, despite the fact that our a
priori power calculations suggested that our study was
TABLE 3. Beta Coefficients From Multivariable Linear Regression With
Predictor Variables of Age, Sex, Contact Lens Use, and Lens Group, and
the Dependent Variable of Change in CFF Following the Computer
Task (More Negative Change in CFF ¼More Eye Fatigue)
Predictor Variable Adjusted b95% CI of bPValue
Age 0.398 0.684 to 0.112 0.008
Sex, 1 ¼female 0.306 0.759 to 1.370 0.562
Contact lens use 0.607 0.427 to 1.640 0.240
Lens group
Low-block 0.145 1.193 to 1.484 0.826
High-block 2.310 0.959 to 3.661 0.002
FIGURE 3. Subjects wearing high-blocking eyeglasses during the computer task had a significantly less positive change in symptom score (positive
change ¼more eye strain) on questions related to pain around or inside the eye (A), heaviness of the eyes (B), and itchiness of the eyes (C),
compared to subjects not wearing the high-blocking eyeglasses. Horizontal tick marks denote individual data points; vertical lines depict group
medians (A–C).
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sufficiently powered to detect such a difference if it existed.
However, it remains possible that low-blocking lenses have a
beneficial effect that would have become apparent if subjects
were challenged by a brighter short-wavelength light stimulus
or a longer duration of exposure. Further studies are necessary
to explore the proper level of short-wavelength light attenu-
ation to minimize the health hazards associated with blue light
while permitting sufficient blue light transmission to allow it to
perform its normal physiologic functions.
Although study subjects did not wear the eyeglasses during
the CFF measurements to ensure study personnel were masked
to group assignments, we cannot rule out the possibility that
the subjects themselves may have noticed the visual appear-
ance of their glasses. Although the control eyeglasses with the
no-block lenses were constructed in a way to make them as
similar as possible to the eyeglasses with low- and high-block
lenses, the high-blocking lenses have a brown color, and the
low-blocking lenses have a subtle blue-light reflection espe-
FIGURE 4. There were clear trends (0.05 <P<0.10) with subjects wearing high-blocking eyeglasses having a less positive change in symptom
score (positive change ¼more eye strain) on questions related to tiredness of the eyes (A), difficulty focusing eyesight when doing work at a
computer or at a desk (B), and tiredness when doing work at a computer or at a desk (C). (D–J) There were no significant differences or trends for
the remaining questionnaire items. Horizontal tick marks denote individual data points; vertical lines depict group medians (A–J).
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cially when viewed under the light, making it impossible to
completely mask the subjects. However, given that the subjects
were not provided an opportunity to compare their eyeglasses
to those provided to the other groups, it is unlikely that this
limitation would have affected our results.
Moreover, although we randomized the subjects to each
lens group, we had a serendipitous difference in age in the low-
block group compared to the no-block group. In addition, the
baseline CFF in the high-block group was lower than that of
the low-block group, suggesting that randomization may not
have been sufficient to account for all confounding factors. To
account for this possibility, we generated a multivariable linear
regression model to adjust our results for age, sex, and contact
lens use. These adjusted results confirmed our findings by
showing that assignment to the high-block group still
predicted a more positive change in CFF after the computer
task after controlling for these covariates. Nonetheless, future
studies with a larger sample size and/or studies using a ‘‘ within-
subjects,’’ repeated-measures study design may be necessary to
completely eliminate the possibility that unidentified con-
founding factors affected our findings.
As with any study of this size, it is difficult to generalize
broadly based on our results alone. However, our findings
provided a strong foundation for future work more carefully
characterizing the benefits associated with short-wavelength
light-blocking lenses. Additionally, it will be important to
extend these studies to subjects of a greater age range. The
aged human lens is known to become less able to transmit
short-wavelength light,
16
which not only can be protective in
reducing potential phototoxicity but also can be deleterious by
interfering with circadian rhythms. Studying the effect of
attenuating short-wavelength light given these competing
interests will provide much-needed clarity.
Cumulatively, our findings support our hypothesis that
short-wavelength light-blocking lenses may reduce eye strain
based on a physiologic correlate of eye fatigue and subjective
reports of eye strain. Given the increasing number of sources
of short-wavelength light in our environment, these findings
have wide applicability and may inform the development of
devices that modify potential hazards associated with excessive
blue light exposure.
Acknowledgments
JIN CO., LTD. provided the lenses used in this study, prepared the
randomization schedule, and masked the investigators to the
lenses used in each pair of glasses.
Supported by JIN CO., LTD (CJB at UMSL) and by the UMSL
Optometry Scholar Fund (BWG). The authors alone are responsi-
ble for the content and writing of this paper.
Disclosure: J.B. Lin, None; B.W. Gerratt, None; C.J. Bassi, JIN
CO., LTD (F); R.S. Apte, JIN CO., LTD (C, F, R)
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APPENDIX A
1. My eyes feel tired.
2. When doing work at my computer or at my desk, I find
it hard to focus my eyesight.
3. I see written or computer text as blurry.
4. My computer monitor looks too bright.
5. I feel tired when doing work at my desk or on my
computer.
6. My eyes feel dry from time to time.
7. I feel as if there is something in my eye.
8. My neck, shoulders, back, and lower back hurt.
9. My finger(s) hurt.
10. I feel mentally stressed.
11. I feel pain around or inside my eyes.
12. The sun’s glare affects my eyes when outdoors.
13. I find fluorescent office lighting to be bothersome to
my eyes.
14. My eyes feel heavy.
15. My eyes feel itchy.
Short-Wavelength Light-Blocking Eyeglasses IOVS jJanuary 2017 jVol. 58 jNo. 1 j447
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