Volume 17, Issue 1 (2020)
ioh 2020, 17(1): 634-644 |
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mousavi N, rahmani S, Akbarzade baghban A, khorrami nejhad M, kangari H, khosravi B. Evaluation of visual complications among professional computer users. ioh 2020; 17 (1) :634-644
URL: http://ioh.iums.ac.ir/article-1-2974-en.html
URL: http://ioh.iums.ac.ir/article-1-2974-en.html
Nasrin Mousavi * 
, Saeed Rahmani , Alireaza Akbarzade baghban , Masoud Khorrami nejhad , Haleh Kangari , Bahram Khosravi
, Saeed Rahmani , Alireaza Akbarzade baghban , Masoud Khorrami nejhad , Haleh Kangari , Bahram Khosravi
School of Rehabilitation Sciences, Shahid Beheshti University of Medical Siences, Tehran, Iran , nasrinmusavi@yahoo.com
Abstract: (1672 Views)
Background and aims: computer vision syndrome refers to a set of visual and non-visual symptoms due to long-term use of video terminals and causes complaints such as; blur vision, difficulty in vision of near and far, burning, headache, back and neck discomfort. Considering the increasing use of computers in the official environments and various jobs and the consequent increasing in clinical referrals of computer users due to eye complaints caused by working with computer, computer vision syndrome has become one of the most important health issues in society. In Iran, the most common eye problems were related to extra ocular problems with a prevalence of 46.2% and eye strain with a prevalence of 45.4% and the prevalence of eye fatigue due to working with video terminals was reported to be 91.4%. In Saudi Arabia, headaches and vision problems were reported with 68% and 65% prevalence, respectively. In Ghana, the prevalence of computer vision syndrome was 51.5%. This study was aimed to evaluate visual problems and functions in professional computer users.
Methods: This cross- sectional study was carried out on 40 professional computer users, aged between 20 and 30 years old, who used the computer at least 4 hours per day in 1397. The inclusion criteria were as follows: Age range 20 to 30 years, no amblyopia, no strabismus, no history of refractive surgery, no pathological eye diseases and systemic diseases such as diabetes, high blood pressure and MS and do not take any ophthalmic and systemic drugs that affect the eyes such as the antidepressants and antibiotics. A questionnaire was used to assess visual complications in four sections: eye strain, visual difficulty, ocular disorders and extra ocular disorders. Then visual examinations including: visual acuity in far and near distances, heterophoria measurement in far and near distances, stereoacuity, accommodation amplitude, accommodation facility and response, near point of convergence, fusional vergence, contrast sensitivity in the four spatial frequencies of 3, 6, 12 and 18 cycle per degree and tear break up time were performed. Refractive errors were measured using a Japanese-made Topcon Autokerato Refractometer (ARK-KR.8800, Topcon, Tokyo, Japan). The monocular and binocular vision was recorded with the best optical correction at a distance of 6 meters and 40 centimeters by logarithmic chart based on the Log MAR system. The deviation of cases was measured by the cover test method at a distance of 6 m and at 40 cm. To examine the accommodation amplitude, the near point of accommodation was measured using the push-up method. The accommodation response of cases was measured by Monocular Estimation Method (MEM). The near point of convergence was also measured by push-up method. The TNO random dot test was used to assess stereopsis. Fusional vergences were measured by prism bar both at a distance of 6 m and at 40 cm. To measure contrast sensitivity, the CSV-1000 Chart (VectorVision, Inc., OH, USA) was used. By measuring the tear break up time, the stability of the tear film were examined and the cases of dry eye were identified by using the slide lamp and fluorescent. For statistical analysis, descriptive statistics including concentration and dispersion criteria of SPSS 20 were used.
