Domains and learning outcomes (C108912)
• One distance learning CPD point for optometrists, dispensing opticians and contact lens opticians.
Clinical practice
Upon completion of this CPD, ECPs will be able to describe the latest evidence linking ocular surface disease to digital eye strain (s5)
Specialty CPD – contact lens optician
Upon completion of this CPD, contact lens practitioners will be able to describe the evidence for solutions which may help manage ocular surface issues related to digital eye strain (s5)

Digital devices are slowly being integrated into nearly every aspect of our lives. We now have computers, tablets, smartphones, smartwatches, WiFi televisions and smart appliances, just to name a few. These devices can now even be integrated and controlled from a single device, which has the potential to further increase screen time. While all these innovations can add convenience and/or safety to our lives, their frequent utilisation may also cause the user to develop digital eye strain (DES).1

DES has been recently defined by the Tear Film and Ocular Surface Society (TFOS) as ‘the development or exacerbation of recurrent ocular symptoms and/or signs related specifically to digital device screen viewing.’1 The term computer vision syndrome (CVS) has also been used in the past, yet DES is currently the preferred term because as noted above, we now use a multitude of digital devices in addition to traditional computers.1 Although the prevalence of DES varies widely based on how it has been defined by a study or by the subjects who were evaluated in the study, DES may affect more than 90% of people who live in developed societies at least occasionally.1 

DES can affect the whole body (eg neck or back pain), though the ocular symptoms are one of the most pronounced issues with this condition.2 Since understanding the ocular surface component of DES is key to eye care professionals, this article will focus on understanding the key symptoms associated with DES as well as the underlying mechanism of the ocular surface component of DES, and some cost-effective treatments aimed at treating ocular surface disease in patients with DES.

DES has been recently defined by the Tear Film and Ocular Surface Society (TFOS) as ‘the development or exacerbation of recurrent ocular symptoms and/or signs related specifically to digital device screen viewing’.

Symptoms

The most used validated questionnaire for diagnosing DES is the Computer Vision Syndrome Questionnaire (CVS-Q).3 The CVS-Q was introduced by Segui in 2015,3 and it is scored by multiplying the frequency score (never = 0, occasionally = 1, often or always = 2) by intensity score (moderate = 1, intense = 2) for each of the 16 ocular surface symptoms evaluated by the measure: burning, itching, foreign body sensation, tearing, excessive blinking, eye redness, eye pain, heavy eyelids, dryness, blurred vision, double vision, difficulty focusing for near vision, increased sensitivity to light, coloured halos around objects, feeling that sight is worsening, and headaches. 

These values are then added together to obtain a final score. Scores ≥6 units are considered symptomatic and may suggest the need for a treatment.3 Although the CVS-Q is not commonly used in typical optometric practice, it describes key symptoms that should be inquired about during a patient history if a clinician is concerned about DES. It should be noted that DES symptoms have significant overlap with dry eye disease (DED) symptoms, so a clear link between the symptoms and digital device use should be established.3, 4

Primary Mechanism of Ocular Surface Symptoms in DES

Ocular surface symptoms in DES may stem from the environment (eg low humidity, heating/air conditioning systems), age, female sex, medications or contact lens use, yet the two likely primary instigators of ocular surface symptoms in DES sufferers are abnormal blinking and increased ocular surface exposure.2 It has been specifically hypothesised that a patient who is viewing a digital device is evoking neurostimulation, which significantly reduces the blink frequency and increases the percentage of incomplete blinks, so the patient can focus on the text.5 These prolonged blink cycles result in the tears breaking up, in some cases seconds before a patient blinks, which causes excessive tear evaporation, increased tear osmolarity and increased ocular surface redness and inflammation.5 

These physiological changes subsequently cause ocular surface cell damage and decreased mucus production, which further promotes ocular surface damage.5 Incomplete blinking may further delay tear renewal and increase the time the ocular surface is exposed to the environment.5 The negative impact of incomplete blinking in DES is bolstered by Rosenfield’s work, which found that incomplete blinking and symptoms scores are positively correlated.2 Furthermore, the literature suggests viewing posture has an impact on ocular surface exposure. 

