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VISUAL ACUITY DYNAMICS OF SCHOOL-AGE CHILDREN IN ILGUCIEMS
SECONDARY SCHOOL, LATVIA
Edgars Girons
Sixth year student Riga Stradins University, Latvia Edgars Licis Sixth year student Riga Stradins University, Latvia Zane Garsele Sixth year student Riga Stradins University, Latvia Anita Bergmane Sixth year student University of Latvia, Latvia Elza Apeinane Sixth year student Riga Stradins University, Latvia Maija Eglite Dr. habil. med., professor Riga Stradins University, Latvia
ILGUCIEMA VIDUSSKOLAS SKOLENU REDZES ASUMA SALIDZINAJUMS DINAMIKA
ABSTRACT
Introduction. Structures of the eye in children continue to develop until about age 7-8 years. This is the time, when the child is most perceptible to harmful factors affecting their eyesight. One of the major factors affecting the ciliary muscle and leading to abnormal changes in accommodation is the improper use of electronic devices. Nowadays, due to increasing availability to internet, electronic devices are becoming more popular not only as a work tool, but also as a tool for leisure and spending free time. 77,4% of North American and 10,9% of African population use internet daily. On a more global scale, more than a quarter (28,7%) of the world population use internet daily [1].
Aim. The aim was to prove, that school-age students have premature degeneration of visual acuity. To prove that younger students need vision correction more often compared to older students. To prove that visual acuity of students nowadays is more decreased compared to same grade students up to 12 years before. To find out the habits of using electronic device among students.
Materials and methods. Research has been carried out in Ilguciems secondary school (ISS). Two research tools were used: data on the current and past visual acuity gathered from annual visual acuity checkup records done by using Snellen visual acuity chart decimal scale for the timeframe of2004 until 2015. Habits of using electronic devices explored using self made questionnaire consisting of 5 questions. Total amount of students in ISS was 532, of which 497 valid visual acuity records were gathered on both eyes. Total amount of valid questionnaire sheets received 325.
Results. The older the class becomes, the more decrease in visual acuity: 4,5% de-crease in fourth grade, to 8,9% decrease in eighth grade. The younger the class, the more rapid the degeneration of VA.
The same data concerning older grades (10-12), show relatively constant VA up to year 2010, after which the VA decreases rapidly. 2010 was the year, when smart phones became cheaper and more available for general public. Results in a fixed number of grade over the years show the following: in all cases, students nowadays have worse VA compared to same grade up to 12 years before.
Questionnaire results show: average first grade student of 2015 uses TV, PC, and smart phone combined for 6,3 hours per day, rising 23 % to 8 hours in the 11th grade. The use of PC alone increases by 47 %, use of phone increases by 59 %. Popularity of TV decreases during years, starting with 3 hours per day in first grade, decreasing to 1,1 hour per day in 11th grade. Younger classes have far more
Conclusion. According to the survey and data acquired from the VA records, school-age students have premature degeneration of VA. Younger students need vision correction more often compared to both older students and students up to 12 years before in the same class. There is a lack of data on causes and prevalence of decreased vision in children and adults due to rapid development of causing factors such as electronic devices. It is important to educate school staff on the dangers and effects of using electronic devices, since it is an easily avoidable factor causing many vision problems.
Key words: Decrease of visual acuity (VA), effect of electronic devices on visual acuity, causes of decreased vision, increasing need for vision correction, premature degeneration of visual acuity, computer vision syndrome.
Atslegas vardi: Redzes asuma samazinasanas, elektronisko iekartu ietekme uz redzes asumu, sliktas redzes iemesli, pieaugosa nepieciesamtba pec redzes korekcijas, priekslaictga redzes asuma samazinasanas, datora redzes sindroms.
INTRODUCTION
Visual acuity can also be called clarity of vision. Decreased VA has many definitions. Functional definition explains, that decreased vision or decreased VA is a condition, when the person has decreased occupational functions, or when seeing normally close and far objects become problematic. The problems can manifest as fatigue of eyes, need to strain eyes, concentrate additionally, to get closer or further from the viewed object. [2] Other definition explains decreased VA as uncontrollable and permanent decrease of VA starting from 20/70 or 0,25. That means that a person with 20/70 eyesight will see the object at 20 feet, whereas person with normal eyesight will see the same object at 70 feet [1;2].
Refraction is explained as the furthest point that projects on the retina and is seen clearly. If the rays coming from a distant object refract in the lens and project on the retina, it is called emmetropia. As the furthest point is located in the infinity, emmetropes have a good distant vision. Near vision is provided by accommodation [4].
If the rays focus before or after retina, visual acuity will be decreased and the image will be blurred. That is called ammetropia, it has two types - myopia and hypermetropia [4].