Results: In this study, the mean and standard deviation of age was 26.48±2.72 and the mean and standard deviation of using computer was 5.82±0.84 hours per day (range 4 to 8 hours). According to the results, the mean visual acuity of all cases with the best optical correction was 0.0 logarithm. At a distance of 40 cm, 70% of the cases had no heterophoria and 30% of the cases had exophoria with less than 10 prism diopters. The means and standard deviations of blur, break and recovery by base out prism at 6 meter were: 11.40±3.30, 17.85±4.11 and 12.78±3.83 prism diopter respectively and at 40 centimeter were 17.59±2.76, 25.40±5.16 and 17.25±3.49 prism diopter respectively and by base in prism at 6 meters were: 0.55±1.28, 8.80±1.80 and 6.30±1.78 prism diopter respectively and at 40 centimeter were: 12.90±2.67, 19.05±3.02 and 14.05±2.77 prism diopter respectively. The means and standard deviations of stereoacuity, accommodation amplitude, accommodation facility and response, near point of convergence and tear break up time were respectively; 52.0±11.36 seconds of arc, 9.65±2.48 diopter, 10.5±3.0 cycle per minutes, 0.35±0.23 diopter, 2.85±3.37 centimeters and 7.45±3.17 seconds and the means and standard deviations of contrast sensitivity in the spatial frequencies of 3, 6, 12 and 18 cycle per degree were respectively: 1.75±0.11, 2.11±0.14, 1.86±0.13 and 1.44±0.13 log units. According to the questionnaire the most common complaints were in the ocular surface problems section with 32% and eye strain with 27%.
Conclusion: In this study, two important issues were discussed, one of which includes questions related to computer vision problems from the point of view of professional users and the other is the results of eye examinations of them. In the first part, based on the questionnaire the most complaints were in the section of ocular surface disorders with 32% and eye strain with 27%. In fact, long-term computer usage causes symptoms such as; Feeling dryness, burning, tearing when working with a computer and eye strain.
In the second part, it was found that the contrast sensitivity at all frequencies and the accommodation amplitude were nearly decreased, and in a low percentage of people, a decrease in the accommodation facility were observed. The tear break up time was significantly decreased. Stereopsis of the cases was in the normal range and according to this study was not affected by computer work. In this study, at a distance of 6 m, heterophoria in the cases were in the normal range of exophoria, and at a distance of 40 cm, 30% of cases had small degrees of exophoria. One of the reasons for the increase in near exophoria in these people can be a decrease in the accommodation amplitude and also recede of the near point of convergence, which can cause symptoms such as fatigue, headache, blurred vision and diplopia. According to Morgan's table of normal values of fusional vergences, the fusional versions of the studied cases were in the normal range at 6 meters and 40 centimeters. In the present study, the near point of convergence of more than 5 cm was considered as a problem and statistical studies showed that 75% of users had a near point of convergence of less than 5 cm, so this study showed that the near point of convergence was not affected by working with a computer.
An examination of the accommodation facility of the cases showed that the binocular accommodation facility in 35% of people was less than 10 cycles per minute. Accommodation facility helps to maintain a clear and single image while working in near distance. If accommodation facility is reduced, the flexibility to focus at a variety of viewing distances immediately after long-term use of the computer will be difficult, which can cause blurred vision and eye strain in some users.
The accommodation response of cases were within the normal range of 0.5±0.25 diopter. If the accommodation response is greater than the accommodation diopter stimulation, symptoms such as blurred vision and eye fatigue were reported. This study found that, this eye function was not affected by computer use. Considering the average age of the cases, the accommodation amplitude of less than 8 diopters was considered as a decrease in the accommodation amplitude, which about 35% of people had 8 diopters or less than 8 diopters, but the mean accommodation amplitude was within normal range. Prolonged use of the computer can reduce the accommodation amplitude and cause symptoms such as fatigue and blurred vision. The exact cause of this decrease is not clear, but it seems to be more due to accommodation fatigue.
