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 Table of Contents  
ORIGINAL ARTICLE
Year : 2020  |  Volume : 21  |  Issue : 3  |  Page : 139-145

Computer vision syndrome among individuals using visual display terminals for more than two hours


1 Department of Optometry and Visual Sciences, CL Gupta Eye Institute, Moradabad, Uttar Pradesh, India
2 Department of Clinical Research, CL Gupta Eye Institute, Moradabad, Uttar Pradesh, India
3 Department of Pediatric Ophthalmology, Strabismus, and Neuro-ophthalmology, CL Gupta Eye Institute, Moradabad, Uttar Pradesh, India

Date of Submission19-Nov-2019
Date of Decision24-Jan-2020
Date of Acceptance04-Mar-2020
Date of Web Publication23-Sep-2020

Correspondence Address:
B. Optometry Uzma Rafeeq
Department of Optometry and Visual Sciences, CL Gupta Eye Institute, Ram Ganga Vihar Phase II Ext, Moradabad 244001, Uttar Pradesh
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/DJO.DJO_65_19

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  Abstract 


Purpose Nowadays exposure to visual display terminals (VDT) is an integral part of our daily life. Adolescents are also exposed to extended use of VDTs. This study aimed to assess the proportion of individuals experiencing various ocular symptoms according to their VDT usage and age.
Patients and methods This cross-sectional comparative study was conducted from April 2017 to March 2018. Validated computer vision syndrome (CVS) questionnaire was used for the assessment of CVS. The questionnaire includes 16 symptoms that are scored using two rating scales, one for frequency and the other for intensity. Study participants were divided into two groups: group I included individuals using VDT more than or equal to 6 h per day and group II included those using VDT for less than 6 h per day.
Results A total of 120 individuals were included in this study. The total symptom severity score of more than or equal to 6 (i.e. with CVS) was recorded in 83 (69.2%) patients. The median symptom severity score was 8 (SD: 10.2, range: 0–46). In CVS patients, headache (79 patients=95.2%) was the most prevalent symptom followed by blurred vision (70 patients=84.3%), dryness (57 patients=68.7%), heavy eyelid (57 patients=68.7%), eye redness (55 patients=66.3%), and eye pain (53 patients=63.9%). Among group I, 50 (68.4%) patients had CVS while in group II, 33 (70.2%) patients had CVS (P=1.0; c2 test). In adults, 57 (67.1%) patients had CVS compared with 26 (74.3%) patients among adolescents (P=0.001, Fisher’s exact test).
Conclusion The proportion of CVS among individuals who were using VDT for more than 2 h was significantly higher in adolescents as compared with the adult age group.

Keywords: adolescent, adults, computer vision syndrome, ocular symptoms, visual display terminal usage


How to cite this article:
Rafeeq U, Omear M, Chauhan L, Maan V, Agarwal P. Computer vision syndrome among individuals using visual display terminals for more than two hours. Delta J Ophthalmol 2020;21:139-45

How to cite this URL:
Rafeeq U, Omear M, Chauhan L, Maan V, Agarwal P. Computer vision syndrome among individuals using visual display terminals for more than two hours. Delta J Ophthalmol [serial online] 2020 [cited 2020 Oct 20];21:139-45. Available from: http://www.djo.eg.net/text.asp?2020/21/3/139/295885




