GB/T 40230.1-2021 PDF English
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Methods of visual fatigue test and evaluation - Part 1: Ophthalmology and optometry
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GB/T 40230.1-2021: PDF in English (GBT 40230.1-2021) GB/T 40230.1-2021
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 13.180
CCS A 25
Methods of Visual Fatigue Test and Evaluation - Part 1:
Ophthalmology and Optometry
ISSUED ON: MAY 21, 2021
IMPLEMENTED ON: DECEMBER 1, 2021
Issued by: State Administration for Market Regulation;
Standardization Administration of the People’s Republic of China.
Table of Contents
Foreword ... 3
Introduction ... 4
1 Scope ... 6
2 Normative References ... 6
3 Terms and Definitions ... 6
4 Overall Requirements ... 9
4.1 Principles ... 9
4.2 Test Environment ... 9
4.3 Requirements for Subject Selection ... 9
4.4 Requirements for Experimenter Qualification ... 10
4.5 Requirements for Instruments and Equipment ... 10
4.6 Requirements for Experimental Data Record ... 10
4.7 Requirements for Experimental Data Report ... 10
5 Test Method ... 10
5.1 Accommodative Response ... 10
5.2 Accommodative Microfluctuations ... 12
5.3 Near Point of Accommodation ... 13
5.4 CA / C Ratio ... 14
5.5 AC /A Ratio ... 15
5.6 Tear Film Break-up Time ... 16
Appendix A (normative) Documentation Requirements for Test Result Report ... 17
Bibliography ... 18
Methods of Visual Fatigue Test and Evaluation - Part 1:
Ophthalmology and Optometry
1 Scope
This document specifies the test methods and technical requirements for ophthalmology and
optometry of visual fatigue.
This document is applicable to the test and evaluation of visual fatigue caused by the long-term
application of visual display terminal products or lighting products in various places of work
and life, etc.
This document is not applicable to the measurement of photo-biological safety effects on human
beings brought by display or lighting products.
2 Normative References
Through the normative references in this text, the contents of the following documents
constitute indispensable clauses of this document. In terms of references with a specified date,
only versions with a specified date are applicable to this document. In terms of references
without a specified date, the latest version (including all the modifications) is applicable to this
document.
This document does not have normative references.
3 Terms and Definitions
The following terms and definitions are applicable to this document.
3.1 Visual Fatigue
Visual fatigue refers to symptoms of discomfort when working with eyes for a long time.
NOTE: the symptoms of visual fatigue include blurred vision, headache, dry eyes and diplopia, etc.
3.2 Refraction
In optometry, when light passes from one medium to another medium with a different refractive
index, a change of direction will occur.
NOTE: the unit for measuring the size of refraction is diopter (represented by the symbol D and
expressed in m1).
3.3 Accommodation
Accommodation refers to the ability of the human eye to change the ocular refraction in order
to clearly see close objects.
3.4 Experimenter; Observer
Experimenter / observer refers to the personnel in charge of the progress of the experiment
during the experiment.
NOTE: the task of the experimenter / observer is to give instructions to the test subjects in
accordance with the experimental design and guide them to perform experimental
procedures in the experiment.
3.5 Subject; Participant
Subject / participant refers to the personnel participating in the experimental process or
receiving the experiment during the experiment.
NOTE: subject / participant is also known as receiver or tester.
3.6 Accommodative Response
Accommodative response refers to the actual amount of accommodation generated by the
stimulation of the fixating eye to the near-fixed optotype.
3.7 Rapid Serial Visual Presentation; RSVP
Rapid serial visual presentation refers to a visual graphic presentation method that rapidly
displays a string of character streams, a string of word (sentence) streams or a picture stream at
the same position on the screen in chronological order.
3.8 Accommodative Stimulus
Accommodative stimulus refers to the amount of accommodation required by the eye to see
objects at a specific distance.
NOTE: the unit is diopter.
3.9 Lag of Accommodation
Lag of accommodation refers to the situation that the amount of accommodative response is
less than the amount of accommodative stimulus.
3.10 Accommodative Microfluctuations
When the eye is fixed on a stationary object, its accommodation is not fixed, and there are
constant micro changes around the average accommodative response.
on the same optotype.
3.17 Tear Film
Tear film refers to a layer of tear fluid that covers the surface of the cornea and conjunctiva
between the upper and lower eyelids.
3.18 Tear Film Break-up Time
Tear film break-up time refers to the time when the tear film firstly breaks up without blinking.
4 Overall Requirements
4.1 Principles
Considering the constraints in the actual measurement, the principles of the measurement
methods involved in this document are mainly direct observation method, minimum change
method and adaptive method of psychophysics.
4.2 Test Environment
Temperature: 15 C ~ 30 C, preferably 23 C ~ 28 C.