In the present study, the mean contrast sensitivity decreased in all spatial frequencies. However, according to the normal values provided by Vectorvision for ages 20 to 55 years, the contrast sensitivity in the spatial frequencies of 3, 6, 12 and 18 cycles per degree were: 1.84±0.14, 2.09±0.16, 1.76±0.17 and 1.33±0.19 in the logarithmic unit respectively, the contrast sensitivity of users was within the normal range. In this study, tear break up time of more than 10 seconds was considered to be normal and less than this amount was considered as a problem in the stability of the tear film. Using a computer affects the pattern of blinking, eye level hemostasis and tear film function. In fact, reducing the rate of blinking disturbs the balance of replenishment and evaporation of the tear film. On the other hand, if the screen angle is higher than the primary gaze of viewing, this evaporation will occur more frequently, which will cause symptoms such as burning, redness and tearing in computer users. To reduce eye problems and symptoms, users can be advised to rest their eyes at regular intervals. It is also recommended that future studies use qualitative tests in addition to quantitative tests to assess the tear layer. The impact of computers and other devices such as mobile phones and tablets on the visual functions of different age groups can also be examined.
Methods: This cross- sectional study was carried out on 40 professional computer users, aged between 20 and 30 years old, who used the computer at least 4 hours per day in 1397. The inclusion criteria were as follows: Age range 20 to 30 years, no amblyopia, no strabismus, no history of refractive surgery, no pathological eye diseases and systemic diseases such as diabetes, high blood pressure and MS and do not take any ophthalmic and systemic drugs that affect the eyes such as the antidepressants and antibiotics. A questionnaire was used to assess visual complications in four sections: eye strain, visual difficulty, ocular disorders and extra ocular disorders. Then visual examinations including: visual acuity in far and near distances, heterophoria measurement in far and near distances, stereoacuity, accommodation amplitude, accommodation facility and response, near point of convergence, fusional vergence, contrast sensitivity in the four spatial frequencies of 3, 6, 12 and 18 cycle per degree and tear break up time were performed. Refractive errors were measured using a Japanese-made Topcon Autokerato Refractometer (ARK-KR.8800, Topcon, Tokyo, Japan). The monocular and binocular vision was recorded with the best optical correction at a distance of 6 meters and 40 centimeters by logarithmic chart based on the Log MAR system. The deviation of cases was measured by the cover test method at a distance of 6 m and at 40 cm. To examine the accommodation amplitude, the near point of accommodation was measured using the push-up method. The accommodation response of cases was measured by Monocular Estimation Method (MEM). The near point of convergence was also measured by push-up method. The TNO random dot test was used to assess stereopsis. Fusional vergences were measured by prism bar both at a distance of 6 m and at 40 cm. To measure contrast sensitivity, the CSV-1000 Chart (VectorVision, Inc., OH, USA) was used. By measuring the tear break up time, the stability of the tear film were examined and the cases of dry eye were identified by using the slide lamp and fluorescent. For statistical analysis, descriptive statistics including concentration and dispersion criteria of SPSS 20 were used.
Results: In this study, the mean and standard deviation of age was 26.48±2.72 and the mean and standard deviation of using computer was 5.82±0.84 hours per day (range 4 to 8 hours). According to the results, the mean visual acuity of all cases with the best optical correction was 0.0 logarithm. At a distance of 40 cm, 70% of the cases had no heterophoria and 30% of the cases had exophoria with less than 10 prism diopters. The means and standard deviations of blur, break and recovery by base out prism at 6 meter were: 11.40±3.30, 17.85±4.11 and 12.78±3.83 prism diopter respectively and at 40 centimeter were 17.59±2.76, 25.40±5.16 and 17.25±3.49 prism diopter respectively and by base in prism at 6 meters were: 0.55±1.28, 8.80±1.80 and 6.30±1.78 prism diopter respectively and at 40 centimeter were: 12.90±2.67, 19.05±3.02 and 14.05±2.77 prism diopter respectively. The means and standard deviations of stereoacuity, accommodation amplitude, accommodation facility and response, near point of convergence and tear break up time were respectively; 52.0±11.36 seconds of arc, 9.65±2.48 diopter, 10.5±3.0 cycle per minutes, 0.35±0.23 diopter, 2.85±3.37 centimeters and 7.45±3.17 seconds and the means and standard deviations of contrast sensitivity in the spatial frequencies of 3, 6, 12 and 18 cycle per degree were respectively: 1.75±0.11, 2.11±0.14, 1.86±0.13 and 1.44±0.13 log units. According to the questionnaire the most common complaints were in the ocular surface problems section with 32% and eye strain with 27%.
