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  5. FP109 : Ocular and Economic Impact of Digital Exposure

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Dr. Upma Awasthi, A13917, Dr. Surabhi Dutt

Introduction:

India being one of the major economic centers of the world has a very high population of young professionals who works on the digital screens. Government itself has encouraged the use of computers and other multimedia devices for faster and better performance at work.  It is known that screen usage as low as 1 hour can lead to various adverse effects which are termed as digital strain (1,2) .Its features are dry eye(DES), low back pain, tension headaches, psychosocial stress etc. Many studies have reported the association between prolonged computer use and adverse effects (1-9) .Most of them mainly focused on Western adult subjects. However, very little work has been done on the effect of computer use on Indian population(10,11) .None of these studies have assessed the effect of digital exposure on ocular surface and neither has studied economic impact on the patients.

Thus the present study was conducted to assess the effects of digital exposure on ocular health and economic burden in the Indian population.

Methodology

An interventional case study was conducted at a tertiary eye centre from December 2016 to August 2017. The study was in compliance with Declaration of Helsinki. Informed consent was taken from each enrolled subject.

Patients between the age group of 15 to 60 years with history of prolonged computer exposure were enrolled in the study. Persons using digital screens including computers, mobiles and televisions for more than 2 hours per day or 15 hours per week were included.  Based on the objective of the study a structured questionnaire has been developed.

Patients were excluded if they have uncorrected refractive errors, were contact lens users, on treatment with topical or systemic steroids, secondary dry eyes due to meibomian gland disease (MGD), any autoimmune conditions like Stevens-Johnson syndrome (SJS), systemic lupus erythrematosis (SLE), pregnant and lactating women. Patient on systemic medications like anti-hypertensives, anti-depressants, anti-allergics were also excluded. Patients who had undergone corneal surgery or any ocular surgery in the preceding one year were also excluded.

A self administered questionnaire was used to collect socio-demographic data, symptoms of CVS, details of computer usage and potential risk factors. Questions on symptoms of CVS were adapted from the Ocular Surface Disease Index (OSDI) questionnaire (12) .The Ocular Surface Disease Index (OSDI) is the best validated questionnaire. It is composed of twelve questions that provide a rapid assessment of the symptoms of ocular irritation consistent with DES and their impact on vision-related functioning (13)   DEWS 2 was adapted for the severity grading of OSDI (14) .

Age, gender and province of residence were assessed as demographic data. The information collected on computer usage was daily digital usage that included cumulated hours spent on computer, television and mobile/tablet. Questions on potential risk factors were prepared after reviewing the articles on CVS in the literature.

Subjects underwent a detailed ophthalmic examination, including best-corrected visual acuity, intraocular pressure measurement with noncontact tonometer, anterior segment and fundus examination with a slit-lamp biomicroscope. The tests were administered at the end of the work day and measurement conditions remained the same for all subjects.

Following the OSDI questionnaire and ophthalmic examination, subjects underwent the fluorescein tear break up time (F-BUT), corneal and conjunctival fluorescein staining and the Schirmer’s test. A gap of 5 min was kept between fluorescein staining and Schirmer’s test.  Sequence of tests was kept as described by Bron (15)     

To measure F-BUT, a sterile strip of fluorescein was applied in the lower eyelid fornix and then removed. The subject was asked to blink three times and then look straight forward, without blinking. The tear film was observed under the cobalt blue filtered light of the slit lamp microscope and the time that elapsed between the last blink and appearance of the first break in the tear film was recorded with a stopwatch. This procedure was repeated three times on both eyes. A F-BUT of less than 10 seconds was considered consistent with DES. It was further graded into mild (6-9 sec), moderate (1-5 sec) and severe (0 sec).

Corneal staining was assessed and was recorded as central and peripheral staining. Conjunctival staining was noted as present or absent.

Five minutes after the F-BUT, Schirmer’s I test (with anesthesia) was performed to evaluate reflex tear secretion. In the Schirmer’s I test, a filter paper strip (35 × 5 mm) was used to measure the amount of tears produced over 5 minutes. The strip was placed at the junction of the middle and the lateral thirds of the lower eyelid. The test was performed under ambient light. The patients were directed to look forward and to blink normally during the course of the test (5 minutes). Then wetting of the filter paper in 5 minutes was recorded. Wetting less than 10 mm was considered consistent with DES. It was further graded into mild (7-10 sec), moderate (4-6 sec) and severe (0-3 sec).

Treatment was prescribed as per our severity grading criteria of digital strain. Patients with F-BUT >5 sec with only conjunctival staining were described as mild digital strain and were given lubricants in the form of eye drops and gel. Patients with F-BUT less than 5 but not 0 and with peripheral corneal staining were described as moderate digital strain and short course of mild steroid (Fluorometholone 0.1%) was added. Patients with F-BUT 0 sec and/or with central corneal staining were described as severe digital strain and doxycycline/omega-3 fatty acids were added to their medications for 3 months.