Humidity: 25% ~ 75%.
Noise: the background noise should be within 25 dB ~ 45 dB.
Illumination: the initial ambient illumination shall be 0 lx; the ambient illumination conditions
should be set to be adjustable, and satisfy the environmental conditions required for most
equipment test. The specific illumination setting shall be set in accordance with the test
equipment and the purpose and task of the experiment.
4.3 Requirements for Subject Selection
Basic requirements: people with normal or corrected-to-normal vision, and without eye diseases
shall be recruited as the subjects.
The subjects shall have a clear and unmistakable understanding of the task to be completed
during the test.
Different test equipment and test contents may have different requirements for the subjects. For
the requirements related to test methods and equipment, see the section of each test method.
The selection basis, sample size, sample selection method, history of eye disease and history of
brain disease of the subjects shall be recorded and archived. The archival date shall be based on
the retention time of the original data by the laboratory.
4.4 Requirements for Experimenter Qualification
Persons with a background in ophthalmology or optometry, or those engaged in optics, visual
sciences, psychology, sociology and biology and other related fields, and have been trained
shall be selected as the experimenters.
4.5 Requirements for Instruments and Equipment
The instruments and equipment shall comply with the precision requirements.
4.6 Requirements for Experimental Data Record
The experimental data records shall be complete and clear, and shall include the necessary basic
information of the subjects, such as: age, gender, history of eye disease, and whether they have
mental or brain diseases, etc.
The retention and destruction of test data shall be carried out in accordance with relevant rules
and regulations.
4.7 Requirements for Experimental Data Report
Data in the result presentation shall be rounded to two decimal places.
The data result report shall describe in detail the test subjects, test tools and test procedures,
etc., and shall comply with the requirements of Appendix A.
5 Test Method
5.1 Accommodative Response
5.1.1 Test equipment
An open infrared automatic refractometer should be adopted. The sampling rate shall be not
less than 5 Hz (5 measurements within 1 s, the higher the sampling rate, the shorter the test
time); the equipment resolution shall be not greater than 0.01 Hz.
5.1.2 Test environment
When adopting the open infrared automatic refractometer, the test shall be performed in a
normal lighting environment; it shall be ensured that the pupil diameter is greater than or equal
to 2.3 mm.
Test method: the optotype is a single black Chinese character continuously displayed by the
RSVP software in the center of the LCD screen in front of the eye; in accordance with different
test subjects (for example, age), choose text content (story, novel or book) with different levels
of difficulty. The size of the test window should be 142.24 mm (5.6 inches); the brightness of
the display screen should be 40 cd/m2 ~ 170 cd/m2; the resolution should be 1,280 pixel 800
LensPower---the power added before the eye, expressed in (D).
5.1.6 Result presentation
Mark the accommodative response at different distances:
---right-eye accommodative response: X1 (D);
---left-eye accommodative response: X2 (D).
NOTE: X1 represents the specific value of the accommodative response of the right eye; X2
represents the specific value of the accommodative response of the left eye.
5.2 Accommodative Microfluctuations
5.2.1 Test equipment
The requirements for the equipment are the same as 5.1.1.
5.2.2 Test environment
The requirements for the environment are the same as 5.1.2.
5.2.3 Test procedures
Taking the infrared automatic refractometer as an example, the test procedures are as follows:
a) After wearing the equivalent spherical lenses in accordance with the binocular diopter
of the subjects, ensure that the corrected visual acuity of one eye is greater than or
equal to 1.0. Before measurement, let the eyes relax for at least 5 min.
b) Instruction setting: inform the subjects of a short text that will be presented in the
form of RSVP in front of them, and ask them to silently read the Chinese characters
presented in front of them and understand the short text. After the experiment is over,
instruct them to repeat the summary of the short text.
c) Measurement of accommodative response: accommodate the subjects’ line of sight
and the position of the optotype on the screen, so that the subjects’ visual axis, the
measurement optical axis of the automatic refractometer and the accommodated
optotype are at the same level. Continuously measure the accommodative response of
one eye of the subjects, which should be greater than or equal to 1 min. When
calculating the accommodative response, relatively stable values in the middle of the
whole measurement process should be taken.
d) Adopt the same method to continuously measure the accommodative response of one
eye of the subjects.
5.2.4 Result calculation
Data screening and conversion: select the relatively stable accommodative response values in
the middle of the measurement; after eliminating the obvious abnormal values caused by factors
like blinking or tear film break-up, select the data within the range of twice the standard
deviation of all the measured accommodative response values as the experimental data (more
than 100 values); calculate the standard deviation of the experimental data, which is the
accommodative microfluctuations.