Conclusion: In this study, two important issues were discussed, one of which includes questions related to computer vision problems from the point of view of professional users and the other is the results of eye examinations of them. In the first part, based on the questionnaire the most complaints were in the section of ocular surface disorders with 32% and eye strain with 27%. In fact, long-term computer usage causes symptoms such as; Feeling dryness, burning, tearing when working with a computer and eye strain.
In the second part, it was found that the contrast sensitivity at all frequencies and the accommodation amplitude were nearly decreased, and in a low percentage of people, a decrease in the accommodation facility were observed. The tear break up time was significantly decreased. Stereopsis of the cases was in the normal range and according to this study was not affected by computer work. In this study, at a distance of 6 m, heterophoria in the cases were in the normal range of exophoria, and at a distance of 40 cm, 30% of cases had small degrees of exophoria. One of the reasons for the increase in near exophoria in these people can be a decrease in the accommodation amplitude and also recede of the near point of convergence, which can cause symptoms such as fatigue, headache, blurred vision and diplopia. According to Morgan's table of normal values of fusional vergences, the fusional versions of the studied cases were in the normal range at 6 meters and 40 centimeters. In the present study, the near point of convergence of more than 5 cm was considered as a problem and statistical studies showed that 75% of users had a near point of convergence of less than 5 cm, so this study showed that the near point of convergence was not affected by working with a computer.
An examination of the accommodation facility of the cases showed that the binocular accommodation facility in 35% of people was less than 10 cycles per minute. Accommodation facility helps to maintain a clear and single image while working in near distance. If accommodation facility is reduced, the flexibility to focus at a variety of viewing distances immediately after long-term use of the computer will be difficult, which can cause blurred vision and eye strain in some users.
The accommodation response of cases were within the normal range of 0.5±0.25 diopter. If the accommodation response is greater than the accommodation diopter stimulation, symptoms such as blurred vision and eye fatigue were reported. This study found that, this eye function was not affected by computer use. Considering the average age of the cases, the accommodation amplitude of less than 8 diopters was considered as a decrease in the accommodation amplitude, which about 35% of people had 8 diopters or less than 8 diopters, but the mean accommodation amplitude was within normal range. Prolonged use of the computer can reduce the accommodation amplitude and cause symptoms such as fatigue and blurred vision. The exact cause of this decrease is not clear, but it seems to be more due to accommodation fatigue.
In the present study, the mean contrast sensitivity decreased in all spatial frequencies. However, according to the normal values provided by Vectorvision for ages 20 to 55 years, the contrast sensitivity in the spatial frequencies of 3, 6, 12 and 18 cycles per degree were: 1.84±0.14, 2.09±0.16, 1.76±0.17 and 1.33±0.19 in the logarithmic unit respectively, the contrast sensitivity of users was within the normal range. In this study, tear break up time of more than 10 seconds was considered to be normal and less than this amount was considered as a problem in the stability of the tear film. Using a computer affects the pattern of blinking, eye level hemostasis and tear film function. In fact, reducing the rate of blinking disturbs the balance of replenishment and evaporation of the tear film. On the other hand, if the screen angle is higher than the primary gaze of viewing, this evaporation will occur more frequently, which will cause symptoms such as burning, redness and tearing in computer users. To reduce eye problems and symptoms, users can be advised to rest their eyes at regular intervals. It is also recommended that future studies use qualitative tests in addition to quantitative tests to assess the tear layer. The impact of computers and other devices such as mobile phones and tablets on the visual functions of different age groups can also be examined.
Type of Study: Research |
Subject:
Occupational Diseases
Received: 2019/11/27 | Accepted: 2020/07/4 | Published: 2020/09/23
Received: 2019/11/27 | Accepted: 2020/07/4 | Published: 2020/09/23
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