For example, Argilés et al’s work specifically determined that looking straight ahead caused greater ocular surface exposure since the eyelids are more retracted than when the eyes are in down gaze.6 Reading text on a printed page, a tablet or a computer all decrease blink frequency, and they all increase the percentage of incomplete blinks compared to distance viewing. All these digital devices evaluated negatively impacted blinking, though they also result in slightly different ocular exposures from their required viewing angles.6

Furthermore, the literature suggests viewing posture has an impact on ocular surface exposure. 

The impact of blinking on dry eye metrics has been overwhelmingly supported by the literature. Prabhaswat et al, for example, recruited 30 non-dry eye subjects who were randomised to read an e-book or a printed book, and their symptoms were evaluated with a visual analog scale (VAS).7 

The authors found that symptom scores were significantly worse after e-book reading and worse after reading printed text with respect to eye irritation, blurred vision, dryness and burning; however, when directly comparing e-book and reading printed text, the authors found that when subjects were reading e-books that they had significantly worse burning and tearing symptoms scores.7 

Prabhaswat et al furthermore found that tear break up times (TBUT) were about two seconds worse in both groups after reading tasks, yet there were no between group differences for TBUT.7

Khezrzade et al interestingly performed a similar experiment in a group 30 non-dry eye subjects who were asked to silently read on a laptop computer or printed texted placed at the same location as the laptop computer.8 All subjects completed both situations at least 24 hours apart, and the authors found that subjects who read for 30 minutes on the laptop had significantly worse TBUT scores compared to when they read a printed text for 30 minutes. 

Choi et al next compared dry eye metrices between normal subjects who used two different types of digital devices.9 The authors specifically evaluated 50 smartphone users and 30 computer users, and they determined that both had worse Ocular Surface Disease Index (OSDI) scores at one hour and four hours of reading compared to baseline. They likewise found that both groups had worse TBUT scores after four hours of reading compared to baseline, though tear volume as measured by Schirmer’s test did not change over the four-hour evaluation period.

Morales et al next evaluated 67 symptomatic office works by dividing them into two groups.10 One group worked on a computer for two to six hours per day while the other worked on a computers for seven to 12 hours per day, and the authors found that symptoms scores as envaulted with the Computer Vision Symptom Scale-17 (CVSS17) and TBUT were significantly worse in the group of subjects who worked on a computer for a longer duration. 

This same study also found that MUC5AC was upregulated possibly as a compensatory mechanism to prevent ocular surface damage and catalase activity was upregulated possibily to help protect against oxidative stress in the longer reading group.10 Srivastav et al next evaluated 70 age-matched subjects who did or did not have dry eye symptoms by having them watch a video on a laptop for one hour, and the authors found the dry eye symptoms group had significantly worse TBUT and blink rates after watching the video; nevertheless, TBUT and blink rates were unaffected in the non-dry eye group who watched the video.11 

The difference between the dry eye symptoms group and the asymptomatic group may suggest that subjects with dry eye may have less of a compensatory mechanism while using digital devices.

Talens-Estarelles et al lastly evaluated how a contact lens might affect dry eye metrics in digital devices users by evaluating 34 healthy subjects who were using a smartphone or computer and either uncorrected, corrected with contact lenses, or corrected with contact lenses and using artificial tears.12 All reading tasks were performed for 20 minutes. 

When comparing smartphone and computer use groups, there were no significant differences in ocular symptoms, yet adding artificial tears with contact lens use did improve ocular symptoms and signs (TBUT, bulbar redness) when using both types of digital devices. Contact lens use did not have an impact on these same ocular surface signs, but subject in this study were only asked to perform reading tasks for 20 minutes. 

The authors may have gotten a different result if they required the subjects to read for several hours like Choi et al.9 The above data overall suggest that normal subjects have worse ocular symptoms and signs post-reading, though symptoms may be slightly worse in digital device users compared to reading printed text. The above data likewise suggest that subjects who have DED may be more impacted by DES.