Cost analysis was done by summing up the medications cost and consultation charges. Average monthly cost was done by summing the monthly average medication cost, 2 consultations per year, cost of blue-blocker glasses and screen filters. This was hypothesized that oral supplements were required for 3 months. Mild steroid and lubricant gel were required only for 1 course so only 1 vial required per patient per year. Lubricating eye drops were required 1 vial per month per patient.

Statistical analysis was done with SPSS software using descriptive analysis, correlation analysis.

Results

A total of 26 subjects participated in the study; 7 (26.9%) were female and 19 (73.1%) were male. The mean age was 26.76 ± 5.16 years and 76.92% patients were less than 30 years of age with significant male preponderance (p=0.019).

Mean duration of exposure was 9.84 ± 2.50 hours/day (range 4–15 hours). Males have higher mean usage (10 hours versus 9.42 hours) though it was not found to be significant (p=0.298). There was no significant relation between the gender distribution in low (<8 hours) and high usage (>8 hours) of digital screens (p=0.09) (Table 1) .

Table 1: Age-wise gender distribution and duration of exposure 

 

Age-Group

(in years)

 Gender Distribution Mean Exposure Duration

(in Hours)
Male Female Male Female
<30 15 6 9.86+/-2.85 9.17+/-0.98
31-40 4 0 10.5+/-3.32 0
>40 0 1 0 11+/-0

 

Most common presenting complaints were headache and redness of the eyes (22.22% each). Others reported complaints were heaviness, foreign body sensation, irritation, burning sensation, pain, glare and blurring in decreasing frequency.

As per OSDI grading, 65% of the patients were in severe grade. Males have significantly higher tendency to have moderate to severe scores as compared to females (p=0.000). OSDI is also found to be significantly correlating with Corneal (p=0.000) and Conjunctival (p=0.006) staining. Patients with central corneal staining had moderate to severe OSDI score (mean OSDI 36.98).

Schirmer’s was in normal range in 78.85% of the patients. F-BUT was less than 5 sec in 92.3% and 0 sec in only 7.69% of the patients (Table 2). It did not significantly correlate with age, gender, exposure duration, OSDI and Schirmer’s test. Expenditure significantly correlated with F-BUT (p=0.000). Conjunctival staining was present in 38 eyes while corneal staining was present in 39 eyes. Central corneal staining was present in 8 eyes.

Table 2: Means values of various tests

Mean Min Max
OSDI 38.56+/-11.52 20.8 68.75
Schirmer’s 14.88 +/-8.02 2 35
F-BUT 3.04 +/- 2.11 0 10

As per our treatment protocol, 6 patients were in mild group, 15 patients were in moderate group and 5 patients were in severe group.

Average expenditure was rupees 451.11 per patient in the 1st month and average expenditure on medications, consultations and protective filters was rupees 1094 /patient/month. Average expenditure on medications only was rupees 177 /patient/month.

Discussion

This study was undertaken to evaluate DES in digital screen users with easily done objective tests which include Schirmer’s, F-BUT and ocular surface staining. No study was done in past to evaluate these objective tests in digital strain. We also evaluated financial burden owing to digital strain for the first time.

We found 76.92% of the patients were in the age group less than 30. Various other studies also reported similar prevalence in less than 30 years age group (7,10,11) .Our study found higher prevalence in males which also corroborates with previous studies (10,16) .

Mean exposure duration was highest in 30-40 years age group (10.5 hours in 30-40 years vs 9.66 hours in < 30 years) but this difference was not found to be significant (p=0.458). This can be explained by the lesser number of patients in the >30 years group. All except one patient has exposure duration >6 hours. Armugam et al reported 66.5% of computer professionals were working on screens for 7-10 hours, 33.5% were working for more than 10 hours, no one were working for <6 hours.(11) Ranashinge et al studied 2212 patients and found mean daily computer usage in patients with digital strain was 7.8 ± 3.3 hours (16)    .

Asthenopic symptoms like headache, heaviness and glare were the most common presenting complaint in 44.67% of the patients. Symptoms related to digital screens were classified by Porcar et al in 2016 and they also reported that asthenopia is the most common presentation (8) .

OSDI significantly correlated with gender (p=0.00), ocular surface staining (p=0.00) and schirmer’s test (p=0.015). Patients with ocular surface staining were having mean OSDI score of 40.05. This can be interpreted as patients with ocular surface damage were more symptomatic. OSDI was not found to be significantly correlating with exposure duration (p=0.201) and F-BUT (p=0.422). Unlu et al did not found significant correlation between exposure duration (range 1-12 hours) and OSDI. They also reported 42% incidence of dry eyes with TBUT and 35 % incidence with OSDI>35. They found significant correlation of FBUT with OSDI in diagnosis of DES (17) . This discrepancy in results can be explained partly by their higher cut-off value of OSDI (score 35) as compared to cut-off value used in our study (OSDI score 12). They also have not mentioned cut-off values of TBUT. Their mean value of TBUT was also higher (11.37 sec) as compared to ours values (3.03 sec).