  Introduction Top


Use of computers and mobile phones has become an integral part of our daily life. Since the last few years, the use of computer and smartphones in India has been the latest and the most popular development. The number of mobile internet users in India was estimated to be 478 million by June 2018 [1]. Prolonged use of a computer screen and other visual display terminals (VDT) can lead to computer vision syndrome (CVS) or digital eye strain. The American Optometric Association defines CVS as the complex of eye and vision problems related to near work, which are experienced during or related to computer use. Many individuals experience eye discomfort with the use of VDTs. Reported prevalence of CVS ranges from 64 to 90% among computer users [2]. Prevalence of CVS reported by Logaraj et al. [3] from India was 80.3%. However, they included neck and shoulder pain as a symptom of CVS. Bali et al. [4] reported the prevalence of asthenopia in computer operators to be 46.3%. Dry and irritated eyes, eye strain/fatigue, blurred vision, red eyes, burning eyes, excessive tearing, double vision, headache, light/glare sensitivity, and slowness in changing focus are the ocular symptoms of CVS [4],[5]. One may experience any one of them. The reported prevalence of asthenopia (eye strain/fatigue) among computer users ranged from 31.9 to 68.5% [6],[7],[8],[9]. Mocci et al. [6] reported an association of asthenopia with age and sex.

Although the visual impact of prolonged computer use and its associated symptoms have been extensively studied in adults [4],[5],[6],[7], there is paucity of literature available on the effects of computer use on the physical health of users among the adolescent age group [3]. Kozeis [10] reported that children with CVS can experience the same symptoms as adults.

This study was conducted to assess the prevalence of CVS among VDT users. As there is no good estimate of the prevalence in the adolescent age group (12–18 years), this study also reported the comparison of ocular symptoms between adolescent (12–18 years) and adult age (>18 years) groups.


  Patients and methods Top


This cross-sectional comparative study was conducted at a Tertiary Eye Care Institute. The study was conducted from April 2017 to March 2018. The study was approved by CL Gupta Eye Institute Ethics Committee (ECR/1310/Inst/UP/2019) and was conducted in compliance with the tenets of the Declaration of Helsinki. All participants or their legal guardians signed a written informed consent to participate in the study and for publication of data before enrollment into the study. Parental consent along with assent from participants was taken from patients of adolescent age.

Individuals 12 years or over with a best corrected visual acuity of 20/20 and self-reported VDT use of minimum 2 h per day were enrolled in the study. Patients with systemic illness were excluded. Patients with any other pathology (congenital or acquired) and structural deformity were also excluded. All patients underwent a complete ophthalmic examination. Monocular visual acuity was measured and recorded with an internally illuminated logMAR chart at a distance of 6 m under normal lighting conditions. Near point of convergence was measured with a royal air force ruler at primary gaze by moving the single dot target on the ruler along the scale toward the eye. Convergence of less than 10 cm was considered normal, 11–15 cm reduced, and more than 15 cm was considered abnormal.

Computer vision syndrome questionnaire

Authors used the CVS questionnaire developed and validated by del Mar Seguí et al. [11] for the assessment of CVS.

CVS questionnaire has acceptable psychometric properties in VDT users. The questionnaire includes 16 symptoms that are scored using two rating scales, one for frequency and the other for intensity. The responses to the two rating scales for each symptom were combined multiplicatively into one rating scale for the analysis, resulting in a single symptom severity score. The questionnaire has 16 symptoms which includes: burning, itching, feeling of a foreign body, tearing, excessive blinking, eye redness, eye pain, heavy eyelids, dryness, blurred vision, double vision, difficulty focusing for near vision, increased sensitivity to light, colored halos around objects, feeling that eyesight is worsening, and headache.

To measure the frequency of occurrence, that is, how often the symptom was presented, a rating scale of 0–3 points was used, with the following categories: never=0, occasionally=1 (sporadic episodes or once a week), often=2 (two or three times a week), and very often or always=3 (almost every day). The three levels of intensity, or strength of the symptom, were graded similarly, on a scale of 1–3 points, where moderate=1, intense=2, and very intense=3. A symptom rated as never occurring was treated as 0 (none) on the intensity scale. The total score of the questionnaire was calculated by following expression:



If the total score is more than or equal to 6 points, the person is considered to suffer from CVS.

Statistical analysis

The statistical analysis was performed with SPSS 17.0 software (SPSS Inc., Chicago, Illinois, USA). Descriptive statistics were obtained to determine the frequency and proportions. Mean and SD was calculated for continuous variables. The alpha-type error was set to 0.05. Two groups were made on the basis of per day VDT usage: group I of patients using VDT more than or equal to 6 h per day and group II of patients using VDT less than 6 h per day. Univariate analysis using the c2 test was done to compare the identified variables between the two groups.