5.2.5 Result presentation
Mark the accommodative microfluctuations at different distances:
---right-eye accommodative microfluctuations: X1 (D);
---left-eye accommodative microfluctuations: X2 (D).
NOTE: X1 represents the specific value of the accommodative microfluctuations of the right eye;
X2 represents the specific value of the accommodative microfluctuations of the left eye.
5.3 Near Point of Accommodation
5.3.1 Test equipment
For the accommodation of the optotypes (letter optotypes or other small optotypes), the smallest
single optotype that can always be clearly seen in the eye chart should be used.
5.3.2 Test environment
The test shall be carried out in a close-range reading lighting environment, and the illuminance
should be set to 500 lx ~ 700 lx.
5.3.3 Test procedures
The test procedures are as follows:
a) The subjects are completely corrected for refractive errors; under normal lighting,
cover the non-detected eye. Place the near optotype 40 cm in front of the subjects’
eyes;
b) Instruct the subjects to look at the optotype on the upper line of the best vision. At a
speed of about 2 cm/s, the near optotype should be moved closer to the subjects, until
it is reported by the subjects that the optotype is persistently blurred, then, return to
the final position, where the optotype remains clear; measure the distance between
the optotype and the plane of the subjects’ glasses at this moment, which is the near
point of accommodation.
5.3.4 Result calculation
Measure the distance between the optotype and the plane of the subjects’ glasses at the end
NOTE: the advance of accommodation means that the amount of accommodative response is
greater than the amount of accommodative stimulus.
5.4.5 Result presentation
CA / C ratio: X (D/6).
NOTE: X represents the specific value of CA / C ratio; D/6 represents the change in convergence
accommodation caused by the convergence change of 6.
5.5 AC /A Ratio
5.5.1 Test equipment
Comprehensive refractometer, near vision card.
5.5.2 Test procedures
The test procedures are as follows:
a) The subjects are completely corrected for refractive errors. Place the near optotype 40
cm in front of the subjects’ eyes.
b) Place Risley prism in front of the subjects’ eyes; place a 12 with the bottom facing
inward in front of the right eye; place a 6 with the bottom facing upward in front of
the left eye. Instruct the subjects to look at the smallest single optotype that has been
clearly seen in the near vision chart. At this moment, the subjects will see two
optotypes: one at the lower left and the other at the upper right. Instruct the subjects
to look at the optotype at the lower left, while looking at the optotype at the upper
right with the peripheral vision. Then, at a speed of 2/s, move the right optotype,
until the upper and lower optotypes are aligned in the vertical direction; record the
direction and power of the prism base at this time.
c) Meanwhile, do not pause, continue to turn the prism in the same direction, until the
subjects see two more optotypes: one at the lower right and the other at the upper left.
Then, turn the prism in the opposite direction, until it is reported by the subjects that
the two optotypes are aligned in the vertical direction again; record the direction and
power of the prism base at this time. The data difference between the two vertical
alignments needs to be less than 3. The result shall take the average value of the
prismatic power of the two alignments.
d) On the basis of distance refractive correction, simultaneously add +1.00 D in front of
both eyes. Then, repeat Step 2 and Step 3 to obtain the measured values of two phoria.
5.5.3 Result calculation
The absolute value of the difference between the measured values of two phoria is the AC / A
ratio, which shall be calculated in accordance with Formula (3).
Where,
P---AC / C ratio;
P1---the average value of the prismatic power measured through Step c) in 5.5.2;
P2---the average value of the prismatic power measured through Step d) in 5.5.2.
5.5.4 Result presentation
AC / A ratio: X (/D).
NOTE: X represents the specific value of AC / A ratio.
5.6 Tear Film Break-up Time
5.6.1 Test equipment
Fluorescein test strips.
5.6.2 Test environment
The test should be performed indoor. There are no special requirements.
5.6.3 Requirements for subject selection
Except for patients with corneal diseases, for example, corneal ulcers, it is advisable to select
all groups of people who can cooperate with the examination.
5.6.4 Test method
Gently place the moistened fluorescein test strip on the subjects’ lower fornix, then, take it out.
Instruct the subjects to blink several times, then, open their eyes and look ahead. The examiner
adopts cobalt blue light examination to measure the time from the beginning of eye opening to
the occurrence of the first dark spot on the cornea, which is the tear film break-up time. Conduct
the measurement for 3 times and take the average value. A tear film break-up time of less than
10 s is deemed as unstable tear film.
5.6.5 Result calculation
Conduct the measurement for 3 times and take the average value.
5.6.6 Result presentation
Tear film break-up time: X (s).
NOTE: X represents the specific time value of tear film break-up.
......
Source: Above contents are excerpted from the PDF -- translated/reviewed by: www.chinesestandard.net / Wayne Zheng et al.
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