Ong et al calculated discordance score (DS) for symptoms and signs in 326 patients of DES with mean age of 62 years. The ‘discordance score’ was the difference between the patient’s ranked score on their transformed OSDI (range 0–1) and their ranked composite signs severity score (range 0–1). As such, discordance scores ranged from −1 (minimal symptoms and maximal signs) to 1 (maximal symptoms and minimal signs). A positive discordance score indicates more symptoms than signs. They reported that age was negatively correlated with DEDS (r=−0.30, p<0.0005) (18). In our study patients were younger so non-significant correlation of OSDI and F-BUT can be explained by higher DS in younger patients.

F-BUT was not found to correlating with any variable. It may be explained by two factors. One is high exposure duration in all the groups. Previous studies reported continuous exposure as long as 1 hour can cause symptoms of DES (1,2) and the minimum exposure duration in our study was 4 hours. It may also be because of small sample size and unequal distribution of patients in different sub-groups. There is no other study that has reported this analysis before and there is no minimum safe exposure duration defined. We have found that even exposure duration of 4 hours can cause decrease in F-BUT. But future large case-control studies are required to compare the effect of low and high exposure duration.

Ocular surface staining was present in 74% patients. We have not graded conjunctival staining and corneal staining was divided only in peripheral and central staining. Central corneal staining was present in 15.38%. Patients with central corneal staining were found to have T-BUT <3 sec.

Schirmer’s 1 test was normal (>10mm) in 35 out of 52 eyes. Sensitivity of Schirmer’s test was found to be 32.69%. Lucca and Farris also reported low sensitivity of Schirmer’s tests in their studies(19,20) .DEWS 2 also reported high variability in sensitivity, specificity and repeatability of Schirmer’s. And they not mentioned Schirmer’s in their proposed diagnostic test battery. This report also mentioned about the ways to decrease the chances of error (14). Despite having low sensitivity, Schirmer’s test significant correlation with OSDI can be explained by the reflex epiphora. This may be because of ineffective anesthesia. It is a flaw in our study. We should have repeated Schirmer’s after re-anesthetizing eyes. But we have not used Schirmer’s values for our severity grading thus it has no impact on our treatment protocol.

There is no consensus on the treatment guidelines for the management of DES. We have proposed a new treatment protocol as per the severity of DES in patients of digital strain.  As per our grading, 19.23% patients were in severe grade and as per OSDI 65.38% were in severe grade. As per our grading, 76.92% patients and as per OSDI grading 88.46% patients were in moderate to severe group. This discordance is reported by Ong et al (18). But there is decreased gap between the both severity grading if we merge moderate and severe group. It can be interpreted as majority of the patients have F-BUT <5 sec and corneal staining. Goto et al also found cut-off value of F-BUT < 5 sec to be 98% sensitive (21). We need to follow the patients and assess the response to validate our grading. For this purpose, a prospective study will be planned in future. If validated, it can serve as simplified treatment protocols and also there will not be any disparity in management.

We also analyzed financial burden on each patient. Keeping Indian scenario and increasing digitalization in mind, amount of 1094 Rupees/month cannot be considered as small amount. Though the expenditure on medications was not as high but expenditure on protective filter screens/glasses that are usually recommended for preventing digital strain is high. This may be a factor of not using these protective measures but this can worsens ocular surface. This may result in more frequent visits and thus increasing expenditures.

But our study results should be interpreted with caution because of small sample size thus sub-group analysis could have been skewed. But demographics of our study correlated with those of previous prevalence studies; this decreased the chances of skewed results. Furthermore, we have included only digital screen users and excluded all other causes and confounding factors thus cannot comment on effect on other causes. Also we have not included Schirmer’s for treatment protocols; it might have affected our results. But it is not advised in DEWS II battery tests for the diagnosis of DES, thus we can say our results are unbiased.

There are few strong points also in our study. We have compared OSDI with diagnostic tests and found them correlating. We have proposed a new severity based treatment protocol which corresponds well with OSDI score in moderate to severe cases. We have also analyzed estimated value of financial burden on patients. Despite this, further studies with large sample size will be required to reinforce results found in this study and validate our severity based treatment protocol.

Conclusions

With this study, we can conclude that digital screens are causing ocular surface damage. Also it is increasing substantial financial burden. Our severity based treatment guidelines can serve as common protocol in treating patients with digital strain. This will help in decreasing disparity of treatments prescribed in this group of patients.

Financial disclosure: None

Conflict of interest: None

References

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