  Results Top


A total of 120 individuals were enrolled in this study. The mean age of the participants was 21.7±7.2 years. Of all, 93 (77.5%) individuals were men and 27 (22.5%) were women Of all, 51.7% of participants were students and 24.2% each were in government and private service. The total symptom severity score of more than or equal to 6 (i.e. with CVS) was recorded in 83 (69.2%) individuals. The median symptom severity score was 8 (SD: 10.2, range: 0–46).

The duration of VDT use was more than or equal to 6 h in 73 (60.8%) individuals and was less than 6 h in 47 (39.2%) individuals. Among group I, 50 (68.4%) individuals had CVS while in group II 33 (70.2%) individuals had CVS (P=1.0; c2 test). Symptom score of dryness (P=0.04, Fisher exact test) differed significantly between the two groups. The comparison of the symptom severity score between the two groups is presented in [Table 1]. The near point of accommodation in group I was 9.71±2.56 as compared with 8.85±2.18 in group II (P=0.05, independent t test). The near point of convergence in group I was 8.41±1.98 cm, and in group II was 8.21±1.42 cm (P=0.52, independent t test).
Table 1 Symptom score among visual display terminal users of more than or equal to 6 h compared with users of less than 6 h

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Of all cases, 85 (70.8%) individuals were adults and 35 (29.2%) individuals were adolescents. The mean age of adults was 24.8±6.1 years (range, 18–48 years), and of adolescents was 14.3±1.9 years (range, 11–17 years). One patient of 11 years was enrolled inadvertently. Data of this patient were not removed from the analysis. Among adult individuals, 64 (75.2%) were men and 21 (24.7%) were women. Among adolescents 29 (82.8%) were men and six (17.2%) were women. The median CVS score of adults was nine (SD: 10.7, range: 0–46), and of adolescents was seven (SD: 9.7, range: 0–45).

In the adult group, 60 (70.5%) were using VDT for more than or equal to 6 h per day as compared with 13 (37.1%) in the adolescent group (P=0.001, Fisher’s exact test). In adults, 57 (67.1%) had CVS as compared with 26 (74.3%) in adolescents (P=0.001, Fisher’s exact test). The comparison of symptom severity score between adults and adolescent are presented in [Table 2]. Symptom score of eye redness (P=0.005, Fisher’s exact test), heavy eyelids (P=0.0009, Fisher’s exact test), colored halos (P=0.02, Fisher’s exact test), feeling of sight worsening (P=0.01, Fisher’s exact test), and headache differed significantly between adult and adolescent groups.
Table 2 Comparison of ocular symptom scores between adult and adolescent age groups

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Computer vision syndrome

Headache (79 patients=95.2%) was the most prevalent symptom followed by blurred vision (70=84.3%), dryness (57=68.7%), heavy eyelid (57=68.7%), eye redness (55=66.3%), and eye pain (53=63.9%) ([Table 3]). Among men, 65 (69.8%; n=65/97) had CVS and among women, 18 (66.7%; n=18/27) had CVS (P=0.81, Fisher’s exact test). Frequency distribution of all symptoms among men and women are presented in [Figure 1].
Table 3 Distribution of ocular symptoms in computer vision syndrome patients

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Figure 1 Frequency distribution of symptoms among male and female computer vision syndrome patients.

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On comparing adult and adolescent CVS patients, a significant difference was reported in eye redness (33/57 vs. 22/26; P=0.02), heavy eyelid (35/57 vs. 22/26; P=0.04), blurred vision (45/57 vs. 25/26; P=0.05), colored halos (27/57 vs. 20/26; P=0.01), and sight worsening feeling (30/57 vs. 21/26; P=0.01) ([Figure 2]).
Figure 2 Frequency distribution of symptoms among adult and female adolescent computer vision syndrome patients.