In the case of hypermetropia, the rays focus after or behind the retina due to decreased eye bulb or decreased refraction of the rays. In the case of myopia, the rays focus before or in front of retina due to increased size of eye bulb or increased refraction of eye structures [4].
Nowadays, due to internet, computers have become not only a self evident part of daily work, but also an integral part of free and leisure time for the people of developed countries. 77,4 % of North American and 10,9 % of African population use internet daily. On a more global scale, more than a quarter (28,7 %) of the world population use internet daily [1].
Digital screens are not restricted to workplace, nowadays monitors, laptops, tablets and smart phones are used from home. Mentioned devices can be used as a work station as well as for recreational purposes for children and adults. In the year 2000, children of USA from age eight to 18 spent 7,5 hours daily using electronic devices: 4,5 hours TV, 1,5 hours PC and little over 1 hour playing video games [6].
American Optometric association define Computer vision syndrome (CVS) as eye and vision problems in connection with use of computers [7]. 64 to 90 % of computer users experience eye symptoms such as tired eyes, head ache, dry eye syndrome, doubled vision or blurred vision while looking in the computer screen or after lengthy use of computer [8]. These symptoms are much more pronounced in the ones who use computer more than 4 hours per day [9]. Our times do not restrict us in using stationary computers, but also laptops and other compact devices, that allow us to have access to internet almost anywhere and at the same time put us under more risk of CVS [3]
The open question remains whether the symptoms are caused by directly looking in the screen or by any other activity
that requires lengthy concentration on a near object. Research has shown that visual symptoms, especially blurred vision is more pronounced carrying out activities that require reading from a screen, compared to reading from a paper format document. And those who worked on a computer needed more rest breaks and more mistakes were vitiated [10].
To successfully carry out a task, without doubling or blurring of vision, the image is required to project precisely on the retina. That is why hypermetropia and myopia have to be maximally corrected to achieve optimized visual stimuli, accommodation and to decrease the blurring of vision as well as correction of astigmatism. Two research groups carried out separate studies and concluded that 0,5 - 0,1 dioptre uncorrected astigmatism caused considerable increase of eye symptoms. In order to avoid the symptoms, person should use toric lenses, or have vision correction with eyeglasses during work [11;12].
When using smart phones, due to the small size of the display and details, the accommodation mechanism in the eye does extra straining compared to working with printouts. In the year 2010 Bilton N. recommended using smart phones at the distance of 30 cm, computers at the distance of 60 cm and to watch TV from the distance not less than 3 meters. By using the mentioned devices from a closer range, there is a risk of increased strain on the accommodation mechanism, especially, when used for prolonged period of time, which increased the eye symptoms [13].
There are two main problems in connection with CVS: inadequate oculomotor response and dry eye syndrome. These symptoms are not only affected by the viewing distance, but also by a poorly organized workspace, such as bad lighting [3]. Although there are specific criteria for lighting requirements in school and other work places, it is rarely controlled and the lighting can be decreased due to outdated equipment. By taking into consideration the height difference of students in different age groups, it is impossible to achieve perfect viewing distance for each and every individual, since chairs and tables are mostly not adjustable. According to Occupational Health administration (USA) the computer classes in schools should have adjustable office chairs and computer tables, so each individual could adjust the workplace so the eyes to monitor distance is between 60 -100 cm. Additionally the centre of monitor should be localized 15-20 degrees under the horizontal level of eyes and the surrounding display should be localized in a way where in all times any point in the display would not exceed 60 degrees of visual angle [14,15].
MATERIAL AND METHODS
Research was carried out in Ilguciems secondary school, Latvia. Population of research were all students of ISS, with total of 532 students. Two research tools were used to acquire the data: self made questionnaire consisting of 5 questions (current grade, does the person have vision correction, how many hours per day the person uses one of the following - TV, PC, smart phone.) For unknown reason no answer sheets were gathered from the 10th and 12th grade of 2015. As the second
research tool, current and past visual acuity records gathered from annual visual acuity checkups done by using Snellen visual acuity chart decimal scale for the time frame of 2004 until 2015. Students were not divided by gender, race or exact age, due to not having influence on the study results.
RESULTS OF THE STUDY
Total time spent using electronic devices increases from first to 12th grade. In the first grade, electronic devices are used 6,3 hours per day, increasing to 8 hours per day by 11th grade, which is an increase of 23%.
In the first grade, the TV is being used 3 hours per day, decreasing to 1,1 hour per day in the 11th grade, which is a 44% decrease.
In the first grade, the computer is being used 1,6 hours per day, increasing to 3 hours per day in the 11th grade, which is a 47% increase.
In the first grade, the smart phone is being used for 1,6 hour per day, increasing to 3,9 hours per day in the 11th grade, which is a 59% increase.