Basic Treatments  

While the full TFOS DED treatment algorithm may be applicable to DES patients who have ocular surface disease depending upon the severity of their disease,13 the literature does suggest that treating the root cause of DES, poor blinking and ocular surface exposure, may be beneficial. As described by Talens-Estarelles et al above, artificial tear use can have a positive impact on both ocular surface signs and symptoms.12 

Pucker et al furthermore evaluated the impact of artificial tear use on digital device users who had poor work domain scores on the Impact of Dry Eye on Daily Life (IDEEL) questionnaire (feeling distracted, unable to concentrate, having to take breaks from work, having to change the way one works, having to change one’s work environment) and found that after two weeks of artificial tear use, work-related symptoms dramatically improved.14 

These same subjects also showed significant improvement in IDEEL questionnaire domains related to performing daily activities and feelings. Pucker et al’s study was later corroborated by Duncan et al within a similar subject pool who were treated with an alternative artificial tear for two weeks.15

Kim et al has similarly demonstrated that blinking training is an effective means for treating ocular surface symptoms.16 The authors specifically evaluated a group of 41 subjects who had DED. Subjects in this study were asked to complete a blinking exercise regimen that first had the subjects close their eyes for two seconds. They then opened their eyes. They then closed their eyes for two more seconds and opened their eyes, and they then closed their eyes and squeezed their eyelids together for two seconds to help promote meibum production, and they finally opened their eyes. 

The authors then required that the subjects repeat this regime every 20 minutes while awake for four weeks. Kim et al subsequently determined that within five minutes after initial in-office blinking exercise training that meant TBUT times increased by about one second, and they later found at four weeks that TBUT scores further improved while also finding a clinically meaningful improvement in OSDI scores.16 

The authors lastly determined that the training had a positive impact on reducing the percentage of incomplete blinks. While it may be challenging to get patients to incorporate a blinking exercise regimen into their lives, there are currently smartphone applications that are able to assist patients (eg MyDryEye).    

Conclusion

DES is becoming a common and unfortunate aspect of modern life, yet simply understanding that the negative effects of DES on the ocular surface typically stem from poor blinking, increased ocular exposure and induced evaporative dry eye can make initial treatment selection easy for clinicians.

  • Clinicians should first educate patients that DES tends to stem from poor blinking.5, 6
  • They could give patients blinking exercises, and they can even assist their patients by installing reminder applications on their smartphones.16
  • Although the 20/20/20 rule is commonly recommended to patients,1 with the tactic of having a patient take a 20 second break to look at least 20 feet away every 20 minutes, there is no strong literature suggesting that this is an optimal amount of break time,17-19 so suggesting that patients simply take regular breaks may be sufficient.
  • Clinicians can likewise provide patients with specific artificial tear recommendations with having the subjects using these supplements at least twice a day while using their digital devices.14, 15 There is no clear evidence at this time that one artificial tear is superior to another, yet a lipid-containing artificial tears may be beneficial with DES patients given the evaporative aspect of DES.20 Furthermore, low viscosity tears may be preferable, so they have a limited impact on vision during the workday.21
  • If patients feel that they need to use artificial tears four or more times per day, they may benefit from using a non-preserved artificial tear, which is designed help avoid ocular surface irritation from the preservatives,22 and the clinician may also want to consider additional DED treatments at this point, especially if symptoms persist while not using digital devices. 
  • Dr Andrew Pucker is senior director of clinical and medical science with Lexitas Pharma Services. He holds an undergraduate degree in cellular and molecular biology, following which he earned his optometry degree, Masters and PhD.
  • Disclosures: Dr Pucker has received research support from Alcon Research, LLC and Art Optical. Dr Pucker has served as a consultant for Alcon Research, LLC, Euclid Systems, and Hanall Biopharma. Dr Pucker is currently an employee of Lexitas Pharma Services, which is a company that does not sell or market drugs or devices; Lexitas Pharma Services only performs research for hire.

References

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