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  Discussion Top


The prevalence of CVS has been reported using different diagnostic criteria. In this study, 69.7% of the individuals with more than 2 h of screen time were diagnosed with CVS. This prevalence was similar to that reported by Ranasinghe et al. (67.4%) [12], although the criteria for diagnosing CVS were different between the two studies. Ranasinghe et al. [12] defined the presence of any one of the ocular symptoms (presence of pain in and around the eyes, headache, blurred near vision, blurred distant vision, dry eyes, sore/irritated eyes, red eyes, excessive tearing, double vision, twitches of eyelids, and changes in visualizing colors), either intermittently or continuously for at least 1 week during the previous year as the presence of CVS. This may be subjected to the recall bias of the participants. However, we have used the frequency and severity of 16 symptoms in every participant for the assessment of CVS. Logaraj et al. [3] from Chennai (India) reported that 80.3% of their study population of engineering and medical students had CVS. They defined CVS, as the presence of any one or more symptoms of redness, eye burning sensation, headache, blurred vision, dry eyes, and neck and shoulder pain. Bhanderi et al. [7] reported that 26% of computer users experienced at least one asthenopic symptom every day. Al Rashidi and Alhumaidan [13] also reported the prevalence of ocular symptoms among computer users. In their study, eye strain was the most common symptom that was reported in 62.14% of the patients.

Toomingas et al. [14] reported a higher incidence of ocular symptoms in women. Uchino et al. [15] found that the prevalence of dry eye associated with VDT was more in women as compared with men. Similarly, Ranasinghe et al. [12] reported a higher prevalence of CVS in women. Bhanderi et al. [7] reported marginally higher proportion of asthenopia in women. On the other hand, Logaraj et al. [3] reported significantly higher proportion of ocular symptoms in men. However, in the current study, a similar proportion of CVS patients was reported among men and women. In addition, the frequency of symptoms between men and women did not differ significantly.

Significantly higher proportion of CVS patients was reported in the adolescent age group as compared with the adult age group. The proportion of redness, heavy eyelid, blurred vision, colored halos, and sight worsening feeling differed significantly between adult and adolescent CVS patients. In this study, the proportion of headache and blurred vision was marginally higher in adults. The proportion of tearing, redness, heavy eyelid, dryness, blurred vision, colored halos, feeling that sight is worsening, and headache was higher in the adolescent age group. The proportion of burning, itching, feeling of foreign body, eye pain, light sensitivity, and difficulty in focusing near work was higher in the adult age group. The proportion of blinking and double vision was similar in both groups.

The maximum possible CVS score for one symptom is nine [(frequency: very often/always (3))×(intensity: very intense (3))=9]. None of the participants had a score of 9 for any symptom. The maximum CVS score for any symptom in this study was 4. Other scores of individual symptoms were 0, 1, and 2. None of the participants had a CVS score of 3. This showed that none of the patients experienced very high frequency of any symptom (grade of 3), as well as high intensity (grade 3) of symptoms. The median CVS score was higher in adults as compared with the adolescent age group. This showed that the symptoms were either more frequent and/or more severe in the adult age group. However, the similar range of CVS scores of both groups suggests that the frequency and severity of asthenopic symptoms were evenly distributed among both age groups. Individuals with CVS can experience moderate to intense symptoms of CVS with low frequency. It is not necessary that they experience symptoms of CVS every day. Both frequency and intensity of the symptom has been associated with CVS.

There were few limitations of this study. The study population was selected from a tertiary eye care hospital and thus is not the true representation of CVS population in an area. In addition, there was a male preponderance in the study sample. Also, the two groups of VDT use of more and less than 6 h were not equal.


  Conclusion Top


In conclusion, longer exposure to VDTs was found to be associated with CVS. No difference of CVS score was found between men and women. Adolescent population had significantly higher CVS scores than adults. Headache and blurred vision were the most frequent symptoms among patients with CVS.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
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