The questionnaire was filled by 325 students from different grades, except 10th and 12th grades, which is 62% of handed out sheets. Most of the answers were received from first grade students (56) and the least amount from the 11th grade. Received amount of answers correlates with the student apportionment between classes (Fig.l.).
From the mentioned devices, TV is the most used device in the early grades, but least used device in the older grades. Smart phones are being used just as much as computers in the first grades, but becomes the most used device by the 11th grade.
497 records on both eyes (right eye(OD) and left eye (OS)) were obtained from annual visual acuity checkups. Results from VA records show the following. By following the changes of VA of students in a specific grade, while it gets older, the VA decreases rapidly. The older the class gets, the more decreased VA becomes. In the second grade, the decrease of VA is only 1%. Until the fourth grade, VA has already decreased by 4,5 %. By the sixth grade, there is a decrease of 8,6% and by the eighth grade, the decrease is 8,9% (Fig.2.).
Fig.1. Distribution of students between classes 2015
Fig.2. Visual acuity decrease of 8,9% by the eighth grade
For the grades that were old enough to gather enough data relatively constant. Starting from 2010, in the next following 4
bout before and after 2010, following pattern is seen. Until years, the visual acuity had deacreased 8%, compared to 0% in
year 2010, the VA of 10th and 12th grade students remained all previous years (Fig.3.).
Fig.3. VA decrease starting from year 2010 of 10th grade
When comparing VA of same grade number between different years, following pattern appears. In the first grades of 2015, the VA was 2% lower compared to first grade students in 2004. The fifth grade students of 2015 had 6,3% lower VA
The questionnaire results about required vision correction are as follows. Vision correction among first grade students has increased compared to up to 12 years before. In the first grades of 2004, 2005, 2006 there were no students in need of vision correction. Starting from year 2010, there is an increase of required vision correction with a peak in year 2014 (8 students). The total amount of first grade students of 2015 and 2016 in need of vision correction is 17, which is 3,4 times more compared to all other first grade years combined (5).
compared to fifth grade students in 2008. Sixth grade students of 2015 had 7,1% lower VA compared to sixth grade students of 2009 (Fig.4.). And the ninth grade students of 2015 had 5,5% lower VA compared to ninth grade students of 2012.
Between second grade students of 2015, there were 9 students in need of vision correction, which is 4,5 times more compared to second grade students in 2005 (Fig.5.). The mentioned trend remains in all classes up to ninth grade, where ninth grade students of 2015 had 3,6 times more students with need in vision correction (11), compared to ninth grade students of 2012. 12th grade students of 2015 reached their maximum amount of students with vision correction in the third grade (3), compared to ninth grade of 2015, whereas each year new students need vision correction due to decreased VA.
Fig.4. Comparison of VA between sixth grade students in different years
Fig.5. Second grade students with need of vision correction between different years
DISCUSSION
Among mentioned electronic devices, the most popular and widely used device is smart phone, which means that smart phones affect student eyesight more compared to TV and PC. School-age children use smart phones in different body positions - sitting, walking, lying down, which means that the viewing distance is not controlled and monitored during the activity.
Higher grade students maintained their visual acuity for a longer period of time compared to younger grades. Younger grades need vision correction more often and earlier compared to older grades.
Compared to previous studies on the time spent using electronic devices, this study shows different, results, showing that students spend more time using the devices. This can be explained by the fact that the technologies are evolving faster, than the research studies can gather data and for further studies, newest technologies and possible changes in human behavior should be taken into consideration.
This study did not take into consideration students that were transferred in our out of the program during the years, as well as the students who are left in the same grade for the second year, which affects the results slightly.
Data concerning older grade students tend to fluctuate due to fewer students in each class, which means single deviations from the norm affect the overall results more.
The data gathered from the annual VA checkups, did not include students who were prescribed vision correction at the specific moment, that means the VA acquired is of the students having no vision correction. Due to this fact, actual
VA of affected students is much lower, since the graphs reflect the average VA of all students including the ones with normal eyesight.
Similar future studies should consider the fact, that some students do not wear glasses to school even if the vision correction is officially prescribed, due to unwanted cosmetic effect or other personal reasons.
To confirm validity of research, similar studies should be carried out in a population deprived of mentioned electronic devices, expecting far better results and higher, unaffected VA.
CONCLUSIONS
According to the results of the study and explored background of the problem, we can anticipate further and increasing problems for the next generations in association with electronic devices. The problems caused are easily avoided by restricting the time spent using the devices, improving the work space accordingly to the local guidelines and most importantly by educating workers and parents. Easiest steps to achieve amelioration are to inspect, improve if needed and regulate the furniture and accessories in computer classes and all classes in general.
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